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A permanent magnet tubular linear generator for wave energy conversion
NASA Astrophysics Data System (ADS)
A novel three-phase permanent magnet tubular linear generator (PMTLG) with Halbach array is proposed for the sea wave energy conversion. Non-linear axi-symmetrical finite element method (FEM) is implemented to calculate the magnetic fields along air-gap for different Halbach arrays of PMTLGs. The PMTLG characteristics are analyzed and the simulation results are validated by the experiment. An assistant tooth is implemented to greatly minimize the end and cogging effects which cause the oscillatory detent force.
Yu, Haitao; Liu, Chunyuan; Yuan, Bang; Hu, Minqiang; Huang, Lei; Zhou, Shigui
Direct fission fragment energy conversion utilizing magnetic collimation
NASA Astrophysics Data System (ADS)
The objective of this dissertation was to determine the technological feasibility of direct fission fragment energy conversion utilizing magnetic collimation (DFFEC-MC). This objective was accomplished by producing a conceptual design for a DFFEC-MC system and by analysis of the potential DFFEC-MC system performance. Consistent analysis and evaluation of the technological feasibility of the DFFEC-MC concept were achieved using state-of-the-art computer codes that allowed realistic and consistent modeling of the important physical processes governing DFFEC-MC system performance. Unique computational schemes, including three-dimensional modeling, were constructed and applied to obtain the performance characteristics of DFFEC-MC systems. Special effort was made to include all important physical processes. Important simplifications introduced due to modeling limitations were also assessed. The analysis takes into consideration a wide range of operational aspects including fission fragment (FF) escape from the fuel, FF collimation, FF collection, criticality, long-term performance, energy conversion efficiency, heat removal, and safety characteristics. Required engineering conditions are formulated that must be satisfied in order for the DFFEC-MC concept to have a reasonable chance to demonstrate technological feasibility. Specific characteristics of individual system components and the entire DFFEC-MC system are evaluated. To identify which technological improvements are needed, several possible design solutions are provided for some of the components along with analyses of the corresponding DFFEC-MC system performance. As a result of the computational analysis, the conditions for achieving an attractive (high) system efficiency are demonstrated. A technologically feasible DFFEC-MC system layout with promising operational characteristics is presented. The resulting DFFEC-MC system is envisioned as an advanced DFFEC system that combines advantageous design solutions proposed for application in both fission and fusion reactors. The analysis identifies possible application areas where the DFFEC-MC system might be competitive with other advanced direct and indirect energy conversion systems. To bring closer the time when the DFFEC-MC systems might become a reality, design challenges and required experimental studies are indicated.
Tsvetkov, Pavel Valeryevich
Multiphysics simulation of wave energy to electric energy conversion by permanent magnet linear generator
The possibility to use three-phase permanent magnet linear generators to convert sea wave energy into electric energy is investigated by multiphysics simulations. The results show a possibility, which needs to be further verified by experimental tests, for a future step toward a sustainable electric power production from ocean waves by using direct conversion. The results suggest that wave energy can
Mats Leijon; Hans Bernhoff; Olov �gren; Jan Isberg; Jan Sundberg; Marcus Berg; Karl Erik Karlsson; Arne Wolfbrandt
Transverse Flux Permanent Magnet Generator for Ocean Wave Energy Conversion
\\u000a Modern energy demands led the scientific community to renewable energy sources, such as ocean wave energy. The present work\\u000a describes a model for a cost efficient rotary electrical generator, optimized for ocean wave energy conversion. The electrical\\u000a power, supplied by low speed mechanical movement, requires the use of electrical machinery capable of generating high amounts\\u000a of torque. Among the analyzed
Jos� Lima; Anabela Pronto; M�rio Ventim Neves
Scaling the energy conversion rate from magnetic field reconnection to different bodies
Magnetic field reconnection is often invoked to explain electromagnetic energy conversion in planetary magnetospheres, stellar coronae, and other astrophysical objects. Because of the huge dynamic range of magnetic fields in these bodies, it is important to understand energy conversion as a function of magnetic field strength and related parameters. It is conjectured theoretically and shown experimentally that the energy conversion rate per unit area in reconnection scales as the cube of an appropriately weighted magnetic field strength divided by the square root of an appropriately weighted density. With this functional dependence, the energy release in flares on the Sun, the large and rapid variation of the magnetic flux in the tail of Mercury, and the apparent absence of reconnection on Jupiter and Saturn, may be understood. Electric fields at the perihelion of the Solar Probe Plus mission may be tens of V/m.
Mozer, F. S.; Hull, A. [Space Sciences Laboratory, University of California, Berkeley, California 94720 (United States)
Neural network controller for a permanent magnet generator applied in a wind energy conversion system
In this paper a neural network controller for achieving maximum power tracking as well as output voltage regulation, for a wind energy conversion system (WECS) employing a permanent magnet synchronous generator, is proposed. The permanent magnet generator (PMG) supplies a DC load via a bridge rectifier and two buck�boost converters. Adjusting the switching frequency of the first buck�boost converter achieves
Mona N. Eskander
Energy conversion and transfer for plasmas in a magnetic expansion configuration
NASA Astrophysics Data System (ADS)
A two-dimensional axisymmetric particle-in-cell code with Monte Carlo collision conditions has been used to study particle energy transfer in plasmas and conversion in applied magnetic and electric fields appropriate to coaxial acceleration. The research incorporates a computation scheme with: a model of single particle magnetic interactions; a model of single particle interactions in electric and magnetic fields; and a model of multi-particle collisional interactions in order to understand the energy transfer processes and conversion mechanisms of charged plasma particles. This approach predicts electron and ion motions along with their energy variations for physical conditions that occur in the related models; the results allow comparison with experimental data for magnetic field strengths of 0.01-0.05 T and electrode voltages of 22.0-32.0 V. With the incorporation of magnetic and electric field effects on charged particles, the multi-particle model includes electron-neutral ionization collisions, ion-neutral charge exchange collisions, and electron-ion Coulomb collisions. This research presents a new approach to achieve an underlying understanding of the plasma energy transfer and conversion in the external electric and magnetic fields that is not possible using magnetohydrodynamics continuum representations. Results indicate the following innovative conclusions: (1) Radial and azimuthal energies of magnetized electrons are converted into an axial electron energy component in the diverging magnetic field, and the azimuthal kinetic energy of unmagnetized ions is converted into axial and radial components. (2) In electric and magnetic fields, electric field energy is primarily converted into axial kinetic energy of magnetized electrons by the energy transformation effects of magnetic fields, and for unmagnetized ions, the radial kinetic energy component dominates in the conversion of electric field energy. (3) For the collisional plasma, electron kinetic energy tends to increase (or decrease) to a terminal value since electrons lose energy in collisions then gain energy again from the field. Ions acquire most energy directly from the electric field, although part of the electric field energy arrives to the ions by collisions. Further, the ion axial energy component dominates the total ion energy. The collision processes are found to be integral and essential for the conversion of the plasma non-directed energy gain to be converted into the resultant axial energy, the magnitudes of which are found to be in agreement with experimental results.
Cheng, Jiao; Tang, Hai-Bin; York, Thomas M.
Rare earth permanent magnets and energy conversion processes
Traditionally in magnetoelectric devices the stator has been the massive and static part of the device and the dynamic element has been a moving coil. With improvements in the volumetric efficiency of permanent magnets it is possible to rearrange magnetic circuit elements and invert devices. Rare earth permanent magnets exhibit a high magnetic moment per unit volume and have extreme
R. J. Parker
NSDL National Science Digital Library
Students evaluate various everyday energy conversion devices and draw block flow diagrams to show the forms and states of energy into and out of the device. They also identify the forms of energy that are useful and the desired output of the device as well as the forms that are not useful for the intended use of the item. This can be used to lead into the law of conservation of energy and efficiency. The student activity is preceded by a demonstration of a more complicated system to convert chemical energy to heat energy to mechanical energy. Drawing the block energy conversion diagram for this system models the activity that the students then do themselves for other simpler systems.
Office Of Educational Partnerships
Magnetic flux conversion and relaxation toward a minimum-energy state in S-1 spheromak plasmas
S-1 Spheromak currents and magnetic fluxes have been measured with Rogowski coils and flux loops external to the plasma. Toroidal plasma currents up to 350 kA and spheromak configuration lifetimes over 1.0 msec have been achieved at moderate power levels. The plasma formation in the S-1 Spheromak device is based on an inductive transfer of poloidal and toroidal magnetic flux from a toroidal ''flux core'' to the plasma. Formation is programmed to guide the configuration into a force-free, minimum-energy Taylor state. Properly detailed programming of the formation process is found not to be essential since plasmas adjust themselves during formation to a final equilibrium near the Taylor state. After formation, if the plasma evolves away from the stable state, then distinct relaxation oscillation events occur which restore the configuration to that stable state. The relaxation process involves reconnection of magnetic field lines, and conversion of poloidal to toroidal magnetic flux (and vice versa) has been observed and documented. The scaling of toroidal plasma current and toroidal magnetic flux in the plasma with externally applied currents is consistent with the establishment of a Taylor state after formation. In addition, the magnetic helicity is proportional to that injected from the flux core, independent of how that helicity is generated.
Janos, A.
The book provides a review of ocean wave mechanics and an introduction to wave energy conversion. Physical and mathematical descriptions are given of the nine generic wave energy conversion techniques along with their uses and performance characteristics. A number of electro-mechanical energy conversion techniques are described. Attention is also given to the possible environmental effects associated with wave energy conversion.
M. E. McCormick
Optimal design of permanent magnet synchronous generator for wind energy conversion considering annual energy input and magnet volume
In this paper a multi-objective criterion function is introduced to maximize annual energy input (AEI) and minimize permanent magnet (PM) volumes in a permanent magnet synchronous generator (PMSG). First, a PMSG is designed and modeled analytically to achieve above mentioned targets. After that, effects of various generator parameters on the two above-mentioned objective functions are analyzed using this model. The
Jawad Faiz; Bashir Mahdi Ebrahimi; M. Rajabi-Sebdani; A. Khan
Vocational-Technical Physics Project. The Alternator: I. Current Electricity, II. Magnets from Electricity, III. Electricity from Magnets, IV. Energy Conversion. Field Test Edition.
ERIC Educational Resources Information Center
This vocational physics individualized instructional student module on the alternator consists of the four units: Current electricity, magnets from electricity, electricity from magnets, and energy conversion. Designed with a laboratory orientation, the units present explanations of the concepts and experiments. Laboratory data sheets,�
Forsyth Technical Inst., Winston-Salem, NC.
Study on variable speed direct drive wind energy conversion system with doubly salient electro-magnetic generator
This paper aims to discuss a novel variable speed direct drive wind energy conversion system (WECS) based on doubly salient electro-magnetic (DSEM) generator. The basic characteristic of the DSEM generator is firstly introduced. Then, for the relatively low speed of the rotor in large scale direct drive application, some special structures of the DSEM generator are presented. In order to
Jie Chen; Ran Chen; Chunying Gong; Zhihui Chen; Yangguang Yan
Research in Energy Conversion.
National Technical Information Service (NTIS)
The results of investigations dealing with a broad spectrum of topics in energy conversion are presented. The individual studies are: Techniques for fabrication of large, thin silicon single crystals; Cathodes for thermionic energy conversion; Carnot-limi...
W. B. Nowak K. Weiss R. N. Wiener
Magnetohydrodynamics of atmospheric transients. IV. Nonplane two-dimensional analyses of energy conversion and magnetic field evolution
The evolution of the magnetic field and the manner of conversion of thermal energy into different forms in the corona following a solar flare are examined by a nonplane magnetohydrodynamic (MHD) analysis. In the analysis all three components of magnetic field and velocity are treated in a physically self-consistent manner, with all physical variables as functions of time (t) and two spatial coordinates (r,theta). The difference due to the initial magnetic field, either twisted (force-free) or nontwisted (potential), is demonstrated. In both cases, of course, the field becomes non-force-free after the energy release, i.e., a flare. As in Papers I and II of this series, two initial field topologies (open vs. closed) are considered. The results show that the conversion of magnetic energy is faster for the case of the initially twisted (force-free) field in comparison with the initially untwisted (potential) field. Also, the twisted field produces a complex structure of the density enhancements. Comparison of the asymmetric topological evolution of the initially twisted magnetic fields with several white-light coronal transients (observed recently during the Solar Maximum year suggests that some preflare, magnetic topologies above the site of the energy release are nonpotential. This suggestion is based on the asymmetrial, somewhat concentric (''tennis racket'' shape), electron density enhancement obtained together with the twisted magnetic field lines in this study.
Wu, S.T.; Nakagama, Y.; Han, S.M.; Dryer, M.
Bi-stable frequency up-conversion piezoelectric energy harvester driven by non-contact magnetic repulsion
NASA Astrophysics Data System (ADS)
This paper presents miniaturized energy harvesters, where the frequency up-conversion technique is used to improve the bandwidth of vibration energy harvesters. The proposed and developed miniature piezoelectric energy harvester utilizes magnetic repulsion forces to achieve non-contact frequency up-conversion, thereby avoiding mechanical collision and wear for long-term working durability. A pair of piezoelectric resonant cantilevers is micro-fabricated to generate electric power. A simplified model involving linear oscillators and magnetic interaction is deployed to demonstrate the feasibility of the device design. A bench-top harvester has been fabricated and characterized, resulting in average power generation of over 10 �W within a broad frequency range of 10-22 Hz under 1g acceleration.
Tang, Q. C.; Yang, Y. L.; Li, Xinxin
Perspectives on Permanent Magnetic Materials for Energy Conversion and Power Generation
NASA Astrophysics Data System (ADS)
Permanent magnet development has historically been driven by the need to supply larger magnetic energy in ever smaller volumes for incorporation in an enormous variety of applications that include consumer products, transportation components, military hardware, and clean energy technologies such as wind turbine generators and hybrid vehicle regenerative motors. Since the 1960s, the so-called rare-earth "supermagnets," composed of iron, cobalt, and rare-earth elements such as Nd, Pr, and Sm, have accounted for the majority of global sales of high-energy-product permanent magnets for advanced applications. In rare-earth magnets, the transition-metal components provide high magnetization, and the rare-earth components contribute a very large magnetocrystalline anisotropy that donates high resistance to demagnetization. However, at the end of 2009, geopolitical influences created a worldwide strategic shortage of rare-earth elements that may be addressed, among other actions, through the development of rare-earth-free magnetic materials harnessing sources of magnetic anisotropy other than that provided by the rare-earth components. Materials engineering at the micron scale, nanoscale, and Angstrom scales, accompanied by improvements in the understanding and characterization of nanoscale magnetic phenomena, is anticipated to result in new types of permanent magnetic materials with superior performance.
Lewis, Laura H.; Jim�nez-Villacorta, F�lix
Energy conversion alternatives study
NASA Technical Reports Server (NTRS)
Comparison of coal based energy systems is given. Study identifies and compares various advanced energy conversion systems using coal or coal derived fuels for baselaoad electric power generation. Energy Conversion Alternatives Study (ECAS) reports provede government, industry, and general public with technically consistent basis for comparison of system's options of interest for fossilfired electric-utility application.
Shure, L. T.
A Permanent-Magnet Tubular Linear Generator for Ocean Wave Energy Conversion
This paper presents a novel permanent-magnet tubular linear generator (PMTLG) buoy system designed to convert the linear motion of ocean waves into electrical energy. The design incorporates no working seals and a saltwater air-gap bearing surface integration between the PMTLG buoy components. The internal generator design will be discussed, in addition to the system integration with the buoy structure. The
Joseph Prudell; Martin Stoddard; Ean Amon; Ted K. A. Brekken; Annette von Jouanne
Evaluating Energy Conversion Efficiency
NASA Technical Reports Server (NTRS)
Devices that convert solar radiation directly into storable chemical or electrical energy, have characteristic energy absorption spectrum; specifically, each of these devices has energy threshold. The conversion efficiency of generalized system that emcompasses all threshold devices is analyzed, resulting in family of curves for devices of various threshold energies operating at different temperatures.
Byvik, C. E.; Smith, B. T.; Buoncristiani, A. M.
Photochemical Energy Conversion.
ERIC Educational Resources Information Center
Describes procedures for two demonstrations: (1) photochemical energy conversion using ferric oxalate actinometry and (2) liquification of gases using Freon 114. Safety precautions are given for both demonstrations, as are procedures and material specifications. (JM)
Batschelet, William H.; George, Arnold
Algae Harvest Energy Conversion
\\u000a Algae harvest energy conversion to biofuel technology is a promising alternative to fossil fuel that has inherent pollution\\u000a attachment. With present resources available for the microalgae mass production and hence, high oil yield, microalgal can\\u000a sufficiently be a new source of renewable energy to replace the fossil fuels. In this chapter, algae description, composition,\\u000a cultivation, its conversion to biofuel, and
Yung-Tse Hung; O. Sarafadeen Amuda; A. Olanrewaju Alade; I. Adekunle Amoo; Stephen Tiong-Lee Tay; Kathleen Hung Li
Regional Energy Conversations Report
NSDL National Science Digital Library
In 2009 and 2010, ATEEC facilitated a series of seven regional Energy Conversations. The primary purpose of the conversations was to obtain a snapshot view of existing and upcoming energy jobs and to determine which jobs are currently needed in different regions of the country, including the Mid-Atlantic, North Central, Northwest, South Central, Southeast, Southwest, and West. The resulting report on these Energy Conversations is intended to provide a preliminary labor market analysis and needs assessment. This information allows educational organizations to most effectively target regional energy industry requirements and to provide both short-and long-term education and training for the energy technicians of the 21st century workforce. Ultimately, this report should contribute to addressing the workforce development needs of business, industry, and government by providing educators with information needed to develop relevant curriculum that prepares students for energy technology careers.
Reconnection and Energy Conversion at the Magnetopause as Influenced by Earth's Dipole Tilt Angle and Interplanetary Magnetic Field
NASA Astrophysics Data System (ADS)
We study the effect of Earth's dipole tilt angle and interplanetary magnetic field (IMF) Bx and By components on the location of reconnection and the energy conversion at the magnetopause. We simulate southward IMF satisfying both inward- and outward-type Parker spiral conditions during three different dipole tilt angles using a global magnetohydrodynamic model GUMICS-4. Different combinations of dipole tilt angle and IMF Bx and By components change the magnetopause reconnection morphology and magnitude. This can be studied by comparing the location of the reconnection line and the location and strength of the energy conversion for different parameter combinations. We find that the IMF Bx and the dipole tilt angle modify the reconnection line location and both magnitude and location of the energy conversion. We discuss the relative role of the non-zero Bx and the dipole tilt angle in dayside reconnection first separately and then by letting the parameters change simultaneously. We find that positive (negative) Bx moves the reconnection line northward (southward) and positive (negative) tilt angle moves the line southward (northward). When both tilt angle and Bx are positive or negative they reverse each others effect so that the reconnection line location is almost the same as it is when both Bx and tilt angle are zero. When these two parameters have opposite signs they enhance each other's effects. We find evidence that reconnection-induced processes modify the shape of the magnetopause, which in turn has and effect on the reconnection location. Therefore intrinsic processes within the magnetosphere - the magnetic flux transfer to nightside and the subsequent return of the closed flux - can influence the basic reconnection processes within the dayside magnetopause.
Hoilijoki, S.; Palmroth, M.
ABSTRACT Ocean energy conversion has been of interest for many,years. Recent developments,such as concern over global warming,have renewed,interest in the topic. This report focuses on wave energy converters (WEC) as opposed to ocean current energy converters. The point absorber and oscillating water column,WEC devices are addressed with regards tocommercial prospects, environmental concerns, and current state-of-the art. This report also provides
Jennifer Vining
NASA Technical Reports Server (NTRS)
The conversion of laser energy to other, more useful, forms is an important element of any space power transmission system employing lasers. In general the user, at the receiving sight, will require the energy in a form other than laser radiation. In particular, conversion to rocket power and electricity are considered to be two major areas where one must consider various conversion techniques. Three systems (photovoltaic cells, MHD generators, and gas turbines) have been identified as the laser-to-electricity conversion systems that appear to meet most of the criteria for a space-based system. The laser thruster also shows considerable promise as a space propulsion system. At this time one cannot predict which of the three laser-to-electric converters will be best suited to particular mission needs. All three systems have some particular advantages, as well as disadvantages. It would be prudent to continue research on all three systems, as well as the laser rocket thruster. Research on novel energy conversion systems, such as the optical rectenna and the reverse free-electron laser, should continue due to their potential for high payoff.
Jalufka, N. W.
Maximum power point tracking control and voltage regulation of a DC grid-tied wind energy conversion system based on a novel permanent magnet reluctance generator
This research paper aims to employ a new permanent magnet reluctance generator in a variable speed wind energy conversion system (WECS) of a grid-tied distributed generation application. The grid integration of WECS is achieved through cascaded dc-dc converters ensuring maximum power extraction from the wind energy while maintaining a constant output voltage at the grid side. The surplus power is
Kazmi Syed Muhammad Raza; Hiroki Goto; Hai-Jiao Guo; Osamu Ichinokura
Mechanochemical Energy Conversion
ERIC Educational Resources Information Center
Summarizes the thermodynamics of macromolecular systems, including theories and experiments of cyclic energy conversion with rubber and collagen as working substances. Indicates that an early introduction into the concept of chemical potential and solution thermodynamics is made possible through the study of the cyclic processes. (CC)
Pines, E.; And Others
NSDL National Science Digital Library
How do physicists make new particles? In this page of a particle physics tutorial, students are introduced to the concept of converting kinetic energy to mass. Students read that low-mass particles placed into an accelerator can be smashed together to produce more massive particles through the conversion of energy to mass. They see an example in which two pieces of fruit are accelerated and smashed, and additional types of fruit are produced. Copyright 2005 Eisenhower National Clearinghouse
Group, Lawrence B.
The wind energy conversion system includes a wind machine having a propeller connected to a generator of electric power, the propeller rotating the generator in response to force of an incident wind. The generator converts the power of the wind to electric power for use by an electric load. Circuitry for varying the duty factor of the generator output power is connected between the generator and the load to thereby alter a loading of the generator and the propeller by the electric load. Wind speed is sensed electro-optically to provide data of wind speed upwind of the propeller, to thereby permit tip speed ratio circuitry to operate the power control circuitry and thereby optimize the tip speed ratio by varying the loading of the propeller. Accordingly, the efficiency of the wind energy conversion system is maximized.
Longrigg, Paul (Golden, CO) [Golden, CO
Magnetohydrodynamics of atmospheric transients. IV - Nonplane two-dimensional analyses of energy conversion and magnetic field evolution. [during corona following solar flare
NASA Technical Reports Server (NTRS)
The evolution of the magnetic field and the manner of conversion of thermal energy into different forms in the corona following a solar flare are investigated by means of a nonplane magnetohydrodynamic (MHD) analysis. All three components of magnetic field and velocity are treated in a physically self-consistent manner, with all physical variables as functions of time (t) and two spatial coordinates (r, theta). The difference arising from the initial magnetic field, either twisted (force-free) or non-twisted (potential), is demonstrated. Consideration is given to two initial field topologies (open vs. closed). The results demonstrate that the conversion of magnetic energy is faster for the case of the initially twisted (force-free) field than for the initially untwisted (potential) field. In addition, the twisted field is found to produce a complex structure of the density enhancements.
Wu, S. T.; Nakagawa, Y.; Han, S. M.; Dryer, M.
The energy conversion system includes a photo-voltaic array for receiving solar radiation and converting such radiation to electrical energy. The photo-voltaic array is mounted on a stretched membrane that is held by a frame. Tracking means for orienting the photo-voltaic array in predetermined positions that provide optimal exposure to solar radiation cooperate with the frame. An enclosure formed of a radiation transmissible material includes an inside containment space that accommodates the photo-voltaic array on the stretched membrane, the frame and the tracking means, and forms a protective shield for all such components. The enclosure is preferably formed of a flexible inflatable material and maintains its preferred form, such as a dome, under the influence of a low air pressure furnished to the dome. Under this arrangement the energy conversion system is streamlined for minimizing wind resistance, sufficiently weatherproof for providing protection against weather hazards such as hail, capable of using diffused light, lightweight for low-cost construction, and operational with a minimal power draw.
Murphy, Lawrence M. (Lakewood, CO)
The energy conversion system includes a photo-voltaic array for receiving solar radiation and converting such radiation to electrical energy. The photo-voltaic array is mounted on a stretched membrane that is held by a frame. Tracking means for orienting the photo-voltaic array in predetermined positions that provide optimal exposure to solar radiation cooperate with the frame. An enclosure formed of a radiation transmissible material includes an inside containment space that accommodates the photo-voltaic array on the stretched membrane, the frame and the tracking means, and forms a protective shield for all such components. The enclosure is preferably formed of a flexible inflatable material and maintains its preferred form, such as a dome, under the influence of a low air pressure furnished to the dome. Under this arrangement the energy conversion system is streamlined for minimizing wind resistance, sufficiently weathproof for providing protection against weather hazards such as hail, capable of using diffused light, lightweight for low-cost construction and operational with a minimal power draw.
Murphy, L.M.
Thermal Energy Conversion Branch
NASA Technical Reports Server (NTRS)
The Thermal Energy Conversion Branch (5490) leads the way in designing, conducting, and implementing research for the newest thermal systems used in space applications at the NASA Glenn Research Center. Specifically some of the most advanced technologies developed in this branch can be broken down into four main areas: Dynamic Power Systems, Primary Solar Concentrators, Secondary Solar Concentrators, and Thermal Management. Work was performed in the Dynamic Power Systems area, specifically the Stirling Engine subdivision. Today, the main focus of the 5490 branch is free-piston Stirling cycle converters, Brayton cycle nuclear reactors, and heat rejection systems for long duration mission spacecraft. All space exploring devices need electricity to operate. In most space applications, heat energy from radioisotopes is converted to electrical power. The Radioisotope Thermoelectric Generator (RTG) already supplies electricity for missions such as the Cassini Spacecraft. The focus of today's Stirling research at GRC is aimed at creating an engine that can replace the RTG. The primary appeal of the Stirling engine is its high system efficiency. Because it is so efficient, the Stirling engine will significantly reduce the plutonium fuel mission requirements compared to the RTG. Stirling is also being considered for missions such as the lunar/Mars bases and rovers. This project has focused largely on Stirling Engines of all types, particularly the fluidyne liquid piston engine. The fluidyne was developed by Colin D. West. This engine uses the same concepts found in any type of Stirling engine, with the exception of missing mechanical components. All the working components are fluid. One goal was to develop and demonstrate a working Stirling Fluidyne Engine at the 2nd Annual International Energy Conversion Engineering Conference in Providence, Rhode Island.
Bielozer, Matthew C.; Schreiber, Jeffrey, G.; Wilson, Scott D.
Dynamic Modelling, Simulation and Analysis of an Offshore Variable-Speed Directly-Driven Permanent-Magnet Wind Energy Conversion and Storage System (WECSS)
This paper presents the modelling, simulation and analysis of a 2 MW variable-speed directly-driven permanent magnet synchronous generator (PMSG) wind energy conversion and storage system (WECSS). The WECSS model presented consists of a pitch controlled wind turbine directly driving a 2 MW PMSG. The PMSG is connected to a host AC grid network via a controlled full-scale power converter system
Nicholas P. W. Strachan; D. Jovcic
This patent describes a light-weight and self-contained solar energy conversion apparatus for converting solar radiation to electrical energy, which consists of: an array of photovoltaic cells mounted on a thin film substrate membrane and connected together to provide an electric power source, the thin film being stretched and mounted on a circular rim; support means connected to the rim for supporting the array of photovoltaic cells in a position adapted to be exposed to solar radiation, the support means being adjustable about two orthogonal axes and having strength design parameters sufficient to support the array, substrate membrane, and rim safely in a still atmosphere without regard to ambient outside wind and hail loads; and a substantially spherical dome positioned over and enclosing a chamber around the array of photovoltaic cells and support means, the dome being comprised of a specularly translucent, flexible, thin film material anchored around the support means and inflated to a pressure in the chamber in the range of about 0.02 to 0.10 pounds per square inch more than the pressure outside the chamber. The thin film material of the dome is also tear-resistant and sufficiently strong to withstand normal wind and hail storm forces and having sufficient resilience to yield without puncturing to hail stones, yet to recover to its spherical surface shape under the urging of the inflation pressure in the chamber.
Murphy, L.M.
Direct conversion of muon catalyzed fusion energy
In this paper a method of direct conversion of muon catalyzed fusion (MCF) energy is proposed in order to reduce the cost of muon production. This MCF concept is based on a pellet composed of many thin solid deuterium-tritium (DT) rods encircled by a metallic circuit immersed in a magnetic field. The direct energy conversion is the result of the heating of the pellet by beam injection and fusion alphas. The expanding DT rods causes the change of magnetic flux linked by the circuit. Our calculation shows that the direct conversion method reduces the cost of one muon by a factor of approximately 2.5 over the previous methods. The present method is compatible with a reactor using the pellet concept, where the muon sticking is reduced by the ion cyclotron resonance heating and the confinement of the exploding pellet is handled by magnetic fields and the coronal plasma. 17 refs., 6 figs.
Tajima, T. (Texas Univ., Austin, TX (USA). Inst. for Fusion Studies); Eliezer, S. (Israel Atomic Energy Commission, Yavne (Israel). Soreq Nuclear Research Center); Kulsrud, R.M. (Institute for Advanced Study, Princeton, NJ (USA) Princeton Univ., NJ (USA). Plasma Physics Lab.)
Fluid energy conversion apparatus
US Patent & Trademark Office Database
A fluid energy conversion apparatus including a fluid path assembly having an outside guide assembly, a cylindrical wall inside surface and at least one inside guide assembly is provided. There is also a cylindrical partition wall which extends between the outside guide assembly and the inside guide assembly with its central axis set on the central axis of the cylindrical wall inside surface, the cylindrical wall inside surface of the outside guide assembly and the cylindrical partition wall defining an annular outside path therebetween and the outside peripheral surface of the inside guide assembly and the cylindrical partition wall defining an annular inside path therebetween. There is a plurality of support struts connecting the outside guide assembly, the inside guide assembly and the cylindrical partition wall. Also included is a first rotary member that include an annular hub located adjacent a first end portion of the inside guide assembly and a second rotary member having a second annular hub located adjacent a second end portion of said inside guide assembly. Also included are stator blades, a fluid pressurizing-accelerating device and exhaust nozzles formed in both sides of each of the first turbine rotor blades in a position adjacent to a trailing edge of each of the first turbine rotor blades.
Research in Photochemical Energy Conversion.
National Technical Information Service (NTIS)
The results of investigations dealing with the following topics in photochemical energy conversion are presented: Apparatus for Photochemical Studies; Studies of Charge Transfer Systems; The Photochemistry of Perinaphthenone; The Photoreduction of Phenant...
K. Weiss
Energy Conversion and Storage Program
NASA Astrophysics Data System (ADS)
This report is the 1992 annual progress report for the Energy Conversion and Storage Program, a part of the Energy and Environment Division of the Lawrence Berkeley Laboratory. Work described falls into three broad areas: electrochemistry; chemical applications; and materials applications. The Energy Conversion and Storage Program applies principles of chemistry and materials science to solve problems in several areas: (1) production of new synthetic fuels, (2) development of high-performance rechargeable batteries and fuel cells, (3) development of advanced thermochemical processes for energy conversion, (4) characterization of complex chemical processes and chemical species, and (5) study and application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis. Electrochemistry research aims to develop advanced power systems for electric vehicle and stationary energy storage applications. Chemical applications research includes topics such as separations, catalysis, fuels, and chemical analyses. Included in this program area are projects to develop improved, energy-efficient methods for processing product and waste streams from synfuel plants, coal gasifiers, and biomass conversion processes. Materials applications research includes evaluation of the properties of advanced materials, as well as development of novel preparation techniques. For example, techniques such as sputtering, laser ablation, and poised laser deposition are being used to produce high-temperature superconducting films.
Cairns, E. J.
A thermal-mechanical energy converting device is disclosed that has at least two rotatably supported wheels and with one or more endless transmission elements of a material having a memory effect capable in the bending mode of converting thermal energy into mechanical energy when heated from a temperature below its transition temperature to a temperature above its transition temperature; the transmission elements serve to drive one wheel from the other wheel upon application of thermal energy to the transmission elements, whereby the thermal energy is transferred from the other wheel to the transmission elements over at least a major portion of the circumferential contact of the transmission elements with the other wheel.
Wang, F.E.
Energy conversion and storage program
NASA Astrophysics Data System (ADS)
The Energy Conversion and Storage Program applies chemistry and materials science principles to solve problems in: (1) production of new synthetic fuels; (2) development of high-performance rechargeable batteries and fuel cells; (3) development of advanced thermochemical processes for energy conversion; (4) characterization of complex chemical processes; and (5) application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis. Electrochemistry research aims to develop advanced power systems for electric vehicle and stationary energy storage applications. Topics include identification of new electrochemical couples for advanced rechargeable batteries, improvements in battery and fuel-cell materials, and the establishment of engineering principles applicable to electrochemical energy storage and conversion. Chemical Applications research includes topics such as separations, catalysis, fuels, and chemical analyses. Included in this program area are projects to develop improved, energy-efficient methods for processing waste streams from synfuel plants and coal gasifiers. Other research projects seek to identify and characterize the constituents of liquid fuel-system streams and to devise energy-efficient means for their separation. Materials Applications research includes the evaluation of the properties of advanced materials, as well as the development of novel preparation techniques. For example, the use of advanced techniques, such as sputtering and laser ablation, are being used to produce high-temperature superconducting films.
Cairns, E. J.
Energy Conversion and Storage Program
The Energy Conversion and Storage Program applies chemistry and materials science principles to solve problems in (1) production of new synthetic fuels, (2) development of high-performance rechargeable batteries and fuel cells, (3) development of advanced thermochemical processes for energy conversion, (4) characterization of complex chemical processes, and (5) application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis. Electrochemistry research aims to develop advanced power systems for electric vehicle and stationary energy storage applications. Topics include identification of new electrochemical couples for advanced rechargeable batteries, improvements in battery and fuel-cell materials, and the establishment of engineering principles applicable to electrochemical energy storage and conversion. Chemical Applications research includes topics such as separations, catalysis, fuels, and chemical analyses. Included in this program area are projects to develop improved, energy-efficient methods for processing waste streams from synfuel plants and coal gasifiers. Other research projects seek to identify and characterize the constituents of liquid fuel-system streams and to devise energy-efficient means for their separation. Materials Applications research includes the evaluation of the properties of advanced materials, as well as the development of novel preparation techniques. For example, the use of advanced techniques, such as sputtering and laser ablation, are being used to produce high-temperature superconducting films.
Cairns, E.J.
The Sun provides Earth with a staggering amount of energy - enough to power the great oceanic and atmospheric currents, the cycle of evaporation and condensation that brings fresh water inland and drives river flow, and the typhoons, hurricanes, and tornadoes that so easily destroy the natural and built landscape. The San Francisco earthquake of 1906, with magnitude 7.8, released an estimated 10{sup 17} joules of energy, the amount the Sun delivers to Earth in one second. Earth's ultimate recoverable resource of oil, estimated at 3 trillion barrels, contains 1.7 x 10{sup 22} joules of energy, which the Sun supplies to Earth in 1.5 days. The amount of energy humans use annually, about 4.6 x 10{sup 20} joules, is delivered to Earth by the Sun in one hour. The enormous power that the Sun continuously delivers to Earth, 1.2 x 10{sup 5} terawatts, dwarfs every other energy source, renewable or nonrenewable. It dramatically exceeds the rate at which human civilization produces and uses energy, currently about 13 TW.
Crabtree, G. W.; Lewis, N. S.; Materials Science Division; Cal Tech
Energy conversion in the coronal plasma
NASA Technical Reports Server (NTRS)
Solar and stellar X-ray emission are the observed waste products of the interplay between magnetic fields and the motion of stellar plasma. Theoretical understanding of the process of coronal heating is of utmost importance, since the high temperature is what defines the corona in the first place. Most of the research described deals with the aspects of the several rivalling theories for coronal heating. The rest of the papers deal with processes of energy conversion related to flares.
Martens, P. C. H.
Research on Electrochemical Energy Conversion Systems.
National Technical Information Service (NTIS)
The research on electrochemical energy conversion systems has involved work on three tasks; high energy galvanic cells, the mathematical analysis of electrochemical energy conversion processes, and exploratory research. The investigation of high energy ga...
C. D. Thompson, D. H. Bomkamp, R. T. Foley
Review of betavoltaic energy conversion
NASA Technical Reports Server (NTRS)
Betavoltaic energy conversion refers to the generation of power by coupling a beta source to a semiconductor junction device. The theory of betavoltaic energy conversion and some past studies of the subject are briefly reviewed. Calculations of limiting efficiencies for semiconductor cells versus bandgap are presented along with specific studies for Pm-147 and Ni-63 fueled devices. The approach used for fabricating Pm-147 fueled batteries by the author in the early 1970's is reviewed. Finally, the potential performance of advanced betavoltaic power sources is considered.
Olsen, Larry C.
Turbines For Optomechanical Energy Conversion
NASA Technical Reports Server (NTRS)
Class of proposed optomechanical energy-conversion machines exploit multiple reflections from precise, high-reflectivity mirrors, some of which fixed to turbinelike rotors that spin at high speeds. Basic idea to increase frequencies of photons (and thus energy of light) by repeated Doppler-shifting reflections from moving mirrors. Gain in optical energy in such reflection proportional to speed of mirror, while loss function of imperfections of mirror.
Dick, G. John
An apparatus for maintaining the speed of rotation of a windmill rotor at a fixed ratio to the free flow velocity of the driving wind. This arrangement permits the windmill rotor to rotate at the speed at which its power output is maximized. The apparatus includes a plurality of interleaved rotating and stationary friction discs which convert the rotational kinetic energy of the windmill rotor shaft into thermal energy. An anemometer shaft, which rotates with a velocity which is proportional to the ambient wind velocity, drives a gear train which increases or decreases the pressure on the friction discs so that the load on the rotor is increased or decreased, in an offsetting manner, as the wind velocity changes.
Fuchs, F.J.
Electrochemistry for Energy Conversion
NASA Astrophysics Data System (ADS)
Imagine a laptop computer that runs for 30 hours on a single charge. Imagine a world where you plug your house into your car and power lines are a distant memory. These dreams motivate today's fuel cell research. While some dreams (like powering your home with your fuel cell car) may be distant, others (like a 30-hour fuel cell laptop) may be closer than you think. If you are curious about fuel cells---how they work, when you might start seeing them in your daily life--- this talk is for you. Learn about the state-of-the art in fuel cells, and where the technology is likely to be headed in the next 20 years. You'll also be treated to several ``behind-the scenes'' glimpses of cutting-edge research projects under development in the Renewable Energy Materials Center at the Colorado School of Mines--- projects like an ``ionic transistor'' that works with protons instead of electrons, and a special ceramic membrane material that enables the ``uphill'' diffusion of steam. Associate Professor Ryan O'Hayre's laboratory at the Colorado School of Mines develops new materials and devices to enable alternative energy technologies including fuel cells and solar cells. Prof. O'Hayre and his students collaborate with the Colorado Fuel Cell Center, the Colorado Center for Advanced Ceramics, the Renewable Energy Materials Science and Engineering Center, and the National Renewable Energy Laboratory.[4pt] In collaboration with Ann Deml, Jianhua Tong, Svitlana Pylypenko, Archana Subramaniyan, Micahael Sanders, Jason Fish, Annette Bunge, Colorado School of Mines.
O'Hayre, Ryan
Ocean wave energy conversion concepts
Nine ocean wave energy conversion techniques are described and discussed. These techniques include the use of heaving and pitching bodies, cavity resonators, wave focusing, pressure devices, surging devices, paddles, outriggers and combination devices. Examples of each technique are presented, and required subsystems are described. Finally a comparison study is performed based on efficiency, operational practicality and cost.
M. E. McCormick
Advanced thermionic energy conversion
NASA Technical Reports Server (NTRS)
Basic analytical and experimental exploration was conducted on several types of advanced thermionic energy converters, and preliminary analysis was performed on systems utilizing advanced converter performance. The Pt--Nb cylindrical diode which exhibited a suppressed arc drop, as described in the preceding report, was reassembled and the existence of the postulated hydrid mode of operation was tentatively confirmed. Initial data obtained on ignited and unignited triode operation in the demountable cesium vapor system essentially confirmed the design principles developed in earlier work, with a few exceptions. Three specific advanced converter concepts were selected as candidates for concentrated basic study and for practical evaluation in fixed-configuration converters. Test vehicles and test stands for these converters and a unique controlled-atmosphere station for converter assembly and processing were designed, and procurement was initiated.
Britt, E. J.; Fitzpatrick, G. D.; Hansen, L. K.; Rasor, N. S.
Photochemical conversion of solar energy.
Energy is the most important issue of the 21st century. About 85% of our energy comes from fossil fuels, a finite resource unevenly distributed beneath the Earth's surface. Reserves of fossil fuels are progressively decreasing, and their continued use produces harmful effects such as pollution that threatens human health and greenhouse gases associated with global warming. Prompt global action to solve the energy crisis is therefore needed. To pursue such an action, we are urged to save energy and to use energy in more efficient ways, but we are also forced to find alternative energy sources, the most convenient of which is solar energy for several reasons. The sun continuously provides the Earth with a huge amount of energy, fairly distributed all over the world. Its enormous potential as a clean, abundant, and economical energy source, however, cannot be exploited unless it is converted into useful forms of energy. This Review starts with a brief description of the mechanism at the basis of the natural photosynthesis and, then, reports the results obtained so far in the field of photochemical conversion of solar energy. The "grand challenge" for chemists is to find a convenient means for artificial conversion of solar energy into fuels. If chemists succeed to create an artificial photosynthetic process, "... life and civilization will continue as long as the sun shines!", as the Italian scientist Giacomo Ciamician forecast almost one hundred years ago. PMID:18605661
Balzani, Vincenzo; Credi, Alberto; Venturi, Margherita
All discussions of muscle energetics concern themselves with the Hill force-velocity relation, which is also the general output relation of a class of self-regulated energy converters and as such contains only a single adjustable parameter �the degree of coupling. It is therefore important to see whether in principle muscle can be included in this class. One requirement is that the muscle should possess a working element characterized by a dissipation function of two terms: mechanical output and chemical input. This has been established by considering the initial steady phase of isotonic and isometric tetanic contraction to represent a stationary state of the fibrils (a considerable body of evidence supports this). Further requirements, which can be justified for the working element, are linearity and incomplete coupling. Thus the chemical input of the muscle may be expected to follow the inverse Hill equation (see Part I). The relatively large changes in activities of reactants which the equation demands could only be controlled by local operation of the regulator, and a scheme is outlined to show how such control may be achieved. Objections to this view recently raised by Wilkie and Woledge rest on at least two important assumptions, the validity of which is questioned: (a) that heat production by processes other than the immediate driving reaction is negligible, which disregards the regulatory mechanism (possibly this involves the calcium pump), and (b) that the affinity of the immediate driving reaction is determined by over-all concentrations. The division of heat production into �shortening heat� and �maintenance heat� or �activation heat� is found to be arbitrary.
Caplan, S. R.
Direct solar energy conversion at sea
Hydrogen production and delivery from direct solar energy conversion facilities located at sea is treated, assuming the use of a heat engine\\/electricity generation\\/water electrolysis system. The concept of ocean energy is discussed, noting the distinction between direct and indirect solar energy conversion at sea, and direct solar energy conversion is considered within the framework of the seaward advancement of industrial
W. J. D. Escher; T. Ohta
Materials for thermoelectric energy conversion
NASA Technical Reports Server (NTRS)
The field of thermoelectric energy conversion is reviewed from both a theoretical and an experimental standpoint. The basic theory is introduced and the thermodynamic and solid state views are compared. An overview of the development of thermoelectric materials is presented with particular emphasis being placed on the most recent developments in high-temperature semiconductors. A number of possible device applications are discussed and the successful use and suitability of these devices for space power is manifest.
Wood, C.
Thermodynamics fundamentals of energy conversion
The work reported in the chapters 1-5 focuses on the fundamentals of heat transfer, fluid dynamics, thermodynamics and electrical phenomena related to the conversion of one form of energy to another. Chapter 6 is a re-examination of the fundamental heat transfer problem of how to connect a finite-size heat generating volume to a concentrated sink. Chapter 1 extends to electrical
Nicolae Dan
Pyroelectric energy conversion: optimization principles.
In the framework of microgenerators, we present in this paper the key points for energy harvesting from temperature using ferroelectric materials. Thermoelectric devices profit from temperature spatial gradients, whereas ferroelectric materials require temporal fluctuation of temperature, thus leading to different applications targets. Ferroelectric materials may harvest perfectly the available thermal energy whatever the materials properties (limited by Carnot conversion efficiency) whereas thermoelectric material's efficiency is limited by materials properties (ZT figure of merit). However, it is shown that the necessary electric fields for Carnot cycles are far beyond the breakdown limit of bulk ferroelectric materials. Thin films may be an excellent solution for rising up to ultra-high electric fields and outstanding efficiency. Different thermodynamic cycles are presented in the paper: principles, advantages, and drawbacks. Using the Carnot cycle, the harvested energy would be independent of materials properties. However, using more realistic cycles, the energy conversion effectiveness remains dependent on the materials properties as discussed in the paper. A particular coupling factor is defined to quantify and check the effectiveness of pyroelectric energy harvesting. It is defined similarly to an electromechanical coupling factor as k2=p2theta0/(epsilontheta33cE), where p, theta0, epsilontheta33, cE are pyroelectric coefficient, maximum working temperature, dielectric permittivity, and specific heat, respectively. The importance of the electrothermal coupling factor is shown and discussed as an energy harvesting figure of merit. It gives the effectiveness of all techniques of energy harvesting (except the Carnot cycle). It is finally shown that we could reach very high efficiency using 1110.75Pb(Mg1/3Nb2/3)-0.25PbTiO3 single crystals and synchronized switch harvesting on inductor (almost 50% of Carnot efficiency). Finally, practical implementation key points of pyroelectric energy harvesting are presented showing that the different thermodynamic cycles are feasible and potentially effective, even compared to thermoelectric devices. PMID:18407845
Sebald, Gael; Lefeuvre, Elie; Guyomar, Daniel
Radiation energy conversion in space
NASA Technical Reports Server (NTRS)
Topics discussed at the third NASA conference on radiant energy conversion are reviewed. The unconcentrated-photovoltaic-generation version of a solar power satellite is described, noting that it will consist of a 21.3 x 5.3-sq-km silicon-solar-cell array expected to provide 17 Gw of electrical power, with 1 km in diam transmitters oriented to beam 2.45 GHz microwave power to two receiving/rectifying 'rectennas' on earth. The Solares space-energy-system concept, designed for providing a large fraction of the world's energy needs at costs comparable to those of future coal/nuclear alternative, is considered, as are subsystems for improving the economics of the solar power satellite. A concept proposing the use of relativistic-electron-storage rings for electron-beam energy transmission and storage, and a report on the production of a high temperature plasma with concentrated solar radiation are taken into account. Laser-conversion systems, including the direct-solar-pumped space laser, and the telec-powered spacecraft, are discussed.
Billman, K. W.
Fault ride through capability of grid connected variable speed permanent magnet synchronous generator for wind energy conversion system
This paper discusses the interconnection issues of variable speed permanent magnet synchronous generator (PMSG) connected to grid as per prevailing grid standards during healthy and fault conditions. The variable speed operation of PMSG has been demonstrated while feeding the real power to the grid keeping DC link voltage constant. Further, the fault ride-through capability of PMSG has been demonstrated using
Rajveer Mittal; K. S. Sandhu; D. K. Jain
Ocean thermal-energy conversion
NASA Astrophysics Data System (ADS)
The principles underlying ocean thermal-energy conversion (OTEC) are reviewed, and a schematic layout of a system is included. The two systems currently under study, the open system and the closed system, are described. The prospect now, it is noted, is that OTEC plants will not be commercially viable on a widespread basis, even in the tropics. This is especially true of the large-scale plants that have been envisioned. A strong possibility is seen, however, that smaller plants, generating about 40 megawatts of electrical power, can survive commercially. The following conditions would favor their success: placement on land rather than at sea; placement in areas (such as islands) where alternative energy supplies are at a premium; and designing the plant to operate in conjunction with either an aquaculture or a desalination plant.
Ford, G.; Niblett, C.; Walker, L.
The chemistry of energy conversion and storage.
What's in store: The sustainable development of our society requires the conversion and storage of renewable energy, and these should be scaled up to serve the global primary energy consumption. This special issue on "The Chemistry of Energy Conversion and Storage", assembled by guest editor Dangsheng Su, contains papers dealing with these aspects, and highlights important developments in the chemistry of energy conversion and storage during the last two years. PMID:24832535
Su, Dang Sheng
Solar energy, its conversion and utilization
NASA Technical Reports Server (NTRS)
The work being carried out at the University of Florida Solar Energy and Energy Conversion Laboratory in converting solar energy, our only income, into other needed and useful forms of energy is described. A treatment such as this demonstrates, in proper perspective, how solar energy can benefit mankind with its many problems of shortages and pollution. Descriptions were given of the conversion processes, equipment, and performance. The testing of materials, solar water heating, space heating, cooking and baking, solar distillation, refrigeration and air-conditioning, work with the solar furnace, conversion to mechanical power, hot air engines, solar-heated sewage digestion, conversion to electricity, and other devices will be discussed.
Farber, E. A.
Biological Solar Energy Conversion and U.S. Energy Policy
ERIC Educational Resources Information Center
Surveys energy consumption in the United States and explores the possibility of increasing the amount of energy obtained from biomass conversion (biologically produced energy). Economic and environmental concerns of biomass conversion processes are discussed. (CP)
Pimentel, David; And Others
Tropospheric effects of energy conversion
The tropospheric concentrations of a number of trace gases are increasing due to man's activities. For some trace gases, their atmospheric life cycles are not fully understood and it is difficult to be certain about the role of man's activities. Emissions from the energy industries and energy conversion processes represent an important subset of source terms in these life cycles, along with agriculture, deforestation, cement manufacture, biomass burning, process industries and natural biospheric processes. Global Warming Potentials (GWPs) allow the tropospheric effects of a range of climate forcing trace gases to be assessed on a comparable basis. If a short term view of the commitment to global warming is adopted then the contribution from other trace gases may approach and exceed that of carbon dioxide, itself. Over longer time horizons, the long atmospheric lifetime of carbon dioxide shows through as a major influence and the contributions from the other trace gases appear to be much smaller, representing an additional 13-18[percent] contribution on top of that from CO[sub 2] itself.
Derwent, R.G. (Harwell Lab., Oxfordshire (United Kingdom))
Magnetic energy flow in the solar wind.
NASA Technical Reports Server (NTRS)
Discussion of the effect of rotation (tangential flow) of the solar wind on the conclusions of Whang (1971) suggesting an increase in the solar wind velocity due to the conversion of magnetic energy to kinetic energy. It is shown that the effect of the rotation of the sun on the magnetic energy flow results in most of the magnetic energy being transported by magnetic shear stress near the sun.
Modisette, J. L.
Terrestrial solar thermionic energy conversion systems concept
NASA Technical Reports Server (NTRS)
Results obtained from studies of a (1) solar concentrator, (2) solar energy receiver - thermionic converter system, and (3) solar thermionic topping system are described. Peripheral subsystems, which are required for any solar energy conversion system, are also discussed.
Shimada, K.; Swerdling, M.
Photochemical conversion and storage of solar energy
There are two ways of photochemical conversion of solar energy viz. photochemistry and photoelectrochemistry. Various concepts, developments and uses related to these aspects as well as storage of solar energy have been enumerated.
Bhavani, N.K.; Vijayalakshmi, D.; Seshan, S.
Light energy conversion systems and methods
US Patent & Trademark Office Database
A light energy conversion (LEC) system includes a fluid circuit having a working fluid flowing therethrough and a plurality of light concentrating (LC) modules for converting light energy into electrical energy and for transforming the light energy into thermal energy. The LC modules including a first LC module coupled in series with a second LC module along the fluid circuit. The working fluid absorbs thermal energy while flowing through the first and second LC modules. At least the first LC module includes a light concentrating optical element that is configured to direct light energy toward a focal region and a receiver held at the focal region. The receiver includes a housing having a chamber that holds an energy conversion member. The energy conversion member transforms light energy received from the optical element into electrical and thermal energy.
Energy conversion & storage program. 1994 annual report
The Energy Conversion and Storage Program investigates state-of-the-art electrochemistry, chemistry, and materials science technologies for: (1) development of high-performance rechargeable batteries and fuel cells; (2) development of high-efficiency thermochemical processes for energy conversion; (3) characterization of complex chemical processes and chemical species; (4) study and application of novel materials for energy conversion and transmission. Research projects focus on transport process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis.
Cairns, E.J.
Energy Conversion & Storage Program, 1993 annual report
The Energy Conversion and Storage Program applies chemistry and materials science principles to solve problems in: production of new synthetic fuels; development of high-performance rechargeable batteries and fuel cells; development of high-efficiency thermochemical processes for energy conversion; characterization of complex chemical processes and chemical species; and the study and application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis.
Cairns, E.J.
Entropy fluxes, endoreversibility, and solar energy conversion
NASA Astrophysics Data System (ADS)
A formalism illustrating the conversion of radiation energy into work can be obtained in terms of energy and entropy fluxes. Whereas the Landsberg equality was derived for photothermal conversion with zero bandgap, a generalized inequality for photothermal/photovoltaic conversion with a single, but arbitrary, bandgap was deduced. This result was derived for a direct energy and entropy balance. The formalism of endoreversible dynamics was adopted in order to show the correlation with the latter approach. It was a surprising fact that the generalized Landsberg inequality was derived by optimizing some quantity W(sup *), which obtains it maximum value under short-circuit condition.
de Vos, A.; Landsberg, P. T.; Baruch, P.; Parrott, J. E.
Efficiency of Energy Conversion in Nitinol.
National Technical Information Service (NTIS)
Nitinol - one of several Shape Memory Effect (SME) alloys - is known to be a suitable medium for the conversion of heat to usable mechanical work in a solid state heat engine. In the present study, the efficiency of the energy conversion in Nitinol is inv...
R. D. Kopa
Direct Mechanical Conversion of Ocean Wave Energy
Recently wave energy conversion has attracted renewed interest from governments and developers looking for alternative carbon free energy resources. Ocean waves have been shown to contain large quantities of power. However, it has proven very difficult to capture even a fraction of this energy in real ocean conditions. This paper reviews the complex energy flows associated with ocean waves and
L. Le-Ngoc; A. I. Gardiner
Energy Conversion in Natural and Artificial Photosynthesis
Summary Modern civilization is dependent upon fossil fuels, a nonrenewable energy source originally provided by the storage of solar energy. Fossil fuel dependence has severe consequences including energy security issues and greenhouse gas emissions. The consequences of fossil fuel dependence could be avoided by fuel-producing artificial systems that mimic natural photosynthesis, directly converting solar energy to fuel. This review describes the three key components of solar energy conversion in photosynthesis: light harvesting, charge separation, and catalysis. These processes are compared in natural and artificial systems. Such a comparison can assist in understanding the general principles of photosynthesis and in developing working devices including photoelectrochemical cells for solar energy conversion.
McConnell, Iain; Li, Gonghu; Brudvig, Gary W.
Research on Electrochemical Energy Conversion Systems.
National Technical Information Service (NTIS)
The research on electrochemical energy conversion system has involved work on two tasks: a search for electrolytes alternative to phosphoric acid for direct and indirect hydrocarbon-air fuel cells, and a study of the corrosion characteristics of electroly...
A. A. Adams R. T. Foley
Research on Electrochemical Energy Conversion Systems.
National Technical Information Service (NTIS)
The research on electrochemical energy conversion systems has involved a search for electrolytes alternative to phosphoric acid for direct and indirect hydrocarbon-air fuel cells. It has concentrated on trifluoromethanesulfonic acid monohydrate and perflu...
A. A. Adams R. T. Foley R. M. Goodman
Research on Electrochemical Energy Conversion Systems.
National Technical Information Service (NTIS)
The research on electrochemical energy conversion systems has involved work on two tasks: a search for electrolytes alternative to phosphoric acid for direct and indirect hydrocarbon-air fuel cells, and a study of the corrosion characteristics of electrol...
A. A. Adams R. M. Goodman R. T. Foley
Research on Electrochemical Energy Conversion Systems.
National Technical Information Service (NTIS)
The project on electrochemical energy conversion system has involved two tasks: the determination of the electrochemical behavior of low molecular weight hydrocarbons and alcohols as well as other possible fuels in aqueous trifluoromethanesulfonic acid an...
A. A. Adams R. T. Foley
Research on Electrochemical Energy Conversion Systems.
National Technical Information Service (NTIS)
The research on electrochemical energy conversion systems has involved work on two tasks: a search for electrolytes alternative to phosphoric acid for direct and indirect hydrocarbon-air fuel cells, and a study of the corrosion characteristics of electrol...
A. A. Adams R. T. Foley
Second NASA Conference on Laser Energy Conversion
NASA Technical Reports Server (NTRS)
The possible transmission of high power laser beams over long distances and their conversion to thrust, electricity, or other useful forms of energy is considered. Specific topics discussed include: laser induced chemistry; developments in photovoltaics, including modification of the Schottky barrier devices and generation of high voltage emf'sby laser radiation of piezoelectric ceramics; the thermo electronic laser energy converter and the laser plasmadynamics converters; harmonic conversion of infrared laser radiation in molecular gases; and photon engines.
Billman, K. W. (editor)
Thermionic energy conversion technology - Present and future
NASA Technical Reports Server (NTRS)
Aerospace and terrestrial applications of thermionic direct energy conversion and advances in direct energy conversion (DEC) technology are surveyed. Electrode materials, the cesium plasma drop (the difference between the barrier index and the collector work function), DEC voltage/current characteristics, conversion efficiency, and operating temperatures are discussed. Attention is centered on nuclear reactor system thermionic DEC devices, for in-core or out-of-core operation. Thermionic fuel elements, the radiation shield, power conditions, and a waste heat rejection system are considered among the thermionic DEC system components. Terrestrial applications include topping power systems in fossil fuel and solar power generation.
Shimada, K.; Morris, J. F.
Thermionic Energy Conversion (TEC) topping thermoelectrics
NASA Technical Reports Server (NTRS)
Performance expectations for thermionic and thermoelectric energy conversion systems are reviewed. It is noted that internal radiation effects diminish thermoelectric figures of merit significantly at 1000 K and substantially at 2000 K; the effective thermal conductivity contribution of intrathermoelectric radiative dissipation increases with the third power of temperature. It is argued that a consideration of thermoelectric power generation with high temperature heat sources should include utilization of thermionic energy conversion (TEC) topping thermoelectrics. However TEC alone or TEC topping more efficient conversion systems like steam or gas turbines, combined cycles, or Stirling engines would be more desirable generally.
Morris, J. F.
Geomagnetic activity effects on plasma sheet energy conversion
NASA Astrophysics Data System (ADS)
In this article we use three years (2001, 2002, and 2004) of Cluster plasma sheet data to investigate what happens to localized energy conversion regions (ECRs) in the plasma sheet during times of high magnetospheric activity. By examining variations in the power density, E�J, where E is the electric field and J is the current density obtained by Cluster, we have studied the influence on Concentrated Load Regions (CLRs) and Concentrated Generator Regions (CGRs) from variations in the geomagnetic disturbance level as expressed by the Kp, the AE, and the Dst indices. We find that the ECR occurrence frequency increases during higher magnetospheric activities, and that the ECRs become stronger. This is true both for CLRs and for CGRs, and the localized energy conversion therefore concerns energy conversion in both directions between the particles and the fields in the plasma sheet. A higher geomagnetic activity hence increases the general level of energy conversion in the plasma sheet. Moreover, we have shown that CLRs live longer during magnetically disturbed times, hence converting more electromagnetic energy. The CGR lifetime, on the other hand, seems to be unaffected by the geomagnetic activity level. The evidence for increased energy conversion during geomagnetically disturbed times is most clear for Kp and for AE, but there are also some indications that energy conversion increases during large negative Dst. This is consistent with the plasma sheet magnetically mapping to the auroral zone, and therefore being more tightly coupled to auroral activities and variations in the AE and Kp indices, than to variations in the ring current region as described by the Dst index.
Hamrin, M.; Norqvist, P.; Marghitu, O.; Buchert, S.; Klecker, B.; Kistler, L. M.; Dandouras, I.
Sea Energy Conversion: Problems and Possibilities
Nowadays, policies are being developed in many countries in order to decrease their greenhouse gases emissions. While in this area some technologies are widely installed (wind and solar energy), other ones, like the sea energy, could get an important role in the medium and long term. That is why the most relevant technologies associated to the sea energy conversion are
G. Buigues; I. Zamora; A. J. Maz�n; V. Valverde; F. J. P�rez
Ocean Wave Energy Conversion - A Survey
Ocean energy conversion has been of interest for many years. Recent developments such as concern over global warming have renewed interest in the topic. This paper gives a systematic and comprehensive overview of wave energy converters (WEC) as opposed to ocean current energy converters. The point absorber and oscillating water column WEC devices are addressed with regards to commercial prospects,
A. Muetze; J. G. Vining
Poultry processing industry waste to energy conversion
The paper presents the results of experimental approach on chicken farms residues for energy generation. Based on complete thermal-physical-chemical characterization a series of waste to energy conversion chains are proposed as alternative to incineration disposal solution. The researched focused on combustibility properties quantification for the appropriate waste to energy chain identification. The experiments were carried out for elemental composition, primary
Cosmin Marculescua; Constantin Stana
Neutrino flavor conversion in random magnetic fields
If massive neutrinos possess magnetic moments, a magnetic field can cause a spin flip. In the case of Dirac neutrinos the spin flip converts an active neutrino into a sterile one and vice versa. By constrast, if neutrinos are Majorana particles, a spin flip converts them to a neutrino of a different flavor. We examine the behavior of neutrinos in
G. Domokos; S. Kovesi-Domokos
Photoelectrochemical cells - Conversion of intense optical energy
NASA Technical Reports Server (NTRS)
Conversion of optical energy to chemical energy and/or electrical energy using wet photoelectrochemical cells is described. Emphasis is on (1) the photoelectrolysis of H2O to H2 and O2 using cells having n-type semiconductor photoelectrodes fabricated from TiO2, SnO2, SrTiO3, KTaO3, and KTa(0.77)Nb(0.23)O3, and (2) the conversion of light to electrical energy using CdSe- and CdS-based cells with polysulfide electrolytes.
Wrighton, M. S.; Ellis, A. B.; Kaiser, S. W.
Electromagnetic wave energy conversion research
NASA Technical Reports Server (NTRS)
Known electromagnetic wave absorbing structures found in nature were first studied for clues of how one might later design large area man-made radiant-electric converters. This led to the study of the electro-optics of insect dielectric antennae. Insights were achieved into how these antennae probably operate in the infrared 7-14um range. EWEC theoretical models and relevant cases were concisely formulated and justified for metal and dielectric absorber materials. Finding the electromagnetic field solutions to these models is a problem not yet solved. A rough estimate of losses in metal, solid dielectric, and hollow dielectric waveguides indicates future radiant-electric EWEC research should aim toward dielectric materials for maximum conversion efficiency. It was also found that the absorber bandwidth is a theoretical limitation on radiant-electric conversion efficiency. Ideally, the absorbers' wavelength would be centered on the irradiating spectrum and have the same bandwith as the irradiating wave. The EWEC concept appears to have a valid scientific basis, but considerable more research is needed before it is thoroughly understood, especially for the complex randomly polarized, wide band, phase incoherent spectrum of the sun. Specific recommended research areas are identified.
Bailey, R. L.; Callahan, P. S.
Energy Conversion: Nano Solar Cell
Problems of fossil-fuel-induced climate change have sparked a demand for sustainable energy supply for all sectors of economy. Most laboratories continue to search for new materials and new technique to generate clean energy at affordable cost. Nanotechnology can play a major role in solving the energy problem. The prospect for solar energy using Si-based technology is not encouraging. Si photovoltaics
Muhammad Yahaya; Chi Chin Yap; Muhamad Mat Salleh
Harnessing surface plasmons for solar energy conversion
NASA Technical Reports Server (NTRS)
NASA research on the feasibility of solar-energy conversion using surface plasmons is reviewed, with a focus on inelastic-tunnel-diode techniques for power extraction. The need for more efficient solar converters for planned space missions is indicated, and it is shown that a device with 50-percent efficiency could cost up to 40 times as much per sq cm as current Si cells and still be competitive. The parallel-processing approach using broadband carriers and tunable diodes is explained, and the physics of surface plasmons on metal surfaces is outlined. Technical problems being addressed include phase-matching sunlight to surface plasmons, minimizing ohmic losses and reradiation in energy transport, coupling into the tunnels by mode conversion, and gaining an understanding of the tunnel-diode energy-conversion process. Diagrams illustrating the design concepts are provided.
Anderson, L. M.
Energy conversion & storage program. 1995 annual report
The 1995 annual report discusses laboratory activities in the Energy Conversion and Storage (EC&S) Program. The report is divided into three categories: electrochemistry, chemical applications, and material applications. Research performed in each category during 1995 is described. Specific research topics relate to the development of high-performance rechargeable batteries and fuel cells, the development of high-efficiency thermochemical processes for energy conversion, the characterization of new chemical processes and complex chemical species, and the study and application of novel materials related to energy conversion and transmission. Research projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials and deposition technologies, and advanced methods of analysis.
Cairns, E.J.
Energy from Biomass for Conversion of Biomass
NASA Astrophysics Data System (ADS)
Along with estimates of minimum energy required by steam explosion pre-treatment of biomass some general problems concerning biomass conversion into chemicals, materials, and fuels are discussed. The energy necessary for processing biomass by steam explosion auto-hydrolysis is compared with the heat content of wood and calculated in terms of the amount of saturated steam consumed per unit mass of the dry content of wood biomass. The fraction of processed biomass available for conversion after steam explosion pre-treatment is presented as function of the amount of steam consumed per unit mass of the dry content of wood. The estimates based on a simple model of energy flows show the energy required by steam explosion pre-treatment of biomass being within 10% of the heat content of biomass - a realistic amount demonstrating that energy for the process can be supplied from a reasonable proportion of biomass used as the source of energy for steam explosion pre-treatment.
Abolins, J.; Gravitis, J.
A new wind energy conversion system
NASA Technical Reports Server (NTRS)
It is presupposed that vertical axis wind energy machines will be superior to horizontal axis machines on a power output/cost basis and the design of a new wind energy machine is presented. The design employs conical cones with sharp lips and smooth surfaces to promote maximum drag and minimize skin friction. The cones are mounted on a vertical axis in such a way as to assist torque development. Storing wind energy as compressed air is thought to be optimal and reasons are: (1) the efficiency of compression is fairly high compared to the conversion of mechanical energy to electrical energy in storage batteries; (2) the release of stored energy through an air motor has high efficiency; and (3) design, construction, and maintenance of an all-mechanical system is usually simpler than for a mechanical to electrical conversion system.
Smetana, F. O.
Cogeneration potential of energy conversion systems
Energy conversion systems for industrial cogeneration, supplying both electricity and process heat, were characterized in order to match each candidate to specific industrial requirements. The ratio of power to process heat is shown to be a critical factor in achieving matches that produce appreciable fuel savings. Economic screening, based on return on incremental investment, further refines the selection. The potential national fuel savings in 1990 are developed for the energy conversion systems with the greatest impact at levels of 0% and a 20% return on investment.
Brown, D.H.
US energy conversion and use characteristics
The long-range goal of the Energy Conversion and Utilization Technology (ECUT) Program is to enhance energy productivity in all energy-use sectors by supporting research on improved efficiency and fuel switching capability in the conversion and utilization of energy. Regardless of the deficiencies of current information, a summary of the best available energy-use information is needed now to support current ECUT program planning. This document is the initial draft of this type of summary and serves as a data book that will present current and periodically updated descriptions of the following aspects of energy use: gross US energy consumption in each major energy-use sector; energy consumption by fuel type in each sector; energy efficiency of major equipment/processes; and inventories, replacement rates, and use patterns for major energy-using capital stocks. These data will help the ECUT program staff perform two vital planning functions: determine areas in which research to improve energy productivity might provide significant energy savings or fuel switching and estimate the actual effect that specific research projects may have on energy productivity and conservation. Descriptions of the data sources and examples of the uses of the different types of data are provided in Section 2. The energy-use information is presented in the last four sections; Section 3 contains general, national consumption data; and Sections 4 through 6 contain residential/commercial, industrial, and transportation consumption data, respectively. (MCW)
Imhoff, C.H.; Liberman, A.; Ashton, W.B.
Power Quality Control and Design of Power Converter for Variable-Speed Wind Energy Conversion System with Permanent-Magnet Synchronous Generator
The control strategy and design of an AC/DC/AC IGBT-PMW power converter for PMSG-based variable-speed wind energy conversion systems (VSWECS) operation in grid/load-connected mode are presented. VSWECS consists of a PMSG connected to a AC-DC IGBT-based PWM rectifier and a DC/AC IGBT-based PWM inverter with LCL filter. In VSWECS, AC/DC/AC power converter is employed to convert the variable frequency variable speed generator output to the fixed frequency fixed voltage grid. The DC/AC power conversion has been managed out using adaptive neurofuzzy controlled inverter located at the output of controlled AC/DC IGBT-based PWM rectifier. In this study, the dynamic performance and power quality of the proposed power converter connected to the grid/load by output LCL filter is focused on. Dynamic modeling and control of the VSWECS with the proposed power converter is performed by using MATLAB/Simulink. Simulation results show that the output voltage, power, and frequency of VSWECS reach to desirable operation values in a very short time. In addition, when PMSG based VSWECS works continuously with the 4.5?kHz switching frequency, the THD rate of voltage in the load terminal is 0.00672%.
Oguz, Yuksel; Guney, Irfan; Cal?k, Huseyin
Power quality control and design of power converter for variable-speed wind energy conversion system with permanent-magnet synchronous generator.
The control strategy and design of an AC/DC/AC IGBT-PMW power converter for PMSG-based variable-speed wind energy conversion systems (VSWECS) operation in grid/load-connected mode are presented. VSWECS consists of a PMSG connected to a AC-DC IGBT-based PWM rectifier and a DC/AC IGBT-based PWM inverter with LCL filter. In VSWECS, AC/DC/AC power converter is employed to convert the variable frequency variable speed generator output to the fixed frequency fixed voltage grid. The DC/AC power conversion has been managed out using adaptive neurofuzzy controlled inverter located at the output of controlled AC/DC IGBT-based PWM rectifier. In this study, the dynamic performance and power quality of the proposed power converter connected to the grid/load by output LCL filter is focused on. Dynamic modeling and control of the VSWECS with the proposed power converter is performed by using MATLAB/Simulink. Simulation results show that the output voltage, power, and frequency of VSWECS reach to desirable operation values in a very short time. In addition, when PMSG based VSWECS works continuously with the 4.5 kHz switching frequency, the THD rate of voltage in the load terminal is 0.00672%. PMID:24453905
O?uz, Y�ksel; G�ney, ?rfan; �al?k, H�seyin
Energy Conversion: Nano Solar Cell
NASA Astrophysics Data System (ADS)
Problems of fossil-fuel-induced climate change have sparked a demand for sustainable energy supply for all sectors of economy. Most laboratories continue to search for new materials and new technique to generate clean energy at affordable cost. Nanotechnology can play a major role in solving the energy problem. The prospect for solar energy using Si-based technology is not encouraging. Si photovoltaics can produce electricity at 20-30 cslash/kWhr with about 25% efficiency. Nanoparticles have a strong capacity to absorb light and generate more electrons for current as discovered in the recent work of organic and dye-sensitized cell. Using cheap preparation technique such as screen-printing and self-assembly growth, organic cells shows a strong potential for commercialization. Thin Films research group at National University Malaysia has been actively involved in these areas, and in this seminar, we will present a review works on nanomaterials for solar cells and particularly on hybrid organic solar cell based on ZnO nanorod arrays. The organic layer consisting of poly[2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEHPPV) and [6, 6]-phenyl C61-butyric acid 3-ethylthiophene ester (PCBE) was spin-coated on ZnO nanorod arrays. ZnO nanorod arrays were grown on FTO glass substrates which were pre-coated with ZnO nanoparticles using a low temperature chemical solution method. A gold electrode was used as the top contact. The device gave a short circuit current density of 2.49�10-4 mA/cm2 and an open circuit voltage of 0.45 V under illumination of a projector halogen light at 100 mW/cm2.
Yahaya, Muhammad; Yap, Chi Chin; Mat Salleh, Muhamad
Reliability assurance of turbine energy conversion systems
The Dynamic Isotope Power System (DIPS) is a 6-k (electric) space power system utilizing a {sup 238}Pu radioisotope heat source and a dual redundant closed Brayton cycle power conversion assembly. The DIPS program is currently funded to design, fabricate, and test a ground demonstration engineering unit. Primary objectives of the test will be to validate design and demonstrate performance and lifetime. The DIPS is one application of a broader group of space power systems known as turbine energy conversion systems (TECS). The TECS couples closed-cycle Brayton energy conversion systems to either a radioisotope, reactor, or solar collector heat source to provide an efficient source of power for a wide spectrum of civilian and military space missions. This paper describes the reliability assurance program for the DIPS that will demonstrate that the highly reliable TECS will be available for space operation in the last decade of this century.
Rutherford, P.D.; Burgess, D.S.; Robb, S.
Thermal Energy Conversion in Nanofluids
NASA Astrophysics Data System (ADS)
A relatively simple subset of nanotechnology---nanofluids---can be obtained by adding nanoparticles to conventional base fluids. The promise of these fluids stems from the fact that relatively low particle loadings (typically <1% volume fractions) can significantly change the properties of the base fluid. This research explores how low volume fraction nanofluids, composed of common base-fluids, interact with light energy. Comparative experimentation and modeling reveals that absorbing light volumetrically (i.e. in the depth of the fluid) is fundamentally different from surface-based absorption. Depending on the particle material, size, shape, and volume fraction, a fluid can be changed from being mostly transparent to sunlight (in the case of water, alcohols, oils, and glycols) to being a very efficient volumetric absorber of sunlight. This research also visualizes, under high levels of irradiation, how nanofluids undergo interesting, localized phase change phenomena. For this, images were taken of bubble formation and boiling in aqueous nanofluids heated by a hot wire and by a laser. Infrared thermography was also used to quantify this phenomenon. Overall, though, this research reveals the possibility for novel solar collectors in which the working fluid directly absorbs light energy and undergoes phase change in a single step. Modeling results indicate that these improvements can increase a solar thermal receiver's efficiency by up to 10%.
Taylor, Robert
Efficiency of energy conversion in Nitinol
The efficiency of the energy conversion in Nitinol was investigated experimentally. An electronically controlled Cycle Simulator subjected a single Nitinol wire element to the stress strain temperature cycles corresponding to a specific thermodynamic cycle. The test parameters, which were varied singly or in combination, included various stress levels, stress rates, percent of elongation of the wire, temperature levels, heating and
R. D. Kopa
Comments on TEC trends. [Thermionic Energy Conversion
NASA Technical Reports Server (NTRS)
The paper comments on published and projected thermionic-energy-conversion (TEC) performance trends. This commentary includes graphs and an appendix relating TEC performance parameters, plots of predicted and actual TEC trends, a figure relating projected cost of electricity to overall efficiency for TEC topping, and a discussion of the implications of these relationships.
Morris, J. F.
Materials for Energy Conversion and Environmental Protection.
National Technical Information Service (NTIS)
The Pan-American Advanced Studies Institute (PASI) on Materials for Energy Conversion and Environmental Protection was held October 20-29, 2003 in Rio de Janeiro, Brazil. The event welcomed twenty distinguished lecturers and forty graduate and post-doctor...
R. P. Chang J. Moncel
Biomimetic Approach to Solar Energy Conversion.
National Technical Information Service (NTIS)
A biomimetic process is carried out in vitro by an inanimate system or apparatus and is based on methods used by living organisms. Specifically, the prospects for using the methods of plant photosynthesis for solar energy conversion are considered. The di...
J. J. Katz T. R. Janson M. R. Wasielewski
Power conversion mechanisms for wave energy
It is easy to make a device that will respond vigorously to the action of sea waves. Indeed, it is quite hard to make one that will not. However, the conversion of the slow, random, reversing energy flows with very high extreme values into phase-locked synchronous electricity with power quality acceptable to a utility network is very much harder. This
S H Salter; J R M Taylor; N J Caldwell
Diffuser designs for improved wind energy conversion
The paper describes experimental work on two classes of compact diffusers for augmenting the power output of wind energy conversion systems. The first employs slot-injected air to energize the boundary layer of the internal flow, while the second employs short ring airfoils. The low pressure distribution along the internal ring surface of high-lift airfoil shapes induces augmented flow through the
K. M. Foreman; B. L. Gilbert
Direct conversion of muon catalyzed fusion energy.
National Technical Information Service (NTIS)
In this paper a method of direct conversion of muon catalyzed fusion (MCF) energy is proposed in order to reduce the cost of muon production. This MCF concept is based on a pellet composed of many thin solid deuterium-tritium (DT) rods encircled by a meta...
T. Tajima S. Eliezer R. M. Kulsrud
Wind energy conversion - An introduction
NASA Astrophysics Data System (ADS)
System integration studies indicate that existing utility grid systems could accept a contribution of about 20 percent of their total power from wind turbines. Similar percentages in fuel savings are envisioned for wind/diesel electricity generation systems in remote areas. An assessment of recent wind turbine development advancements indicates that 20-40 m diameter turbines, with 50-500 kW power ratings, offer the most attractive economics for land-based applications in the near future, yielding energy costs of the order of 2.8-5.6 p/kWh at sites where the annual average wind speed is 5.5 m/sec. In windier locations, the cost will be even lower. Further operational experience is required, however, to demonstrate that reliable operation can be sustained over periods of many years. As experience accumulates and economies of scale associated with mass production become available, the wind turbine market is expected to grow rapidly.
Musgrove, P. J.
Homopolar Transformer for Conversion of Electrical Energy.
National Technical Information Service (NTIS)
The DC voltage of electrical energy applied to a homopolar machine, is converted by transformer windings in response to rotor rotation within the magnetic field of the homopolar machine, to a different voltage level for supply to a load.
R. C. Smith
Mode conversion in a magnetic photonic crystal waveguide
NASA Astrophysics Data System (ADS)
In this work, we have reported a theoretical study of a magnetic photonic crystal waveguide (also called a magneto photonic crystal waveguide). This structure is formed by a triangular lattice of air holes in a bismuth iron garnet (BIG) film, grown on gallium gadolinium garnet substrates. Nonreciprocal TE�TM mode conversion is caused by the Faraday rotation if the magnetization is aligned along the z-axis, parallel to mode of propagation. The properties of this phenomenon are simulated using the beam propagation method. The conversion output has been simulated, and the Faraday rotation and modal birefringence have been calculated by varying the gyrotropy and the thickness of the BIG film. This magnetic photonic crystal waveguide has the advantage of enhancing Faraday rotation in optical isolators.
Otmani, H.; Bouchemat, M.; Hocini, A.; Boumaza, T.
Energy conversion in laser propulsion: III
NASA Astrophysics Data System (ADS)
Conversion of pulses of CO2 laser energy (18 microsecond pulses) to propellant kinetic energy was studied in a Myrabo Laser Lightcraft (MLL) operating with laser heated STP air and laser ablated delrin propellants. The MLL incorporates an inverted parabolic reflector that focuses laser energy into a toroidal volume where it is absorbed by a unit of propellant mass that subsequently expands in the geometry of the plug nozzle aerospike. With Delrin propellant, measurements of the coupling coefficients and the ablated mass as a function of laser pulse energy showed that the efficiency of conversion of laser energy to propellant kinetic energy was approximately 54%. With STP air, direct experimental measurement efficiency was not possible because the propellant mass associated with measured coupling coefficients was not known. Thermodynamics predicted that the upper limit of the efficiency of conversion of the internal energy of laser heated air to jet kinetic energy, (alpha) , is approximately 0.30 for EQUILIBRIUM expansion to 1 bar pressure. For FROZEN expansion (alpha) approximately 0.27. These upper limit efficiencies are nearly independent of the initial specific energy from 1 to 110 MJ/kg. With heating of air at its Mach 5 stagnation density (5.9 kg/m3 as compared to STP air density of 1.18 kg/m3) these efficiencies increase to about 0.55 (equilibrium) and 0.45 (frozen). Optimum blowdown from 1.18 kg/m3 to 1 bar occurs with expansion ratios approximately 1.5 to 4 as internal energy increases from 1 to 100 MJ/kg. Optimum expansion from the higher density state requires larger expansion ratios, 8 to 32. Expansion of laser ablated Delrin propellant appears to convert the absorbed laser energy more efficiently to jet kinetic energy because the effective density of the ablated gaseous Delrin is significantly greater than that of STP air.
Larson, Carl W.; Mead, Franklin B.; Kalliomaa, Wayne M.
Energy conversion in laser propulsion III
NASA Astrophysics Data System (ADS)
Conversion of pulses of CO2 laser energy (18 microsecond pulses) to propellant kinetic energy was studied in a Myrabo Laser Lightcraft (MLL) operating with laser heated STP air and laser ablated delrin propellants. The MLL incorporates an inverted parabolic reflector that focuses laser energy into a toroidal volume where it is absorbed by a unit of propellant mass that subsequently expands in the geometry of the plug nozzle aerospike. With Delrin propellant, measurements of the coupling coefficients and the ablated mass as a function of laser pulse energy showed that the efficiency of conversion of laser energy to propellant kinetic energy was ~ 54%. With STP air, direct experimental measurement of efficiency was not possible because the propellant mass associated with measured coupling coefficients was not known. Thermodynamics predicted that the
Larson, C. William; Mead, Franklin B.; Kalliomaa, Wayne M.
Approaches for biological and biomimetic energy conversion
This article highlights areas of research at the interface of nanotechnology, the physical sciences, and biology that are related to energy conversion: specifically, those related to photovoltaic applications. Although much ongoing work is seeking to understand basic processes of photosynthesis and chemical conversion, such as light harvesting, electron transfer, and ion transport, application of this knowledge to the development of fully synthetic and/or hybrid devices is still in its infancy. To develop systems that produce energy in an efficient manner, it is important both to understand the biological mechanisms of energy flow for optimization of primary structure and to appreciate the roles of architecture and assembly. Whether devices are completely synthetic and mimic biological processes or devices use natural biomolecules, much of the research for future power systems will happen at the intersection of disciplines.
LaVan, David A.; Cha, Jennifer N.
Novel Nuclear Powered Photocatalytic Energy Conversion
The University of Massachusetts Lowell Radiation Laboratory (UMLRL) is involved in a comprehensive project to investigate a unique radiation sensing and energy conversion technology with applications for in-situ monitoring of spent nuclear fuel (SNF) during cask transport and storage. The technology makes use of the gamma photons emitted from the SNF as an inherent power source for driving a GPS-class transceiver that has the ability to verify the position and contents of the SNF cask. The power conversion process, which converts the gamma photon energy into electrical power, is based on a variation of the successful dye-sensitized solar cell (DSSC) design developed by Konarka Technologies, Inc. (KTI). In particular, the focus of the current research is to make direct use of the high-energy gamma photons emitted from SNF, coupled with a scintillator material to convert some of the incident gamma photons into photons having wavelengths within the visible region of the electromagnetic spectrum. The high-energy gammas from the SNF will generate some power directly via Compton scattering and the photoelectric effect, and the generated visible photons output from the scintillator material can also be converted to electrical power in a manner similar to that of a standard solar cell. Upon successful implementation of an energy conversion device based on this new gammavoltaic principle, this inherent power source could then be utilized within SNF storage casks to drive a tamper-proof, low-power, electronic detection/security monitoring system for the spent fuel. The current project has addressed several aspects associated with this new energy conversion concept, including the development of a base conceptual design for an inherent gamma-induced power conversion unit for SNF monitoring, the characterization of the radiation environment that can be expected within a typical SNF storage system, the initial evaluation of Konarka's base solar cell design, the design and fabrication of a range of new cell materials and geometries at Konarka's manufacturing facilities, and the irradiation testing and evaluation of these new cell designs within the UML Radiation Laboratory. The primary focus of all this work was to establish the proof of concept of the basic gammavoltaic principle using a new class of dye-sensitized photon converter (DSPC) materials based on KTI's original DSSC design. In achieving this goal, this report clearly establishes the viability of the basic gammavoltaic energy conversion concept, yet it also identifies a set of challenges that must be met for practical implementation of this new technology.
White,John R.; Kinsmen,Douglas; Regan,Thomas M.; Bobek,Leo M.
Energy and free energy analyses of photovoltaic energy conversion
NASA Astrophysics Data System (ADS)
A thermodynamic analysis of the standard solar cell is presented. By using internal energy and entropy continuity equations for the electrons and holes, a free-energy equation for the whole device which identifies the irreversible processes is obtained. Consideration of the interaction of the cell with the radiation field allows the entropy generation associated with this and hence the total heat transfer to the lattice vibrations, acting as a cold heat reservoir, to be calculated. The relation of photovoltaic energy conversion to the thermodynamic Carnot efficiency is explained.
Parrott, J. E.
Conversion of radiant light energy in photobioreactors
The conversion of radiant light energy into chemical affinity by microorganisms in photobioreactors is examined. The kinetics of entropy production in the system is theoretically established from entropy and energy balances for the material and photonic phases in the reactor. A negative chemical affinity term compensated for by a radiant energy term at a higher level of energy characterizes photosynthetic organisms. The local volumetric rate of radiant light energy absorbed, which appears in the dissipation function as an irreversible term, is calculated for monodimensional approximations providing analytical solutions and for general tridimensional equations requiring the solution of a new numerical algorithm. Solutions for the blue-green alga Spirulina platensis cultivated in photoreactors with different geometries and light energy inputs are compared. Thermodynamic efficiency of the photosynthesis is calculated. The highest value of 15% found for low radiant energy absorption rates corresponds to a maximum quantum yield in the reactor.
Cornet, J.F.; Dussap, C.G.; Gros, J.B. (Univ. Blase Pascal, Aubiere (France). Lab. de Genie Chimique Biologique)
Nanoengineered Materials for Thermoelectric Energy Conversion
NASA Astrophysics Data System (ADS)
In this chapter we review recent advances in nanoengineered materials for thermoelectric energy conversion. We start by a brief overview of the fundamental interactions between heat and electricity, i.e., thermoelectric effects. A key requirement to improve the energy conversion efficiency is to increase the Seebeck coefficient (S) and the electrical conductivity (? ), while reducing the thermal conductivity (?). Nanostructures make it possible to modify the fundamental trade-offs between the bulk material properties through the changes in the density of states and interface effects on the electron and phonon transport. We will review recent experimental and theoretical results on superlattice and quantum dot thermoelectrics, nanowires, thin-film microrefrigerators, and solid-state thermionic power generation devices. In the latter case, the latest experimental results for semimetal rare-earth nanoparticles in a III-V semiconductor matrix as well as nitride metal/semiconductor multilayers will be discussed. We will briefly describe recent developments in nonlinear thermoelectrics, as well as electrically pumped optical refrigeration and graded thermoelectric materials. It is important to note that, while the material thermoelectric figure of merit (Z = S2? /? ) is a key parameter to optimize, one has to consider the whole system in an energy conversion application, and system optimization sometimes places other constraints on the materials.We will also review challenges in the experimental characterization of thin film thermoelectric materials. Finally, we will assess the potential of some of the more exotic techniques such as thermotunneling and bipolar thermoelectric effects.
Shakouri, Ali; Zebarjadi, Mona
Thermal to electricity conversion using thermal magnetic properties
A system for the generation of Electricity from Thermal Energy using the thermal magnetic properties of a Ferromagnetic, Electrically Conductive Material (FECM) in one or more Magnetic Fields. A FECM is exposed to one or more Magnetic Fields. Thermal Energy is applied to a portion of the FECM heating the FECM above its Curie Point. The FECM, now partially paramagnetic, moves under the force of the one or more Magnetic Fields. The movement of the FECM induces an electrical current through the FECM, generating Electricity.
West, Phillip B [Idaho Falls, ID; Svoboda, John [Idaho Falls, ID
Power Storage and Conversion from an Ocean Microbial Energy Source
Long term microbial energy is readily available in the ocean, both in sediment and the water column. Making this energy accessible in a useful way for modern electronics requires efficient power conversion and significant bulk energy storage. This paper describes methods based on both direct DC-DC conversion and bulk storage in capacitor banks before conversion
L. R. McBride; P. Girguis; C. E. Reimers
Bio-Inspired Solar Energy Conversion
NASA Astrophysics Data System (ADS)
The areas of solar-powered catalysts for energy rich fuels formation and bio-inspired molecular assemblies for integrating photon-to-fuels pathways have been identified by the Office of Basic Energy Sciences of the U. S. Department of Energy as challenges for the next generation of sustainable, high-efficiency solar energy conversion systems [1]. The light-harvesting, energy-transducing and carbon compound-synthesizing (carbon dioxide-fixing) reactions that are encompassed by natural photosynthesis offer molecular paradigms for efficient free energy capture and storage. We seek to emulate these features in cell-free, protein-based systems. Our goal is to transform the robust (alpha,beta)8-barrel fold of an enzyme that naturally catalyzes radical reactions into a catalytic module for the reduction of carbon dioxide to formate, by using the cobalt-containing cobalamins and other organocobalt centers. The activation of the catalytic center will be driven by photo-reduction, by using soluble and attached organic or semiconductor architectures. Progress on the biochemical, chemical, physical, and molecular biological (including rational design of high binding affinity and reactivity towards carbon dioxide) approaches to the development of the photocatalytic system will be presented.[4pt] [1] Lewis, N.; Crabtree, G. In: Basic Research Needs for Solar Energy Utilization, Basic Energy Sciences Workshop on Solar Energy Utilization, Energy, U.S. Department of Energy, Office of Science: 2005.
Warncke, Kurt
System Performance Projections for TPV Energy Conversion
TPV technology has advanced rapidly in the last five years, with diode conversion efficiency approaching >30%, and filter efficiency of {approx}80%. These achievements have enabled repeatable testing of 20% efficient small systems, demonstrating the potential of TPV energy conversion. Near term technology gains support a 25% efficient technology demonstration in the two year timeframe. However, testing of full size systems, which includes efficiency degradation mechanisms, such as: nonuniform diode illumination, diode and filter variability, temperature non-uniformities, conduction/convection losses, and lifetime reliability processes needs to be performed. A preliminary analysis of these differential effects has been completed, and indicates a near term integrated system efficiency of {approx}15% is possible using current technology, with long term growth to 18-20%. This report addresses the system performance issues.
PF Baldasaro; MW Dashiell; JE Oppenlander; JL Vell; P Fourspring; K Rahner; LR Danielson; S Burger; E Brown
Wind energy conversion: is it environmentally acceptable
An overview of the current status of the knowledge regarding potential environmental impediments to the commercialization of Wind Energy Conversion System (WECS) is presented. The text also identifies pertinent studies conducted in each area and summarizes the conclusions of the studies. In rough order of importance, the identified environmental impediments to the widespread use of WECS are as follows: electromagnetic interference; land use; aesthetics visual pollution; noise; and biophysical effects. Assessment of the environmental impacts of wind energy conversion system as they reflect to the five generic areas investigated is summarized. The results indicate that of the five generic areas, only the television video signal interference and specific very local impacts related to land use and aesthetics are nonnegligible factors. The severity of the television interference problem has been well studied and verified analytical relationships have been established for determining the extent of the interference zone, which in even the worst case is limited to 4 to 6 km (2 or 3 miles) from a WECS with a rotor diameter of 38 m (125 ft). Fringe reception areas, where the worst interference is encountered, generally have access to cable television, which eliminates the problem. With smaller rotor diameters, the problem should be negligible and additional investigations are currently underway to verify this hypothesis. The potential problems relating to land use and aesthetics are site-specific and depending on the nature of the problem may be relatively hard to resolve. However, it can be concluded in general there appear to be no insurmountable environmental constraints on the general widespread use of wind energy conversion systems.
Cingo, R.P.
River Inflow Characteristics for Hydrokinetic Energy Conversion
NASA Astrophysics Data System (ADS)
Most of our knowledge on current energy conversion resource characterization is derived from the wind power industry. River current resource characterization for hydrokinetic technologies can certainly borrow from this knowledge base, but must consider unique attributes associated with river hydrodynamics. Published turbulent flow data from large rivers, a canal and laboratory flumes are reviewed to determine the range of velocities and longitudinal turbulence intensities acting on hydrokinetic technologies, and also to evaluate the validity of classical models that describe the depth variation of the time-mean velocity and turbulent Reynolds stresses. A key challenge in river flow characterization is the high variability of depth and flow over the design life of a hydrokinetic device. This variation will have significant effects on the inflow mean velocity and turbulence intensity experienced by the hydrokinetic device, which requires further investigation. These effects may significantly alter estimates of energy production, structural loads, and ultimately the cost of energy at a river resource site.
Neary, V. S.; Sale, D.; Gunawan, B.
Photovoltaic and photoelectrochemical solar energy conversion
Several essential and common aspects of photovoltaics, photoelectrochemistry, and photogalvanics are considered in an interdisciplinary situation limited to systems which have not or have hardly reached the stage of practical development. The topics covered are the fundamentals of recombination in solar cells, theoretical and experimental aspects of hetrojunctions and semiconductor/metal Schottky barriers, photoelectrochemical cells, photogalvanic cells, and surfactant assemblies. The eight chapters form the proceedings of a NATO Advanced Study Institute on Photovoltaic and Photoelectrochemical Solar Energy Conversion held August 25-September 5, 1980, at Gent, Belgium.
Cardon, F.; Dekeyser, W.; Gomes, W.P.
Alternative energy sources session ocean thermal energy conversion: Technology development
NASA Astrophysics Data System (ADS)
Four ocean-energy technologies with significant promise are explored: ocean thermal energy conversion; wave power; ocean currents; and salinity gradients. The major funding emphasis has been in OTEC. Technical developments, accomplishments and major findings, remaining problems, and proposed plans for the future are discussed.
Richards, W. E.; Vadus, J. R.
Thermophotovoltaic energy conversion: Technology and market potential
NASA Astrophysics Data System (ADS)
This report contains material displayed on poster panels during the Conference. The purpose of the contribution was to present a summary of the business overview of thermophotovoltaic generation of electricity and its market potential. The market analysis has shown that the TPV market, while currently still in an early nucleation phase, is evolving into a range of small niche markets out of which larger-size opportunities can emerge. Early commercial applications on yachts and recreational vehicles which require a quiet and emission-free compact electrical generator fit the current TPV technology and economics. Follow-on residential applications are attractive since they can combine generation of electricity with space and hot water heating in a co-generation system. Development of future markets in transportation, both private and communal or industrial, will be driven by legislation requiring emission-free vehicles, and by a reduction in TPV systems cost. As a result of ``moving down the learning curve,'' growing power and consumer markets are predicted to come into reach of TPV systems, a development favored by high overall energy conversion efficiency due to high radiation energy density and to high electric conversion efficiency available with photovoltaic cells.
Ostrowski, Leon J.; Pernisz, Udo C.; Fraas, Lewis M.
Supramolecular nanoarchitectures for light energy conversion.
Recent developments in synthetic and supramolecular techniques have made it possible to control precisely, organize and arrange molecules at the nanometre level. Such synthetic and supramolecular strategies enable us to construct photofunctional molecular architectures for light energy conversion, such as photovoltaics. In photovoltaic cells, processes such as light-harvesting, charge separation for carrier generation, and carrier transport are generally required. Therefore, the construction of supramolecular assemblies based on these three processes is interesting and promising for the future development of photovoltaics. In this perspective, the focus is on the recent developments of supramolecular systems for light energy conversion, which are mainly composed of porphyrin dyes and nanocarbon materials, such as fullerenes and carbon nanotubes. The specific topics are as follows: (i) preparation, photodynamics, and photoelectrochemistry of self-assembled porphyrin nanoparticles prepared by simple blend, (ii) highly organized supramolecular nanoassemblies of porphyrins and fullerenes using gold nanoparticles, dendritic and polypeptide structures, (iii) the supramolecular formation and photoelectrochemical property of carbon nanotubes, and (iv) supramolecular photofunctional nanorods of porphyrins. PMID:20024442
Hasobe, Taku
Significant achievements in Ocean Thermal Energy Conversion (OTEC) technology have increased the probability of producing OTEC-derived power in this decade with subsequent large-scale commercialization to follow by the turn of the century. Under U.S. Department of Energy funding, Interstate Electronics has prepared an OTEC Programmatic Environmental Assessment (EA) that considers tne development, demonstration, and commercialization of OTEC power systems. The EA considers several tecnnological designs (open cycle and closed cycle), plant configurations (land-based, moored, and plantship), and power usages (baseload electricity and production of ammonia and aluminum). Potencial environmental impacts, health and safety issues, and a status update of international, federal, and state plans and policies, as they may influence OTEC deployments, are included.
Sands, M.Dale
Superconducting magnetic energy storage
Fusion power production requires energy storage and transfer on short time scales to create confining magnetic fields and for heating plasmas. The theta pinch Scyllac Fusion Test Reactor (SFTR) requires 480 MJ of energy to drive the 5-T compression field with a 0.7-ms rise time. Tokamak Experimental Power Reactors (EPR) require 1 to 2 GJ of energy with a 1
J. D. Rogers
Internal conversion coefficients for magnetic multipoles for z=39
Results of new internal conversion calculations for two values of gamma-energy equal to 0.05 mc2 and 0.15 mc2 are presented and compared with earlier works of Rose, and Sliv and Band in the case of Y87. Matrix-elements for the surface current model and the no-penetration model are presented. Differences were found between present calculations and the earlier works for k
C. P. Bhalla
Internal conversion coefficients for magnetic multipoles for z =39
Results of new internal conversion calculations for two values of gamma-energy equal to 0.05 mc2 and 0.15 mc2 are presented and compared with earlier works ofRose, andSliv andBand in the case of Y87. Matrix-elements for the surface current model and the no-penetration model are presented. Differences were found between present calculations and the earlier works fork equal to 0.05 mc2
C. P. Bhalla
Energy conversion efficiencies of thermoelectric pallets (Bi2Pb3,Bi2Te3 and Pb2Te3) under the influences of electric and magnetic fields
NASA Astrophysics Data System (ADS)
This paper aims to introduce the ability of thermo electric pallets to convert waste heat into electricity and also about the effect of electric or magnetic fields, which can exist already or applied in the conditions of their operation. Three thermo electric pallets (Bi2Pb3,Bi2Te3 and Pb2Te3) of cylindrical dimensions are prepared by 15mm mixture of different compositions. Thermo emf generations are carried out in the normal mode and then under the influence of applied electric and magnetic fields of different magnitudes in the temperature range of 460K.
Singh, Jaspal; Verma, S. S.
Principles of photoelectrochemical solar energy conversion
NASA Astrophysics Data System (ADS)
Photoelectrochemical devices for conversion of solar energy into both electrical energy and chemical energy are discussed with emphasis on how the various material properties of the photoactive electrodes influence device efficiency and stability. The similarity between photoelectrochemical cells (PECs) and solid state devices is used to model their behavior and optimize such parameters as band gap, doping level, minority carrier lifetime, etc. A model is presented which calculates the electron affinity of any semiconductor and allows the prediction of the open circuit voltage of wet photovoltaic cells and optimum biasing for chemical producing cells. The effects of absorbed ions at the semiconductor/electrolyte interface are reviewed. The temperature dependence of the energy levels in the semiconductor and the electrolyte are considered and the implications of these results to operation of PECs at elevated temperature are discussed. The major differences between PECs and solid state devices are the stability considerations. The thermodynamics of this problem is discussed. Other important degradation mechanisms and some solutions to these problems are reviewed. Finally, a prognosis of the future of this field is presented.
Butler, M. A.; Ginley, D. S.
Stochastic conversions of TeV photons into axion-like particles in extragalactic magnetic fields
NASA Astrophysics Data System (ADS)
Very-high energy photons emitted by distant cosmic sources are absorbed on the extragalactic background light (EBL) during their propagation. This effect can be characterized in terms of a photon transfer function at Earth. The presence of extragalactic magnetic fields could also induce conversions between very high-energy photons and hypothetical axion-like particles (ALPs). The turbulent structure of the extragalactic magnetic fields would produce a stochastic behaviour in these conversions, leading to a statistical distribution of the photon transfer functions for the different realizations of the random magnetic fields. To characterize this effect, we derive new equations to calculate the mean and the variance of this distribution. We find that, in presence of ALP conversions, the photon transfer functions on different lines of sight could have relevant deviations with respect to the mean value, producing both an enhancement or a suppression in the observable photon flux with respect to the expectations with only absorption. As a consequence, the most striking signature of the mixing with ALPs would be a reconstructed EBL density from TeV photon observations which appears to vary over different directions of the sky: consistent with standard expectations in some regions, but inconsistent in others.
Mirizzi, Alessandro; Montanino, Daniele
Thermoelectric energy conversion with solid electrolytes.
The alkali metal thermoelectric converter (AMTEC) is a device for the direct conversion of heat to electrical energy. The sodium ion conductor beta"- alumina is used to form a high-temperature regenerative concentration cell for elemental sodium. An AMTEC of mature design should have an efficiency of 20 to 40 percent, a power density of 0.5 kilowatt per kilogram or more, no moving parts, low maintenance requirements, high durability, and efficiency independent of size. It should be usable with high-temperature combustion, nuclear, or solar heat sources. Experiments have demonstrated the feasibility of the AMTEC and confirmed the theoretical analysis of the device. A wide range of applications from aerospace power to utility power plants appears possible. PMID:17748444
Cole, T
Engineered nanomaterials for solar energy conversion.
Understanding how to engineer nanomaterials for targeted solar-cell applications is the key to improving their efficiency and could lead to breakthroughs in their design. Proposed mechanisms for the conversion of solar energy to electricity are those exploiting the particle nature of light in conventional photovoltaic cells, and those using the collective electromagnetic nature, where light is captured by antennas and rectified. In both cases, engineered nanomaterials form the crucial components. Examples include arrays of semiconductor nanostructures as an intermediate band (so called intermediate band solar cells), semiconductor nanocrystals for multiple exciton generation, or, in antenna-rectifier cells, nanomaterials for effective optical frequency rectification. Here, we discuss the state of the art in p-n junction, intermediate band, multiple exciton generation, and antenna-rectifier solar cells. We provide a summary of how engineered nanomaterials have been used in these systems and a discussion of the open questions. PMID:23298882
Mlinar, Vladan
Modeling and analysis of energy conversion systems
An investigation was conducted to assess the need for and the feasibility of developing a computer code that could model thermodynamic systems and predict the performance of energy conversion systems. To assess the market need for this code, representatives of a few industrial organizations were contacted, including manufacturers, system and component designers, and research personnel. Researchers and small manufacturers, designers, and installers were very interested in the possibility of using the proposed code. However, large companies were satisfied with the existing codes that they have developed for their own use. Also, a survey was conduced of available codes that could be used or possibly modified for the desired purpose. The codes were evaluated with respect to a list of desirable features, which was prepared as a result of the survey. A few publicly available codes were found that might be suitable. The development, verification, and maintenance of such a code would require a substantial, ongoing effort. 21 refs.
Den Braven, K.R. (Idaho Univ., Moscow, ID (USA). Dept. of Mechanical Engineering); Stanger, S. (EG and G Idaho, Inc., Idaho Falls, ID (USA))
Photovoltaic Energy Conversion - Research Projects on Solar Energy Use.
National Technical Information Service (NTIS)
The report reviews the development of photovoltaic energy conversion and the past and present BMFT-funded research in this field, most of which is orientated towards immediate applicability. There is a trend in the direction of marketable products for sol...
Transport theory of semiconductor energy conversion
A systematic analysis of all the microscopic processes corresponding to macroscopic energy conversion in semiconductors is presented. Starting from the quasi-classical particle Boltzmann equations, a continuity equation for total energy is derived containing terms which can be identified with external electric power transfers. Similar continuity equations for internal energy and entropy are obtained, and from the latter, the irreversible entropy generation rate may be found. Using expressions for the particle and heat currents, the usual ohmic heating, thermoelectric and photoelectric effects are identified together with a new reversible effect whose magnitude is PsidelphidelT/T, where Psi = (sigma/sub e/sigma/sub h//sigma) T(..sigma../sub h/-..sigma../sub e/). Here sigma/sub e/,sigma/sub h/ are partial electron and hole electrical conductivities, sigma = sigma/sub e/ +sigma/sub h/, ..sigma../sub e/ and ..sigma../sub h/ are the partial electron and hole Seebeck coefficients, phi is the difference between the electron and hole quasi-Fermi levels, and T is the temperature. Similarly, a complete account is given of the heating and refrigerating processes within the semiconductor. The analysis allows for the possibility of band structure inhomogeneities.
Parrott, J.E.
New highly polar semiconductor ferroelectrics for solar energy conversion devices
Solar energy is a promising long-term solution for future energy requirements; however, current solar energy conversion devices are plagued by low efficiency. The use of ferroelectric ABO3 perovskite oxides is one approach for boosting conversion efficiency. Ferroelectric oxides possess spontaneous polarization and have been shown to produce a bulk photovoltaic effect, in which charged carriers, specifically electrons and holes, separate
Andrew M. Rappe; Ilya Grinberg; Joseph W. Bennett
Axial inlet conversion to a centrifugal compressor with magnetic bearings
NOVA's Alberta Gas Transmission Division transports natural gas via pipeline throughout the province of Alberta, Canada, exporting it to eastern Canada, US, and British Columbia. There is a continuing effort to operate the facilities and pipeline at the highest possible efficiency. One area being addressed to improve efficiency is compression of the gas. By improving compressor efficiency, fuel consumption and hence operating costs can be reduced. One method of improving compressor efficiency is by converting the compressor to an axial inlet configuration, a conversion that has been carried out more frequently in the past years. Concurrently, conventional hydrodynamic bearings have been replaced with magnetic bearings on many centrifugal compressors. This paper discusses the design and installation for converting a radial overhung unit to an axial inlet configuration, having both magnetic bearings and a thrust reducer. The thrust reducer is required to reduce axial compressor shaft loads, to a level that allows the practical installation of magnetic bearings within the space limitations of the compressor (Bear and Gibson, 1992).
Novecosky, T. (NOVA Corp., Edmonton, Alberta (Canada))
Photonic Crystals for Enhancing Thermophotovoltaic Energy Conversion
Thermophotovoltaics (TPV) converts the radiant energy of a thermal source into electrical energy using photovoltaic cells. TPV has a number of attractive features, including: fuel versatility (nuclear, fossil, solar, etc.), quiet operation, low maintenance, low emissions, light weight, high power density, modularity, and possibility for cogeneration of heat and electricity. Some of these features are highly attractive for military applications (Navy and Army). TPV could also be used for distributed power and automotive applications wherever fuel cells, microturbines, or cogeneration are presently being considered if the efficiencies could be raised to around 30%. This proposal primarily examine approaches to improving the radiative efficiency. The ideal irradiance for the PV cell is monochromatic illumination at the bandgap. The photonic crystal approach allows for the tailoring of thermal emission spectral bandwidth at specific wavelengths of interest. The experimental realization of metallic photonic crystal structures, the optical transmission, reflection and absorption characterization of it have all been carried out in detail and will be presented next. Additionally, comprehensive models of TPV conversion has been developed and applied to the metallic photonic crystal system.
Status of thermoelectronic laser energy conversion, TELEC
NASA Technical Reports Server (NTRS)
A concept known as a thermo-electronic laser energy converter (TELEC), was studied as a method of converting a 10.6 micron CO2 laser beam into electric power. The calculated characteristics of a TELEC seem to be well matched to the requirements of a spacecraft laser energy conversion system. The TELEC is a high power density plasma device which absorbs an intense laser beam by inverse bremsstrahlung with the plasma electrons. In the TELEC process, electromagnetic radiation is absorbed directly in the plasma electrons producing a high electron temperature. The energetic electrons diffuse out of the plasma striking two electrodes which are in contact with the plasma at the boundaries. These two electrodes have different areas: the larger one is designated as the collector, the smaller one is designated as the emitter. The smaller electrode functions as an electron emitter provide continuity of the current. Waste heat is rejected from the collector electrode. An experiment was carried out with a high power laser using a cesium vapor TELEC cell with 30 cm active length. Laser supported plasma were produced in the TELEC device during a number of laser runs over a period of several days. Electric power from the TELEC was observed with currents in the range of several amperes and output potentials of less than 1 volt.
Britt, E. J.
Net energy analysis of small wind energy conversion systems
NASA Astrophysics Data System (ADS)
The net energy of a small wind electric conversion system is calculated and compared with the net energy of other electricity sources. Net energy is the amount of energy remaining for consumer use after deducting the energy required to find and upgrade the energy source and construct and maintain the electricity generating system. A 3 kW rated wind electric system for residential use is examined. The amount of energy obtained from this system is estimated by using a computer-operated simulation model which incorporates wind speeds, residential electricity demands and parameters from the generator, inverter and storage components. The net energy gain for this wind system is better than that of other systems with which it is compared.
Haack, B. N.
Comparison of local energy conversion estimates from Cluster with global MHD simulations
NASA Astrophysics Data System (ADS)
The local energy conversion across the magnetopause has been estimated with Cluster for two magnetopause crossings. A load region, conversion from magnetic to particle energy, was identified on the dayside high-latitude magnetopause during south/dawnward IMF. Another crossing of the dawn flank magnetotail during dominantly duskward IMF was identified as a generator region where the magnetosphere is loaded with magnetic energy. The observations have been compared to results of the BATS-R-US global MHD simulation based on observed IMF conditions. BATS-R-US reproduced the magnetopause regions crossed by Cluster as a load and a generator region, correspondingly. The magnitude of the estimated energy conversion from Cluster and the model are in quite good agreement. BATS-R-US cannot reproduce the observed sharp magnetopause and some topological differences between the observations and the model occur.
Rosenqvist, L.; Opgenoorth, H. J.; Rastaetter, L.; Vaivads, A.; Dandouras, I.; Buchert, S.
Energy Conversion Alternatives Study (ECAS), General Electric Phase 1. Volume 3: Energy conversion subsystems and components. Part 1: Bottoming cycles and materials of construction
NASA Technical Reports Server (NTRS)
Energy conversion subsystems and components were evaluated in terms of advanced energy conversion systems. Results of the bottoming cycles and materials of construction studies are presented and discussed.
Shah, R. P.; Solomon, H. D.
Solar energy conversion using surface plasmons for broadband energy transport
NASA Technical Reports Server (NTRS)
A new strategy for efficient solar energy conversion based on parallel processing with surface plasmons is introduced. The approach is unique in identifying: (1) a broadband carrier with suitable range for energy transport, and (2) a technique to extract more energy from the more energetic photons, without sequential losses or unique materials for each frequency band. The aim is to overcome the fundamental losses associated with the broad solar spectrum and to achieve a higher level of spectrum splitting than has been possible in semiconductor systems.
Anderson, L. M.
Progress on PEP-II Magnet Power Conversion System?
The various power systems for supplying the PEP-II DCmagnets rely exclusively on switch mode conversion, utilizing a varietyof means depending on the requirements. All of the larger power supplies,ranging from 10 to 200 kW, are powered from DC sources utilizingrectified 480 V AC. Choppers can be used for the series connectedstrings, but for smaller groups and individual magnets, inverters drivinghigh-frequency transformers with secondary rectifiers comprise the bestapproach. All of the various systems use a "building block" approach ofmultiple standard-size units connected in series or parallel to mostcost-effectively deal with a great range of voltage and currentrequirements. Utilization of existing infrastructure from PEP-I has beena cost-effective determinant. Equipment is being purchased eitheroff-the-shelf, through performance specification, or by hardware purchasebased on design-through-prototype. The corrector magnet power system,utilizing inexpensive, off-the-shelf four-quadrant switching motorcontrollers, has already proven very reliable: 120 of the total of 900units have been running on the injection system for four months with nofailures.
Bellomo, P.; Genova, L.; Jackson, T.; Shimer, D.
Soft Magnetic Materials for Improved Energy Performance
NASA Astrophysics Data System (ADS)
A main focus of sustainable energy research has been development of renewable energy technologies (e.g. from wind, solar, hydro, geothermal, etc.) to decrease our dependence on non-renewable energy resources (e.g. fossil fuels). By focusing on renewable energy sources now, we hope to provide enough energy resources for future generations. In parallel with this focus, it is essential to develop technologies that improve the efficiency of energy production, distribution, and consumption, to get the most from these renewable resources. Soft magnetic materials play a central role in power generation, conditioning, and conversion technologies and therefore promoting improvements in the efficiency of these materials is essential for our future energy needs. The losses generated by the magnetic core materials by hysteretic, acoustic, and/or eddy currents have a great impact on efficiency. A survey of soft magnetic materials for energy applications will be discussed with a focus on improvement in performance using novel soft magnetic materials designed for these power applications. A group of premiere soft magnetic materials -- nanocrystalline soft magnetic alloys -- will be highlighted for their potential in addressing energy efficiency. These materials are made up of nanocrystalline magnetic transition metal-rich grains embedded within an intergranular amorphous matrix, obtained by partial devitrification of melt-spun amorphous ribbons. The nanoscale grain size results in a desirable combination of large saturation induction, low coercivity, and moderate resistivity unobtainable in conventional soft magnetic alloys. The random distribution of these fine grains causes a reduction in the net magnetocrystalline anisotropy, contributing to the excellent magnetic properties. Recently developed (Fe,Co,Ni)88Zr7B4Cu1 alloys will be discussed with a focus on the microstructure/magnetic property relationship and their effects on the energy efficiency of these materials for AC applications.
Willard, Matthew
Wind Energy Conversion Using a Self-Excited Induction Generator
A wind energy conversion scheme using an induction machine driven by a variable speed wind turbine is described. Excitation control has been obtained by employing a single value capacitor and thyristor controlled inductor. Wind speed cube law is proposed to be followed in loading the induction machine for maximising energy conversion. Performance characteristics of the generation scheme have been evaluated
G. Raina; O. P. Malik
Nanostructured Solar Irradiation Control Materials for Solar Energy Conversion.
National Technical Information Service (NTIS)
Tailoring the solar absorptivity (alpha(sub s)) and thermal emissivity (epsilon(sub T)) of materials constitutes an innovative approach to solar energy control and energy conversion. Numerous ceramic and metallic materials are currently available for sola...
A. Z. Henderson C. Park C. R. Taylor G. Sauti I. A. Marshall J. Ely J. Kang J. W. Kim L. J. Gibbons M. N. Torrico P. T. Lillehei R. G. Bryant S. E. Lowther
Photochemical Solar Energy Conversion. An Assessment of Scientific Accomplishments.
National Technical Information Service (NTIS)
Research on photochemical solar energy conversion has grown exponentially. Basic sciences have benefited most from this research. The tenet of the present Feature Article is that solar energy research has appreciably contributed to the ongoing renaissance...
J. H. Fendler
Coronal Magnetic Energy Releases
NASA Astrophysics Data System (ADS)
This book brings together a variety of review articles on dynamical phenomena in the solar corona in order to work out the unifying aspects of magnetic energy releases. The experimental data from groundbased methods of radio astronomy as well as from satellites are also discussed. The book addresses researchers in astrophysics, and planetary science but should also be accessible to graduate students.
Benz, Arnold O.; Kr�ger, Albrecht
Plasmon-assisted radiolytic energy conversion in aqueous solutions
The field of conventional energy conversion using radioisotopes has almost exclusively focused on solid-state materials. Herein, we demonstrate that liquids can be an excellent media for effective energy conversion from radioisotopes. We also show that free radicals in liquid, which are continuously generated by beta radiation, can be utilized for electrical energy generation. Under beta radiation, surface plasmon obtained by the metallic nanoporous structures on TiO2 enhanced the radiolytic conversion via the efficient energy transfer between plasmons and free radicals. This work introduces a new route for the development of next-generation power sources.
Kim, Baek Hyun; Kwon, Jae W.
A novel Wind Energy Conversion System with power quality improvement features
This paper focuses on design and simulation of a novel small scale Wind Energy Conversion System (WECS) based on Permanent Magnet Generators (PMGs) and power electronic converters. Electric power is generated using a PMG whose output is having variable magnitude and variable frequency due to non-uniform wind velocity. In the proposed system output of PMG is converted to constant DC
Aswathy B. Raj
Open cycle ocean thermal energy conversion system
An improved open cycle ocean thermal energy conversion system including a flash evaporator for vaporizing relatively warm ocean surface water and an axial flow, elastic fluid turbine having a vertical shaft and axis of rotation. The warm ocean water is transmitted to the evaporator through a first prestressed concrete skirt-conduit structure circumferentially situated about the axis of rotation. The unflashed warm ocean water exits the evaporator through a second prestressed concrete skirt-conduit structure located circumferentially about and radially within the first skirt-conduit structure. The radially inner surface of the second skirt conduit structure constitutes a cylinder which functions as the turbine's outer casing and obviates the need for a conventional outer housing. The turbine includes a radially enlarged disc element attached to the shaft for supporting at least one axial row of radially directed blades through which the steam is expanded. A prestressed concrete inner casing structure of the turbine has upstream and downstream portions respectively situated upstream and downstream from the disc element. The radially outer surfaces of the inner casing portions and radially outer periphery of the axially interposed disc cooperatively form a downwardly radially inwardly tapered surface. An annular steam flowpath of increasing flow area in the downward axial direction is radially bounded by the inner and outer prestressed concrete casing structures. The inner casing portions each include a transversely situated prestressed concrete circular wall for rotatably supporting the turbine shaft and associated structure. The turbine blades are substantially radially coextensive with the steam flowpath and receive steam from the evaporator through an annular array of prestressed concrete stationary vanes which extend between the inner and outer casings to provide structural support therefor and impart a desired flow direction to the steam.
Wittig, J. Michael (West Goshen, PA)
Effect of a random magnetic field on active-sterile neutrino conversion in the supernova core
The active-sterile neutrino conversion is studied for a neutrino propagating in the axial potential generated by a magnetized electron plasma in the supernova medium. We consider the effects of a random magnetic field Brms on the average neutrino conversion probability. We obtain the constraint on Deltam2 and sin22theta for different strengths of the random magnetic fields by considering the positive
Sarira Sahu; Vishnu M. Bannur
Tandem filters using frequency selective surfaces for enhanced conversion efficiency in a thermophotovoltaic energy conversion system
This invention relates to the field of thermophotovoltaic (TPV) direct energy conversion. In particular, TPV systems use filters to minimize parasitic absorption of below bandgap energy. This invention constitutes a novel combination of front surface filters to increase TPV conversion efficiency by reflecting useless below bandgap energy while transmitting a very high percentage of the useful above bandgap energy. In particular, a frequency selective surface is used in combination with an interference filter. The frequency selective surface provides high transmission of above bandgap energy and high reflection of long wavelength below bandgap energy. The interference filter maintains high transmission of above bandgap energy and provides high reflection of short wavelength below bandgap energy and a sharp transition from high transmission to high reflection.
Dziendziel, Randolph J. (Middle Grove, NY); DePoy, David Moore (Clifton Park, NY); Baldasaro, Paul Francis (Clifton Park, NY)
Tandem filters using frequency selective surfaces for enhanced conversion efficiency in a thermophotovoltaic energy conversion system
This invention relates to the field of thermophotovoltaic (TPV) direct energy conversion. In particular, TPV systems use filters to minimize parasitic absorption of below bandgap energy. This invention constitutes a novel combination of front surface filters to increase TPV conversion efficiency by reflecting useless below bandgap energy while transmitting a very high percentage of the useful above bandgap energy. In particular, a frequency selective surface is used in combination with an interference filter. The frequency selective surface provides high transmission of above bandgap energy and high reflection of long wavelength below bandgap energy. The interference filter maintains high transmission of above bandgap energy and provides high reflection of short wavelength below bandgap energy and a sharp transition from high transmission to high reflection.
Dziendziel, Randolph J. (Middle Grove, NY); Baldasaro, Paul F. (Clifton Park, NY); DePoy, David M. (Clifton Park, NY)
Semiconductor nanowires for photovoltaic and photoelectrochemical energy conversion
NASA Astrophysics Data System (ADS)
Semiconductor nanowires (NW) possess several beneficial properties for efficient conversion of solar energy into electricity and chemical energy. Due to their efficient absorption of light, short distances for minority carriers to travel, high surface-to-volume ratios, and the availability of scalable synthesis methods, they provide a pathway to address the low cost-to-power requirements for wide-scale adaptation of solar energy conversion technologies. Here we highlight recent progress in our group towards implementation of NW components as photovoltaic and photoelectrochemical energy conversion devices. An emphasis is placed on the unique properties of these one-dimensional (1D) structures, which enable the use of abundant, low-cost materials and improved energy conversion efficiency compared to bulk devices.
Dasgupta, Neil P.; Yang, Peidong
Semiconductor nanowires for photovoltaic and photoelectrochemical energy conversion
Semiconductor nanowires (NW) possess several beneficial properties for efficient conversion of solar energy into electricity and chemical energy. Due to their efficient absorption of light, short distances for minority carriers to travel, high surface-to-volume ratios, and the availability of scalable synthesis methods, they provide a pathway to address the low cost-to-power requirements for wide-scale adaptation of solar energy conversion technologies. Here we highlight recent progress in our group towards implementation of NW components as photovoltaic and photoelectrochemical energy conversion devices. An emphasis is placed on the unique properties of these one-dimensional (1D) structures, which enable the use of abundant, low-cost materials and improved energy conversion efficiency compared to bulk devices.
Dasgupta, Neil; Yang, Peidong
Semiconductor nanowires for photovoltaic and photoelectrochemical energy conversion
NASA Astrophysics Data System (ADS)
Semiconductor nanowires (NW) possess several beneficial properties for efficient conversion of solar energy into electricity and chemical energy. Due to their efficient absorption of light, short distances for minority carriers to travel, high surface-to-volume ratios, and the availability of scalable synthesis methods, they provide a pathway to address the low cost-to-power requirements for wide-scale adaptation of solar energy conversion technologies. Here we highlight recent progress in our group towards implementation of NW components as photovoltaic and photoelectrochemical energy conversion devices. An emphasis is placed on the unique properties of these one-dimensional (1D) structures, which enable the use of abundant, low-cost materials and improved energy conversion efficiency compared to bulk devices.
Dasgupta, Neil P.; Yang, Peidong
NASA Astrophysics Data System (ADS)
Magnetic energy storage has become the foundation for near time and longer range electric utility applications and for current induction in the plasma of fusion devices. The fusion program embraces low loss superconductor strand development with integration into cables capable of carrying 50 kA in pulsed mode at high fields. This evolvement has been paralleled with pulsed energy storage coil development and testing from tens of kJ at low fields to a 20 MJ prototype tokamak induction coil at 7.5 T. Electric utility magnetic storage for prospective application is for diurnal load leveling with massive systems to store 10 GWh at 1.8 K in a dewar structure suported on bedrock underground. An immediate utility application is a 30 MJ system to be used to damp power oscillations on the Bonneville Power Administration electric transmission lines.
Rogers, J. D.
Maximum Power Point Tracking for Ocean Wave Energy Conversion
Many forms of renewable energy exist in the world's oceans, with ocean wave energy showing great potential. However, the ocean environment presents many challenges for cost-effective renewable energy conversion, including optimal control of a wave energy converter (WEC). This paper presents a maximum power point tracking (MPPT) algorithm for control of a point absorber WEC. The algorithm and testing hardware
Ean A. Amon; Ted K. A. Brekken; Alphonse A. Schacher
Economic Factors and Incentives for Ocean Wave Energy Conversion
Ocean energy conversion systems have recently seen renewed interest, stimulated mostly by today's increasing energy discussions. In addition to ocean current energy converters, several commercial ocean wave energy projects have already been undertaken; however, no clear economic model exists for developers to follow. Therefore, this paper focuses on U.S. economic factors that affect the use of wave power for generation
Jennifer G. Vining; Annette Muetze
Economic Factors and Incentives for Ocean Wave Energy Conversion
Ocean energy conversion systems have recently seen renewed interest, stimulated mostly by today's increasing energy discussions. In addition to ocean current energy converters, several commercial ocean wave energy projects have already been undertaken, but no clear economic model exists for developers to follow. Therefore, this paper focuses on U.S. economic factors that affect the use of wave power for generation
J. G. Vining; A. Muetze
Semiconductor Nanowires and Nanotubes for Energy Conversion
NASA Astrophysics Data System (ADS)
In recent years semiconductor nanowires and nanotubes have garnered increased attention for their unique properties. With their nanoscale dimensions comes high surface area and quantum confinement, promising enhancements in a wide range of applications. 1-dimensional nanostructures are especially attractive for energy conversion applications where photons, phonons, and electrons come into play. Since the bohr exciton radius and phonon and electron mean free paths are on the same length scales as nanowire diameters, optical, thermal, and electrical properties can be tuned by simple nanowire size adjustments. In addition, the high surface area inherent to nanowires and nanotubes lends them towards efficient charge separation and superior catalytic performance. In thermoelectric power generation, the nanoscale wire diameter can effectively scatter phonons, promoting reductions in thermal conductivity and enhancements in the thermoelectric figure of merit. To that end, single-crystalline arrays of PbS, PbSe, and PbTe nanowires have been synthesized by a chemical vapor transport approach. The electrical and thermal transport properties of the nanowires were characterized to investigate their potential as thermoelectric materials. Compared to bulk, the lead chalcogenide nanowires exhibit reduced thermal conductivity below 100 K by up to 3 orders of magnitude, suggesting that they may be promising thermoelectric materials. Smaller diameters and increased surface roughness are expected to give additional enhancements. The solution-phase synthesis of PbSe nanowires via oriented attachment of nanoparticles enables facile surface engineering and diameter control. Branched PbSe nanowires synthesized by this approach showed near degenerately doped charge carrier concentrations. Compared to the bulk, the PbSe nanowires exhibited a similar Seebeck coefficient and a significant reduction in thermal conductivity in the temperature range 20 K to 300 K. Thermal annealing of the PbSe nanowires allowed their thermoelectric properties to be controllably tuned by increasing their carrier concentration or hole mobility. After optimal annealing, single PbSe nanowires exhibited a thermoelectric figure of merit (ZT) of 0.12 at 300 K. In addition, using a field-effect gated device, the Seebeck coefficient of single PbSe nanowires could be tuned from 64 to 193 muV?K-1. This direct electrical field control of the electrical conductivity and Seebeck coefficient suggests a powerful strategy for optimizing ZT in thermoelectric devices and these results represent the first demonstration of field-effect modulation of the thermoelectric figure of merit in a single semiconductor nanowire. This novel strategy for thermoelectric property modulation could prove especially important in optimizing the thermoelectric properties of semiconductors where reproducible doping is difficult to achieve. Recent theoretical work has shown large enhancements in ZT for single-crystal nanowires containing nanoscale interfaces along their lengths. M2O3(ZnO) n ( M = In, Ga, Fe) superlattice nanowires were synthesized via a novel solid-state diffusion approach to investigate this possible enhancement. Using atomic resolution Z-contrast STEM imaging a detailed structural analysis was performed on In2-xGaxO3(ZnO) n nanowires, leading to the discovery that octahedral inclusions within the superlattice structure are likely generated through a defect-assisted process. Single-nanowire thermal and electrical measurements on In2-x GaxO3(ZnO)n reveal a simultaneous improvement in all contributing factors to the thermoelectric figure of merit, giving an order of magnitude enhancement over similar bulk materials at room temperature. This is the first report of enhancement of all three thermoelectric parameters (Seebeck coefficient, electrical conductivity, and thermal resistivity) for a nanowire system. Photoelectrochemical water splitting is another exciting renewable energy application that can benefit from the high surface area of nanomaterials. Recently, (Ga1-xZnx)(N1-xOx) has gained
Fardy, Melissa Anne
Nanostructured Composite Materials for High Temperature Thermoelectric Energy Conversion.
National Technical Information Service (NTIS)
The goals of this project were to synthesize, characterize and model bulk nanostructured composite materials for thermoelectric energy conversion applications. The objective was to produce materials which demonstrate an increase in intrinsic thermoelectri...
C. J. O'Connor
Solar Energy Conversion Based on the Principle of Fluorescent Collectors.
National Technical Information Service (NTIS)
The development of fluorescent collectors for solar energy conversion is described. Spectra, fluorescent quantum yields, stability, and absorption properties of dyes were studied. The synthesis of dyes and the manufacture of collector plates are discussed...
A. Goetzberger K. Heidler W. Stahl H. R. Wilson V. Wittwer
SWECS (Small Wind Energy Conversion Systems) Industry in the US.
National Technical Information Service (NTIS)
The small wind energy conversion systems (SWECS) industry in the United States is reviewed from its early beginnings in the 1930's, through the federally supported work, to present uses of wind power. (ERA citation 09:019974)
V. Nelson
Ocean Thermal Energy Conversion: An Overall Environment Assessment.
National Technical Information Service (NTIS)
Significant acccrmplishments in Ocean Thermal Energy Conversion (OTEC) technology have increased the probability of producing OTEC-derived power within this decade with subsequent large scale commercialization following by the turn of the century. Under U...
R. G. Bergman
Potential Impact of Ocean Thermal Energy Conversion (OTEC) on Fisheries.
National Technical Information Service (NTIS)
The commercial development of ocean thermal energy conversion (OTEC) operations will involve some environmental perturbations for which there is no precedent experience. The pumping of very large volumes of warm surface water and cold deep water and its s...
E. P. Myers D. E. Hoss W. M. Matsumoto D. S. Peters M. P. Seki
Novel Nuclear Powered Photocatalytic Energy Conversion (Final Report).
National Technical Information Service (NTIS)
The University of Massachusetts Lowell Radiation Laboratory (UMLRL) is involved in a comprehensive project to investigate a unique radiation sensing and energy conversion technology with applications for in-situ monitoring of spent nuclear fuel (SNF) duri...
J. R. White D. Kinsman T. M. Regan L. M. Bobek
Monolithic Interconnected Modules (MIMs) for Thermophotovoltaic Energy Conversion.
National Technical Information Service (NTIS)
Monolithic Interconnected Modules (MIM) are under development for thermophotovoltaic (TPV) energy conversion applications. MIM devices are typified by series-interconnected photovoltaic cells on a common, semi-insulating substrate and generally include re...
D. Wilt, R. Wehrer, M. Palmisiano, M. Wanlass, C. Murray
Experimental demonstration of thermoacoustic energy conversion in a resonator.
Using thermoacoustic energy conversions, both amplification and damping of acoustic intensity are demonstrated. A differentially heated regenerator is installed near the velocity node of the resonator and thereby a high specific acoustic impedance and a traveling wave phase are obtained. It is shown that the gain of acoustic intensity resulting from the traveling wave energy conversion reaches 1.7 in a positive temperature gradient and 0.3 in a negative gradient. When the regenerator is replaced with a stack, it is found that the gain reaches 2.3, exceeding the temperature ratio (=1.9) of both ends of the stack. This is brought about by the addition of standing wave energy conversion. The present results would contribute to the development of new acoustic devices using thermoacoustic energy conversion. PMID:15244723
Biwa, Tetsushi; Tashiro, Yusuke; Mizutani, Uichiro; Kozuka, Motoki; Yazaki, Taichi
Chemical Energy Storage for Solar Thermal Conversion. Final Report.
National Technical Information Service (NTIS)
The technical and economic aspects of using reversible chemical reactions to store energy in Solar Thermal Electric Conversion (STEC) facilities have been studied. The study included identification of nine promising chemical reactions from a list of over ...
R. D. Smith
An Overview of the Progress in Photoelectrochemical Energy Conversion.
ERIC Educational Resources Information Center
Provides an overview of advances made in the field of photoelectrochemistry. Includes a short historical account of the development of the field, a review of the state-of-the-art of photoelectrochemical energy conversion and future prospects. (JN)
Parkinson, Bruce
Superconducting energy storage magnet
NASA Technical Reports Server (NTRS)
A superconducting magnet is formed having composite conductors arrayed in coils having turns which lie on a surface defining substantially a frustum of a cone. The conical angle with respect to the central axis is preferably selected such that the magnetic pressure on the coil at the widest portion of the cone is substantially zero. The magnet structure is adapted for use as an energy storage magnet mounted in an earthen trench or tunnel where the strength the surrounding soil is lower at the top of the trench or tunnel than at the bottom. The composite conductor may be formed having a ripple shape to minimize stresses during charge up and discharge and has a shape for each ripple selected such that the conductor undergoes a minimum amount of bending during the charge and discharge cycle. By minimizing bending, the working of the normal conductor in the composite conductor is minimized, thereby reducing the increase in resistance of the normal conductor that occurs over time as the conductor undergoes bending during numerous charge and discharge cycles.
Boom, Roger W. (Inventor); Eyssa, Yehia M. (Inventor); Abdelsalam, Mostafa K. (Inventor); Huang, Xianrui (Inventor)
Thermionic Energy Conversion Using Solid-State and Vacuum Devices
Research activities at the newly formed ONR MURI center on Thermionic Energy Conversion will be described. Center's goal is to design, fabricate and characterize direct energy conversion systems that could operate at hot side temperatures 300-650C with high efficiencies (>15-20%). The core of the solution we are investigating is an integrated approach to engineer electrical, thermal and optical properties of
Ali Shakouri
Space electric power design study. [laser energy conversion
NASA Technical Reports Server (NTRS)
The conversion of laser energy to electrical energy is discussed. Heat engines in which the laser heats the gas inside the engine through a window as well as heat engines in which the gas is heated by a thermal energy storage reservoir which has been heated by laser radiation are both evaluated, as well as the necessary energy storage, transmission and conversion components needed for a full system. Preliminary system concepts are presented and a recommended development program is outlined. It appears possible that a free displacer Stirling engine operating directly a linear electric generator can convert 65% of the incident laser energy into electricity.
Martini, W. R.
Linear mode conversion of Langmuir/z-mode waves to radiation in plasmas with various magnetic field strength
NASA Astrophysics Data System (ADS)
Linear mode conversion of Langmuir/z waves to radiation near the plasma and upper hybrid frequency at density gradients is potentially relevant to multiple solar radio emissions, ionospheric radar experiments, pulsars, and continuum radiation for planetary magnetospheres. Here we study mode conversion in warm magnetized plasmas using a numerical electron fluid simulation code when the density gradient has a wide range of angles ? to the ambient magnetic field B0 for a range of incident Langmuir/z wavevectors. Our results include: (1) Left-handed polarized ordinary (oL) and right-handed polarized extraordinary (xR) mode waves are produced between strongly and sometimes together in various range of ?=(?L/c)1/3(?ce/?) < 1.5, where ?ce is the (angular) electron cyclotron frequency, ? the angular wave frequency, L the length scale of the (linear) density gradient, and c the speed of light; (2) The xR mode is produced only for 40� <60� in the intermediately magnetized plasmas of ?=1.0 and 1.5, while it is produced in wide range of 0�?? ?90� for weakly magnetized plasmas of ?=0.1 and 0.7; (3) The maximum total conversion efficiencies for wave power from the Langmuir/z mode to radiation are of order 50-99% and the corresponding energy conversion efficiencies are 5-14% (depending on ??) for various ?; (4) The mode conversion window becomes wide as ? and ? increase. The results in this paper hence confirm that linear mode conversion under these conditions can explain the weak total circular polarizations of type II and III solar radio bursts because the strong xR mode can be generated via linear mode conversion near ? ~ 45�.
Kim, E.; Cairns, I. H.; Johnson, J.
Linear mode conversion of Langmuir/z-mode waves to radiation in plasmas with various magnetic field strength
NASA Astrophysics Data System (ADS)
Linear mode conversion of Langmuir/z waves to electromagnetic radiation near the plasma and upper hybrid frequency in the presence of density gradients is potentially relevant to type II and III solar radio bursts, ionospheric radar experiments, pulsars, and continuum radiation for planetary magnetospheres. Here, we study mode conversion in warm, magnetized plasmas using a numerical electron fluid simulation code when the density gradient has a wide range of angle, ?, to the ambient magnetic field, B0, for a range of incident Langmuir/z wavevectors. Our results include: (1) Left-handed polarized ordinary (oL) and right-handed polarized extraordinary (xR) mode waves are produced in various ranges of ? for ?0 = (?L/c)1/3(?ce/?) < 1.5, where ?ce is the (angular) electron cyclotron frequency, ? is the angular wave frequency, L is the length scale of the (linear) density gradient, and c is the speed of light; (2) the xR mode is produced most strongly in the range, 40� < ? < 60�, for intermediately magnetized plasmas with ?0 = 1.0 and 1.5, while it is produced over a wider range, 0� ? ? ? 90�, for weakly magnetized plasmas with ?0 = 0.1 and 0.7; (3) the maximum total conversion efficiencies for wave power from the Langmuir/z mode to radiation are of order 50%-99% and the corresponding energy conversion efficiencies are 5%-14% (depending on the adiabatic index ? and ? = Te/mec2, where Te is the electron temperature and me is the electron) for various ?0; (4) the mode conversion window becomes wider as ?0 and ? increase. Hence, the results in this paper confirm that linear mode conversion under these conditions can explain the weak total circular polarization of interplanetary type II and III solar radio bursts because a strong xR mode can be generated via linear mode conversion near ? � 45�.
Kim, Eun-Hwa; Cairns, Iver. H.; Johnson, Jay R.
Reliability assurance of turbine energy conversion systems
The Dynamic Isotope Power System (DIPS) is a 6-k (electric) space power system utilizing a ²³⁸Pu radioisotope heat source and a dual redundant closed Brayton cycle power conversion assembly. The DIPS program is currently funded to design, fabricate, and test a ground demonstration engineering unit. Primary objectives of the test will be to validate design and demonstrate performance and lifetime.
P. D. Rutherford; D. S. Burgess; S. Robb
Preliminary Energy Sector Assessments of Jamaica. Volume III: Renewable Energy. Part IV: Energy Conversion from Waste.
National Technical Information Service (NTIS)
The study considers the feasibility of energy conversion from wastes. Specifically, the study analyzes the potential for energy recovery from urban wastes in Jamaica, with the Kingston area serving as a case study, and assesses the feasibility of building...
Push-n-Go: A Dynamic Energy Conversion Lesson.
ERIC Educational Resources Information Center
Focuses on the use of push and go toys to discuss with students how the toy acquires potential energy when work is done on it and how this energy is stored in the internal mechanism for later conversion into kinetic energy. (DDR)
Taylor, Beverly A. P.
Advanced thermionic energy conversion: Joint highlights
NASA Technical Reports Server (NTRS)
A theoretical model was used to study the effects of structured electrodes on converter I-V characteristics and results are given. An auxiliary-ion-source triode operated as a plasmatron was used for studying the enhancement distribution and magnetic effects, and results are reported. Design features of the high current-zero power (ZEPO) converter tests are given.
Superconducting magnetic energy storage
Recent programmatic developments in Superconducting Magnetic Energy Storage (SMES) have prompted renewed and widespread interest in this field. In mid 1987 the Defense Nuclear Agency, acting for the Strategic Defense Initiative Office, issued a request for proposals for the design and construction of SMES Engineering Test Model (ETM). Two teams, one led by Bechtel and the other by Ebasco, are now engaged in the first phase of the development of a 10 to 20 MWhr ETM. This report presents the rationale for energy storage on utility systems, describes the general technology of SMES, and explains the chronological development of the technology. The present ETM program is outlined; details of the two projects for ETM development are described in other papers in these proceedings. The impact of high T/sub c/ materials on SMES is discussed. 69 refs., 3 figs., 3 tabs.
Hassenzahl, W.
Energy-based modelling and control of wind energy conversion system with DFIG
Focusing on wind energy conversion system (WECS) at the doubly-fed induction generator (DFIG) control level, a novel control approach was proposed to optimise wind energy capture from consideration of physical nature and energy relationship. According to energy flowing, the WECS was divided into several multi-ports energy conversion subsystems, and the structure matrices of the subsystems were elaborately designed. Based on
H. H. Song; Y. B. Qu
Cogeneration Technology Alternatives Study (CTAS). Volume 4: Energy conversion systems
NASA Astrophysics Data System (ADS)
Industrial processes from the largest energy consuming sectors were used as a basis for matching a similar number of energy conversion systems that are considered as candidate which can be made available by the 1985 to 2000 time period. The sectors considered included food, textiles, lumber, paper, chemicals, petroleum, glass, and primary metals. The energy conversion systems included steam and gas turbines, diesels, thermionics, stirling, closed-cycle and steam injected gas turbines, and fuel cells. Fuels considered were coal, both coal and petroleum-based residual and distillate liquid fuels, and low Btu gas obtained through the on-site gasification of coal. An attempt was made to use consistent assumptions and a consistent set of ground rules specified by NASA for determining performance and cost. The advanced and commercially available cogeneration energy conversion systems studied in CTAS are fined together with their performance, capital costs, and the research and developments required to bring them to this level of performance.
Brown, D. H.; Gerlaugh, H. E.; Priestley, R. R.
Cogeneration Technology Alternatives Study (CTAS). Volume 4: Energy conversion systems
NASA Technical Reports Server (NTRS)
Industrial processes from the largest energy consuming sectors were used as a basis for matching a similar number of energy conversion systems that are considered as candidate which can be made available by the 1985 to 2000 time period. The sectors considered included food, textiles, lumber, paper, chemicals, petroleum, glass, and primary metals. The energy conversion systems included steam and gas turbines, diesels, thermionics, stirling, closed-cycle and steam injected gas turbines, and fuel cells. Fuels considered were coal, both coal and petroleum-based residual and distillate liquid fuels, and low Btu gas obtained through the on-site gasification of coal. An attempt was made to use consistent assumptions and a consistent set of ground rules specified by NASA for determining performance and cost. The advanced and commercially available cogeneration energy conversion systems studied in CTAS are fined together with their performance, capital costs, and the research and developments required to bring them to this level of performance.
Brown, D. H.; Gerlaugh, H. E.; Priestley, R. R.
Preliminary results on the conversion of laser energy into electricity
A preliminary experiment was performed to investigate conversion of 10.6-..mu..m laser energy to electrical energy via a laser-sustained argon plasma. Short-circuit currents of 0.7 A were measured between thoriated-tungsten emitter and collector electrodes immersed in the laser-sustained argon plasma. Open-circuit voltages of approx.1.5 V were inferred from the current-voltage load characteristics. The dominant mechanism of laser energy conversion is uncertain at this time. Much higher output powers appear possible.
Thompson, R.W.; Manista, E.J.; Alger, D.L.
Preliminary results on the conversion of laser energy into electricity
NASA Technical Reports Server (NTRS)
A preliminary experiment was performed to investigate conversion of 10.6 micron laser energy to electrical energy via a laser-sustained argon plasma. Short-circuit currents of 0.7 A were measured between a thoriated-tungsten emitter and collector electrodes immersed in the laser-sustained argon plasma. Open-circuit voltages of about 1.5 V were inferred from the current-voltage load characteristics. The dominant mechanism of laser energy conversion is uncertain at this time. Much higher output powers appear possible.
Thompson, R. W.; Manista, E. J.; Alger, D. L.
Status of wind-energy conversion
NASA Technical Reports Server (NTRS)
The utilization of wind energy is technically feasible as evidenced by the many past demonstrations of wind generators. The cost of energy from the wind has been high compared to fossil fuel systems; a sustained development effort is needed to obtain economical systems. The variability of the wind makes it an unreliable source on a short term basis. However, the effects of this variability can be reduced by storage systems or connecting wind generators to: (1) fossil fuel systems; (2) hydroelectric systems; or (3) dispersing them throughout a large grid network. Wind energy appears to have the potential to meet a significant amount of our energy needs.
Thomas, R. L.; Savino, J. M.
Research and development on ocean thermal energy conversion in Japan
The study of Ocean Thermal Energy Conversion (OTEC) in Japan has been conducted under the leadership of a team of the ''Sunshine Project'', a national new energy development project promoted by the Ministry of International Trade and Industries (MITI) since 1974. At present, two experimental OTEC power plants -Nauru's OTEC plant and Imari's OTEC plant are operating. In this paper,
H. Uehara
Photoelectrochemical conversion of solar energy using semiconductor electrodes
NASA Astrophysics Data System (ADS)
The principles of operation of semiconductor photoelectrochemical converters of solar energy into chemical or electrical energy are discussed. The properties of suitable semiconductor materials are examined, and methods for the protection of the electrodes from photocorrosion are described. Ways to increase the conversion efficiency are considered, and efficiency values obtained for various materials are tabulated. A review of the recent literature is included.
Arutiunian, V. M.
Codes and standards for Small Wind Energy Conversion Systems (SWECS)
Small Wind Energy Conversion Systems (SWECS) are in North America to stay, as a viable, energy producing product for homes, cottages, farms and various commercial applications-either remote with battery storage or interfaced with the local utility grid. Standards or design guidelines on electrical output and overall performance vary with the manufacturer, and may or may not be according to claim
Biomimetic approach to solar energy conversion: Artificial photosynthesis
Results of efforts to devise apparatus and systems for using solar energy for chemical purposes by methods that mimic those used by photosynthetic organisms are reported. Sufficient progress has been made in the understanding of plant photosynthesis to make artificial photosynthesis a reasonable goal. Artificial photoreaction centers, the apparatus used by photosynthetic organisms for light energy conversion to chemical oxidizing
J. J. Katz
Heat exchanger development for Ocean Thermal Energy Conversion
Heat exchangers comprise one of the largest cost drivers for Ocean Thermal Energy Conversion (OTEC) systems. Reductions in fabrication costs and improvements in performance are critical to successfully commercialize sustainable energy power plants using this low (?20�C) ?T resource. Heat exchanger (HX) units should maximize heat transfer per unit area (U value) while minimizing pressure losses, corrosion and cost. Current
Michael P. Eldred; Joseph C. Van Ryzin; Steven Rizea; In Chieh Chen; Robert Loudon; N. John Nagurny; Scott Maurer; Eugene Jansen; Andrew Plumb; Michael R. Eller; Victor R. R. Brown
Apply intelligent control strategy in wind energy conversion system
The wind energy conversion system (WECS) was a strong nonlinear system. The wind energy parameters of wind farm possessed high stochastic, various uncertainties that weren't exactly recognized. As this kind of system had unmodel or does not have accurate modeled part, it was very difficult to be controlled effectively. The self-features and merits of intelligent control methods were extremely suitable
Yang Junhua; Wu Jie; Yang Jinming; Yang Ping
Fundamentals of ocean wave energy conversion, modeling, and control
A collection of slides covering the fundamentals of ocean wave energy conversion, modeling and control was presented. The author first discussed the wave energy and resources fundamentals. A simple modelling and control assuming frequency independent hydrodynamic parameters and linearity was presented.
T. Brekken
Wind Energy Conversion Systems. A Unit of Instruction.
ERIC Educational Resources Information Center
The number of secondary schools, colleges, and universities offering courses in wind energy machine construction, repair, and installation, continues to increase. It is the purpose of this unit to include the study of wind energy conversion systems (WECS) as an integral part of related vocational and technical curriculum materials. The unit's�
Greenwald, Martin
Manipulation of atom-to-molecule conversion in a magnetic lattice
NASA Astrophysics Data System (ADS)
Atom-to-molecule conversion by the technique of optical Feshbach resonance in a magnetic lattice is studied in the mean-field approximation. For the case of a shallow lattice, we give the dependence of the atomto-molecule conversion efficiency on tunnelling strength and atomic interaction by taking a double-well as an example. We find that one can obtain a high atom-to-molecule conversion by tuning the tunnelling and interaction strengths of the system. For the case of a deep lattice, we show that the existence of the lattice can improve the atom-to-molecule conversion for certain initial states.
Hui, Ning-Ju; Lu, Li-Hua; Fu, Li-Bin; Li, You-Quan
Energy Conversion and Storage Program. 1990 annual report
The Energy Conversion and Storage Program applies chemistry and materials science principles to solve problems in (1) production of new synthetic fuels, (2) development of high-performance rechargeable batteries and fuel cells, (3) development of advanced thermochemical processes for energy conversion, (4) characterization of complex chemical processes, and (5) application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis. Electrochemistry research aims to develop advanced power systems for electric vehicle and stationary energy storage applications. Topics include identification of new electrochemical couples for advanced rechargeable batteries, improvements in battery and fuel-cell materials, and the establishment of engineering principles applicable to electrochemical energy storage and conversion. Chemical Applications research includes topics such as separations, catalysis, fuels, and chemical analyses. Included in this program area are projects to develop improved, energy-efficient methods for processing waste streams from synfuel plants and coal gasifiers. Other research projects seek to identify and characterize the constituents of liquid fuel-system streams and to devise energy-efficient means for their separation. Materials Applications research includes the evaluation of the properties of advanced materials, as well as the development of novel preparation techniques. For example, the use of advanced techniques, such as sputtering and laser ablation, are being used to produce high-temperature superconducting films.
Cairns, E.J.
Status of wind-energy conversion
NASA Technical Reports Server (NTRS)
The utilization of wind energy is technically feasible as evidenced by the many past demonstrations of wind generators. The cost of energy from the wind has been high compared to fossil fuel systems. A sustained development effort is needed to obtain economical systems. The variability of the wind makes it an unreliable source on a short-term basis. However, the effects of this variability can be reduced by storage systems or connecting wind generators to fossil fuel systems, hydroelectric systems, or dispersing them throughout a large grid network. The NSF and NASA-Lewis Research Center have sponsored programs for the utilization of wind energy.
Thomas, R. L.; Savino, J. M.
Polymer Based Nanocomposites for Solar Energy Conversion
Organic semiconductor-based photovoltaic devices offer the promise of low cost photovoltaic technology that can be manufactured via large-scale, roll-to-roll printing techniques. Existing organic photovoltaic devices are currently limited to solar power conversion efficiencies of 3?5%. This is because of poor overlap between the absorption spectrum of the organic chromophores and the solar spectrum, non-ideal band alignment between the donor and acceptor species, and low charge carrier mobilities. To address these issues, we are investigating the development of dendrimeric organic semiconductors that are readily synthesized with high purity. They also benefit from optoelectronic properties, such as band gap and band positions, which can be easily tuned by substituting different chemical groups into the molecule. Additionally, we are developing nanostructured oxide/conjugated polymer composite photovoltaics. These composites take advantage of the high electron mobilities attainable in oxide semiconductors and can be fabricated using low-temperature solution-based growth techniques. Here, we discuss the synthesis and preliminary device results of these novel materials and composites.
Shaheen, S.; Olson, D.; White, M.; Mitchell, W.; Miedaner, A.; Curtis, C.; Rumbles, G.; Gregg, B.; Ginley, D.
Thermochemical conversion activities funded by the Biomass Energy Systems Branch, US Department of Energy
The US Department of Energy (DOE) is actively developing renewable energy sources through research and development programs sponsored by the Biomass Energy Systems Branch. The mission of the thermochemical conversion element of the Biomass Energy Systems Program is to develop competitive processes for the conversion of renewable biomass resources into clean fuels and chemical feedstocks which can supplement those produced
G. F. Schiefelbein; L. J. Sealock; S. Ergun
Supramolecular Structures for Photochemical Energy Conversion
OAK B188 The goal of this project is to mimic the energy transduction processes by which photosynthetic organisms harvest sunlight and convert it to forms of energy that are more easily used and stored. The results may lead to new technologies for solar energy harvesting based on the natural photosynthetic process. They may also enrich our understanding and control of photosynthesis in living organisms, and lead to methods for increasing natural biomass production, carbon dioxide removal, and oxygen generation. In our work to date, we have learned how to make synthetic antenna and reaction center molecules that absorb light and undergo photoinduced electron transfer to generate long-lived, energetic charge-separated states. We have assembled a prototype system in which artificial reaction centers are inserted into liposomes (artificial cell-like constructs), where they carry out light-driven transmembrane translocation of hydrogen ions to generate proton motive force. By insertion of natural ATP synthase into the liposomal bilayer, this proton motive force has been used to power the synthesis of ATP. ATP is a natural biological energy currency. We are carrying out a systematic investigation of these artificial photosynthetic energy harvesting constructs in order to understand better how they operate. In addition, we are exploring strategies for reversing the direction of the light-powered proton pumping. Most recently, we have extended these studies to develop a light-powered transmembrane calcium ion pump that converts sunlight into energy stored as a calcium ion concentration gradient across a lipid bilayer.
Gust, Devens; Moore, Thomas A.; Moore, Ana L.
Layout design optimization for magneto-electro-elastic laminate composites for maximized energy conversion under mechanical loading
NASA Astrophysics Data System (ADS)
Magneto-electro-elastic (MEE) laminate composites with piezoelectric and piezomagnetic phases can be utilized as materials providing energy conversion among magnetic, electric and mechanical energies. This work is concerned with the development of a systematic design method of MEE composites with maximized conversion of mechanical energy to electric and/or magnetic energy. To predict the energy conversion phenomena, a fully coupled MEE theory is employed. A composite plate is assumed to be simply supported and is discretized into a number of laminates for analysis using a semi-analytic finite element method. Since the optimal stacking sequences for piezoelectric/piezomagnetic phases and the optimal thickness for each phase must be simultaneously determined, we propose formulating the design problem as a topology optimization problem. To implement the topology optimization, two interpolation models, the standard SIMP (solid isotropic material with penalization) model and the micromechanics model, are investigated. After solving benchmark test problems, design examples dealing with multifunctional composites are considered.
Sun, Kyung Ho; Kim, Yoon Young
The plasmatron: Advanced mode thermionic energy conversion
NASA Technical Reports Server (NTRS)
A theory of the plasmatron was developed. Also, a wide range of measurements were obtained with two versatile, research devices. To gain insight into plasmatron performance, the experimental results are compared with calculations based on the theoretical model of plasmatron operation. Results are presented which show that the plasma arc drop of the conventional arc (ignited) mode converter can be suppressed by use of an auxiliary ion source. The improved performance, however, is presently limited to low current densities because of voltage losses due to plasma resistance. This resistance loss could be suppressed by an increase in the plasma electron temperature or a decrease in spacing. Plasmatron performance characteristics for both argon and cesium are reported. The argon plasmatron has superior performance. Results are also presented for magnetic cutoff effects and for current distributing effects. These are shown to be important factors for the design of practical devices.
Hansen, L. K.; Hatch, G. L.; Rasor, N. S.
Functionalization of graphene for efficient energy conversion and storage.
As global energy consumption accelerates at an alarming rate, the development of clean and renewable energy conversion and storage systems has become more important than ever. Although the efficiency of energy conversion and storage devices depends on a variety of factors, their overall performance strongly relies on the structure and properties of the component materials. Nanotechnology has opened up new frontiers in materials science and engineering to meet this challenge by creating new materials, particularly carbon nanomaterials, for efficient energy conversion and storage. As a building block for carbon materials of all other dimensionalities (such as 0D buckyball, 1D nanotube, 3D graphite), the two-dimensional (2D) single atomic carbon sheet of graphene has emerged as an attractive candidate for energy applications due to its unique structure and properties. Like other materials, however, a graphene-based material that possesses desirable bulk properties rarely features the surface characteristics required for certain specific applications. Therefore, surface functionalization is essential, and researchers have devised various covalent and noncovalent chemistries for making graphene materials with the bulk and surface properties needed for efficient energy conversion and storage. In this Account, I summarize some of our new ideas and strategies for the controlled functionalization of graphene for the development of efficient energy conversion and storage devices, such as solar cells, fuel cells, supercapacitors, and batteries. The dangling bonds at the edge of graphene can be used for the covalent attachment of various chemical moieties while the graphene basal plane can be modified via either covalent or noncovalent functionalization. The asymmetric functionalization of the two opposite surfaces of individual graphene sheets with different moieties can lead to the self-assembly of graphene sheets into hierarchically structured materials. Judicious application of these site-selective reactions to graphene sheets has opened up a rich field of graphene-based energy materials with enhanced performance in energy conversion and storage. These results reveal the versatility of surface functionalization for making sophisticated graphene materials for energy applications. Even though many covalent and noncovalent functionalization methods have already been reported, vast opportunities remain for developing novel graphene materials for highly efficient energy conversion and storage systems. PMID:23030244
Dai, Liming
Photoassisted electrolysis of water - Conversion of optical to chemical energy
NASA Technical Reports Server (NTRS)
A description is given of devices, termed photoelectrochemical cells, which can, in principle, be used to directly convert light to fuels and/or electricity. The fundamental principles on which the photoelectrochemical cell is based are related to the observation that irradiation of a semiconductor electrode in an electrochemical cell can result in the flow of an electric current in the external circuit. Attention is given to the basic mechanisms involved, the energy conversion efficiency, the advantages of photoelectrochemical cells, and the results of investigations related to the study of energy conversion via photoelectrochemical cells.
Wrighton, M. S.; Bolts, J. M.; Kaiser, S. W.; Ellis, A. B.
Nanofluidic sustainable energy conversion using a 1D nanofluidic network.
We propose a 1-dimensional (1D) nanofluidic energy conversion device by implementing a surface-patterned Nafion membrane for the direct energy conversion of the pressure to electrical power. By implementing a -200-nm-thick nano-bridge with a 5-nm pore size between two microfluidic channels, we acquired an effective streaming potential of 307 mV and output power of 94 pW with 0.1 mM KCI under pressure difference of 45 MPa. The experimental results show both the effects of applied pressure differences and buffer concentrations on the effective streaming potential, and are consistent with the analytical prediction. PMID:24734635
Kim, Sang Hui; Kwak, Seungmin; Han, Sung Il; Chun, Dong Won; Lee, Kyu Hyoung; Kim, Jinseok; Lee, Jeong Hoon
Direct Energy Conversion Nano-hybrid Fuel
Most of the exothermic nuclear reactions transfer the mass defect or binding and surplus energy into kinetic energy of the resulting particles. These particles are traveling through material lattices, interacting by ionization and nuclear collisions. Placing an assembly of conductive-insulating layers in the path of such radiation, the ionization energy is transformed into charge accumulation by polarization. The result is a super-capacitor charged by the moving particles and discharged electrically. Another more promising solution is to use bi-material nanoparticles organized such as to act like a serial connection and add the voltage. A spherical symmetry fission products source coated in several nano-layers is desired for such structures. The system may operate as dry or liquid-immersed battery, removing the fission products from the fissile material. There is a tremendous advantage over the current heat flow based thermal stabilization system allowing a power density up to 1000 times higher. (author)
Popa-Simil, Liviu [R and D, LAVM LLC., Los Alamos, NM, 87544 (United States)
An optimized photovoltaic system using an effective energy conversion
This paper describes an autonomous photovoltaic (PV) system with an effective energy conversion. An optimized maximum-power-point tracking algorithm based on a perturb-and-observe system makes the maximum-power-point research more stable and fast thanks to an auto-adaptive current step. The energy storage of the system is also improved by using a hybrid energy storage which combines batteries and ultracapacitors. The goal of
T. A. Singo; A. Martinez; S. Saadate; S. Rael
Conversion of acoustic energy by lossless liners
NASA Technical Reports Server (NTRS)
The Blokhintzev acoustic energy equation is applied to a two-dimensional duct containing a uniform flow with a finite length lining. It is shown that the difference of the incident and outgoing acoustic energy differs in general from the energy dissipated in the liner, the difference being related to the displacements at the liner's edges. It is shown that in the case of a locally reacting lossless liner for frequencies below the first cut-off frequency and for low Mach number acoustic energy is generated if the flow and the incident sound wave are in the same direction and is absorbed if these two directions are opposite unless special edge conditions are met. Furthermore it is shown under the same conditions that the ratio of the reflection coefficient at finite flow velocity to the reflection coefficient at vanishing velocity is to first order in Mach number independent of the liner characteristics. A numerical calculation confirms these predictions at least for mass-like linear admittance.
Moehring, W.; Eversman, W.
NASA Astrophysics Data System (ADS)
The fusion program embraces low loss superconductor strand development with integration into cables capable of carrying 50 kA in pulsed mode at high fields. This evolvement was paralleled with pulsed energy storage coil development and testing from tens of kJ at low fields to a 20 MJ prototype Tokamak induction coil at 7.5 T. Energy transfer times have ranged from 0.7 ms to several seconds. Electric utility magnetic storage for prospective application is for diurnal load leveling with massive systems of store 10 GWh at 1.8 K in a dewar structure supported on bedrock underground. An immediate utility application is a 30 MJ system to be used to damp power oscillations on the Bonneville Power Administration electric transmission lines. An off shoot of this last work is a program for electric utility VAR control with the potential for use to suppress subsynchronous resonance. This paper presents work in progress, work planned, and recently completed unusual work.
Rogers, J. D.
Chemoelectrical energy conversion of adenosine triphosphate
NASA Astrophysics Data System (ADS)
Plant and animal cell membranes transport charged species, neutral molecules and water through ion pumps and channels. The energy required for moving species against established concentration and charge gradients is provided by the biological fuel - adenosine triphosphate (ATP) -synthesized within the cell. The adenosine triphosphatase (ATPases) in a plant cell membrane hydrolyze ATP in the cell cytoplasm to pump protons across the cell membrane. This establishes a proton gradient across the membrane from the cell exterior into the cell cytoplasm. This proton motive force stimulates ion channels that transport nutrients and other species into the cell. This article discusses a device that converts the chemical energy stored in adenosine triphosphate into electrical power using a transporter protein, ATPase. The V-type ATPase proteins used in our prototype are extracted from red beet(Beta vulgaris) tonoplast membranes and reconstituted in a bilayer lipid membrane or BLM formed from POPC and POPS lipids. A pH7 medium that can support ATP hydrolysis is provided on both sides of the membrane and ATP is dissolved in the pH7 buffer on one side of the membrane. Hydrolysis of ATP results in the formation of a phosphate ion and adenosine diphosphate. The energy from the reaction activates ATPase in the BLM and moves a proton across the membrane. The charge gradient established across the BLM due to the reaction and ion transport is converted into electrical current by half-cell reference electrodes. The prototype ATPase cell with an effective BLM area of 4.15 mm2 carrying 15 ?l of ATPase proteins was observed to develop a steady state peak power output of 70 nW, which corresponds to a specific power of 1.69 ?W/cm2 and a current density of 43.4 ?A/cm2 of membrane area.
Sundaresan, Vishnu Baba; Sarles, Stephen Andrew; Leo, Donald J.
Nanorod structures for energy conversion applications
NASA Astrophysics Data System (ADS)
The remarkable size-, surface-, and shape-dependence of physical, optical, and electronic properties of nanoscale materials make them compelling components of modern materials applications in a variety of fields. They are currently playing a key role in the development of alternate energy devices like fuel cells and solar cells as well as modern energy storage devices like lithium-ion batteries. Oblique angle deposition (OAD) is a technique which allows for fabrication of unique nanostructures, which cannot be grown by advanced lithographic techniques. OAD is a physical vapor deposition technique in which flux arrives at a large oblique incidence angle from the substrate normal. It is simple, fast, cheap, has high mass production capability and can generate unique two- and thee-dimensional nanostructures with large aspect ratio and controllable porosity, shape and symmetry. The fact that these structures can be integrated onto a substrate platform makes them practical for many realistic applications. We have tried to utilize nanorods grown by OAD in various key device applications of today's energy starved society. We first explained the enhanced photoemissive response of nanostructured topologies, which could result in the development of new photo-multiplier systems with dramatically improved performance. We optimized the growth of single crystalline ZnO nanorods and ITO nanorods by magnetron sputtering at low temperatures and explored their use as enhanced transparent conducting electrodes for polymeric photovoltaic cells. We studied various Pt nanorod based electrode architectures for proton exchange membrane fuel cells and showed that they give higher mass specific performance than conventional Pt-black electrodes. We demonstrated that nanostructured Si thin film based anodes are potentially better than conventional carbon based anodes and can lead to enhanced rechargeable Li-ion batteries with higher capacity.
Teki, Ranganath
Nanostructured semiconductors for thermoelectric energy conversion: Synthesis and transport properties
NASA Astrophysics Data System (ADS)
Increasing energy demands and decreasing natural energy resources have sparked search for alternative clean and renewable energy sources. For instance, currently there is a tremendous interest in thermoelectric and photovoltaic solar energy production technologies. Half-Heusler (HH) alloys are among the most popular material systems presently under widespread investigations for high temperature thermoelectric energy conversion. Approaches to increase the thermoelectric figure of merit (ZT) of HH range from (1) chemical substitution of atoms with different masses within the same atomic position in the crystal structure to optimize carrier concentration and enhance phonon scattering via mass fluctuation and (2) embedding secondary phonon scattering centers in the matrix (nanostructuring) to further reduce thermal conductivity. This work focuses on three material systems. The first part describes the synthesis and properties (thermal conductivity, electrical conductivity, magnetic) of various oxide nanostructures (NiO, Co3O4) which were subsequently used as inclusion phases in a HH matrix to reduce the thermal conductivity. Detailed reviews of the past efforts along with the current effort to optimize synthetic routes are presented. The effects of the synthesis conditions on the thermoelectric properties of compacted pellets of NiO and Co3O4 are also discussed. The second part of the work discusses the development of synthetic strategies for the fabrication of p-type and n-type bulk nanostructured thermoelectric materials made of a half-Heusler matrix based on (Ti,Hf)CoSb, containing nanostructures with full-Heusler (FH) compositions and structures coherently embedded inside the half-Heusler matrix. The role of the nanostructures in the regulation of phonon and charge carrier transports within the half-heusler matrix is extensively discussed by combining transport data and electron microscopy images. It was found that the FH nanoinclusions form staggered heterojunctions with a valence band (VB) offset energy at the HH/FH phase boundaries. The resulting energy barrier discriminates existing holes with respect to their energy by trapping low energy holes, while promoting the transport of high energy holes through the VB of the FH-quantum dots. This "carrier culling" results in surprisingly large increase in the mobility and the effective mass of high energy holes contributing to electronic conduction. The simultaneous reduction in the density and the increase in the effective mass of holes resulted in large enhancements of the thermopower, whereas the increase in the mobility minimizes the drop in the electrical conductivity. In the third part, the application of this concept of nanostructuring on the Copper Selenide material system is described. Various synthetic approaches such as liquid assisted solid-state reaction and mechanical alloying are utilized for the fabrication of copper selenide compositions. We found that the mechanical alloying clearly decreases the thermal conductivity of the composition as well increases the Seebeck due to decrease in carrier concentrations.
Sahoo, Pranati
Power tracking control challenges in Hydrokinetic energy conversion systems
Hydrokinetic energy conversion technologies, being tested under controlled environment\\/pilot project, are at a juncture of pre-commercial or commercial de- ployment. Among various challenges, system control and operation is one where more attention needs to be focused. This article serves the purpose of providing a high- level subjective overview of the maximum power tracking problem in this class of technologies. Various
Jahangir Khan; Tariq Iqbal; John Quaicoe
Quantitative evaluation of Ocean Thermal Energy Conversion (OTEC): Executive briefing
NASA Astrophysics Data System (ADS)
The results of an independent quantitative evaluation of Ocean Thermal Energy Conversion (OTEC) for central station applications are summarized. A central station power plant located in the Gulf of Mexico and delivering power to the mainland United States was emphasized. The evaluation of OTEC is based on three important issues: resource availability, technical feasibility, and cost.
Gritton, E. C.; Pei, R. Y.; Hess, R. W.
Decreasing geothermal energy conversion costs with advanced materials
If the Geothermal Technology Division (GTD) is to meet its programmatic objectives in hydrothermal fluid production and energy conversion, it is essential that new materials of construction be available. Level III Program Objectives include (1) reducing the costs associated with lost circulation episodes by 30% by 1992, (2) reducing the costs of deep wells and directionally dried wells by 10%
Probabilistic production costing of diesel-wind energy conversion systems
This paper describes the development of a general probabilistic model of a diesel-wind energy conversion system (DWECS) composed of several diesel units, several wind turbines (wind farm), and battery storage feeding a load. The model allows the simulation of a diesel system with a wind farm of different wind turbine types considering system stability, and outages due to hardware failure
Sami H. Karaki; Riad B. Chedid; Rania Ramadan
Dynamic instabilities and energy conversion processes in hurricane core regions
A series of numerical simulations of axisymmetric hurricane-like vortices is performed to examine dynamic instabilities and energy conversion processes in a hurricane core area. The numerical experiments in this study consist of simulations of idealized dry vortices and moist vortices. The dry experiment is designed to show that the existence of baroclinic and barotropic instabilities is possible in realistic hurricane-like
Young C. Kwon
Intelligent control of a class of wind energy conversion systems
This paper discusses the control problem for a class of wind energy conversion systems (WECS). It first develops a detailed model and then compares four control algorithms based on conventional and intelligent control theories. A simple PI conventional controller for the exciter loop is carried out by using a first order model. When the system operating points change, the PI
R. Chedid; F. Mrad; M. Basma
Probabilistic performance assessment of wind energy conversion systems
This paper describes the development of a general probabilistic model of an autonomous wind energy conversion system (WECS) composed of several wind turbines (wind farm) connected to a load and a battery storage. The proposed technique allows the simulation of wind farms containing identical or different wind turbines types and considers a bidirectional flow of power in and out of
S. H. Karaki; R. B. Chedid; R. Ramadan
Technology Assessment for Energy Conversion and Conservation. Final Report.
National Technical Information Service (NTIS)
The major thrust of this effort was to assemble a panel of seven technical experts with varied backgrounds who could take a fresh approach to recommending research topics in the area of energy conservation and conversion. The Panel had two meetings, with ...
J. A. Belding, M. D. Shapiro
Aerodynamic Aspects of Wind Energy Conversion
NASA Astrophysics Data System (ADS)
This article reviews the most important aerodynamic research topics in the field of wind energy. Wind turbine aerodynamics concerns the modeling and prediction of aerodynamic forces, such as performance predictions of wind farms, and the design of specific parts of wind turbines, such as rotor-blade geometry. The basics of the blade-element momentum theory are presented along with guidelines for the construction of airfoil data. Various theories for aerodynamically optimum rotors are discussed, and recent results on classical models are presented. State-of-the-art advanced numerical simulation tools for wind turbine rotors and wakes are reviewed, including rotor predictions as well as models for simulating wind turbine wakes and flows in wind farms.
S�rensen, Jens N�rk�r
Proceedings of the 33. intersociety energy conversion engineering conference
These papers were presented at the Intersociety Energy Conversion Engineering Conference, August of 1998. The topics of the papers included aerospace power analyses and simulation, space energy conversion, applications and requirements for space power systems, space solar power, terrestrial energy, aerospace batteries, aerospace power management, aerospace power electronics, aircraft power, dual use technologies, electric propulsion, wireless energy transmission, terrestrial thermoelectric, heat pumps, innovative concepts, stirling engine and heat pump applications, stirling engines and components, stirling analysis, magnetohydrodynamics, thermionics, AMTEC advanced modular power systems, advanced cycles, co-generation and heat engines, alkali batteries, other batteries, terrestrial fuel cells, fuel cells in distributed generation systems, fuel cells in buildings applications, systems modeling and analysis of fuel cells, polymer electrolyte fuel cells, fuel processing for fuel cells, alternative fuel vehicles, clean energy options, electric vehicles, energy and the environment, thermal storage, building energy systems, concepts in cold fusion, power systems control, electric power systems, simulation and modeling, nuclear power systems, fossil fuels, energy policy, deregulation of electric utilities, photovoltaic energy technology, modeling and simulation, advanced solar house and building, wind energy, hydrogen energy systems, energy from waste and biomass, geothermal, cryogenic heat transfer, heat pipes, loop heat pipes, and capillary pumped loops, spacecraft and aircraft thermal control, numerical analysis and code verification, two phase heat and mass transfer.
Anghaie, S. [ed.
Piezoelectric ribbons printed onto rubber for flexible energy conversion.
The development of a method for integrating highly efficient energy conversion materials onto stretchable, biocompatible rubbers could yield breakthroughs in implantable or wearable energy harvesting systems. Being electromechanically coupled, piezoelectric crystals represent a particularly interesting subset of smart materials that function as sensors/actuators, bioMEMS devices, and energy converters. Yet, the crystallization of these materials generally requires high temperatures for maximally efficient performance, rendering them incompatible with temperature-sensitive plastics and rubbers. Here, we overcome these limitations by presenting a scalable and parallel process for transferring crystalline piezoelectric nanothick ribbons of lead zirconate titanate from host substrates onto flexible rubbers over macroscopic areas. Fundamental characterization of the ribbons by piezo-force microscopy indicates that their electromechanical energy conversion metrics are among the highest reported on a flexible medium. The excellent performance of the piezo-ribbon assemblies coupled with stretchable, biocompatible rubber may enable a host of exciting avenues in fundamental research and novel applications. PMID:20102189
Qi, Yi; Jafferis, Noah T; Lyons, Kenneth; Lee, Christine M; Ahmad, Habib; McAlpine, Michael C
Ocean Thermal Energy Conversion Program Management Plan
The Office of the Associate Laboratory Director for Energy and Environmental Technology has established the OTEC Program Management Office to be responsible for the ANL-assigned tasks of the OTEC Program under DOE's Chicago Operations and Regional Office (DOE/CORO). The ANL OTEC Program Management Plan is essentially a management-by-objective plan. The principal objective of the program is to provide lead technical support to CORO in its capacity as manager of the DOE power-system program. The Argonne OTEC Program is divided into three components: the first deals with development of heat exchangers and other components of OTEC power systems, the second with development of biofouling counter-measures and corrosion-resistant materials for these components in seawater service, and the third with environmental and climatic impacts of OTEC power-system operation. The essential points of the Management Plan are summarized, and the OTEC Program is described. The organization of the OTEC Program at ANL is described including the functions, responsibilities, and authorities of the organizational groupings. The system and policies necessary for the support and control functions within the organization are discussed. These functions cross organizational lines, in that they are common to all of the organization groups. Also included are requirements for internal and external reports.
Combs, R E
Ocean thermal energy conversion: a review
The OTEC principle is discussed along with general system and cycle types, specific OTEC designs, OTEC applications, and the ocean thermal resource. The historic development of OTEC is briefly reviewed, and the status of French, Japanese, EUROCEAN, and US programs is assessed. US efforts are detailed and DOE's strategy outlined with OTEC-1 and Mini-OTEC information. Power system components of the more technically advanced closed-cycle OTEC concept are discussed. These include: heat exchangers, corrosion and biofouling countermeasures, working fluids, ammonia power systems, and on-platform seawater systems. Several open-cycle features are also discussed. A critical review is presented of the ocean engineering aspects of OTEC power systems. Major subsystems such as platform, cold water pipe, mooring system, dynamic positioning system, power transmission cable system are assessed for their relationships with the ocean environment and with each other. Nine available studies of OTEC costs are reviewed. Tentative comparisons are made between OTEC and traditional fuel costs, and OTEC products and markets are considered. Possible environmental and social effects of OTEC development are discussed. International, national, and local laws regulating OTEC plants and OTEC energy products are reviewed. Tax incentives, attitudes of the utilities, and additional legislative needs are considered. (LEW)
Yuen, P.C.
New elements in wind energy conversion siting
The purpose of this investigation is to quantify a number of site characteristics for site selection for wind powered generators. It is assumed that the wind powered generators will be integrated in a utility grid which is in addition supplied from conventional power sources and does not have energy storage capabilities. The objective is to enable the selection of the available sites in such a manner as to maximize the desirable benefits from the installation of the wind powered generators, i.e. either installed capacity displacement or fuel savings. The hourly wind speeds from three sites for the year 1975 are utilized to demonstrate the quantification of the parameters based in part on the notions of reliability analysis. It is shown that individual sites differ significantly from each other and that a ''composite'' site can be constructed using dispersed installations in such a manner as to obtain the desirable characteristics. It is assumed that the electric power distribution grid under consideration is of sufficient extent so that several wind regimes can be found.
Lois, L.
Saturation and energy-conversion efficiency of auroral kilometric radiation
NASA Technical Reports Server (NTRS)
A quasi-linear theory is used to study the saturation level of the auroral kilometric radiation. The investigation is based on the assumption that the emission is due to a cyclotron maser instability as suggested by Wu and Lee and Lee et al. The thermodynamic bound on the radiation energy is also estimated separately. The energy-conversion efficiency of the radiation process is discussed. The results are consistent with observations.
Wu, C. S.; Tsai, S. T.; Xu, M. J.; Shen, J. W.
Environmental assessment of waste-to-energy conversion systems
The Fuels Technology Branch of EPA's Industrial Environmental Research Laboratory in Cincinnati is sponsoring a program at Midwest Research Institute (MRI) to conduct environmental assessments of some waste-to-energy conversion processes. The overall objective of this program is to evaluate the potential multi-media environmental impacts resulting from using combustible wastes as an energy source and thereby identify control technology needs. As
K. P. Ananth; M. A. Golembiewski; H. M. Freeman
Control policies for wind-energy conversion systems
Wind energy is usually converted into electrical energy through a wind rotor driving a generator. It is well known that maximum conversion efficiency occurs when the wind rotor is loaded in such a way that its rotational speed is allowed to fluctuate in sympathy with wind-speed variations. In the paper, the wind-rotor\\/generator dynamics are investigated for a number of control
I. K. Buehring; L. L. Freris
Photochemical solar energy conversion. An assessment of scientific accomplishments
Research on photochemical solar energy conversion has grown exponentially. Basic sciences have benefited most from this research. The tenet of this article is that solar energy research has appreciably contributed to the ongoing renaissance of colloid chemistry and to the development of ever-more-sophisticated models for light-sensitized distance-controlled electron transfers. The need for compartmentalizing components of the photosynthetic apparatus-sensitizers: electron donors,
Janos H. Fendler
SPS energy conversion and power management workshop. Final report
In 1977 a four year study, the concept Development and Evaluation Program, was initiated by the US Department of Energy and the National Aeronautics and Space Administration. As part of this program, a series of peer reviews were carried out within the technical community to allow available information on SPS to be sifted, examined and, if need be, challenged. The SPS Energy Conversion and Power Management Workshop, held in Huntsville, Alabama, February 5 to 7, 1980, was one of these reviews. The results of studies in this particular field were presented to an audience of carefully selected scientists and engineers. This first report summarizes the results of that peer review. It is not intended to be an exhaustive treatment of the subject. Rather, it is designed to look at the SPS energy conversion and power management options in breadth, not depth, to try to foresee any troublesome and/or potentially unresolvable problems and to identify the most promising areas for future research and development. Topics include photovoltaic conversion, solar thermal conversion, and electric power distribution processing and power management. (WHK)
Not Available
Control of Melt Conversion Using Traveling Magnetic Fields
NASA Technical Reports Server (NTRS)
An axisymmetric traveling magnetic wave induces a meridional base flow in a cylindrical zone of an electrically conducting liquid. This remotely induced flow can be conveniently controlled, in magnitude and direction, and can have benefits for crystal growth applications. In particular, it can be used to significantly offset natural convection. Theoretical basics of this new technological method are presented.
Mazurruk, Konstantin; Rose, M. Franklin (Technical Monitor)
Linear mode conversion of Langmuir/z mode waves to radiation: Averaged energy conversion efficiencies, polarization, and applications to Earth's continuum radiation
NASA Astrophysics Data System (ADS)
Linear mode conversion (LMC) is the linear transfer of energy from one wave mode to another in a density gradient. It is relevant to planetary continuum radiation, type II and III radio bursts, and ionospheric radio emissions. This paper analyzes LMC by calculating angle-averaged energy (?) and power (?p) conversion efficiencies in both 2-D and 3-D for Langmuir/z mode waves (including upper hybrid waves for perpendicular wave vectors) converting to free-space radiation in turbulent plasmas. The averages are over the distributions of the incoming Langmuir/z mode wave vectors k, density scale lengths L, and angles ? and ?, where ? is the angle between k and the background magnetic field B0 and ? is the angle between the density gradient ?N0 and B0. The results show that the averaged and unaveraged conversion efficiencies are dependent on ??, where ? is the adiabatic index and ? is related to the electron temperature Te by ? = Te/mec2. The averaged energy conversion efficiencies are proportional to ?? in 2-D and to (??)3/2 in 3-D, whereas the power conversion efficiencies are proportional to (??)1/2 in 2-D and ?? in 3-D. The special case of a perpendicular density gradient (??90�) is considered and used to predict the conversion efficiencies of terrestrial continuum radiation (TCR) in three known source regions: the plasmapause, magnetopause, and the plasma sheet. The observed energy conversion efficiencies are estimated and are found to be consistent with the 2-D and 3-D predicted efficiencies; importantly, these results imply that LMC is a possible generation mechanism for TCR. The polarization of TCR is also predicted: TCR should be produced primarily in the o mode at the plasmapause and in both the o and x modes at the magnetopause and plasma sheet. These predictions are consistent with previous independent predictions and observations.
Schleyer, Fiona; Cairns, Iver H.; Kim, Eun-Hwa
Magnetic Confinement Fusion Energy Research.
National Technical Information Service (NTIS)
Controlled Thermonuclear Fusion offers probably the only relatively clean energy solution with completely inexhaustible fuel and unlimited power capacity. The scientific and technological problem consists in magnetically confining a hot, dense plasma (pre...
H. Grad
Ocean wave energy conversion: inexpensive energy source yields significant results through simple methods
Pneumatic ocean wave energy conversion has been in existence since the early twentieth century. In pneumatic wave energy conversion, internal water motions are excited by the external water wave. Depending on the volume of water in the capture chamber, resonance with the external wave may occur. That is, the natural frequency of the rising and falling internal water column may
Mode Conversion and Energy Partitioning at Active Volcanoes
NASA Astrophysics Data System (ADS)
It has recently been shown that correlations of seismic noise and coda wave provide rich information on the Green�s function between observation sites. Such technique, known as seismic interferometry, are often based on the assumption of equipartitioning, and thus the energy partitioning of diffuse waves has been widely studies from the view points of wave theory and experimental/field observations. Recently, using an active seismic experiment at Asama volcano, Japan, Yamamoto and Sato (2010) quantified the scattering characteristics of multiple scattering and conversion scattering, and pointed out that P energy from active sources is rapidly converted to S energy and it takes only a few seconds that the local energy ratio approaches the equipartition based on the radiative transfer modeling using the estimated scattering parameters. To obtain a direct evidence of mode conversion and energy partitioning in shallow heterogeneous structure of active volcanoes and have implications for seismic interferometry, we conducted a seismic array observation in Nov. 2008 as a part of an active seismic experiment at Sakurajima volcano, Japan. We deployed a small square-shaped array composed of four three-component short-period seismometers, and decomposed the observed wavefield into P and S energies. Observed seismograms are characterized by spindle-like envelopes having small P-onsets and long codas lasting for more than 10 sec, and the decomposed P and S energies show the following characteristics in high frequency bands (4-8Hz and 8-12Hz): S energy rapidly increase just after the arrival of direct P wave, and S energy exceed P energy about 2 sec after the first arrival; the ratio of P and S energies make the gradual transition to the equipartition over about 5-10 sec. These behaviors can be well explained by the radiative transfer theory including mode conversion in a medium having the mean free path of about 1km. Another interesting finding from the array observation is that the local energy ratios in ambient noise and coda wave are almost the same. The fact indicates that even the ambient noise, which is basically generated by random excitation of ballistic waves, is in equipartition state due to strong scattering in heterogeneous volcanic environment. Observed good correlation between the site amplification factors estimated from ambient noise and coda wave also supports the hypothesis that these wave fields share almost same composition. These results suggest that the mode conversion and multiple scattering have an indispensable effect on the seismic wave propagation in heterogeneous volcanic environments. We expect our results on the energy partitioning and its transition to be of help to justify the applicability of seismic interferometry and pseudo-reflection method at active volcanoes.
Yamamoto, M.; Nishimura, T.; Tsutsui, T.; Iguchi, M.
New highly polar semiconductor ferroelectrics for solar energy conversion devices
NASA Astrophysics Data System (ADS)
Solar energy is a promising long-term solution for future energy requirements; however, current solar energy conversion devices are plagued by low efficiency. The use of ferroelectric ABO3 perovskite oxides is one approach for boosting conversion efficiency. Ferroelectric oxides possess spontaneous polarization and have been shown to produce a bulk photovoltaic effect, in which charged carriers, specifically electrons and holes, separate to prevent recombination. Once separated, the high-energy electrons are available for electrical work or for the catalytic splitting of water into hydrogen and oxygen. Currently, most solid oxide ferroelectrics have a band gap of at least 3 eV, absorbing primarily in the ultra-violet (UV) region. Since UV light comprises only 8% of the solar spectrum, new materials with a decreased band gap and large polarization would be highly desirable. We use first-principles density functional theory (DFT) calculations to investigate the ground state structures of PbTiO3 solid solutions containing Ni, Pd and Pt. We predict that these proposed materials will display a decreased band gap when compared to PbTiO3, while maintaining or enhancing polarization. They are promising candidates for use as semi-conducting ferroelectric substrates for solar conversion devices.
Rappe, Andrew M.; Grinberg, Ilya; Bennett, Joseph W.
High-Speed Liquid Projectiles: an Efficient Energy Conversion Tool
NASA Astrophysics Data System (ADS)
Application of high speed liquid projectiles for enhancement of the efficiency and reduction of the emission of fuel combustion is discussed. Overall energy efficiency of combustion can be improved if combustion products generated at an extreme high rate are used as a working fluid in material processing or energy conversion operations. In the course of a performed study the products of the powder combustion were used for generation of high speed (1000-1750 m/s) liquid projectiles. The energy effectiveness of the use of these projectiles for metal forming, welding and rocks boring was demonstrated. The feasibility of development of an emission free coal combustion technology is also discussed.
Geskin, Ernest S.
Linear generators for direct-drive wave energy conversion
The Archimedes Wave Swing (AWS) is a system that converts ocean wave energy into electric energy. The goal of the research described in this paper is to identify the most suitable generator type for this application. Of the more conventional generator types, the three-phase permanent-magnet synchronous generator with iron in both stator and translator is most suitable, because it is
H. Polinder; B. C. Mecrow; A. G. Jack; P. Dickinson; M. A. Mueller
Continuous reconnection line and pressure-dependent energy conversion on the magnetopause in a global MHD model
We present results on magnetopause reconnection processes in the Gumics-4 global MHD simulation model. The reconnection line on the magnetopause is identified using a topological method, and its behavior as a function of the interplanetary magnetic field (IMF) direction is shown to be consistent with the component reconnection hypothesis. Energy conversion associated with reconnection is quantified using integrals of Poynting
T. V. Laitinen; M. Palmroth; T. I. Pulkkinen; P. Janhunen; H. E. J. Koskinen
Performance-Oriented Electric Motors Diagnostics in Modern Energy Conversion Systems
This paper presents the analysis of a performance- oriented electric motors diagnostics in modern energy conversion system. With increased demand for electrical energy in world industries, the population of energy conversion devices such as generators\\/motors has greatly increased. As emerging and not being a mature enough technology in the application of renewable energy conversion or electric-drive transportation, the protection and
Seungdeog Choi; Bilal Akin; Mina M. Rahimian; Hamid A. Toliyat
Thermoelectric Energy Conversion: Future Directions and Technology Development Needs
NASA Technical Reports Server (NTRS)
This viewgraph presentation reviews the process of thermoelectric energy conversion along with key technology needs and challenges. The topics include: 1) The Case for Thermoelectrics; 2) Advances in Thermoelectrics: Investment Needed; 3) Current U.S. Investment (FY07); 4) Increasing Thermoelectric Materials Conversion Efficiency Key Science Needs and Challenges; 5) Developing Advanced TE Components & Systems Key Technology Needs and Challenges; 6) Thermoelectrics; 7) 200W Class Lightweight Portable Thermoelectric Generator; 8) Hybrid Absorption Cooling/TE Power Cogeneration System; 9) Major Opportunities in Energy Industry; 10) Automobile Waste Heat Recovery; 11) Thermoelectrics at JPL; 12) Recent Advances at JPL in Thermoelectric Converter Component Technologies; 13) Thermoelectrics Background on Power Generation and Cooling Operational Modes; 14) Thermoelectric Power Generation; and 15) Thermoelectric Cooling.
Fleurial, Jean-Pierre
Quantum dot nanoscale heterostructures for solar energy conversion.
Quantum dot nanoscale semiconductor heterostructures (QDHs) are a class of materials potentially useful for integration into solar energy conversion devices. However, realizing the potential of these heterostructured systems requires the ability to identify and synthesize heterostructures with suitably designed materials, controlled size and morphology of each component, and structural control over their shared interface. In this review, we will present the case for the utility and advantages of chemically synthesized QDHs for solar energy conversion, beginning with an overview of various methods of heterostructured material synthesis and a survey of heretofore reported materials systems. The fundamental charge transfer properties of the resulting materials combinations and their basic design principles will be outlined. Finally, we will discuss representative solar photovoltaic and photoelectrochemical devices employing QDHs (including quantum dot sensitized solar cells, or QDSSCs) and examine how QDH synthesis and design impacts their performance. PMID:23229593
Selinsky, Rachel S; Ding, Qi; Faber, Matthew S; Wright, John C; Jin, Song
Magnetic and M�ssbauer studies on superparamagnetic Fe-Mn clusters for syngas conversion
NASA Astrophysics Data System (ADS)
Insitu magnetic and M�ssbauer studies showed the conversion of Fe 0 metal to Fe-carbides during syngas (CO + H 2) reaction over unsupported Fe-Mn oxide catalysts. Catalysts with 48% Fe, reduced in CO and exposed to syngas contained predominantly Fe 5C 2, the active component in this reaction. During the reduction an intermediate Mn-ferrite was detected.
Mulay, L. N.; Lo, C.; Pannaparayil, T.; Diffenbach, R. A.
Magnetic and M�ssbauer studies on superparamagnetic Fe-Mn clusters for syngas conversion
Insitu magnetic and M�ssbauer studies showed the conversion of Fe0 metal to Fe-carbides during syngas (CO + H2) reaction over unsupported Fe-Mn oxide catalysts. Catalysts with 48% Fe, reduced in CO and exposed to syngas contained predominantly Fe5C2, the active component in this reaction. During the reduction an intermediate Mn-ferrite was detected.
L. N. Mulay; C. Lo; T. Pannaparayil; R. A. Diffenbach
Energy: A continuing bibliography with indexes, February 1975. [solar energy, energy conversion
NASA Technical Reports Server (NTRS)
Reports, articles, and other documents introduced into the NASA scientific and technical information system from July 1, 1974 through September 30, 1974 are cited. Regional, national, and international energy systems; research and development on fuels and other sources of energy; energy conversion, transport, transmission, distribution, and storage, with emphasis on the use of hydrogen and solar energy are included along with methods of locating or using new energy resources. Emphasis is placed on energy for heating, lighting, and powering aircraft, surface vehicles, or other machinery.
Magnetohydrodynamic energy conversion by using convexly divergent channel
NASA Astrophysics Data System (ADS)
We describe a magnetohydrodynamic (MHD) electrical power generator equipped with a convexly divergent channel, as determined through shock-tunnel-based experiments. The quality of MHD power-generating plasma and the energy conversion efficiency in the convexly divergent channel are compared with those from previous linearly divergent channel. The divergence enhancement in the channel upstream is effective for suppressing an excessive increase in static pressure, whereby notably high isentropic efficiency is achieved.
Murakami, Tomoyuki; Okuno, Yoshihiro
Dynamics of the Brazil-Malvinas Confluence: Energy Conversions
NASA Astrophysics Data System (ADS)
In this work, we investigated the mesoscale dynamics of the Brazil-Malvinas Confluence (BMC) region. Particularly, we were interested in the role of geophysical instability in the formation and development of the mesoscale features commonly observed in this region. We dynamically analyzed the results of numerical simulations of the BMC region conducted with 'Hybrid Coordinate Ocean Model' (HYCOM). We quantified the effect of barotropic and baroclinic energy conversions in the modeled flow and showed the dominance of the latter in the region.
Francisco, C. P. F.; da Silveira, I. C. A.; Campos, E. J. D.
Thermophotovoltaic energy conversion using photonic bandgap selective emitters
A method for thermophotovoltaic generation of electricity comprises heating a metallic photonic crystal to provide selective emission of radiation that is matched to the peak spectral response of a photovoltaic cell that converts the radiation to electricity. The use of a refractory metal, such as tungsten, for the photonic crystal enables high temperature operation for high radiant flux and high dielectric contrast for a full 3D photonic bandgap, preferable for efficient thermophotovoltaic energy conversion.
Gee, James M. (Albuquerque, NM); Lin, Shawn-Yu (Albuquerque, NM); Fleming, James G. (Albuquerque, NM); Moreno, James B. (Albuquerque, NM)
NSF/Tokyo Report: Report On Ocean Wave Energy Conversion Projects
Title: NSF/Tokyo Report: Report On Ocean Wave Energy Conversion Projects Date: April 23, 1998 The ... Report On Ocean Wave Energy Conversion Projects Summary This report presents a brief overview of the ...
Conversion of electromagnetic energy in Z-pinch process of single planar wire arrays at 1.5 MA
NASA Astrophysics Data System (ADS)
The electromagnetic energy conversion in the Z-pinch process of single planar wire arrays was studied on Qiangguang generator (1.5 MA, 100 ns). Electrical diagnostics were established to monitor the voltage of the cathode-anode gap and the load current for calculating the electromagnetic energy. Lumped-element circuit model of wire arrays was employed to analyze the electromagnetic energy conversion. Inductance as well as resistance of a wire array during the Z-pinch process was also investigated. Experimental data indicate that the electromagnetic energy is mainly converted to magnetic energy and kinetic energy and ohmic heating energy can be neglected before the final stagnation. The kinetic energy can be responsible for the x-ray radiation before the peak power. After the stagnation, the electromagnetic energy coupled by the load continues increasing and the resistance of the load achieves its maximum of 0.6-1.0 ? in about 10-20 ns.
Liangping, Wang; Mo, Li; Juanjuan, Han; Jian, Wu; Ning, Guo; Aici, Qiu
HEDL magnetic fusion energy programs
Progress is described in three HEDL programs supported by the U.S. Department of Energy's Division of Magnetic Fusion Energy. They are: (1) irradiation effects analysis, (2) mechanical performance of MFE materials, and (3) preparation and presentation of design data. Helium production cross sections for isotopes of Fe, Ni, and Cr, calculated with the HAUSER 4 code, are tabulated at 15
D. G. Doran
Magnetic confinement fusion energy research
Controlled thermonuclear fusion offered a relatively clean energy solution with completely inexhaustible fuel and unlimited power capacity. The scientific and technological problem consisted in magnetically confining a hot, dense plasma for an appreciable fraction of a second. The scientific and mathematical problem was to describe the behavior, such as confinement, stability, flow, compression, heating, energy transfer and diffusion of this
H. Grad
Thermionic Energy Conversion with Nanoscale Materials and Devices
NASA Astrophysics Data System (ADS)
Prior studies on electron emission show possibly beneficial effects of nanoscale phenomena on energy-conversion characteristics. For example, recent work has shown that the electric field around a nanoscale field emission device can increase the average energy of emitted electrons. This geometric effect could be useful in cooling devices based on the Nottingham effect. We consider here the hypothesis that nanoscale effects can favorably influence the energy-conversion efficiency and capacity of thermionic and field emission devices. Required improvements in experimental and computational tools for characterizing such effects include new methods of measuring electron energy distributions (EEDs) from nanoscale emitters and improved modeling of transport between bulk and quantum-confined materials. Accurate emission modeling requires calculation of a self-consistent solution to Schr�dinger's equation and Poisson's equation. A particularly promising approach is the non-equilibrium Green's function (NEGF) formalism. Using NEGF, tractable solutions can be obtained for complex quantum problems because of several features inherent to the approach. For emission modeling, the primary benefit of the NEGF is that boundaries can be treated as bulk sources, which eliminates the need for periodic boundary conditions and enables the coupling of transport between bulk and confined materials. Recent work on EED measurements reveals indications of quantum confinement, as shown by the multiple peaks in the energy distribution. This paper includes representative simulation results and associated electron energy distribution measurements that identify interesting and potentially useful features of thermally excited electron emission phenomena. The paper concludes with recommendations for further study and engineering development.
Liu, Yang; Fisher, Timothy S.
A magnet system for the suppression of conversion electrons in alpha spectrometry.
A new magnet system has been designed and constructed to reduce coincidence effects between alpha particles and conversion electrons in high-resolution alpha-particle spectrometry. By means of a magnetic field, the conversion electrons are deflected away from the PIPS(�) detector. Compared to existing magnet systems, the new system is not restricted to point sources and can accommodate source diameters up to about 30 mm. Two yokes were built, allowing for configurations with 20 mm or 36 mm distance between the magnets. The effectiveness of both configurations is demonstrated by measuring the conversion electron spectrum of a (237)Np source. The magnet system effectively rejects 93 (7)% of electrons up to 85 keV (36 mm) and 90 (9)% of electrons up to 320 keV (20 mm). It has been successfully applied in the alpha-particle spectrometry of the long-lived nuclides (236)U and (238)U, resulting in significant improvement of the accuracy of alpha emission probabilities. PMID:24291529
Paepen, J; Dirican, A; Marouli, M; Pomm�, S; Van Ammel, R; Stroh, H
Longitudinal Density Modulation and Energy Conversion in Intense Beams
Density modulation of charged particle beams may occur as a consequence of deliberate action, or may occur inadvertently because of imperfections in the particle source or acceleration method. In the case of intense beams, where space charge and external focusing govern the beam dynamics, density modulation may under some circumstances be converted to velocity modulation, with a corresponding conversion of potential energy to kinetic energy. Whether this will occur depends on the properties of the beam and the initial modulation. This paper describes the evolution of discrete and continuous density modulations on intense beams, and discusses three recent experiments related to the dynamics of density-modulated electron beams.
Harris, J; Neumann, J; Tian, K; O'Shea, P
Longitudinal density modulation and energy conversion in intense beams
Density modulation of charged particle beams may occur as a consequence of deliberate action, or may occur inadvertently because of imperfections in the particle source or acceleration method. In the case of intense beams, where space charge and external focusing govern the beam dynamics, density modulation may, under some circumstances, be converted to velocity modulation, with a corresponding conversion of potential energy to kinetic energy. Whether this will occur depends on the properties of the beam and the initial modulation. This paper describes the evolution of discrete and continuous density modulations on intense beams and discusses three recent experiments related to the dynamics of density-modulated electron beams.
Harris, J. R.; Neumann, J. G.; Tian, K.; O'Shea, P. G. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Naval Research Laboratory, Washington, DC 20379 (United States); Department of Electrical and Computer Engineering, University of Maryland, College Park, Maryland 20740 (United States)
Compact magnetic energy storage module
A superconducting compact magnetic energy storage module in which a plurality of superconducting toroids, each having a toroidally wound superconducting winding inside a poloidally wound superconducting winding, are stacked so that the flow of electricity in each toroidally wound superconducting winding is in a direction opposite from the direction of electrical flow in other contiguous superconducting toroids. This allows for minimal magnetic pollution outside of the module. 4 figures.
Prueitt, M.L.
Compact magnetic energy storage module
A superconducting compact magnetic energy storage module in which a plurality of superconducting toroids, each having a toroidally wound superconducting winding inside a poloidally wound superconducting winding, are stacked so that the flow of electricity in each toroidally wound superconducting winding is in a direction opposite from the direction of electrical flow in other contiguous superconducting toroids. This allows for minimal magnetic pollution outside of the module.
Prueitt, Melvin L. (Los Alamos, NM)
Nanocrystal-based Dyads for Solar to Electric Energy Conversion.
NASA Astrophysics Data System (ADS)
We describe a new project which aims to develop a systematic and modular approach to creating a new generation of Gratzel-inspired solar energy conversion devices with the following novel advantages: the ability to capture the entire available range of solar irradiance by employing sets of linked nanoparticles, fabrication by self-assembly, enhanced robustness, and lowered cost through use of nanostructured, rather than molecular, charge transfer elements. The project team is designing, creating, and characterizing linked-nanoparticle dyads, which will act as the charge separation ``engine'' in new generation solar cells. By employing a mixture of dyads it should be possible to efficiently capture the entire solar spectrum. The proposed device architecture has two important advantages over existing solar conversion devices: It can be produced by a self-assembly process. Because of its modularity, each of its components (nanoparticles or organic linker) can be optimized separately.
Wang, Lei; Wu, Mingyan; Waldeck, David
Refractory semiconductors for high temperature thermoelectric energy conversion
NASA Technical Reports Server (NTRS)
Thermoelectric energy conversion utilizing nuclear heat sources has been employed for several decades to generate power for deep space probes. In the past, lead telluride and, more recently, silicon-germanium alloys have been the prime choices as thermoelectric materials for this application. Currently, a number of refractory semiconductors are under investigation at the Jet Propulsion Laboratory in order to produce power sources of higher conversion efficiency and, thus, lower mass per unit of power output. Included among these materials are improved Si-Ge alloys, rare earth compounds and boron-rich borides. The criteria used to select thermoelectric materials, in general, and the above materials, in particular, will be discussed. The current state of the art and the accomplishments to date in thermoelectric materials research will be reviewed.
Wood, Charles
Investigation of direct solar-to-microwave energy conversion techniques
NASA Technical Reports Server (NTRS)
Identification of alternative methods of producing microwave energy from solar radiation for purposes of directing power to the Earth from space is investigated. Specifically, methods of conversion of optical radiation into microwave radiation by the most direct means are investigated. Approaches based on demonstrated device functioning and basic phenomenologies are developed. There is no system concept developed, that is competitive with current baseline concepts. The most direct methods of conversion appear to require an initial step of production of coherent laser radiation. Other methods generally require production of electron streams for use in solid-state or cavity-oscillator systems. Further development is suggested to be worthwhile for suggested devices and on concepts utilizing a free-electron stream for the intraspace station power transport mechanism.
Chatterton, N. E.; Mookherji, T. K.; Wunsch, P. K.
Transmission and conversion of magnetoacoustic waves on the magnetic canopy in a quiet Sun region
NASA Astrophysics Data System (ADS)
Context. We present evidence for the conversion and transmission of wave modes on the magnetic flux tubes that constitute mottles and form the magnetic canopy in a quiet Sun region. Aims: Our aim is to highlight the details and the key parameters of the mechanism that produces power halos and magnetic shadows around the magnetic network observed in H?. Methods: We use our previous calculations of the magnetic field vector and the height of the magnetic canopy, and based on simple assumptions, we determine the turning height, i.e., the height at which the fast magnetoacoustic waves reflect at the chromosphere. We compare the variation of 3, 5, and 7 min power in the magnetic shadow and the power halo with the results of a two-dimensional model on mode conversion and transmission. The key parameter of the model is the attack angle, which is related to the inclination of the magnetic field vector at the canopy height. Our analysis takes also into account that 1) there are projection effects on the propagation of waves; 2) the magnetic canopy and the turning height are curved layers; 3) waves with periods longer than 3 min only reach the chromosphere in the presence of inclined magnetic fields (ramp effect); 4) mottles in H? are canopy structures; and 5) the wings of H? contain mixed signal from low- and high-? plasma. Results: The dependence of the measured power on the attack angle follows the anticipated by the two-dimensional model very well. Long-period slow waves are channeled to the upper chromospheric layers following the magnetic field lines of mottles, while short-period fast waves penetrate the magnetic canopy and are reflected back higher, at the turning height. Conclusions: Although both magnetoacoustic modes contribute to velocity signals, making the interpretation of observations a challenging task, we conclude that conversion and transmission of the acoustic waves into fast and slow magnetoacoustic waves are responsible for forming power halos and magnetic shadows in the quiet Sun region.
Kontogiannis, I.; Tsiropoula, G.; Tziotziou, K.
Energy conversion issues for airborne directed energy weapons
The ability of an airborne directed energy weapon (DEW) to effectively strike a target depends strongly on the ability to develop, deliver, and manage the required energy for the onboard DEW source. The energy flow within various generic airborne DEW systems is examined from power generation to waste heat management. Each airborne DEW system is analyzed by considering the energy
Steven F. Adams; John G. Nairus
Efficient computerized model for dynamic analysis of energy conversion systems
NASA Astrophysics Data System (ADS)
In searching for the optimum parameters that minimize the total life cycle cost of an energy conversion system, various combinations of components are examined and the resulting system performance and associated economics are studied. The systems performance and economics simulation computer program (SPECS) was developed to fill this need. The program simulates the fluid flow, thermal, and electrical characteristics of a system of components on a quasi-steady state basis for a variety of energy conversion systems. A unique approach is used in which the set of characteristic equations is solved by the Newton-Raphson technique. This approach eliminates the tedious iterative loops which are found in comparable programs such as TRNSYS or SOLTES-1. Several efficient features were also incorporated such as the centralized control and energy management scheme, and analogous treatment of energy flow in electrical and mechanical components, and the modeling of components of similar fundamental characteristics using generic subroutines. Initial tests indicate that this model can be used effectively with a relatively small number of time steps and low computer cost.
Hughes, R. D.; Lansing, F. L.; Khan, I. R.
Magnetic flux concentration methods for magnetic energy harvesting module
NASA Astrophysics Data System (ADS)
This paper presents magnetic flux concentration methods for magnetic energy harvesting module. The purpose of this study is to harvest 1 mW energy with a Brooks coil 2 cm in diameter from environmental magnetic field at 60 Hz. Because the harvesting power is proportional to the square of the magnetic flux density, we consider the use of a magnetic flux concentration coil and a magnetic core. The magnetic flux concentration coil consists of an air�core Brooks coil and a resonant capacitor. When a uniform magnetic field crossed the coil, the magnetic flux distribution around the coil was changed. It is found that the magnetic field in an area is concentrated larger than 20 times compared with the uniform magnetic field. Compared with the air�core coil, our designed magnetic core makes the harvested energy ten�fold. According to ICNIRP2010 guideline, the acceptable level of magnetic field is 0.2 mT in the frequency range between 25 Hz and 400 Hz. Without the two magnetic flux concentration methods, the corresponding energy is limited to 1 �W. In contrast, our experimental results successfully demonstrate energy harvesting of 1 mW from a magnetic field of 0.03 mT at 60 Hz.
Tashiro, Kunihisa; Hattori, Gen-ya; Wakiwaka, Hiroyuki
Surface conversion techniques for low energy neutral atom imagers
NASA Technical Reports Server (NTRS)
This investigation has focused on development of key technology elements for low energy neutral atom imaging. More specifically, we have investigated the conversion of low energy neutral atoms to negatively charged ions upon reflection from specially prepared surfaces. This 'surface conversion' technique appears to offer a unique capability of detecting, and thus imaging, neutral atoms at energies of 0.01 - 1 keV with high enough efficiencies to make practical its application to low energy neutral atom imaging in space. Such imaging offers the opportunity to obtain the first instantaneous global maps of macroscopic plasma features and their temporal variation. Through previous in situ plasma measurements, we have a statistical picture of large scale morphology and local measurements of dynamic processes. However, with in situ techniques it is impossible to characterize or understand many of the global plasma transport and energization processes. A series of global plasma images would greatly advance our understanding of these processes and would provide the context for interpreting previous and future in situ measurements. Fast neutral atoms, created from ions that are neutralized in collisions with exospheric neutrals, offer the means for remotely imaging plasma populations. Energy and mass analysis of these neutrals provides critical information about the source plasma distribution. The flux of neutral atoms available for imaging depends upon a convolution of the ambient plasma distribution with the charge exchange cross section for the background neutral population. Some of the highest signals are at relatively low energies (well below 1 keV). This energy range also includes some of the most important plasma populations to be imaged, for example the base of the cleft ion fountain.
Quinn, J. M.
Renewable energy from corn residues by thermochemical conversion
NASA Astrophysics Data System (ADS)
Declining fossil oil reserve, skyrocket price, unsecured supplies, and environment pollution are among the many energy problems we are facing today. It is our conviction that renewable energy is a solution to these problems. The long term goal of the proposed research is to develop commercially practical technologies to produce energy from renewable resources. The overall objective of my research is to study and develop thermochemical processes for converting bulky and low-energy-density biomass materials into bio-fuels and value-added bio-products. The rationale for the proposed research is that, once such processes are developed, processing facility can be set up on or near biomass product sites, reducing the costs associated with transport of bulky biomass which is a key technical barrier to biomass conversion. In my preliminary research, several conversion technologies including atmospheric pressure liquefaction, high pressure liquefaction, and microwave pyrolysis have been evaluated. Our data indicated that microwave pyrolysis had the potential to become a simple and economically viable biomass conversion technology. Microwave pyrolysis is an innovative process that provides efficient and uniform heating, and are robust to type, size and uniformity of feedstock and therefore suitable for almost any waste materials without needing to reduce the particle size. The proposed thesis focused on in-depth investigations of microwave pyrolysis of corn residues. My first specific aim was to examine the effects of processing parameters on product yields. The second specific research aim was to characterize the products (gases, bio-oils, and solid residues), which was critical to process optimization and product developments. Other research tasks included conducting kinetic modeling and preliminary mass and energy balance. This study demonstrated that microwave pyrolysis could be optimized to produce high value syngas, liquid fuels and pyrolytic carbons, and had a great potential to become a commercial process according to the mass and energy balance. One-step global model and two-step consecutive-reaction kinetic model offered a clue to the key mechanistic steps in the overall pyrolysis of corn residues. These results should have a positive impact on advancing renewable energy technologies and establishing the University's leadership status in the area of renewable energy development.
Yu, Fei
Optical materials technology for energy efficiency and solar energy conversion 9
This book contains papers related to optical materials and solar energy conversion. It is organized under the following sessions. Transparent infrared reflectors, Solar cell materials, Chromogenics, Solar collector materials, Transparent materials.
Granqvist, C.G.; Lampert, C.M.
Electrical System for Home Conversion and Storage of Solar Energy.
Energy storage has long been a problem in connection with home utilization of solar energy. A solution which utilizes solar semiconductor cells for conversion to d-c power is proposed. The d-c power is used to drive an alternator which is connected directly across the residential power lines. Thus a-c power is delivered to the power lines when a surplus of power is available in the home and is used in other parts of the power distribution system. At latitude 42 degrees N there is 3 times more yearly energy recoverable than is used by an average residence on the basis of a 10-by-10-m collection area. At the present state of technical development the cost of such a large-area semiconductor solar cell would be prohibitive. PMID:17732892
Giacoletto, L J
Solar energy conversion by dye-sensitized photovoltaic cells.
The quality of human life depends to a large degree on the availability of energy. This is threatened unless renewable energy resources can be developed in the near future. Chemistry is expected to make important contributions to identify environmentally friendly solutions of the energy problem. One attractive strategy discussed in this Forum Article is the development of solar cells that are based on the sensitization of mesoscopic oxide films by dyes or quantum dots. These systems have already reached conversion efficiencies exceeding 11%. The underlying fundamental processes of light harvesting by the sensitizer, heterogeneous electron transfer from the electronically excited chromophore into the conduction band of the semiconductor oxide, and percolative migration of the injected electrons through the mesoporous film to the collector electrode will be described below in detail. A number of research topics will also be discussed, and the examples for the first outdoor application of such solar cells will be provided. PMID:16180840
Gr�tzel, Michael
Artificial photosynthesis: biomimetic approaches to solar energy conversion and storage.
Using sun as the energy source, natural photosynthesis carries out a number of useful reactions such as oxidation of water to molecular oxygen and fixation of CO(2) in the form of sugars. These are achieved through a series of light-induced multi-electron-transfer reactions involving chlorophylls in a special arrangement and several other species including specific enzymes. Artificial photosynthesis attempts to reconstruct these key processes in simpler model systems such that solar energy and abundant natural resources can be used to generate high energy fuels and restrict the amount of CO(2) in the atmosphere. Details of few model catalytic systems that lead to clean oxidation of water to H(2) and O(2), photoelectrochemical solar cells for the direct conversion of sunlight to electricity, solar cells for total decomposition of water and catalytic systems for fixation of CO(2) to fuels such as methanol and methane are reviewed here. PMID:20439158
Kalyanasundaram, K; Graetzel, M
Science in Focus: Transfer and Conversion of Energy
NSDL National Science Digital Library
What happens when energy is converted from one form to another? This free one-hour professional development video for K-8 teachers explores the topic through examples of conversion between potential and kinetic energy. The video is designed so that teachers come away with an understanding that will help them engage students in their own explorations. Editor's Note: This resources offer excellent support for teachers to update content knowledge in energy conservation, important to meet revised science curriculum standards being adopted by many states. This collection is part of a larger set of video workshops published and maintained by the Annenberg Foundation. Other workshop topics in physical science include Forces and Motion, Chemistry, and Light.
Nanostructured Solar Irradiation Control Materials for Solar Energy Conversion
NASA Technical Reports Server (NTRS)
Tailoring the solar absorptivity (alpha(sub s)) and thermal emissivity (epsilon(sub T)) of materials constitutes an innovative approach to solar energy control and energy conversion. Numerous ceramic and metallic materials are currently available for solar absorbance/thermal emittance control. However, conventional metal oxides and dielectric/metal/dielectric multi-coatings have limited utility due to residual shear stresses resulting from the different coefficient of thermal expansion of the layered materials. This research presents an alternate approach based on nanoparticle-filled polymers to afford mechanically durable solar-absorptive and thermally-emissive polymer nanocomposites. The alpha(sub s) and epsilon(sub T) were measured with various nano inclusions, such as carbon nanophase particles (CNPs), at different concentrations. Research has shown that adding only 5 wt% CNPs increased the alpha(sub s) and epsilon(sub T) by a factor of about 47 and 2, respectively, compared to the pristine polymer. The effect of solar irradiation control of the nanocomposite on solar energy conversion was studied. The solar irradiation control coatings increased the power generation of solar thermoelectric cells by more than 380% compared to that of a control power cell without solar irradiation control coatings.
Kang, Jinho; Marshall, I. A.; Torrico, M. N.; Taylor, C. R.; Ely, Jeffry; Henderson, Angel Z.; Kim, J.-W.; Sauti, G.; Gibbons, L. J.; Park, C.; Lowther, S. E.; Lillehei, P. T.; Bryant, R. G.
Visible light to electrical energy conversion using photoelectrochemical cells
NASA Technical Reports Server (NTRS)
Sustained conversion of low energy visible or near i.r. light (>1.25 eV) to electrical energy has been obtained using wet photoelectrochemical cells where there are no net chemical changes in the system. Stabilization of n-type semi-conductor anodes of CdS, CdSe, CdTe, GaP, GaAs and InP to photoanodic dissolution is achieved by employing selected alkaline solutions of Na.sub.2 S, Na.sub.2 S/S, Na.sub.2 Se, Na.sub.2 Se/Se, Na.sub.2 Te and Na.sub.2 Te/Te as the electrolyte. The oxidation of (poly) sulfide, (poly)selenide or (poly)telluride species occurs at the irradiated anode, and reduction of polysulfide, polyselenide or polytelluride species occurs at the dark Pt cathode of the photoelectrochemical cell. Optical to electrical energy conversion efficiencies approaching 15% at selected frequencies have been observed in some cells. The wavelength for the onset of photocurrent corresponds to the band gap of the particular anode material used in the cell.
Wrighton, Mark S. (Inventor); Ellis, Arthur B. (Inventor); Kaiser, Steven W. (Inventor)
Advanced solar energy conversion. [solar pumped gas lasers
NASA Technical Reports Server (NTRS)
An atomic iodine laser, a candidate for the direct solar pumped lasers, was successfully excited with a 4 kW beam from a xenon arc solar simulator, thus proving the feasibility of the concept. The experimental set up and the laser output as functions of operating conditions are presented. The preliminary results of the iodine laser amplifier pumped with the HCP array to which a Q switch for giant pulse production was coupled are included. Two invention disclosures - a laser driven magnetohydrodynamic generator for conversion of laser energy to electricity and solar pumped gas lasers - are also included.
Lee, J. H.
Analysis of dynamic effects in solar thermal energy conversion systems
NASA Technical Reports Server (NTRS)
The paper examines a study the purpose of which is to assess the performance of solar thermal power systems insofar as it depends on the dynamic character of system components and the solar radiation which drives them. Using a dynamic model, the daily operation of two conceptual solar conversion systems was simulated under varying operating strategies and several different time-dependent radiation intensity functions. These curves ranged from smoothly varying input of several magnitudes to input of constant total energy whose intensity oscillated with periods from 1/4 hour to 6 hours.
Hamilton, C. L.
Low cost composite materials for wind energy conversion systems
NASA Technical Reports Server (NTRS)
A winding process utilizing a low-cost E-glass fabric called transverse-filament tape for low-cost production of wind turbine generators (WTG) is described. The process can be carried out continuously at high speed to produce large one-piece parts with tapered wall thicknesses on a tapered mandrel. It is being used to manufacture blades for the NASA/DOE 200-ft-diameter MOD-1 WTG and Rockwell/DOE 40-kW small wind energy conversion system (SWECS).
Weingart, O.
Method and apparatus for testing electrochemical energy conversion devices
NASA Technical Reports Server (NTRS)
A system for testing electrochemical energy conversion and storage devices includes means for sensing the current from the storage device and varying the load across the storage device in response to the current sensed. The system is equally adaptable to batteries and fuel cells. Means is also provided to sense system parameters from a plurality of locations within the system. Certain parameters are then stored in digital form for archive purposes and certain other parameters are used to develop control signals in a host processor.
Cisar, Alan J. (Inventor); Murphy, Oliver J. (Inventor)
Nuclear spin conversion of water inside fullerene cages detected by low-temperature nuclear magnetic resonance.
The water-endofullerene H2O@C60 provides a unique chemical system in which freely rotating water molecules are confined inside homogeneous and symmetrical carbon cages. The spin conversion between the ortho and para species of the endohedral H2O was studied in the solid phase by low-temperature nuclear magnetic resonance. The experimental data are consistent with a second-order kinetics, indicating a bimolecular spin conversion process. Numerical simulations suggest the simultaneous presence of a spin diffusion process allowing neighbouring ortho and para molecules to exchange their angular momenta. Cross-polarization experiments found no evidence that the spin conversion of the endohedral H2O molecules is catalysed by (13)C nuclei present in the cages. PMID:24852537
Mamone, Salvatore; Concistr�, Maria; Carignani, Elisa; Meier, Benno; Krachmalnicoff, Andrea; Johannessen, Ole G; Lei, Xuegong; Li, Yongjun; Denning, Mark; Carravetta, Marina; Goh, Kelvin; Horsewill, Anthony J; Whitby, Richard J; Levitt, Malcolm H
Nuclear spin conversion of water inside fullerene cages detected by low-temperature nuclear magnetic resonance
NASA Astrophysics Data System (ADS)
The water-endofullerene H2O@C60 provides a unique chemical system in which freely rotating water molecules are confined inside homogeneous and symmetrical carbon cages. The spin conversion between the ortho and para species of the endohedral H2O was studied in the solid phase by low-temperature nuclear magnetic resonance. The experimental data are consistent with a second-order kinetics, indicating a bimolecular spin conversion process. Numerical simulations suggest the simultaneous presence of a spin diffusion process allowing neighbouring ortho and para molecules to exchange their angular momenta. Cross-polarization experiments found no evidence that the spin conversion of the endohedral H2O molecules is catalysed by 13C nuclei present in the cages.
Mamone, Salvatore; Concistr�, Maria; Carignani, Elisa; Meier, Benno; Krachmalnicoff, Andrea; Johannessen, Ole G.; Lei, Xuegong; Li, Yongjun; Denning, Mark; Carravetta, Marina; Goh, Kelvin; Horsewill, Anthony J.; Whitby, Richard J.; Levitt, Malcolm H.
The Photochemical Conversion of Solar Energy into Electrical Energy: Eosin-D-Xylose System
A photosensitizer-Eosin and a reductant-D-Xylose were used in the photogalvanic cell for photochemical conversion of solar energy into electrical energy. The generated photopotential and photocurrent were 825.0 mV and 250.0 ?A, respectively, whereas maximum power of the cell was 206.25 ?W. The observed power at the power point was 70.85 ?W and conversion efficiency was 0.6812%. The experimentally determined fill
K. M. Gangotri; M. K. Bhimwal
Kinetic simulation of the O-X conversion process in dense magnetized plasmas
NASA Astrophysics Data System (ADS)
One scheme for heating a dense magnetized plasma core, such as in a tokamak, involves launching an ordinary (O) electromagnetic wave at the low density edge. It is converted to a reflected extraordinary (X) electromagnetic wave under certain conditions, and then transformed into an electron Bernstein wave able to reach high density regions inaccessible to most other waves. The O-X mode conversion is important in heating and diagnostic processes in different devices such as tokamaks, stellarators, and some types of pinches. The goal of this study has been to demonstrate that the kinetic particle-in-cell (PIC) scheme is suitable for modeling the O-X conversion process as the first step toward a more complete simulation of O-X-B heating. The O-X process is considered and simulated with a kinetic particle model for parameters of the TJ-II stellarator using the PIC code, XOOPIC. This code is able to model the non-monotonic density and the magnetic profile of the TJ-II stellarator. It can also statistically represent the self-consistent distribution function of the plasma, which has not been possible in previous fluid models. By considering the electric and magnetic components of launched and reflected waves, the O-mode and X-mode waves can be detected, and the O-X conversion can be demonstrated. In this work, the optimum angle for conversion efficiency, as predicted by the previous theory and experimentally confirmed, is used. Via considering the power of the launched O-mode wave and the converted X-mode wave, the efficiency of 63% for O-X conversion for the optimum theoretical launch angle of 47\\convolu is obtained, which is in good agreement with efficiencies computed via full-wave simulations.
Ali Asgarian, M.; Verboncoeur, J. P.; Parvazian, A.; Trines, R.
Energy Conversion Alternatives Study (ECAS), General Electric Phase 1. Volume 1: Executive summary
A data base for the comparison of advanced energy conversion systems for utility applications using coal or coal-derived fuels was developed. Estimates of power plant performance (efficiency), capital cost, cost of electricity, natural resource requirements, and environmental intrusion characteristics were made for ten advanced conversion systems. Emphasis was on the energy conversion system in the context of a base loaded
J. C. Corman
On converse magnetoelectric effect in a twisted carbon nanotube under the influence of applied magnetic field
NASA Astrophysics Data System (ADS)
We present theoretical results concerning some unusual properties of linear converse magnetoelectric effect (MEE) in a twisted carbon nanotube under the influence of applied magnetic field Bz. In addition to twist angle ? dependence of the zero-field paramagnetic MEE coefficient ?, we found that for magnetic fields Bz exceeding deformation induced intrinsic pseudomagnetic field Bzd??? (generated by the constant twist), ? changes its sign and becomes diamagnetic. The estimates of the model parameters suggest quite an optimistic possibility to experimentally realize the discussed phenomena in twisted carbon nanotubes and graphene nanoribbons.
Sergeenkov, S.; Araujo-Moreira, F. M.
National Technical Information Service (NTIS)
The fusion program embraces low loss superconductor strand development with integration into cables capable of carrying 50 kA in pulsed mode at high fields. This evolvement has been paralleled with pulsed energy storage coil development and testing from t...
J. D. Rogers
Investigation on energy conversion technology using biochemical reaction elements, 2
NASA Astrophysics Data System (ADS)
For measures taken for resource/energy and environmental issues, a study is made on utilization of microbial biochemical reaction. As a reaction system using chemical energy, cited is production of petroleum substitution substances and food/feed by CO2 fixation using hydrogen energy and hydrogen bacteria. As to photo energy utilization, regarded as promising are CO2 fixation using photo energy and microalgae, and production of hydrogen and useful carbon compound using photosynthetic organisms. As living organism/electric energy interconversion, cited is the culture of chemoautotrophic bacteria which fix CO2 using electric energy. For enhancing its conversion efficiency, it is important to develop a technology of gene manipulation of the bacteria and a system to use functional biochemical elements adaptable to the electrode reaction. With regard to utilization of the microorganism metabolic function, the paper presents emission of soluble nitrogen in the hydrosphere into the atmosphere using denitrifying bacteria, removal of phosphorus, reduction in environmental pollution caused by heavy metal dilute solutions, and recovery as resources, etc.
Mode conversion of fast magnetosonic waves and minority ion heating in a longitudinally inhomogeneous magnetic field
Mode conversion process in ICRF (Ion Cyclotron Range of Frequencies) in a longitudinally inhomogeneous two-ion-species plasma is clarified in the HIEI tandem mirror experiments. Measurements of wave number parallel to the magnetic field reveal that the fast magnetosonic wave of low-field-side incidence converts into the slow ion-cyclotron wave near the ion�ion hybrid resonance. The propagation of the slow wave is
O. Sakai; Y. Yasaka
Energy and data conversion circuits for low power sensory systems
NASA Astrophysics Data System (ADS)
This dissertation focuses on the problem of increasing the lifetime of wireless sensors. This problem is addressed from two different angles: energy harvesting and data compression. Energy harvesting enables a sensor to extract energy from its environment and use it to power itself or recharge its batteries. Data compression, on the other hand, allows a sensor to save energy by reducing the radio transmission bandwidth. This dissertation proposes a fractal-based photodiode fabricated on standard CMOS process as an energy harvesting device with increased efficiency. Experiments show that, the fractal based photodiodes are 6% more efficient compared to the conventional square shaped photodiode. The fractal shape photodiode has more perimeter-to-area ratio which increases the lateral response, improving its efficiency. With increased efficiency, more current is generated but the open-circuit voltage still remains low (0.3V--0.45V depending on illumination condition). These voltages have to be boosted up to higher values if they are going to be used to power up any sensory circuit or recharge a battery. We propose a switched-inductor DC-DC converter to boost the low voltage of the photodiodes to higher voltages. The proposed circuit uses two on-chip switches and two off-chip Components: an inductor and a capacitor. Experiments show a voltage up to 2.81V can be generated from a single photodiode of 1mm2 area. The voltage booster circuit achieved a conversion efficiency of 59%. Data compression was also explored in an effort to reduce energy consumption during radio transmission. An analog-to-digital converter (ADC), which can jointly perform the tasks of digital conversion and entropy encoding, has also been proposed in this dissertation. The joint data conversion/compression help savings in area and power resources, making it suitable for on-sensor compression. The proposed converter combines a cyclic converter architecture and Golomb-Rice entropy encoder. The converter hardware design is based on current-mode circuits and it was fabricated on a 0.5 mum CMOS process and tested. Experiment results show a lossless compression ratio of 1.52 and a near-lossless compression of 5.2 can be achieved for 32 x 32 pixel image.
Ghosh, Suvradip
A preliminary assessment was made of the environmental impacts of several types of conversion processes for producing energy or fuels from agricultural and forestry residues. Fifteen examples were selected to represent various combinations of agricultural residues and conversion ...
Wind energy conversion system analysis model (WECSAM) computer program documentation
Described is a computer-based wind energy conversion system analysis model (WECSAM) developed to predict the technical and economic performance of wind energy conversion systems (WECS). The model is written in CDC FORTRAN V. The version described accesses a data base containing wind resource data, application loads, WECS performance characteristics, utility rates, state taxes, and state subsidies for a six state region (Minnesota, Michigan, Wisconsin, Illinois, Ohio, and Indiana). The model is designed for analysis at the county level. The computer model includes a technical performance module and an economic evaluation module. The modules can be run separately or together. The model can be run for any single user-selected county within the region or looped automatically through all counties within the region. In addition, the model has a restart capability that allows the user to modify any data-base value written to a scratch file prior to the technical or economic evaluation. Thus, any user-supplied data for WECS performance, application load, utility rates, or wind resource may be entered into the scratch file to override the default data-base value. After the model and the inputs required from the user and derived from the data base are described, the model output and the various output options that can be exercised by the user are detailed. The general operation is set forth and suggestions are made for efficient modes of operation. Sample listings of various input, output, and data-base files are appended. (LEW)
Downey, W T; Hendrick, P L
Nanostructured Tungsten Trioxide Photoanodes for Solar Energy Conversion
NASA Astrophysics Data System (ADS)
Nanostructured tungsten trioxide (WO3) photoelectrodes are potential candidates for the anodic portion of an integrated solar water-splitting device that generates hydrogen fuel and oxygen from water. These nanostructured materials can potentially offer improved performance in photooxidation reactions compared to unstructured materials because of enhancements in light scattering, increases in surface area, and their decoupling of the directions of light absorption and carrier collection. To evaluate the presence of these effects and their contributions toward energy conversion efficiency, a variety of nanostructured WO3 photoanodes were synthesized by electrodeposition within nanoporous templates and by anodization of tungsten foils. A robust fabrication process was developed for the creation of oriented WO3 nanorod arrays, which allows for control nanorod diameter and length. Films of nanostructured WO3 platelets were grown via anodization, the morphology of the films was controlled by the anodization conditions, and the current-voltage performance and spectral response properties of these films were studied. The observed photocurrents were consistent with the apparent morphologies of the nanostructured arrays. Measurements of electrochemically active surface area and other physical characteristics were correlated with observed differences in absorbance, external quantum yield, and photocurrent density for the anodized arrays. The capability to quantify these characteristics and relate them to photoanode performance metrics can allow for selection of appropriate structural parameters when designing photoanodes for solar energy conversion.
Wiggenhorn, David Craig
Proceedings of the Chornobyl phytoremediation and biomass energy conversion workshop
Many concepts, systems, technical approaches, technologies, ideas, agreements, and disagreements were vigorously discussed during the course of the 2-day workshop. The workshop was successful in generating intensive discussions on the merits of the proposed concept that includes removal of radionuclides by plants and trees (phytoremediation) to clean up soil in the Chornobyl Exclusion Zone (CEZ), use of the resultant biomass (plants and trees) to generate electrical power, and incorporation of ash in concrete casks to be used as storage containers in a licensed repository for low-level waste. Twelve years after the Chornobyl Nuclear Power Plant (ChNPP) Unit 4 accident, which occurred on April 26, 1986, the primary 4radioactive contamination of concern is from radioactive cesium ({sup 137}Cs) and strontium ({sup 90}Sr). The {sup 137}Cs and {sup 90}Sr were widely distributed throughout the CEZ. The attendees from Ukraine, Russia, Belarus, Denmark and the US provided information, discussed and debated the following issues considerably: distribution and characteristics of radionuclides in CEZ; efficacy of using trees and plants to extract radioactive cesium (Cs) and strontium (Sr) from contaminated soil; selection of energy conversion systems and technologies; necessary infrastructure for biomass harvesting, handling, transportation, and energy conversion; radioactive ash and emission management; occupational health and safety concerns for the personnel involved in this work; and economics. The attendees concluded that the overall concept has technical and possibly economic merits. However, many issues (technical, economic, risk) remain to be resolved before a viable commercial-scale implementation could take place.
Hartley, J. [Pacific Northwest National Lab., Richland, WA (United States)] [Pacific Northwest National Lab., Richland, WA (United States); Tokarevsky, V. [State Co. for Treatment and Disposal of Mixed Hazardous Waste (Ukraine)] [State Co. for Treatment and Disposal of Mixed Hazardous Waste (Ukraine)
Plasmadynamics and ionization kinetics of thermionic energy conversion
To reduce the plasma arc-drop, thermionic energy conversion is studied with both analytical and numerical tools. Simplifications are made in both the plasmadynamic and ionization-recombination theories. These are applied to a scheme proposed presently using laser irradiation to enhance the ionization kinetics of the thermionic plasma and thereby reduce the arc-drop. It is also predicted that it is possible to generate the required laser light from a thermionic-type cesium plasma. The analysis takes advantage of theoretical simplifications derived for the ionization-recombination kinetics. It is shown that large laser ionization enhancements can occur and that collisional cesium recombination lasing is expected. To complement the kinetic theory, a numerical method is developed to solve the thermionic plasma dynamics. To combine the analysis of ionization-recombination kinetics with the plasma dynamics of thermionic conversion, a finite difference computer program is constructed. It is capable of solving for both unsteady and steady thermionic converter behavior including possible laser ionization enhancement or atomic recombination lasing. A proposal to improve thermionic converter performance using laser radiation is considered. In this proposed scheme, laser radiation impinging on a thermionic plasma enhances the ionization process thereby raising the plasma density and reducing the plasma arc-drop. A source for such radiation may possibly be a cesium recombination laser operating in a different thermionic converter. The possibility of this being an energy efficient process is discussed. (WHK)
Lawless, J.L. Jr.; Lam, S.H.
ECUT (Energy Conversion and Utilization Technologies) program: Biocatalysis Project
NASA Technical Reports Server (NTRS)
Fiscal year 1987 research activities and accomplishments for the Biocatalysis Project of the U.S. Department of Energy, Energy Conversion and Utilization Technologies (ECUT) Division are presented. The project's technical activities were organized into three work elements. The Molecular Modeling and Applied Genetics work element includes modeling and simulation studies to verify a dynamic model of the enzyme carboxypeptidase; plasmid stabilization by chromosomal integration; growth and stability characteristics of plasmid-containing cells; and determination of optional production parameters for hyper-production of polyphenol oxidase. The Bioprocess Engineering work element supports efforts in novel bioreactor concepts that are likely to lead to substantially higher levels of reactor productivity, product yields, and lower separation energetics. The Bioprocess Design and Assessment work element attempts to develop procedures (via user-friendly computer software) for assessing the economics and energetics of a given biocatalyst process.
Controlled cellular energy conversion in brown adipose tissue thermogenesis
NASA Technical Reports Server (NTRS)
Brown adipose tissue serves as a model system for nonshivering thermogenesis (NST) since a) it has as a primary physiological function the conversion of chemical energy to heat; and b) preliminary data from other tissues involved in NST (e.g., muscle) indicate that parallel mechanisms may be involved. Now that biochemical pathways have been proposed for brown fat thermogenesis, cellular models consistent with a thermodynamic representation can be formulated. Stated concisely, the thermogenic mechanism in a brown fat cell can be considered as an energy converter involving a sequence of cellular events controlled by signals over the autonomic nervous system. A thermodynamic description for NST is developed in terms of a nonisothermal system under steady-state conditions using network thermodynamics. Pathways simulated include mitochondrial ATP synthesis, a Na+/K+ membrane pump, and ionic diffusion through the adipocyte membrane.
Horowitz, J. M.; Plant, R. E.
ECUT (Energy Conversion and Utilization Technologies) program: Biocatalysis Project
NASA Astrophysics Data System (ADS)
Fiscal year 1987 research activities and accomplishments for the Biocatalysis Project of the U.S. Department of Energy, Energy Conversion and Utilization Technologies (ECUT) Division are presented. The project's technical activities were organized into three work elements. The Molecular Modeling and Applied Genetics work element includes modeling and simulation studies to verify a dynamic model of the enzyme carboxypeptidase; plasmid stabilization by chromosomal integration; growth and stability characteristics of plasmid-containing cells; and determination of optional production parameters for hyper-production of polyphenol oxidase. The Bioprocess Engineering work element supports efforts in novel bioreactor concepts that are likely to lead to substantially higher levels of reactor productivity, product yields, and lower separation energetics. The Bioprocess Design and Assessment work element attempts to develop procedures (via user-friendly computer software) for assessing the economics and energetics of a given biocatalyst process.
Solid State Energy Conversion Alliance 2nd Annual Workshop Proceedings
The National Energy Technology Laboratory (NETL) and the Pacific Northwest National Laboratory (PNNL) are pleased to provide the proceedings of the second annual Solid State Energy Conversion Alliance (SECA) Workshop held on March 29-30, 2001 in Arlington. The package includes the presentations made during the workshop, a list of participants, and the results of the breakout sessions. Those sessions covered stack materials and processes, power electronics, balance of plant and thermal integration, fuel processing technologies, and stack and system performance modeling. The breakout sessions have been reported as accurately as possible; however, due to the recording and transcription process errors may have occurred. If you note any significant omissions or wish to provide additional information, we welcome your comments and hope that all stakeholder groups will use the enclosed information in their planning endeavors.
National Energy Technology Laboratory
Current developments in small wind energy conversion systems
NASA Astrophysics Data System (ADS)
The development of Small Wind Energy Conversion Systems (SWECS) with capacities under 100 kW and rotor diameters of approximately 30 meters is surveyed with a view to current prototypes, design programs, cost factors and wind systems testing. The characteristics of development SWECS and the projected cost of energy from the new prototypes are given. A primary objective of the Rocky Flats Test Center is the determination of the SWECS power output as a function of average wind speed. One-second average values of wind speed and power output are continuously recorded for each wind turbine and the data are analyzed using the Method of Bins. Areas of research discussed include rotor/wind dynamic interaction, and measurements of power output and blade root bending moments. It is noted that a reliable method of load spectrum prediction would be invaluable in designing for fatigue.
Hansen, A. C.; Butterfield, C. P.
Selective blacks for enhanced photothermal solar energy conversion
NASA Astrophysics Data System (ADS)
The optical and physical requirements of selective surfaces for maximum absorption of solar thermal energy are reviewed, along with processes to fabricate the selective coatings. Noting that the solar energy which reaches the ground is usually in wavelengths of 0.3-2 microns, the desired qualities of coatings are listed as stability of performance, good adherence to the substructure, ease of application, low emissivity above two microns, and economical fabrication. Selective surfaces comprise absorber-reflector tandems, which allow or reflect IR passage, multilayer interference stacks, which involve successive deposition of metallic coatings, and controlled surface morphology, which entails either geometric irregularities, Mie scattering films, corrugated surfaces, or wire mesh surfaces. Preparation can be by electrodeposition, chemical conversion, spray pyrolysis, paint coatings, vacuum deposition, and chemical vapor deposition (CVD), which is stressed as offering the most attractive option for economical large scale coating of solar selective surfaces.
Agarwal, R. C.; Pillai, P. K. C.
Design requirements for interfaces in solar energy conversion technologies
NASA Astrophysics Data System (ADS)
Candidate materials for improving the durability and economics of solar energy conversion systems (SECS) are reviewed. A 30-yr lifetime is regarded as necessary for solar collector and concentrator materials in order to offset the high initial costs of SECS in parabolic dish, heliostat, parabolic trough, flat plate collector, OTEC, solar cell, and wind turbine configurations. The materials are required to transfer a maximum amount of intercepted energy without degrading from exposure to UV radiation, wind, water, dust, and temperature cycling. Glass and mirrored surfaces for reflecting or refracting optical subsystems are currently made from soda-lime, boro- and aluminosilicate, and must resist chemicals, abrasion, and permeability, and have good strength, flexibility, coefficient of expansion, and Young's modulus. Additional concerns are present in photochemical, solar cell, and in substrata components and systems.
Butler, B. L.
Physlets Tour 5: Conversion from Kinetic Energy to Thermal Energy
NSDL National Science Digital Library
A heavy ball with an initial kinetic energy of 4000 J is trapped inside a box with rigid walls containing a cylinder constructed of small lightweight spheres. The vertical bar on to the right of each frame shows the kinetic energy of the ball. To the right are 80 small objects representing a solid that will be crushed and vaporized through impact with the disk.
Christian, Wolfgang; Belloni, Mario
Segregated tandem filter for enhanced conversion efficiency in a thermophotovoltaic energy conversion system
A filter system to transmit short wavelength radiation and reflect long wavelength radiation for a thermophotovoltaic energy conversion cell comprises an optically transparent substrate segregation layer with at least one coherent wavelength in optical thickness; a dielectric interference filter deposited on one side of the substrate segregation layer, the interference filter being disposed toward the source of radiation, the interference filter including a plurality of alternating layers of high and low optical index materials adapted to change from transmitting to reflecting at a nominal wavelength {lambda}{sub IF} approximately equal to the bandgap wavelength {lambda}{sub g} of the thermophotovoltaic cell, the interference filter being adapted to transmit incident radiation from about 0.5{lambda}{sub IF} to {lambda}{sub IF} and reflect from {lambda}{sub IF} to about 2{lambda}{sub IF}; and a high mobility plasma filter deposited on the opposite side of the substrate segregation layer, the plasma filter being adapted to start to become reflecting at a wavelength of about 1.5{lambda}{sub IF}. 10 figs.
Brown, E.J.; Baldasaro, P.F.; Dziendziel, R.J.
Segregated tandem filter for enhanced conversion efficiency in a thermophotovoltaic energy conversion system
A filter system to transmit short wavelength radiation and reflect long wavelength radiation for a thermophotovoltaic energy conversion cell comprises an optically transparent substrate segregation layer with at least one coherent wavelength in optical thickness; a dielectric interference filter deposited on one side of the substrate segregation layer, the interference filter being disposed toward the source of radiation, the interference filter including a plurality of alternating layers of high and low optical index materials adapted to change from transmitting to reflecting at a nominal wavelength .lambda..sub.IF approximately equal to the bandgap wavelength .lambda..sub.g of the thermophotovoltaic cell, the interference filter being adapted to transmit incident radiation from about 0.5.lambda..sub.IF to .lambda..sub.IF and reflect from .lambda..sub.IF to about 2.lambda..sub.IF ; and a high mobility plasma filter deposited on the opposite side of the substrate segregation layer, the plasma filter being adapted to start to become reflecting at a wavelength of about 1.5.lambda..sub.IF.
Brown, Edward J. (Clifton Park, NY); Baldasaro, Paul F. (Clifton Park, NY); Dziendziel, Randolph J. (Middlegrove, NY)
Experimental and Analytical Studies on Pyroelectric Waste Heat Energy Conversion
NASA Astrophysics Data System (ADS)
This study is concerned with direct conversion of thermal energy into electrical energy by subjecting pyroelectric materials to the Olsen cycle. The Olsen cycle consists of two isoelectric field and two isothermal process on the electric displacement versus electric field diagram. The energy and power generation capabilities of copolymer poly(vinylidene fluoridetrifluorethylene) [P(VDF-TrFE)] films and lead lanthanum zirconate titanate (PLZT) ceramics were evaluated by executing the Olsen cycle via so-called "stamping experiments" and "dipping experiments". The stamping experiments consisted of alternatively pressing a pyroelectric material in thermal contact with hot and cold aluminum blocks under specified electric fields. It was performed to assess the pyroelectric energy conversion performance using heat conduction. The largest energy density generated in the stamping experiments was 155 J/L/cycle with 60/40 P(VDF-TrFE) thin film at 0.066 Hz between 25 and 110�C and electric fields cycled between 20 and 35 MV/m. This energy density exceeded the 130 J/L/cycle achieved by our previous prototypical device using oscillatory laminar convective heat transfer. However, the performance was limited by poor thermal contact between the aluminum blocks and pyroelectric material and also by excessive leakage current inherent to P(VDF-TrFE) at high temperatures and/or large electric fields. On the other hand, dipping experiments consisted of successively immersing a pyroelectric material into isothermal hot and cold thermal reservoirs at different temperatures while simultaneously cycling the electric fields. It was performed on relaxor ferroelectric
Lee, Felix
Overview of biomass thermochemical conversion activities funded by the biomass energy systems branch of DOE
The US Department of Energy (DOE) is actively involved in the development of renewable energy sources through research and development programs sponsored by the Biomass Energy Systems Branch. The overall objective of the thermochemical conversion element of the Biomass Energy Systems Program is to develop competitive processes for the conversion of renewable biomass resources into clean fuels and chemical feedstocks
G. F. Schiefelbein; L. J. Jr. Sealock; S. Ergun
Radiation energy receiver for high performance energy conversion cycles
Blackbody receivers, which are used to collect the high intensity radiation flux in solar power plants, are limited in performance and confined to low temperature applications. In this study, a novel type of radiation receiver is presented, in which the radiation energy is directly transferred to the working fluid of a thermodynamic cycle through volumetric absorption. The characteristics of such
Refractory materials for high-temperature thermoelectric energy conversion
NASA Technical Reports Server (NTRS)
Theoretical work of two decades ago adequately explained the transport behavior and effectively guided the development of thermoelectric materials of high conversion efficiencies of conventional semiconductors (e.g., SiGe alloys). The more significant contributions involved the estimation of optimum doping concentrations, the reduction of thermal conductivity by solid solution doping and the development of a variety of materials with ZT approx. 1 in the temperature range 300 K to 1200 K. ZT approx. 1 is not a theoretical limitation although, experimentally, values in excess of one were not achieved. Work has continued with emphasis on higher temperature energy conversion. A number of promising materials have been discovered in which it appears that ZT 1 is realizable. These materials are divided into two classes: (1) the rare-earth chalcogenides which behave as itinerant highly-degenerate n-type semiconductors at room-temperature, and (2) the boron-rich borides, which exhibit p-type small-polaronic hopping conductivity.
Wood, C.; Emin, D.
Energy Conversion Options for Advanced Radioisotope Power Systems
NASA Astrophysics Data System (ADS)
Static and dynamic energy conversion technologies for Advanced Radioisotope Power Systems (ARPSs) are reviewed and their impact on the system's total mass and specific electrical power and the amount of 238PuO2 fuel needed for the heat source are assessed and compared. Conversion technologies considered are Segmented and cascaded Thermoelectric, Alkali-Metal Thermal-to-Electric Conversion, and Free Piston Stirling Engines (FPSEs) and, for comparison, SiGe thermoelectric. Estimates for a 100 We ARPS indicate that when using SiGe thermoelectric, operating between 1273 K and 573 K, 8 General Purpose Heat Source (GPHS) modules would be required and the system's specific power is ~ 4.6 We/kg. Using STE converters, operating between 973 K and 373 K, 5 GPHS modules are required and the ARPS's specific power is ~ 7.28 We/kg. The next generation STE converters that could operate between 1273 K and 573 K, for a projected system efficiency of 13.8%, decrease the number of GPHS modules needed to 4 and increase the system's specific power to ~ 9.9 We/kg. With cascaded SiGe-STE converters, operating between 1273 K and 373 K, the system's efficiency could be as much as 16%, requiring only 3 GPHS modules, for an estimated specific power of 10.7 We/kg. This specific power is more than twice that for SOA RTG. With the current version 1.0 of FPSEs, the 100 We ARPS needs only two GPHS modules, but its specific power (4.1 we/kg) is slightly lower than that of SOA RTG (4.6 We/kg). Future introduction of versions 1.1 and 2.0 engines, with slightly higher conversion efficiency and significantly lower mass, could increase the system's specific power to ~ 7.5 We/kg, using the same number of GPHS modules as version 1.0 engines. With Na-AMTEC and K-AMTEC, the 100 We ARPS needs 3 and 4 GPHS modules, respectively, for an estimated specific power of 5.3 and 5.8 We/kg, respectively.
El-Genk, Mohamed S.
Bio-inspired Approaches to Solar Energy Conversion
NASA Astrophysics Data System (ADS)
Natural photosynthesis is carried out by organized assemblies of photofunctional tetrapyrrole chromophores and catalysts within proteins that provide specifically tailored environments to optimize solar energy conversion. Artificial photosynthetic systems for practical solar fuels production must collect light energy, separate charge, and transport charge to catalytic sites where multi-electron redox processes will occur. The primary goal of our research in this field is to understand the fundamental principles needed to develop integrated artificial photosynthetic systems. These principles include how to promote and control: 1) energy capture, charge separation, and long-range directional energy and charge transport, 2) coupling of separated charges to multi-electron catalysts for fuel formation, and 3) supramolecular self-assembly for scalable, low-cost processing from the nanoscale to the macroscale. The central scientific challenge is to develop small, functional building blocks, having a minimum number of covalent linkages, which also have the appropriate molecular recognition properties to facilitate self-assembly of complete, functional artificial photosynthetic systems. This lecture will describe our use of ultrafast optical spectroscopy and time-resolved EPR spectroscopy to understand charge transport in self-assembled structures for artificial photosynthesis.
Wasielewski, Michael
ECUT (Energy Conversion and Utilization Technologies Program). Biocatalysis Project
NASA Astrophysics Data System (ADS)
Presented are the FY 1985 accomplishments, activities, and planned research efforts of the Biocatalysis Project of the U.S. Department of Energy, Energy Conversion and Utilization Technologies (ECUT) Program. The Project's technical activities were organized as follows: In the Molecular Modeling and Applied Genetics work element, research focused on (1) modeling and simulation studies to establish the physiological basis of high temperature tolerance in a selected enzyme and the catalytic mechanisms of three species of another enzyme, and (2) determining the degree of plasmid amplification and stability of several DNA bacterial strains. In the Bioprocess Engineering work element, research focused on (1) studies of plasmid propagation and the generation of models, (2) developing methods for preparing immobilized biocatalyst beads, and (3) developing an enzyme encapsulation method. In the Process Design and Analysis work element, research focused on (1) further refinement of a test case simulation of the economics and energy efficiency of alternative biocatalyzed production processes, (2) developing a candidate bioprocess to determine the potential for reduced energy consumption and facility/operating costs, and (3) a techno-economic assessment of potential advancements in microbial ammonia production.
Materials and structures for stretchable energy storage and conversion devices.
Stretchable energy storage and conversion devices (ESCDs) are attracting intensive attention due to their promising and potential applications in realistic consumer products, ranging from portable electronics, bio-integrated devices, space satellites, and electric vehicles to buildings with arbitrarily shaped surfaces. Material synthesis and structural design are core in the development of highly stretchable supercapacitors, batteries, and solar cells for practical applications. This review provides a brief summary of research development on the stretchable ESCDs in the past decade, from structural design strategies to novel materials synthesis. The focuses are on the fundamental insights of mechanical characteristics of materials and structures on the performance of the stretchable ESCDs, as well as challenges for their practical applications. Finally, some of the important directions in the areas of material synthesis and structural design facing the stretchable ESCDs are discussed. PMID:24643976
Xie, Keyu; Wei, Bingqing
Performance assessment and cost effectiveness of wind energy conversion systems
NASA Astrophysics Data System (ADS)
Performance and cost characteristics of wind energy conversion systems (WECS) are assessed. Both technological and cost-effectiveness considerations are discussed for these systems with emphasis on developing appropriate economic measures for the application of electric power generation. A cost-effectiveness analysis is developed for target costs per unit frontal area for such systems showing the influence of annual mean windspeed, tower height, atmospheric boundary layer stability, capital-cost financing rates, and the cost escalation rate of the fossil fuel displaced. The latter two parameters are particularly sensitive ones in assessing both lifetime cost-effectiveness and payback time. Although allowable costs vary be several orders of magnitude, initial target costs for cost-effectiveness seem to be of the order of $50 to $400/sq m of frontal area.
Miller, G.; Hoffert, M.; Corren, D.
Photochemical energy conversion by membrane-bound photoredox systems
NASA Astrophysics Data System (ADS)
Most of our effort during the past grant period has been directed towards investigating electron transfer processes involving redox proteins at lipid bilayer/aqueous interfaces. This theme, as was noted in our previous three year renewal proposal, is consistent with our goal of developing biomimetic solar energy conversion systems which utilize the unique properties of biological electron transfer molecules. Thus, small redox proteins such as cytochrome c, plastocyanin and ferredoxin function in biological photosynthesis as mediators of electron flow between the photochemical systems localized in the membrane, and more complex soluble or membrane bound redox proteins which are designed to carry out specific biological tasks such as transbilayer proton gradient formation, dinitrogen fixation, ATP synthesis, dihydrogen synthesis, generation of strong reductants, etc. In these studies, we have utilized two principal experimental techniques, laser flash photolysis and cyclic voltammetry, both of which permit direct measurements of electron transfer processes.
Tollin, G.
Tandem photovoltaic solar cells and increased solar energy conversion efficiency
NASA Technical Reports Server (NTRS)
Tandem photovoltaic cells, as proposed by Jackson (1955) to increase the efficiency of solar energy conversion, involve the construction of a system of stacked p/n homojunction photovoltaic cells composed of different semiconductors. It had been pointed out by critics, however, that the total power which could be extracted from the cells in the stack placed side by side was substantially greater than the power obtained from the stacked cells. A reexamination of the tandem cell concept in view of the development of the past few years is conducted. It is concluded that the use of tandem cell systems in flat plate collectors, as originally envisioned by Jackson, may yet become feasible as a result of the development of economically acceptable solar cells for large scale terrestrial power generation.
Loferski, J. J.
Monolithic Interconnected Modules (MIMs) for Thermophotovoltaic Energy Conversion
NASA Technical Reports Server (NTRS)
Monolithic Interconnected Modules (MIM) are under development for thermophotovoltaic (TPV) energy conversion applications. MIM devices are typified by series-interconnected photovoltaic cells on a common, semi-insulating substrate and generally include rear-surface infrared (IR) reflectors. The MIM architecture is being implemented in InGaAsSb materials without semi-insulating substrates through the development of alternative isolation methodologies. Motivations for developing the MIM structure include: reduced resistive losses, higher output power density than for systems utilizing front surface spectral control, improved thermal coupling and ultimately higher system efficiency. Numerous design and material changes have been investigated since the introduction of the MIM concept in 1994. These developments as well as the current design strategies are addressed.
Wilt, David; Wehrer, Rebecca; Palmisiano, Marc; Wanlass, Mark; Murray, Christopher
Siting handbook for small wind energy conversion systems
This handbook was written to serve as a siting guide for individuals wishing to install small wind energy conversion systems (WECS); that is, machines having a rated capacity of less than 100 kilowatts. It incorporates half a century of siting experience gained by WECS owners and manufacturers, as well as recently developed siting techniques. The user needs no technical background in meteorology or engineering to understand and apply the siting principles discussed; he needs only a knowledge of basic arithmetic and the ability to understand simple graphs and tables. By properly using the siting techniques, an owner can select a site that will yield the most power at the least installation cost, the least maintenance cost, and the least risk of damage or accidental injury.
Wegley, H.L.; Ramsdell, J.V.; Orgill, M.M.; Drake, R.L.
Plasmon enhanced solar-to-fuel energy conversion.
Future generations of photoelectrodes for solar fuel generation must employ inexpensive, earth-abundant absorber materials in order to provide a large-scale source of clean energy. These materials tend to have poor electrical transport properties and exhibit carrier diffusion lengths which are significantly shorter than the absorption depth of light. As a result, many photoexcited carriers are generated too far from a reactive surface and recombine instead of participating in solar-to-fuel conversion. We demonstrate that plasmonic resonances in metallic nanostructures and multilayer interference effects can be engineered to strongly concentrate sunlight close to the electrode/liquid interface, precisely where the relevant reactions take place. On comparison of spectral features in the enhanced photocurrent spectra to full-field electromagnetic simulations, the contribution of surface plasmon excitations is verified. These results open the door to the optimization of a wide variety of photochemical processes by leveraging the rapid advances in the field of plasmonics. PMID:21749077
Thomann, Isabell; Pinaud, Blaise A; Chen, Zhebo; Clemens, Bruce M; Jaramillo, Thomas F; Brongersma, Mark L
Photochemical energy conversion by membrane-bound photoredox systems
Most of our effort during the past grant period has been directed towards investigating electron transfer processes involving redox proteins at lipid bilayer/aqueous interfaces. This theme, as was noted in our previous three year renewal proposal, is consistent with our goal of developing biomimetic solar energy conversion systems which utilize the unique properties of biological electron transfer molecules. Thus, small redox proteins such as cytochrome c, plastocyanin and ferredoxin function is biological photosynthesis as mediators of electron flow between the photochemical systems localized in the membrane, and more complex soluble or membrane-bound redox proteins which are designed to carry out specific biological tasks such as transbilayer proton gradient formation, dinitrogen fixation, ATP synthesis, dihydrogen synthesis, generation of strong reductants, etc. In these studies, we have utilized two principal experimental techniques, laser flash photolysis and cyclic voltammetry, both of which permit direct measurements of electron transfer processes.
Tollin, G.
Energy from agriculture - The most economic method of large scale solar energy conversion
The economics of terrestrial growth of vegetation for its energy content is far more favorable than other more technically sophisticated methods of large-scale solar energy conversion - mirrors, photovoltaics, etc. This paper summarizes our view of what might be attainable in biomass production, hoping, thereby, to stimulate interest in the concept. The types of vegetation best suited for an intensive
J. A. Alich Jr.; R. E. Inman
Review of pyroelectric thermal energy harvesting and new MEMs based resonant energy conversion techniques
Harvesting electrical energy from thermal energy sources using pyroelectric conversion techniques has been under investigation for over 50 years, but it has not received the attention that thermoelectric energy harvesting techniques have during this time period. This lack of interest stems from early studies which found that the energy conversion efficiencies achievable using pyroelectric materials were several times less than those potentially achievable with thermoelectrics. More recent modeling and experimental studies have shown that pyroelectric techniques can be cost competitive with thermoelectrics and, using new temperature cycling techniques, has the potential to be several times as efficient as thermoelectrics under comparable operating conditions. This paper will review the recent history in this field and describe the techniques that are being developed to increase the opportunities for pyroelectric energy harvesting. The development of a new thermal energy harvester concept, based on temperature cycled pyroelectric thermal-to-electrical energy conversion, are also outlined. The approach uses a resonantly driven, pyroelectric capacitive bimorph cantilever structure that can be used to rapidly cycle the temperature in the energy harvester. The device has been modeled using a finite element multi-physics based method, where the effect of the structure material properties and system parameters on the frequency and magnitude of temperature cycling, and the efficiency of energy recycling using the proposed structure, have been modeled. Results show that thermal contact conductance and heat source temperature differences play key roles in dominating the cantilever resonant frequency and efficiency of the energy conversion technique. This paper outlines the modeling, fabrication and testing of cantilever and pyroelectric structures and single element devices that demonstrate the potential of this technology for the development of high efficiency thermal-to-electrical energy conversion devices.
Hunter, Scott Robert [ORNL; Lavrik, Nickolay V [ORNL; Mostafa, Salwa [ORNL; Rajic, Slobodan [ORNL; Datskos, Panos G [ORNL
Energy Conversion Alternatives Study (ECAS): General Electric Phase I, final report. Volume III. Energy conversion subsystems and components. Part 2. Primary heat input systems and heat exchangers
A parametric study was performed to assist in the development of a data base for the comparison of advanced energy conversion systems for utility applications using coal or coal-derived fuels. Estimates of power plant performance (efficiency), capital cost, cost of electricity, natural resource requirements, and environmental intrusion characteristics were made for ten advanced conversion systems. Over 300 parametric points were
J. C. Corman; J. H. Eskesen; A. S. Robertson; R. D. Stewart
Alkali layered compounds interfaces for energy conversion and energy storage
NASA Technical Reports Server (NTRS)
During year one a new ultra-high vacuum, an Ar(+) ion sputterer, a low energy electron diffraction (LEED) system, an Auger electron spectrometer (AES), a work function measurement device with a Kelvin probe, and related accessories were used. The study found a focus in the adsorption of chalcogenides on Si and III-V compound semiconductors. In the second year, a scanning tunneling microscope was obtained along with a quadrapole mass spectrometer, power supplies, a computer, a chart recorder, etc. We started the systematic study on the adsorption of chalcogenides on the compound semiconductor surfaces. The third year saw the mounting of the scanning tunneling microscope (STM) on the existing UHV system. The investigation continued with the adsorption of Cs (alkali) on S-covered Si(100)2x1 surfaces. Then the adsorption of S on Cs-covered Si(100) surfaces was studied.
Papageorgopoulos, Chris A.
A novel thermally biased mechanical energy conversion cycle
NASA Astrophysics Data System (ADS)
This paper demonstrates a new power cycle for direct conversion of mechanical energy into electrical energy under a thermal bias. The cycle consisted sequentially of (i) an electric poling process under zero stress, (ii) an isoelectric process consisting of applying a uniaxial compressive stress ?H followed by (iii) an electric de-poling process under constant compressive stress, and finally (iv) an isoelectric process consisting of removing the compressive stress. The new cycle was performed at constant bias-temperature Tb. It was demonstrated on [001]-poled 0.72PbMg1/3Nb2/3O3-0.28PbTiO3 single crystals. The power density increased with increasing cycle frequency and compressive stress for frequency up to 1 Hz. Maximum energy and power densities of 44 J/l/cycle and 44 W/l were achieved at 1 Hz for bias-temperature Tb of 80 �C and electric field cycled between 0.2 and 0.8 MV/m with compressive stress ?H = 25.13 MPa. This was attributed to a tetragonal-monoclinic-orthorhombic phase transition sequence. The material efficiency reached up to 87% and exceeded that of a similar thermomechanical power cycle performed on pyroelectric material. Finally, a physical model predicting the power density was derived and yielded accurate predictions of experimental data for all bias-temperatures considered and cycle frequency up to 1 Hz.
McKinley, Ian M.; Goljahi, Sam; Lynch, Christopher S.; Pilon, Laurent
Thermal energy conversion by coupled shape memory and piezoelectric effects
NASA Astrophysics Data System (ADS)
This work gives experimental evidence of a promising method of thermal-to-electric energy conversion by coupling shape memory effect (SME) and direct piezoelectric effect (DPE) for harvesting quasi-static ambient temperature variations. Two original prototypes of thermal energy harvesters have been fabricated and tested experimentally. The first is a hybrid laminated composite consisting of TiNiCu shape memory alloy (SMA) and macro fiber composite piezoelectric. This composite comprises 0.1 cm3 of active materials and harvests 75 �J of energy for each temperature variation of 60 �C. The second prototype is a SME/DPE �machine� which uses the thermally induced linear strains of the SMA to bend a bulk PZT ceramic plate through a specially designed mechanical structure. The SME/DPE �machine� with 0.2 cm3 of active material harvests 90 �J over a temperature increase of 35 �C (60 �J when cooling). In contrast to pyroelectric materials, such harvesters are also compatible with both small and slow temperature variations.
Zakharov, Dmitry; Lebedev, Gor; Cugat, Orphee; Delamare, Jerome; Viala, Bernard; Lafont, Thomas; Gimeno, Leticia; Shelyakov, Alexander
Performance analysis of energy conversion via caloric effects in first-order ferroic phase transformations.
A finite-time thermodynamic model of ferroic refrigerators and generators, based on first order phase transformation, is given. We use this model to evaluate a novel method of converting heat directly into electricity based on the martensitic phase transformation accompanied by an abrupt change in magnetic ordering recently discovered [Srivastava et al., Adv. Energy Mater., 2011, 1, 97]. In this paper, we study the efficiency and power output of this method. The formulas of efficiency and power output in terms of material constants, design parameters, and working conditions are derived. The Clausius-Clapeyron coefficient is shown to be important to the efficiency. The figure of merit, as a dimensionless parameter, of energy conversion using the new method is introduced. It is shown that, as the figure of merit goes to infinity, the efficiency approaches the Carnot efficiency. Thermodynamic cycles of the new energy conversion method are optimized for a maximum power output. The matching criteria between materials and working temperatures of such optimized cycles are derived. Using these criteria, one can choose the most suitable materials under given working conditions, or decide the best working conditions for available materials. PMID:24836947
Song, Yintao
NASA Technical Reports Server (NTRS)
Power conversion and control methods for renewable energy sources
NASA Astrophysics Data System (ADS)
In recent years, there has been an increase in the use of renewable energy due to the growing concern over the pollution caused by fossil-fuel-based energy. Renewable energy sources, such as photovoltaic (PV) and fuel cell, can be used to enhance the safety, reliability, sustainability, and transmission efficiency of a power system. This dissertation focuses on the power conversion and control for two major renewable-energy sources: PV and fuel cell. Firstly, a current-based, maximum power-point tracking (MPPT) algorithm is proposed for PV energy. An economical converter system using the above scheme for converting the output from PV panels into 60 Hz AC voltage is developed and built. Secondly, a novel circuit model for the Proton Exchange Membrane (PEM) fuel-cell stack that is useful in the design and analysis of fuel-cell-based power systems is proposed. This Pspice-based model uses elements available in the Pspice library with some modifications to represent both the static and dynamic responses of a PEM fuel-cell module. The accuracy of the model is verified by comparing the simulation and experimental results. Thirdly, a DSP-controlled three-phase induction-motor drive using constant voltage over frequency is built and can be used in a fuel-cell automobile. A hydrogen sensor is used in the drive to both sound an alarm and shut down the inverter trigger pulses through the DSP. Finally, a hybrid power system consisting of PV panels and fuel cell is proposed and built. In the proposed system, PV panels can supply most of the power when the sunlight is available, and the excess power required by the load is supplied by a fuel cell. Load sharing between a fuel cell (FC) and the PV panel is investigated by both simulation and experiments.
Yu, Dachuan
Magnetic Resonance Studies of Energy Storage Materials
NASA Astrophysics Data System (ADS)
In today's society there is high demand to have access to energy for portable devices in different forms. Capacitors with high performance in small package to achieve high charge/discharge rates, and batteries with their ability to store electricity and make energy mobile are part of this demand. The types of internal dielectric material strongly affect the characteristics of a capacitor, and its applications. In a battery, the choice of the electrolyte plays an important role in the Solid Electrolyte Interphase (SEI) formation, and the cathode material for high output voltage. Electron Paramagnetic Resonance (EPR) and Nuclear Magnetic Resonance (NMR) spectroscopy are research techniques that exploit the magnetic properties of the electron and certain atomic nuclei to determine physical and chemical properties of the atoms or molecules in which they are contained. Both EPR and NMR spectroscopy technique can yield meaningful structural and dynamic information. Three different projects are discussed in this dissertation. First, High energy density capacitors where EPR measurements described herein provide an insight into structural and chemical differences in the dielectric material of a capacitor. Next, as the second project, Electrolyte solutions where an oxygen-17 NMR study has been employed to assess the degree of preferential solvation of Li+ ions in binary mixtures of EC (ethylene carbonate) and DMC (dimethyl carbonate) containing LiPF6 (lithium hexafluo-rophosphate) which may be ultimately related to the SEI formation mechanism. The third project was to study Bismuth fluoride as cathode material for rechargeable batteries. The objective was to study 19F and 7Li MAS NMR of some nanocomposite cathode materials as a conversion reaction occurring during lithiation and delithation of the BiF3/C nanocomposite.
Vazquez Reina, Rafael
Advanced Energy Conversion Technologies and Architectures for Earth and Beyond
NASA Technical Reports Server (NTRS)
Research, development and studies of novel space-based solar power systems, technologies and architectures for Earth and beyond are needed to reduce the cost of clean electrical power for terrestrial use and to provide a stepping stone for providing an abundance of power in space, i.e., manufacturing facilities, tourist facilities, delivery of power between objects in space, and between space and surface sites. The architectures, technologies and systems needed for space to Earth applications may also be used for in-space applications. Advances in key technologies, i.e., power generation, power management and distribution, power beaming and conversion of beamed power are needed to achieve the objectives of both terrestrial and extraterrestrial applications. There is a need to produce "proof-ofconcept" validation of critical WPT technologies for both the near-term, as well as far-term applications. Investments may be harvested in near-term beam safe demonstrations of commercial WPT applications. Receiving sites (users) include ground-based stations for terrestrial electrical power, orbital sites to provide power for satellites and other platforms, future space elevator systems, space vehicle propulsion, and space surface sites. Space surface receiving sites of particular interest include the areas of permanent shadow near the moon s North and South poles, where WPT technologies could enable access to ice and other useful resources for human exploration. This paper discusses work addressing a promising approach to solar power generation and beamed power conversion. The approach is based on a unique high-power solar concentrator array called Stretched Lens Array (SLA) applied to both solar power generation and beamed power conversion. Since both versions (solar and laser) of SLA use many identical components (only the photovoltaic cells need to be different), economies of manufacturing and scale may be realized by using SLA on both ends of the laser power beaming system in a space solar power application. Near-term uses of this SLA-laser-SLA system may include terrestrial and space exploration in near Earth space. Later uses may include beamed power for bases or vehicles on Mars. Strategies for developing energy infrastructures in space which utilize this technology are presented. This dual use system produces electrical energy efficiently from either coherent light, such as from a highly coherent laser, or from conventional solar illumination. This allows, for example, supplementing solar energy with energy provided by highly coherent laser illumination during periods of low solar illumination or no illumination. This reduces the need for batteries and alternate sources of power. The capability of using laser illumination in a lowest order Gaussian laser mode provides means for transmitting power optically with maximum efficiency and precision over the long distances characteristic of space. A preliminary receiving system similar to that described here, has been produced and tested under solar and laser illumination. A summary of results is given.
Howell, Joe T.; Fikes, John C.; Phillips, Dane J.; Laycock, Rustin L.; ONeill, Mark; Henley, Mark W.; Fork, Richard L.
Oxidant system improvements for MHD energy conversion and industrial processes
NASA Astrophysics Data System (ADS)
An in-depth study was conducted to identify possible improvements to the oxidant supply system for combined cycle MHD power plants which would lead to higher thermal efficiency and reduction in the cost of electricity, COE. Results showed that the oxidant system energy consumption could be minimized when the process was designed to deliver a product O2 concentration of 70 mole percent. The study also led to the development of a new air separation process, referred to as 'liquid pumping and internal compression'. MHD system performance calculations show that the new process would permit an increase in plant thermal efficiency of 0.6 percent while allowing more favorable tradeoffs between magnetic energy and oxidant system capacity requirements.
Juhasz, A. J.
Optical materials technology for energy efficiency and solar energy conversion XI: Photovoltaics, photochemistry, and photoelectrochemistry
The conference, which by a wide margin is the largest one ever in the field of optical materials technology, is a clear testimony to the increased interest in energy efficiency and solar energy conversion. The conference covers photovoltaics, photochemistry and photoelectrochemistry. Advances in solar cell science and technology are given broad and up-to-date coverage. Twenty-six papers were selected for inclusion on the Energy Data Base.
Hugot-Le Goff, A.; Granqvist, C.G.; Lampert, C.M. (eds.)
Eddy shedding and energy conversions in the East Australian Current
NASA Astrophysics Data System (ADS)
Mesoscale variability and eddy shedding in the Tasman Sea, particularly of the East Australian Current (EAC), is studied through the analysis of remotely sensed observations and outputs from a global ocean model. Previous observations of the western boundary current separation from the coast showed strong variability at periods ranging between 90 and 140 days. We show from satellite altimetric observations that rapid northward migration of the separation point of the EAC follows the formation of large eddies at periods of �100 days. After an eddy separation event the normally southward flowing current swiftly assumes a more zonal configuration near the separation latitude, with a cyclonic circulation developing inshore. The formation of large separation eddies is preceded by the southward propagation of sea level anomalies along the east Australian continental slope. From 25�S, sea level anomalies grow as they travel south, eventually being pinched off in the form of large anticyclones at �32�S, in the current retroflection area. Energy conversion terms in a global ocean model and in altimetric data suggest both barotropic and baroclinic instability may account for the growth of these anomalies as they propagate south. East of the main EAC jet there is evidence that eddies may be feeding potential energy back to the mean flow.
Mata, Mauricio M.; Wijffels, Susan E.; Church, John A.; Tomczak, Matthias
Modeling the Q-cycle mechanism of transmembrane energy conversion
NASA Astrophysics Data System (ADS)
The Q-cycle mechanism plays an important role in the conversion of the redox energy into the energy of the proton electrochemical gradient across the biomembrane. The bifurcated electron transfer reaction, which is built into this mechanism, recycles one electron, thus allowing us to translocate two protons per one electron moving to the high-potential redox chain. We study a kinetic model of the Q-cycle mechanism in an artificial system which mimics the bf complex of plants and cyanobacteria in the regime of ferredoxin-dependent cyclic electron flow. Using methods of condensed matter physics, we derive a set of master equations and describe a time sequence of electron and proton transfer reactions in the complex. We find energetic conditions when the bifurcation of the electron pathways at the positive side of the membrane occurs naturally, without any additional gates. For reasonable parameter values, we show that this system is able to translocate more than 1.8 protons, on average, per one electron, with a thermodynamic efficiency of the order of 32% or higher.
Smirnov, Anatoly Yu; Nori, Franco
Optimized vacuum thermionic energy conversion using diamond materials
NASA Astrophysics Data System (ADS)
The vacuum thermionic energy conversion device (TEC) has been an attractive alternative to other means of energy production for some time due to its potentially high efficiency operation, but practical devices have been difficult to develop as a result of the negative space charge effect. It is well known that a hydrogen termination layer on a diamond material induces a negative electron affinity (NEA). In this study we present a theoretical analysis showing it is possible to tune the parameters of a thermionic device featuring a doped diamond material as the emitter electrode to maximize the output power produced. For example, a TEC operating between 950K and 300K with an emitter negative electron affinity of 0.5eV, a collector barrier height of 0.6eV, Richardson's constant of both electrodes equal to 10A cm-2 K-2, emissivity of both electrode of 0.5, and interelectrode spacing of 10?m will have a maximum output power of 1.5W cm-2 and efficiency of 20% occurring at an emitter barrier height of 1.2eV. The efficiency calculation includes electronic and blackbody heat transport across the device. The analysis establishes approaches to increase the efficiency to values greater than 20%. This work was funded by the Office of Naval Research through the TEC MURI Program.
Smith, Joshua; Bilbro, Griff; Nemanich, Robert
Energy Conversion Advanced Heat Transport Loop and Power Cycle
The Department of Energy and the Idaho National Laboratory are developing a Next Generation Nuclear Plant (NGNP) to serve as a demonstration of state-of-the-art nuclear technology. The purpose of the demonstration is two fold 1) efficient low cost energy generation and 2) hydrogen production. Although a next generation plant could be developed as a single-purpose facility, early designs are expected to be dual-purpose. While hydrogen production and advanced energy cycles are still in its early stages of development, research towards coupling a high temperature reactor, electrical generation and hydrogen production is under way. Many aspects of the NGNP must be researched and developed in order to make recommendations on the final design of the plant. Parameters such as working conditions, cycle components, working fluids, and power conversion unit configurations must be understood. Three configurations of the power conversion unit were demonstrated in this study. A three-shaft design with 3 turbines and 4 compressors, a combined cycle with a Brayton top cycle and a Rankine bottoming cycle, and a reheated cycle with 3 stages of reheat were investigated. An intermediate heat transport loop for transporting process heat to a High Temperature Steam Electrolysis (HTSE) hydrogen production plant was used. Helium, CO2, and an 80% nitrogen, 20% helium mixture (by weight) were studied to determine the best working fluid in terms cycle efficiency and development cost. In each of these configurations the relative component size were estimated for the different working fluids. The relative size of the turbomachinery was measured by comparing the power input/output of the component. For heat exchangers the volume was computed and compared. Parametric studies away from the baseline values of the three-shaft and combined cycles were performed to determine the effect of varying conditions in the cycle. This gives some insight into the sensitivity of these cycles to various operating conditions as well as trade offs between efficiency and capital cost. Prametric studies were carried out on reactor outlet temperature, mass flow, pressure, and turbine cooling. Recommendations on the optimal working fluid for each configuration were made. A steady state model comparison was made with a Closed Brayton Cycle (CBC) power conversion system developed at Sandia National Laboratory (SNL). A preliminary model of the CBC was developed in HYSYS for comparison. Temperature and pressure ratio curves for the Capstone turbine and compressor developed at SNL were implemented into the HYSYS model. A comparison between the HYSYS model and SNL loop demonstrated power output predicted by HYSYS was much larger than that in the experiment. This was due to a lack of a model for the electrical alternator which was used to measure the power from the SNL loop. Further comparisons of the HYSYS model and the CBC data are recommended. Engineering analyses were performed for several configurations of the intermediate heat transport loop that transfers heat from the nuclear reactor to the hydrogen production plant. The analyses evaluated parallel and concentric piping arrangements and two different working fluids, including helium and a liquid salt. The thermal-hydraulic analyses determined the size and insulation requirements for the hot and cold leg pipes in the different configurations. Economic analyses were performed to estimate the cost of the va
Oh, C. H.
Direct energy conversion in fission reactors: A U.S. NERI project
In principle, the energy released by a fission can be converted directly into electricity by using the charged fission fragments. The first theoretical treatment of direct energy conversion (DEC) appeared in the literature in 1957. Experiments were conducted over the next ten years, which identified a number of problem areas. Research declined by the late 1960's due to technical challenges that limited performance. Under the Nuclear Energy Research Initiative the authors are determining if these technical challenges can be overcome with todays technology. The authors present the basic principles of DEC reactors, review previous research, discuss problem areas in detail, and identify technological developments of the last 30 years that can overcome these obstacles. As an example, the fission electric cell must be insulated to avoid electrons crossing the cell. This insulation could be provided by a magnetic field as attempted in the early experiments. However, from work on magnetically insulated ion diodes they know how to significantly improve the field geometry. Finally, a prognosis for future development of DEC reactors will be presented .
Functional Nanostructures for Magnetic and Energy Application
NASA Astrophysics Data System (ADS)
Functional nanostructures serve as the basic building blocks for nanodevices and significant efforts have been devoted to their morphology control and properties optimization. In present study, four functional nanostructures, i.e., FePt/B4C multilayer composite film, particle (FePt)/matrix (B4C) monolayer composite film, Ga-doped ZnO nanowire arrays, and CdSe nanotube arrays are designed, synthesized and characterized in detail, in which the first two are expected to be prominent candidates for ultrahigh-density magnetic storage media while the later two have potential applications in solar energy conversion. FePt/B4C multilayer thin films are deposited on silicon substrates using magnetron sputtering with different B4C layer thickness. Experimental results suggest that the B4C layers effectively serve as spacers to separate the FePt layers, making the multilayer configuration stable even after film annealing at elevated temperatures. On the other hand, B and C are found to be incorporated into the FePt layer, which is responsible for the FePt grain growth confinement and grain separation, and eventually affects the properties of the composite film. Based on the experimental results of multilayer composite film, particle (FePt)/matrix (B4C) monolayer composite thin films on Si substrate are synthesized, in which a record coercivity of 2200 Oe is achieved compared to similar system. The size uniformity of the FePt nanoparticles, the well-defined particle-particle separation, together with the good magnetic property and high temperature thermal stability of the overall composite film, make it a very promising candidate for the ultrahigh density magnetic storage media. Semiconductor based one-dimensional nanostructures are investigated as promising building blocks for solar energy conversion devices. Two aspects are explored, aiming at increasing the energy conversion efficiency, i.e., facilitating electron transport and enhancing photon absorbing. In the first case, large area Ga-doped ZnO nanowire arrays are grown on transparent conducting substrate. Experimental results reveal the well-aligned array morphology and the uniform Ga concentration in these nanowires. In particular, direct I-V measurements performed on single nanowire-on-ITO substrate disclose its Ohmic contact with the conducting substrate and the significant conductivity improvement compared to undoped ZnO nanowire, In the second case, a novel synthesis strategy for nanotube arrays is developed and CdSe is used for demonstration, which material possessing more appropriate band gap as effective light harvester compared to that of materials for existing semiconductor nanotube arrays. The controllable tube wall thickness that can be increased until continuous CdSe porous network is obtained. The experimental results suggest a nanotube array formation mechanism that can be generally applied to a wide range of materials.
Zhou, Minjie
Investigation and development of new materials for electrochemical energy conversion
NASA Astrophysics Data System (ADS)
Performance of next generation electrochemical energy conversion devices relies on optimization of both ion selective membranes that retain conductivity at elevated temperatures, and electrode materials active and stable in corrosive environment. The work presented focuses on (1) improving energy conversion in fuel cells by designing novel ion conductive membrane materials optimized by an original optical high-throughput screening technique and (2) development of new stable mixed transition metal sulfide electrocatalysts for industrial bromine recovery. A functionalized fullerene derivative was used to fabricate mechanically strong, flexible organic-inorganic membranes via cooperative sol-gel synthesis. Amorphous materials with nanometer range wormlike structures were obtained. The dependence of conductivity on the concentration of triflic acid was quantitatively described by percolation theory. Fullerene derivatives with arbitrarily attached chains increased disorder of the structure, but before the wormlike network collapsed conductivity 40 times higher than that of the sample with no fullerenes was recorded. This enhancement was attributed to the additional inter-channel connections for proton transport facilitated by the fullerene derivatives. Optimization of the structure by an optical high-throughput screening made possible proton conductivity of 3.2x10-3 S/cm at 130�C and 5% humidity conditions. A series of doped Ru, Fe, Mo, W sulfide catalysts was synthesized, and their hydrogen evolution and oxygen reduction activity in HBr were studied as a function of dopant. RuS2 compounds showed the highest rates of hydrogen evolution and oxygen reduction reactions in HBr. Among all dopants, Co was the most active for hydrogen evolution reaction with overpotentials 100 mV lower than that of Pt at current density of 80 mA/cm2 in 0.5 M HBr. Oxygen reduction activity of RuS2 catalysts was found to change consistently as a function of periodic position of a dopant. Cr, Mn and Fe dopants inhibited oxygen reduction activity of RuS2, while Co, Ni and Cu promoted the activity. Inexpensive Ni-W sulfide was identified as active catalyst for oxygen reduction reaction in HBr. The activity increased with the addition of Ni up to 50%. Although Co-doped RuS2 is unstable in 6 M HBr, it was found to be stable under applied potential during 5 hour hydrogen evolution reaction test.
Ivanovskaya, Anna
Direct Energy Conversion for Nuclear Propulsion at Low Specific Mass
NASA Technical Reports Server (NTRS)
The project will continue the FY13 JSC IR&D (October-2012 to September-2013) effort in Travelling Wave Direct Energy Conversion (TWDEC) in order to demonstrate its potential as the core of a high potential, game-changing, in-space propulsion technology. The TWDEC concept converts particle beam energy into radio frequency (RF) alternating current electrical power, such as can be used to heat the propellant in a plasma thruster. In a more advanced concept (explored in the Phase 1 NIAC project), the TWDEC could also be utilized to condition the particle beam such that it may transfer directed kinetic energy to a target propellant plasma for the purpose of increasing thrust and optimizing the specific impulse. The overall scope of the FY13 first-year effort was to build on both the 2012 Phase 1 NIAC research and the analysis and test results produced by Japanese researchers over the past twenty years to assess the potential for spacecraft propulsion applications. The primary objective of the FY13 effort was to create particle-in-cell computer simulations of a TWDEC. Other objectives included construction of a breadboard TWDEC test article, preliminary test calibration of the simulations, and construction of first order power system models to feed into mission architecture analyses with COPERNICUS tools. Due to funding cuts resulting from the FY13 sequestration, only the computer simulations and assembly of the breadboard test article were completed. The simulations, however, are of unprecedented flexibility and precision and were presented at the 2013 AIAA Joint Propulsion Conference. Also, the assembled test article will provide an ion current density two orders of magnitude above that available in previous Japanese experiments, thus enabling the first direct measurements of power generation from a TWDEC for FY14. The proposed FY14 effort will use the test article for experimental validation of the computer simulations and thus complete to a greater fidelity the mission analysis products originally conceived for FY13.
Scott, John H.
ECUT (Energy Conversion and Utilization Technologies) program: Biocatalysis project
NASA Astrophysics Data System (ADS)
The Annual Report presents the fiscal year (FY) 1988 research activities and accomplishments, for the Biocatalysis Project of the U.S. Department of Energy, Energy Conversion and Utilization Technologies (ECUT) Division. The ECUT Biocatalysis Project is managed by the Jet Propulsion Laboratory, California Institute of Technology. The Biocatalysis Project is a mission-oriented, applied research and exploratory development activity directed toward resolution of the major generic technical barriers that impede the development of biologically catalyzed commercial chemical production. The approach toward achieving project objectives involves an integrated participation of universities, industrial companies and government research laboratories. The Project's technical activities were organized into three work elements: (1) The Molecular Modeling and Applied Genetics work element includes research on modeling of biological systems, developing rigorous methods for the prediction of three-dimensional (tertiary) protein structure from the amino acid sequence (primary structure) for designing new biocatalysis, defining kinetic models of biocatalyst reactivity, and developing genetically engineered solutions to the generic technical barriers that preclude widespread application of biocatalysis. (2) The Bioprocess Engineering work element supports efforts in novel bioreactor concepts that are likely to lead to substantially higher levels of reactor productivity, product yields and lower separation energetics. Results of work within this work element will be used to establish the technical feasibility of critical bioprocess monitoring and control subsystems. (3) The Bioprocess Design and Assessment work element attempts to develop procedures (via user-friendly computer software) for assessing the energy-economics of biocatalyzed chemical production processes, and initiation of technology transfer for advanced bioprocesses.
Baresi, Larry
NSDL National Science Digital Library
It's show time for eighth grade physical science students after a week of designing, building, and refining Conversion Contraptions. The contraptions are fun combinations of moving parts that use many forms of energy and many conversions of energy. It's t
Chahrour, Janet
Optimized Helium-Brayton Power Conversion for Fusion Energy Systems
This paper presents an overview and a few point designs for multiple-reheat helium Brayton cycle power conversion systems using molten salts (or liquid metals or direct helium cooling). All designs are derived from the General Atomics GT-MHR power conversion unit (PCU). The important role of compact, offset fin heat exchangers for heat transfer to the power cycle helium, and the
Zhao Haihua; Grant Fukuda; Ryan P. Abbott; Per F. Peterson
Energy transport velocity in bidispersed magnetic colloids.
Study of energy transport velocity of light is an effective background for slow, fast, and diffuse light and exhibits the photonic property of the material. We report a theoretical analysis of magnetic field dependent resonant behavior in forward-backward anisotropy factor, light diffusion constant, and energy transport velocity for bidispersed magnetic colloids. A bidispersed magnetic colloid is composed of micrometer size magnetic spheres dispersed in a magnetic nanofluid consisting of magnetic nanoparticles in a nonmagnetic liquid carrier. Magnetic Mie resonances and reduction in energy transport velocity accounts for the possible delay (longer dwell time) by field dependent resonant light transport. This resonant behavior of light in bidispersed magnetic colloids suggests a novel magnetophotonic material. PMID:23005411
Bhatt, Hem; Patel, Rajesh; Mehta, R V
Performance and economics of advanced energy conversion systems for coal and coal-derived fuels
The desire to establish an efficient Energy Conversion System to utilize the fossil fuel of the future - coal - has produced many candidate systems. A comparative technical\\/economic evaluation was performed on the seven most attractive advanced energy conversion systems. The evaluation maintains a cycle-to-cycle consistency in both performance and economic projections. The technical information base can be employed to
J. C. Corman; G. R. Fox
Plasmonic-metal nanostructures for efficient conversion of solar to chemical energy
Recent years have seen a renewed interest in the harvesting and conversion of solar energy. Among various technologies, the direct conversion of solar to chemical energy using photocatalysts has received significant attention. Although heterogeneous photocatalysts are almost exclusively semiconductors, it has been demonstrated recently that plasmonic nanostructures of noble metals (mainly silver and gold) also show significant promise. Here we
Phillip Christopher; David B. Ingram; Suljo Linic
Properties of energy conversion regions observed by Cluster in the plasma sheet
We investigate localized energy conversion regions (ECRs) in the Earth's plasma sheet. In total we have studied 151 ECRs during 660h of plasma sheet data from the summer and fall of 2001 when Cluster was close to apogee at an altitude of about 15-20RE. Cluster offers appropriate conditions for the investigation of energy conversion by the evaluation of the power
M. Hamrin; P. Norqvist; O. Marghitu; S. C. Buchert; A. Vaivads; B. Klecker; L. M. Kistler; I. S. Dandouras
Evaluation of the Energy Conversion Ratio of Vapor Explosions for the Assessment of Nuclear Reactor Safety
The calculation of energy conversion ratio of vapor explosion is an important problem for evaluating the integrity of reactor containment and pressure vessel in severe accident. The propagation and expansion stages of vapor explosion are numerically simulated based on both hydrodynamic and thermal fragmentation mechanisms. The thermal fragmentation model gives much higher pressure peak and higher energy conversion ratio than
Jie LIU; Seiichi KOSHIZUKA; Yoshiaki OKA
Advanced materials development for fossil energy conversion applications
Research activities being conducted as part of this project include: (1) fundamental studies of electrochemical processes occurring at surfaces and interfaces in fuel cells, and (2) development of novel materials synthesis and processing methodologies for fossil energy conversion applications. Complex impedance and dc polarization studies of the electrocatalytic activity at the cathode have allowed intrinsic materials properties to be separated from extrinsic properties related to morphology. Mixed conduction in cathode materials was shown to dramatically enhance electrocatalytic activity with this approach. Combustion synthesis methods were used to prepare multicomponent perovskite catalysts in the La{sub 1-x}Sr{sub x}Co{sub 1-y}Fe{sub y}O{sub 3} system. Electronic properties of these catalysts can be altered by adjusting the composition, which affects both catalytic activity and selectivity. Inverse micelles have been utilized to prepare nanosized nickel sulfide particles, which show promise as hydrodesulfurization catalysts for liquefied coal. Self-assembling organic monolayers and derivatized inorganic surfaces have been used to control nucleation and crystal morphology of inorganic phases.
Bates, J.L.; Chick, L.A.; Kingsley, J.J.; Pederson, L.R.; Weber, W.J.; Youngblood, G.E. [Pacific Northwest Lab., Richland, WA (United States); Hurst, J.K.; Bell, A.E.; Grainger, D.W.; Rananavare, S.B.; Roe, D.K.; Thompson, D.H. [Oregon Graduate Inst. of Science and Technology, Beaverton, OR (United States)
Calibration of sonic flowmeters for Ocean Thermal Energy Conversion (OTEC)
NASA Astrophysics Data System (ADS)
Scientists at the Naval Coastal Systems Center (NCSC) at Panama City, Florida, have used a commercially available acoustic flowmeter to monitor critical flow conditions during an OTEC (Ocean Thermal Energy Conversion) funded study of the effects of biofouling on the efficiency of a prototype heat transfer system. Flowmeters of this type are particularly useful in applications requiring unimpeded flow; i.e., no sensor projecting into the moving fluid. Unfortunately, sonic flowmeters are somewhat difficult to calibrate and may be subject to drift. A method of calibration devised by NCSC may thus be of some interest to other users. It is the purpose of this report to document the special procedures used by test personnel to calibrate the flowmeters. Briefly, the calibration consisted of pumping sea water through the flowmeter into a tank suspended beneath a special load cell which provided an output voltage proportional to the weight of water in the tank. A programmable desktop calculator system was used to monitor changes in voltage as a function of time and convert these changes into flow rates for direct comparison with values read from the sonic flowmeter's digital display. Calibration checks were made at metered flows of 8, 10, 12, 14, 16, and 18 gallons per minute (gpm). It was found that computed flows were essentially linear but differed from metered values by as much as 9.0 percent.
Lott, D. F.; Salsman, G. G.; Hodges, C. E.
Energy Conversion by Molecular Motors Coupled to Nucleotide Hydrolysis
NASA Astrophysics Data System (ADS)
Recent theoretical work on the energy conversion by molecular motors coupled to nucleotide hydrolysis is reviewed. The most abundant nucleotide is provided by adenosine triphosphate (ATP) which is cleaved into adenosine diphosphate (ADP) and inorganic phosphate. The motors have several catalytic domains (or active sites), each of which can be empty or occupied by ATP or ADP. The chemical composition of all catalytic domains defines distinct nucleotide states of the motor which form a discrete state space. Each of these motor states is connected to several other states via chemical transitions. For stepping motors such as kinesin, which walk along cytoskeletal filaments, some motor states are also connected by mechanical transitions, during which the motor is displaced along the filament and able to perform mechanical work. The different motor states together with the possible chemical and mechanical transitions provide a network representation for the chemomechanical coupling of the motor molecule. The stochastic motor dynamics on these networks exhibits several distinct motor cycles, which represent the dominant pathways for different regimes of nucleotide concentrations and load force. For the kinesin motor, the competition of two such cycles determines the stall force, at which the motor velocity vanishes and the motor reverses its direction of motion. In general, kinesin is found to be governed by the competition of three distinct chemomechanical cycles. The corresponding network representation provides a unified description for all motor properties that have been determined by single molecule experiments.
Lipowsky, Reinhard; Liepelt, Steffen; Valleriani, Angelo
Draft environmental assessment: Ocean Thermal Energy Conversion (OTEC) Pilot Plants
This Environmental Assessment (EA) has been prepared, in accordance with the National Environmental Policy Act of 1969, for the deployment and operation of a commercial 40-Megawatt (MW) Ocean Thermal Energy Conversion (OTEC) Pilot Plant (hereafter called the Pilot Plant). A description of the proposed action is presented, and a generic environment typical of the candidate Pilot Plant siting regions is described. An assessment of the potential environmental impacts associated with the proposed action is given, and the risk of credible accidents and mitigating measures to reduce these risks are considered. The Federal and State plans and policies the proposed action will encompass are described. Alternatives to the proposed action are presented. Appendix A presents the navigation and environmental information contained in the US Coast Pilot for each of the candidate sites; Appendix B provides a brief description of the methods and calculations used in the EA. It is concluded that environmental disturbances associated with Pilot Plant activities could potentially cause significant environmental impacts; however, the magnitude of these potential impacts cannot presently be assessed, due to insufficient engineering and environmental information. A site- and design-specific OTEC Pilot Plant Environmental Impact Statement (EIS) is required to resolve the potentially significant environmental effects associated with Pilot Plant deployment and operation. (WHK)
Sullivan, S.M.; Sands, M.D.; Donat, J.R.; Jepsen, P.; Smookler, M.; Villa, J.F.
Amphoteric oxide semiconductors for energy conversion devices: a tutorial review.
In this tutorial review, we discuss the defect chemistry of selected amphoteric oxide semiconductors in conjunction with their significant impact on the development of renewable and sustainable solid state energy conversion devices. The effect of electronic defect disorders in semiconductors appears to control the overall performance of several solid-state ionic devices that include oxide ion conducting solid oxide fuel cells (O-SOFCs), proton conducting solid oxide fuel cells (H-SOFCs), batteries, solar cells, and chemical (gas) sensors. Thus, the present study aims to assess the advances made in typical n- and p-type metal oxide semiconductors with respect to their use in ionic devices. The present paper briefly outlines the key challenges in the development of n- and p-type materials for various applications and also tries to present the state-of-the-art of defect disorders in technologically related semiconductors such as TiO(2), and perovskite-like and fluorite-type structure metal oxides. PMID:23257778
Singh, Kalpana; Nowotny, Janusz; Thangadurai, Venkataraman
ECUT (Energy Conversion and Utilization Technologies Program). Biocatalysis Project. Annual Report FY 1985.
National Technical Information Service (NTIS)
Presented are the FY 1985 accomplishments, activities, and planned research efforts of the Biocatalysis Project of the U.S. Department of Energy, Energy Conversion and Utilization Technologies (ECUT) Program. The Project's technical activities were organi...
Basic and applied research related to the technology of space energy conversion systems, 1982 - 1983
NASA Technical Reports Server (NTRS)
Topics on solar energy conversion concepts and applications are discussed. An overview of the current status and future utilization of radiation receivers for electrical energy generation, liquid droplet radiation systems, and liquid droplet heat exchangers is presented.
Hertzberg, A.
ECUT: Energy Conversion and Utilization Technologies Program: Biocatalysis Project: Annual Report, FY 1985.
National Technical Information Service (NTIS)
This report presents the fiscal year 1985 activities, accomplishments, and planned research efforts of the Biocatalysis Project of the US Department of Energy, Energy Conversion and Utilization Technologies Program. In the Molecular Moedling and Applied G...
Synthesis and Characterization of Zirconia Electrolytes for Potential Use in Energy Conversion.
National Technical Information Service (NTIS)
The present work is part of a program to develop ionically conducting materials for potential use in energy storage and conversion systems. With applications in high energy-density batteries, magneto-hydrodynamic (MHD) generators, fuel cells and sensors, ...
T. A. Wheat
ECUT (Energy Conversion and Utilization Technologies) Program: Biocatalysis Project. Annual Report, FY 1988.
National Technical Information Service (NTIS)
The Annual Report presents the fiscal year (FY) 1988 research activities and accomplishments, for the Biocatalysis Project of the U.S. Department of Energy, Energy Conversion and Utilization Technologies (ECUT) Division. The ECUT Biocatalysis Project is m...
L. Baresi
Direct Conversion of Various Forms of Energy into Electric and Mechanical Power.
National Technical Information Service (NTIS)
Contents: Direct conversion of chemical energy to electrical energy (Theory of fuel cells, Fuel cells with solid fuel, Fuel cells with gaseous fuel, Combined (solid-gas) fuel cells, Fuel cells with liquid fuel, Oxidizing reducing cells, Possibilities of a...
G. N. Alekseev
Computer simulation of magnetic switching circuits and magnetic energy losses
A computer simulation has been developed to model the actions of magnetic switching circuits. Simulations are compared to experimental data obtained from a one-stage magnetically switched circuit. Comparisons between experimental and computed switch voltage and current waveforms are made for various operating conditions, pre-saturation leakage currents, and for energy losses. The computer simulation models the actual core saturation process, including
Rhinehart; H. E. Jr
Flywheel energy storage with superconductor magnetic bearings
A system for storing energy in a flywheel suspended by magnetic levitation in a vacuum vessel is described comprising: a rotatable member having a rotation axis in a central shaft said shaft having first and second magnetic tips formed from permanent magnets on opposite ends thereof, superconductor magnetic bearings, positioned to support said first and second magnetic tips and supported in turn by bearing support means, said superconductor magnetic bearings having a main direction of lift; cooling means in thermal contact with said bearing support means; and energy transfer means, connected to said rotatable member, for transferring energy into and extracting energy from said rotatable member, characterized in that: at least one of said superconducting bearings includes a lifting portion comprising melt-processed, directionally solidified material structure having a crystal structure C-axis oriented parallel to said main direction of lift.
Weinberger, B.R.; Lynds, L. Jr.
Mode conversion and absorption of fast waves at high ion cyclotron harmonics in inhomogeneous magnetic fields
NASA Astrophysics Data System (ADS)
The propagation and absorption of high harmonic fast waves is of interest for non-inductive current drives in fusion experiments. The fast wave can be coupled with the ion Bernstein wave that propagates in the high magnetic field side of an ion cyclotron harmonic resonance layer. This coupling and the absorption are analyzed using the hot plasma dispersion relation and a wave equation that was converted from an approximate dispersion relation for the case where ?i=k?2?i2/2?1 (where k? is the perpendicular wave number and ?i is the ion Larmor radius). It is found that both reflection and conversion may occur near the harmonic resonance layer but that they decrease rapidly, giving rise to a sharp increase in the absorption as the parallel wave number increases.
Cho, Suwon; Kwak, Jong-Gu
High-Frequency Mode Conversion Technique for Stiff Lesion Detection with Magnetic Resonance Elastography
A novel imaging technique is described in which the mode conversion of longitudinal waves is used for the qualitative detection of stiff lesions within soft tissue using Magnetic Resonance Elastography (MRE) methods. Due to the viscoelastic nature of tissue, high-frequency shear waves attenuate rapidly in soft tissues but much less in stiff tissues. By introducing minimally attenuating longitudinal waves at a significantly high frequency into tissue, shear waves produced at interfaces by mode conversion will be detectable in stiff regions, but will be significantly attenuated and thus not detectable in the surrounding soft tissue. This contrast can be used to detect the presence of stiff tissue. The proposed technique is shown to readily depict hard regions (mimicking tumors) present in tissue-simulating phantoms and ex vivo breast tissue. In vivo feasibility is demonstrated on a patient with liver metastases where the tumors are readily distinguished. Preliminary evidence also suggests that quantitative stiffness measurements of stiff regions obtained with this technique are more accurate than those from conventional MRE because of the short shear wavelengths. This rapid, qualitative technique may lend itself to applications in which the localization of stiff, suspicious neoplasms is coupled with more sensitive techniques for thorough characterization.
Mariappan, Yogesh K; Glaser, Kevin J; Manduca, Armando; Romano, Anthony J; Venkatesh, Sudhakar K; Yin, Meng; Ehman, Richard L
A twisted wire-shaped dual-function energy device for photoelectric conversion and electrochemical storage.
A wire-shaped energy device that can perform photoelectric conversion and electrochemical storage was developed through a simple but effective twisting process. The energy wire exhibited a high energy conversion efficiency of 6.58?% and specific capacitance of 85.03??F?cm(-1) or 2.13?mF?cm(-2) , and the two functions were alternately realized without sacrificing either performance. PMID:24740877
Sun, Hao; You, Xiao; Deng, Jue; Chen, Xuli; Yang, Zhibin; Chen, Peining; Fang, Xin; Peng, Huisheng
Biomass Conversion Task IV 1987 program of work: International Energy Agency Bioenergy Agreement
Biomass is a major, renewable energy resource through out the world, and extensive research is being conducted by many countries on bioenergy technologies. In an effort to improve communications and cooperation in the area of biomass energy, several nations have agreed to a cooperative program of work under the International Energy Agency's Bioenergy Agreement (IEA/BA). Three areas of major importance have been identified including Short Rotation Forestry, Conventional Forestry, and Biomass Conversion. This document describes the 1987 Program of Work for cooperative activities in the area of Biomass Conversion. The background of the cooperation and descriptions of specific conversion projects are presented. Details of activity funding are also provided. 3 tabs.
Stevens, D.J.
Dam-Atoll for concentration and conversion of ocean wave energy
A simple wave energy conversion device has recently been patented by Lockheed. The Dam-Atoll concept uses passive structure and the principle of wave refraction as the primary elements to convert wave energy into usable energy. Each unit can provide 1 to 2 MW in an area of adequate wave energy resource. Plans have been formulated for additional development work which
T. P. Higgins; C. P. Sherburne
Analysis of coal conversion recycle solvents by liquid chromatography with nuclear magnetic resonance detection
The analyses of two coal conversion recycle process solvents, one of them hydrotreated, via high-performance liquid chromatography (HPLC) with a continuous flow nuclear magnetic resonance (NMR) detector are reported. The differences between these samples with reference to the role of the solvent in coal liquefaction are discussed. The LC-/sup 1/H NMR technique characterized the hydrocarbons and aromatic ethers with a level of certainty not possible with conventional detectors. In addition, qualitative GC-MS analysis of off-line LC fractions was performed on the recycle solvent sample. LC-/sup 1/H NMR and LC-GC-MS were found to be complementary for volatile samples. Gel permeation chromatography-/sup 1/H nuclear magnetic resonance (GPC-/sup 1/H NMR) analysis of the recycle solvent sample was not as successful as LC-/sup 1/H NMR since class separation is almost essential for this sample. But the introduction of GPC-/sup 1/H NMR is still of interest since GPC is the most appropriate mode of separation for many samples.
Haw, J.F.; Glass, T.E.; Dorn, H.C.
Overall efficiencies for conversion of solar energy to a chemical fuel
NASA Astrophysics Data System (ADS)
A complete and consistent scheme for determining the overall efficiency of a generalized process for the conversion of solar energy into a chemical fuel (e.g. hydrogen) is developed and applied to seven conversion processes: thermal, thermochemical, photovoltaic, photogalvanic, photoelectrolysis, photosynthesis and photochemical conversion. It is demonstrated that the overall efficiency of each of these processes is determined by ten common factors: maximum theoretical efficiency, inherent absorption losses, inherent internal losses, rate limiting effects, reflection losses, transmission losses, coverage losses, system construction requirements, parasitic losses and harvesting and conversion losses. Both state-of-the-art and optimistic values are assigned to each factor for each of the seven conversion processes. State-of-the-art overall efficiencies ranged from 5% for thermal conversion down to essentially zero for thermochemical. Optimistic values in the range of about 10 to 15% are calculated for several of the processes.
Fish, J. D.
Hemp as a Feedstock for Biomass-to-Energy Conversion
An increase in the demand for biomass for conversion to heat by combustion is likely. The potential role for hemp in supplying this demand is discussed in this article. For hemp, key characteristics such as net calorific value, ash content, and melting behavior, and the risk of corrosion or polluting emissions, are all favorable. Low bulk density and size reduction
Bernard Rice
Survey of Advanced Energy Conversion Systems and Their Applicability to Army Aircraft Propulsion Requirements.
National Technical Information Service (NTIS)
A survey of advanced energy conversion methods and an evaluation of their applicability to Army aircraft propulsion requirements were carried out. Systems surveyed included: closed Brayton cycle, Rankine cycle, intercool-reheat cycle, fuel cells, MHD conv...
C. C. Silverstein
Water-Related Environmental Control Requirements at Municipal Solid Waste-to-Energy Conversion Facilities.
National Technical Information Service (NTIS)
Water use and waste water production, water pollution control technology requirements, and water-related limitations to their design and commercialization are identified at municipal solid waste-to-energy conversion systems. In Part I, a summary of conclu...
J. C. Young L. D. Johnson
The role of iron in regulating light harvesting and photochemical energy conversion process was examined in the marine unicellular chlorophyte Dunaliella tertiolecta and the marine diatom Phaeodactylum tricornutum. In both species, iron limitation led to a reduction in cellular c...
Seawater test results of open-cycle ocean thermal energy conversion (OC-OTEC) components.
National Technical Information Service (NTIS)
Key components of open-cycle ocean thermal energy conversion systems--the flash evaporator, mist eliminator, passive predeaerator, two surface condenser stages, and two direct-contact condenser stages--have been tested using seawater. These components ope...
F. Zangrando D. Bharathan H. Link C. B. Panchal
Heat Exchanger Cleaning in Support of Ocean Thermal Energy Conversion (OTEC) - Mechanical Subsystem.
National Technical Information Service (NTIS)
This report describes the mechanical systems supporting biofouling countermeasures for Ocean Thermal Energy Conversion (OTEC). Described in the report are the water supply and distribution and the flow driven brush, recirculating sponge rubber ball, and c...
D. F. Lott
Status and summary of laser energy conversion. [for space power transmission systems
NASA Technical Reports Server (NTRS)
This paper presents a survey of the status of laser energy converters. Since the inception of these devices in the early 1970's, significant advances have been made in understanding the basic conversion processes. Numerous theoretical and experimental studies have indicated that laser energy can be converted at wavelengths from the ultraviolet to the far-infrared. These converters can be classified into five general categories: photovoltaics, heat engines, thermoelectronic, optical diode, and photochemical. The conversion can be directly into electricity (such as the photovoltaic, thermoelectronic, and optical diode) or it can go through an intermediate stage of conversion to mechanical energy, as in the heat engines. The photochemical converters result in storable energy such as hydrogen. Projected conversion efficiencies range from about 30% for the photochemical to nearly 75% for the heat engines.
Lee, G.
High-Temperature, High-Power-Density Thermionic Energy Conversion for Space.
National Technical Information Service (NTIS)
Theoretic converter outputs and efficiencies indicate the need to consider thermionic energy conversion (TEC) with greater power densities and higher temperatures within reasonable limits for space missions. Converter-output power density, voltage, and ef...
J. F. Morris
High figure of merit for electrokinetic energy conversion in Nafion membranes
NASA Astrophysics Data System (ADS)
Based on measurements of the streaming potential coefficient, hydraulic permeability and ion conductivity the electrokinetic energy conversion of nanoporous ion conductive Nafion�117 polymer membrane has been evaluated. A high figure-of-merit of 1.1 � 0.2 has been found in 0.03 M aqueous LiCl solution that corresponds to an electrokinetic energy conversion efficiency of approximately 18 � 2%. To the best of our knowledge, this is the first study in the literature designated to the electrokinetic energy conversion in materials where the pores have high surface charge density. The initial results are promising with respect to future electrokinetic generator or pump applications and highly charged polymer membranes might be a future pathway for low-cost high-efficiency electrokinetic energy conversion.
Kilsgaard, Bj�rn Sj�gren; Haldrup, Sofie; Catalano, Jacopo; Bentien, Anders
Wind turbulence used as searching signal for MPPT in variable-speed wind energy conversion systems
The control problem associated to a class of horizontal-axis fixed-pitch variable-speed low-power wind energy conversion systems, working in the partial load region, consisting in the energy conversion maximization, is approached here under the assumption that the wind turbine model and its parameters are poorly known. Using a new approach derived from the optimum seeking methods category, generically called Maximum Power
Iulian Munteanu; Antoneta Iuliana Bratcu; Emil Ceang?
Thermophotovoltaic energy conversion system having a heavily doped n-type region
A thermophotovoltaic (TPV) energy conversion semiconductor device is provided which incorporates a heavily doped n-type region and which, as a consequence, has improved TPV conversion efficiency. The thermophotovoltaic energy conversion device includes an emitter layer having first and second opposed sides and a base layer in contact with the first side of the emitter layer. A highly doped n-type cap layer is formed on the second side of the emitter layer or, in another embodiment, a heavily doped n-type emitter layer takes the place of the cap layer.
DePoy, David M. (Clifton Park, NY); Charache, Greg W. (Clifton Park, NY); Baldasaro, Paul F. (Clifton Park, NY)
Diminiode thermionic energy conversion with lanthanum-hexaboride electrodes
NASA Technical Reports Server (NTRS)
Thermionic conversion data obtained from a variable gap cesium diminiode with a hot pressed, sintered lanthanum hexaboride emitter and an arc melted lanthanum hexaboride collector are presented. Performance curves cover a range of temperatures: emitter 1500 to 1700 K, collector 750 to 1000 K, and cesium reservoir 370 to 510 K. Calculated values of emitter and collector work functions and barrier index are also given.
Kroeger, E. W.; Bair, V. L.; Morris, J. F.
Energy Conversion Alternatives Study (ECAS), General Electric Phase 1. Volume 2: Advanced energy conversion systems. Part 1: Open-cycle gas turbines
NASA Technical Reports Server (NTRS)
Ten energy conversion systems are defined and analyzed in terms of efficiency. These include: open-cycle gas turbine recuperative; open-cycle gas turbine; closed-cycle gas turbine; supercritical CO2 cycle; advanced steam cycle; liquid metal topping cycle; open-cycle MHD; closed-cycle inert gas MHD; closed-cycle liquid metal MHD; and fuel cells. Results are presented.
Brown, D. H.; Corman, J. C.
New Results in Ferroelectric Energy Conversion Using Metastable Ferroelectric Ceramics Resultats Nouveaux dans le Domaine de la Conversion d'Energie Ferroelectriques Metastables.
National Technical Information Service (NTIS)
Ferroelectric ceramics (PbZrTiO3) with high Zr percentage are shown to be usable for mechano-electric energy conversion. Depending on their composition they can be ferro or anti-ferroelectric at room temperature. In the presence of a high electric field a...
F. Bauer Y. Fetiveau L. Eyraud
Energy Conversion Alternatives Study (ECAS), General Electric Phase 1. Volume 2: Advanced Energy Conversion Systems. Part 1: Open-Cycle Gas Turbines.
National Technical Information Service (NTIS)
Ten energy conversion systems are defined and analyzed in terms of efficiency. These include: open-cycle gas turbine recuperative; open-cycle gas turbine; closed-cycle gas turbine; supercritical CO2 cycle; advanced steam cycle; liquid metal topping cycle;...
D. H. Brown J. C. Corman
Control Strategies for Smoothing of Output Power of Wind Energy Conversion Systems
NASA Astrophysics Data System (ADS)
This article presents a control method for output power smoothing of a wind energy conversion system (WECS) with a permanent magnet synchronous generator (PMSG) using the inertia of wind turbine and the pitch control. The WECS used in this article adopts an AC-DC-AC converter system. The generator-side converter controls the torque of the PMSG, while the grid-side inverter controls the DC-link and grid voltages. For the generator-side converter, the torque command is determined by using the fuzzy logic. The inputs of the fuzzy logic are the operating point of the rotational speed of the PMSG and the difference between the wind turbine torque and the generator torque. By means of the proposed method, the generator torque is smoothed, and the kinetic energy stored by the inertia of the wind turbine can be utilized to smooth the output power fluctuations of the PMSG. In addition, the wind turbines shaft stress is mitigated compared to a conventional maximum power point tracking control. Effectiveness of the proposed method is verified by the numerical simulations.
Pratap, Alok; Urasaki, Naomitsu; Senju, Tomonobu
Nanomaterials of silicides and silicon for energy conversion and storage
NASA Astrophysics Data System (ADS)
Our consumption of fossil fuels can be reduced to address the pressing concerns of global climate change by maximizing the efficiency of conversion technologies. Since many of the alternative fuel sources also being examined are intermittent in nature, it is imperative that high capacity and high power density storage devices are also developed. The conversion efficiency of current state-of-the-art thermoelectric materials is too low to meet our needs, but it may be possible to increase the conversion efficiency of thermoelectric materials by moving from the bulk to the nanoscale. The transition metal silicides, including CrSi2, beta-FeSi2 , Mg2Si and MnSi1.7, have been explored as environmentally friendly non-toxic thermoelectric materials. I began my research in the group synthesizing silicide nanowires via chemical vapor transport (CVT), and later expanded my research to include the synthesis of silicide nanocomposites for thermoelectrics and mesoporous silicon nanocomposites for use as high capacity lithium battery electrodes. Nanoscale thermoelectrics and the enhanced thermoelectric figure-of-merit ZT reported by thermoelectric researchers are reviewed in Chapter 1. Chapter 2 reviews the progress being made in the research community with nanoscale and nanostructured silicon battery anodes. The synthesis and characterization of CrSi2 nanowires synthesized via CVT is detailed in Chapter 3, followed by hyperbranched epitaxial FeSi nanostructures exhibiting merohedral twinning in Chapter 4. Nanowires are fundamentally interesting and provide insight into the changes in materials properties compared to the bulk. The synthesis of interesting nanostructured silicide materials are detailed in Chapter 5, where the conversion of diatoms into a nanostructured thermoelectric Mg2Si/MgO nanocomposite that retains the basic diatom structure after conversion is detailed. This reaction was then modified to use mesoporous silica instead of diatoms to reduce the nanocrystalline domain size and to synthesize mesoporous silicon/carbon nanocomposites for use as lithium battery anodes. This nanocomposite is presented in Chapter 6, with details of its preliminary electrochemical performance. Chapter 7 details the synthesis of mesoporous Si1-xGe xO2, which has previously been reported only once in the literature.
Szczech, Jeannine Robin
Proceedings of the 30. intersociety energy conversion engineering conference. Volume 1
This conference provides a forum to present and discuss the engineering aspects of energy conversion, advanced and unconventional energy systems and devices, energy conversion and utilization, environmental issues and policy implications on research, development, and implementation of technologies. The solution for a sustainable future will lie in a mix of all of the available energy resources (renewable and non-renewable) and diverse energy conversion technologies that will maintain quality of life in a sustainable manner. The 129 papers in Volume 1 deal with aerospace power and are divided into the following topical sections: Aircraft power; Aerospace power systems; Batteries for aerospace power; Computer simulation; Power electronics; Power management; Space solar power; Space power systems; Space energy statics/dynamics; Space power--requirements and issues; Space Station power; Terrestrial applications of space power; Thermal management; Wireless transmission; Space nuclear power; Bimodal propulsion; Electric propulsion; Solar thermal; and Solar bimodal. All papers have been processed separately for inclusion on the data base.
Goswami, D.Y. [ed.] [Univ. of Florida, Gainesville, FL (United States); Kannberg, L.D.; Somasundaram, S. [eds.] [Pacific Northwest Lab., Richland, WA (United States); Mancini, T.R. [ed.] [Sandia National Labs., Albuquerque, NM (United States)
Novel multi-mode single leg converter for renewable energy conversion systems
The digital revolution and faster switching devices have introduced more sophisticated control systems that require high quality and reliable operation. The rapidly growing demand for alternative\\/renewable energy generation systems and use of energy sources on a large scale, require new technologies. In this paper, a novel renewable energy conversion system, which has the reduced number of switching elements preserving the
Taehyung Kim
Potential Impacts of Hydrokinetic and Wave Energy Conversion Technologies on Aquatic Environments
A new generation of hydropower technologies, the kinetic hydro and wave energy conversion devices, offers the possibility of generating electricity from the movements of water, without the need for dams and diversions. The Energy Policy Act of 2005 encouraged the development of these sources of renewable energy in the United States, and there is growing interest in deploying them globally.
Glenn Cada; James Ahlgrimm; Michael Bahleda; Tom Bigford; Stefanie Damiani Stavrakas; Douglas Hall; Russell Moursund; Michael Sale
Optimum control strategies in energy conversion of PMSG wind turbine system without mechanical sensors
The amount of energy obtained from a wind energy conversion system (WECS) depends not only on the characteristics of the wind regime at the site, but it also depends on the control strategy used for the WECS. In order to determine the gain in energy derived from one concept as compared against another, models of several autonomous WECS have been
Kelvin Tan; Syed Islam
Mode conversion of Langmuir to electromagnetic waves at magnetic field-aligned density inhomogeneities: Simulations, theory, and applications to the solar wind and the corona
NASA Astrophysics Data System (ADS)
Linear mode conversion of Langmuir waves to radiation near the plasma frequency at density gradients is potentially relevant to multiple solar radio emissions, ionospheric radar experiments, laboratory plasma devices, and pulsars. Here we study mode conversion in warm magnetized plasmas using a numerical electron fluid simulation code with the density gradient parallel to the ambient magnetic field B0 for a range of incident Langmuir wavevectors. Our results include: (1) both o- and x-mode waves are produced for ?=(?L/c)1/3(?c/?)<~1, contrary to previous ideas. Only the o mode is produced for ?>~1.5. Here ?c is the (angular) electron cyclotron frequency, ? is the angular wave frequency, L is the length scale of the (linear) density gradient, and c is the speed of light. A WKB-style analysis accounts semiquantitatively for the production and relative conversion efficiencies of the o and x modes in the simulations. (2) In the unmagnetized limit, equal amounts of o- and x-mode radiation are produced. (3) The mode conversion window narrows as ? increases. (4) As ? increases the total electromagnetic field changes from linear to circular polarization, with the o- and x-mode signals remaining circularly polarized. (5) The conversion efficiency to the x mode decreases monotonically as ? increases while the o-mode conversion efficiency oscillates due to an interference phenomenon between incoming and reflected Langmuir/z modes. (6) The maximum total conversion efficiencies for wave power from the Langmuir/z mode to radiation are of order 50%-70%. They depend strongly on the wave frequency when close to the background plasma frequency but weakly on the electron temperature T0 and ?=T0/mc2. The corresponding energy conversion efficiencies are favored since they allow separation into o and x modes, use directly measured experimental quantities, and generalize easily for wave packets. The total energy conversion efficiency differs from the power conversion efficiency by the ratio of the group speeds for each mode, is less than 10% for the value of ?=0.01 simulated, and decreases linearly with ?. Since ?~10-5-10-4 in the solar wind and corona, this ? dependence is important in applications. (7) The interference effect and the disappearance of the x mode at ?>~1 can be accounted for semiquantitatively using a WKB-type analysis. (8) Constraints on density turbulence are developed for the x mode to be generated and be able to propagate from the source. (9) Standard parameters for the corona and the solar wind near 1 AU suggest that linear mode conversion should produce both o- and x-mode radiation for solar and interplanetary radio bursts. It is therefore possible that linear mode conversion under these conditions might explain the weak total circular polarizations of type II and III solar radio bursts.
Kim, Eun-Hwa; Cairns, Iver H.; Robinson, Peter A.
Sensorless maximum power point tracking control in wind energy generation using permanent magnet synchronous generator
This paper proposes a control strategy for variable speed wind energy conversion system (WECS), incorporating maximum power point tracking (MPPT) algorithm, using direct driven permanent magnet synchronous generator (PMSG). The generator is operated in the speed control mode below the base speed by controlling the terminal voltage using three phase front-end active-rectifier feeding power to the DC bus. The voltage
N. Srighakollapu; P. S. Sensarma
Ocean wave energy conversion using piezoelectric material members
This patent describes an apparatus for converting mechanical energy from surface waves on a body of water to electrical energy comprising a float for up and down movement in response to the waves, a prezoelectric member for converting strains thereof to electrical energy, and energy transfer means for coupling the up and down movement of the float to the member
Application of Nuclear Energy to Bitumen Upgrading and Biomass Conversion
Key drivers for the increasing use of nuclear energy are the need to mitigate global warming and the requirement for energy security. Nuclear energy can be applied not only to generate electricity but also as a heat source. Moreover, nuclear energy can be applied for hydrogen as well as water production. The application of nuclear energy to oil processing and biomass production is studied in this paper. (authors)
Mamoru Numata; Yasushi Fujimura [JGC Corporation (Japan); Takayuki Amaya [Ministry of Education, Culture, Sports, Science and Technology - MEXT, Japan 2-5-1 Marunouchi Chiyoda-ku, Tokyo 100-8959 (Japan); Masao Hori [Nuclear Systems Association, 1-7-6 Toranomon Tokyo, 105-0001 (Japan)
On the space- and time-dependence of barotropic-to-baroclinic tidal energy conversion
NASA Astrophysics Data System (ADS)
Barotropic to baroclinic tidal conversion rates and baroclinic tidal energy fluxes are derived from a high resolution ocean circulation and tide model (STORMTIDE) simulation. Two semi-diurnal (M2 and S2) and two diurnal (K1 and O1) tidal constituents are considered in the present study. The model resolves mesoscale eddies and internal tides and it is forced by a climatological forcing. It is estimated that 1.7 TW of tidal energy is converted from barotropic tides into baroclinic motions. About 32% (50%) of this energy conversion occurs in shallow waters with ocean depths shallower than 1000 m (2000 m). The spatial patterns of tidal energy conversion and the global net conversion are consistent with previous analytical and numerical model studies and it shows that most of the energy is converted in the West Pacific. An important result from the present study is that about 30% (0.11 TW) of diurnal tidal energy is converted poleward of the critical latitudes, and presumably transfered locally to turbulent mixing processes with a high efficiency. Further, a modulation function is derived from the full lunisolar tidal potential described by ephemerides, in order to allow the internal tide generation to be modulated on monthly to bi-decadal timescales. This function reproduces the modulation of the tidal constituents in real-time. The coupling of this function with the spatial conversion rates depicts the regional and temporal dependence of tidal energy conversion. In some regions the nodal cycles of semi-diurnal and diurnal tides interfere destructively (e.g. North Atlantic and South Pacific) and in others the strong diurnal nodal cycle is dominant and modulates the tidal energy conversion by 10-20% (North West Pacific and Southern Ocean). In sight of climate bi-decadal variability this approach shows that the consideration of tidal mixing parameterizations in climate models should acknowledge the spatial and temporal dependence of internal tide generation.
M�ller, M.
Solar energy conversion via hot electron internal photoemission in metallic nanostructures: Efficiency estimates
NASA Astrophysics Data System (ADS)
Collection of hot electrons generated by the efficient absorption of light in metallic nanostructures, in contact with semiconductor substrates can provide a basis for the construction of solar energy-conversion devices. Herein, we evaluate theoretically the energy-conversion efficiency of systems that rely on internal photoemission processes at metal-semiconductor Schottky-barrier diodes. In this theory, the current-voltage characteristics are given by the internal photoemission yield as well as by the thermionic dark current over a varied-energy barrier height. The Fowler model, in all cases, predicts solar energy-conversion efficiencies of <1% for such systems. However, relaxation of the assumptions regarding constraints on the escape cone and momentum conservation at the interface yields solar energy-conversion efficiencies as high as 1%-10%, under some assumed (albeit optimistic) operating conditions. Under these conditions, the energy-conversion efficiency is mainly limited by the thermionic dark current, the distribution of hot electron energies, and hot-electron momentum considerations.
Leenheer, Andrew J.; Narang, Prineha; Lewis, Nathan S.; Atwater, Harry A.
Permanent Magnet Spiral Motor for Magnetic Gradient Energy Utilization: Axial Magnetic Field
NASA Astrophysics Data System (ADS)
The Spiral Magnetic Motor, which can accelerate a magnetized rotor through 90% of its cycle with only permanent magnets, was an energy milestone for the 20th century patents by Kure Tekkosho in the 1970's. However, the Japanese company used old ferrite magnets which are relatively weak and an electrically-powered coil to jump start every cycle, which defeated the primary benefit of the permanent magnet motor design. The principle of applying an inhomogeneous, anisotropic magnetic field gradient force Fz = ? cos J dB/dz, with permanent magnets is well-known in physics, e.g., Stern-Gerlach experiment, which exploits the interaction of a magnetic moment with the aligned electron spins of magnetic domains. In this case, it is applied to dB/d? in polar coordinates, where the force F? depends equally on the magnetic moment, the cosine of the angle between the magnetic moment and the field gradient. The radial magnetic field increases in strength (in the attractive mode) or decreases in strength (in the repulsive mode) as the rotor turns through one complete cycle. An electromagnetic pulsed switching has been historically used to help the rotor traverse the gap (detent) between the end of the magnetic stator arc and the beginning (Kure Tekko, 1980). However, alternative magnetic pulse and switching designs have been developed, as well as strategic eddy current creation. This work focuses on the switching mechanism, novel magnetic pulse methods and advantageous angular momentum improvements. For example, a collaborative effort has begun with Toshiyuki Ueno (University of Tokyo) who has invented an extremely low power, combination magnetostrictive-piezoelectric (MS-PZT) device for generating low frequency magnetic fields and consumes ``zero power'' for static magnetic field production (Ueno, 2004 and 2007a). Utilizing a pickup coil such as an ultra-miniature millihenry inductor with a piezoelectric actuator or simply Wiegand wire geometry, it is shown that the necessary power for magnetic field switching device can be achieved in order to deflect the rotor magnet in transit. The Wiegand effect itself (bistable FeCoV wire called ``Vicalloy'') invented by John Wiegand (Switchable Magnetic Device, US Patent No.4,247,601), utilizing Barkhausen jumps of magnetic domains, is also applied for a similar achievement (Dilatush, 1977). Conventional approaches for spiral magnetic gradient force production have not been adequate for magnetostatic motors to perform useful work. It is proposed that integrating a magnetic force control device with a spiral stator inhomogeneous axial magnetic field motor is a viable approach to add a sufficient nonlinear boundary shift to apply the angular momentum and potential energy gained in 315 degrees of the motor cycle.
Valone, Thomas F.
Ocean Thermal Energy Conversion Mission Analysis Study. Phase II.
National Technical Information Service (NTIS)
The market potential for OTEC has been identified as being electricity, and electrical energy-intensive products (such as ammonia and aluminum). Market penetration scenarios are derived for electrical utilities and energy-intensive industries in Southern ...
Feasibility of MHD Conversion of Pulsed Thermonuclear Reactor Energy.
National Technical Information Service (NTIS)
The authors discuss the possibility of using certain conduction and induction MHD generators schemes for converting the energy of pulsed thermonuclear reactors (PTR), in which energy release occurs in a blanket which absorbs the basic fraction of hard rad...
E. P. Velikhov V. S. Golubev V. V. Chernukha
Bio-inspired constructs for solar energy conversion
Solar energy input to the biosphere is about 10^24 joules\\/year. This makes human needs of even a projected 10^21 joules\\/year a deceptively achievable goal. One key to global-scale use of solar energy is the synthesis of energy-rich fuel materials such as hydrogen and reduced carbon compounds. The latter have the almost inestimable advantage that the energy infrastructure for distribution and
Thomas Moore
Hydrokinetic energy conversion systems: A technology status review
The growing demand for electrical energy is one of the most important subjects today. Decreasing amount and environmental effect of fossil fuels does not seem to surmount this challenge. Renewable energies give a good perspective to be an alternative to fossil and nuclear-fueled power plants, in order to meet growing demand for electrical energy. Hydropower is well known in this
M. S. G�ney; K. Kaygusuz
Biomimetic approach to solar energy conversion - Artificial photosynthesis
Green plants and certain bacteria use the energy of sunlight to drive chemical reactions that require an energy input to proceed in the desired manner. Thus, green plants use solar energy to convert carbon dioxide and water to carbohydrates, proteins, and lipids that are the nutrients for all other living organisms. Plants also produce natural fibers, such as cotton and
J. J. Katz
The wells air turbine for wave energy conversion
The wave energy devices currently in operation in the United Kingdom and India and those that are to be built in Europe are based on the principle of the oscillating water-air column. In these devices the pneumatic energy of the oscillating air column is converted to mechanical energy of rotation by a Wells turbine. A monoplane (single plane) Wells turbine
S. Raghunathan
Investigation of current university research concerning energy conversion and conservation in small single-family dwellings
NASA Technical Reports Server (NTRS)
An investigation was made of university research concerning energy conversion and conservation techniques which may be applied in small single-family residences. Information was accumulated through published papers, progress reports, telephone conversations, and personal interviews. A synopsis of each pertinent investigation is given. Finally, a discussion of the synopses is presented and recommendations are made concerning the applicability of concepts for the design and construction of NASA-Langley Research Center's proposed Technology Utilization House in Hampton, Virginia.
Grossman, G. R.; Roberts, A. S., Jr.
Higher-order lattice Boltzmann simulation of energy conversion of electrokinetic nanobatteries
NASA Astrophysics Data System (ADS)
As a novel green technology to harvest electric power, electrokinetic batteries appeal to more theoretical investigation in order to optimize their physical parameters, and hence to achieve higher energy conversion efficiency at nanoscales as expected. Generally, transport phenomena at nanoscales are out of the scope of continuum fluid mechanics theories. In addition, the electric double layer (EDL) requires a more comprehensive description incorporating image effect and ion size effect. In this study, the higher-order Lattice Boltzmann method (LBM) and the modified Poisson-Boltzmann theory (MPB) are used to investigate electrokinetic phenomena in nanochannels. Energy conversion is studied in terms of ion size, and dielectric properties of liquid and solid. 24.95% mechanical-electrical energy conversion efficiency may be achieved in a 16 nm electrokinetic battery. And hence about 6% mechanical energy can be utilized by the external load of the electrokinetic nanobattery.
Liu, Y.; Yang, J.
Fibrous materials for selective line emission application in a thermal-electrical energy conversion system
Fibrous rare earth composite emitters were developed for the application of thermophotovoltaic (TPV) energy conversion to increase the energy conversion efficiency of the system. In this paper, the authors demonstrated that fibrous composite emitters, with higher selective efficiency and good mechanical properties, were fabricated using a unique material processing technology. The spectra of the emitters, as well as their mechanical properties, were investigated. Some observations in this research have indicated that by using our current technology, we are able to tailor the spectrum by designing the emitter materials. Therefore, in order to achieve high energy conversion efficiency the designed emitters can be matched to the energy bandgap of new developing photovoltaic cells. {copyright} {ital 1997 American Institute of Physics.}
Chen, Z.; Adair, P.L.; Rose, M.F. [Space Power Institute, 231 Leach Center Auburn, Alabama36849 (United States)
Hybrid offshore-wind and tidal turbine (HOTT) energy Conversion I.. (6-pulse GTO rectifier and inverter)
The innovative renewable energy conversion system called ldquoHybrid Offshore-wind and Tidal Turbinerdquo (HOTT) Conversion was proposed. The research includes tidal turbine and offshore-wind turbine, new turbine designs, turbine control of tidal energy and offshore-wind energy absorption, hydrodynamic characteristics, energy conversion, overall design methods, moorings and foundation and system resonance. HOTT will be entire five turbines, four turbines will be tidal
Mohammad Lutfur Rahman; Yasuyuki Shirai
Thermochemical conversion of biomass: an overview of R and D activities sponsored by the Biomass Energy Systems Branch of DOE
The US Department of Energy (DOE) is actively developing renewable energy sources through research and development programs sponsored by the Biomass Energy Systems Branch. The mission of the thermochemical conversion element of the Biomass Energy Systems Program is to develop competitive processes for the conversion of renewable biomass resources into clean fuels and chemical feedstocks which can supplement those produced
G. F. Schiefelbein; L. J. Jr. Sealock; S. Ergun
Efficient conversion of solar energy to biomass and electricity
The Earth receives around 1000�W.m?2 of power from the Sun and only a fraction of this light energy is able to be converted to biomass (chemical energy) via the process of photosynthesis. Out of all photosynthetic organisms, microalgae, due to their fast growth rates and their ability to grow on non-arable land using saline water, have been identified as potential source of raw material for chemical energy production. Electrical energy can also be produced from this same solar resource via the use of photovoltaic modules. In this work we propose a novel method of combining both of these energy production processes to make full utilisation of the solar spectrum and increase the productivity of light-limited microalgae systems. These two methods of energy production would appear to compete for use of the same energy resource (sunlight) to produce either chemical or electrical energy. However, some groups of microalgae (i.e. Chlorophyta) only require the blue and red portions of the spectrum whereas photovoltaic devices can absorb strongly over the full range of visible light. This suggests that a combination of the two energy production systems would allow for a full utilization of the solar spectrum allowing both the production of chemical and electrical energy from the one facility making efficient use of available land and solar energy. In this work we propose to introduce a filter above the algae culture to modify the spectrum of light received by the algae and redirect parts of the spectrum to generate electricity. The electrical energy generated by this approach can then be directed to running ancillary systems or producing extra illumination for the growth of microalgae. We have modelled an approach whereby the productivity of light-limited microalgae systems can be improved by at least 4% through using an LED array to increase the total amount of illumination on the microalgae culture.
Efficient conversion of solar energy to biomass and electricity.
The Earth receives around 1000�W.m(-2) of power from the Sun and only a fraction of this light energy is able to be converted to biomass (chemical energy) via the process of photosynthesis. Out of all photosynthetic organisms, microalgae, due to their fast growth rates and their ability to grow on non-arable land using saline water, have been identified as potential source of raw material for chemical energy production. Electrical energy can also be produced from this same solar resource via the use of photovoltaic modules. In this work we propose a novel method of combining both of these energy production processes to make full utilisation of the solar spectrum and increase the productivity of light-limited microalgae systems. These two methods of energy production would appear to compete for use of the same energy resource (sunlight) to produce either chemical or electrical energy. However, some groups of microalgae (i.e. Chlorophyta) only require the blue and red portions of the spectrum whereas photovoltaic devices can absorb strongly over the full range of visible light. This suggests that a combination of the two energy production systems would allow for a full utilization of the solar spectrum allowing both the production of chemical and electrical energy from the one facility making efficient use of available land and solar energy. In this work we propose to introduce a filter above the algae culture to modify the spectrum of light received by the algae and redirect parts of the spectrum to generate electricity. The electrical energy generated by this approach can then be directed to running ancillary systems or producing extra illumination for the growth of microalgae. We have modelled an approach whereby the productivity of light-limited microalgae systems can be improved by at least 4% through using an LED array to increase the total amount of illumination on the microalgae culture. PMID:24976951
Parlevliet, David; Moheimani, Navid Reza
Electron Energy Levels in Magnetic Nanoparticles.
National Technical Information Service (NTIS)
Final Report for Grant N00014-97-1-0745. Progress is reported on (a) investigations of electron tunneling via individual 'electron-in-a-box' quantum energy levels in magnetic nanoparticles, and the sensitivity of these energy levels to changes in the orie...
D. C. Ralph
Single-phase self-excited inductor alternators for renewable energy electric conversion systems
Single-phase inductor alternators have been shown to be suitable for use with renewable energy electric conversion systems for small power applications. Since both the field and the ac output winding are on the stator, these alternators, in respect of construction and maintenance, have all the advantages of self-excited induction generators presently being employed with renewable energy sources. An attempt has
N. Kumaresan; M. Subbiah; R. Karthigaivel
Compressed natural gas and liquefied petroleum gas conversions: The National Renewable Energy Laboratory`s experience
The National Renewable Energy Laboratory (NREL) contracted with conversion companies in six states to convert approximately 900 light-duty Federal fleet vehicles to operate on compressed natural gas (CNG) or liquefied petroleum gas (LPG). The contracts were initiated in order to help the Federal government meet the vehicle acquisition requirements of the Energy Policy Act of 1992 (EPACT) during a period
R. C. Motta; K. J. Kelly; W. W. Warnock
Probabilistic Model of a Two-Site Wind Energy Conversion System
A general probabilistic model of a two-site wind-energy conversion system (WECS) is described. The wind speeds at the two sites are not assumed independent, thus preventing the convolution theorem from being directly applicable. Instead, a model based on the conditional probability theorem and mutually exclusive events is presented. The model allows the assessment of the energy resource available to supply
S. H. Karaki; B. A. Salim; R. B. Chedid
Understanding Power Electronics and Electrical Machines in Multidisciplinary Wind Energy Conversion System Courses
ERIC Educational Resources Information Center
Wind energy conversion systems (WECS) nowadays offer an extremely wide range of topologies, including various different types of electrical generators and power converters. Wind energy is also an application of great interest to students and with a huge potential for engineering employment. Making WECS the main center of interest when teaching�
Duran, M. J.; Barrero, F.; Pozo-Ruz, A.; Guzman, F.; Fernandez, J.; Guzman, H.
A variable speed wind energy conversion scheme for connection to weak AC systems
A three level control system for a variable speed wind energy conversion scheme (VSWECS) supplying a weak AC power system is presented. The objective of the control strategy is to maximize energy capture and simultaneously to support the voltage of the bus where the VSWECS is connected. Using an insulated gate bipolar transistor (IGBT) inverter, both control of active and
A. S. Neris; N. A. Vovos; G. B. Giannakopoulos
(Coal conversion, renewable energy and energy efficiency in India): Foreign trip report, October 31, 1988December 8, 1988
The US Agency for International Development (USAID) Mission in New Delhi, India, as part of the ongoing Alternative Energy Resources Development (AERD) Project, is initiating follow-on projects related to coal conversion, renewable energy, and energy efficiency. A four-member team was invited to India for three weeks to assist the mission in identifying the activities to be undertaken and the institutional
An Evaluation of Wood-Waste Energy Conversion Systems.
National Technical Information Service (NTIS)
The British Columbia Wood Waste Energy Co-Ordinating Commission was formed to evaluate the potential increased use of wood waste as an energy source in British Columbia. As part of this program, the committee commissioned a study of the technology availab...
B. H. Levelton
Alternatives for heat supply in biomass energy conversion systems
The paper discusses the effects of using different heat sources upon thermoeconomics of anaerobic digestion processes. While a relevant high-grade energy input is associated to biomass production, the processing of wasted biomass is regarded as an energy upgrading practice. Heat recovering from suitable power cycles is found to be the most attractive solution for heat supply, except for those cases
P. de Marchi Desenzani
Deep ocean wave energy conversion using a cycloidal turbine
A lift based wave energy converter, namely, a cycloidal turbine, is investigated. This type of wave energy converter consists of a shaft with one or more hydrofoils attached eccentrically at a radius. The main shaft is aligned parallel to the wave crests and submerged at a fixed depth. In the two-dimensional limit, i.e. for large spans of the hydrofoil (or
S. G. Siegel; T. Jeans; T. E. McLaughlin
Selective blacks for enhanced photothermal solar energy conversion
The optical and physical requirements of selective surfaces for maximum absorption of solar thermal energy are reviewed, along with processes to fabricate the selective coatings. Noting that the solar energy which reaches the ground is usually in wavelengths of 0.3-2 microns, the desired qualities of coatings are listed as stability of performance, good adherence to the substructure, ease of application,
R. C. Agarwal; P. K. C. Pillai
Matrix-assisted energy conversion in nanostructured piezoelectric arrays.
We demonstrate an organic/inorganic hybrid energy-harvesting platform, based on nanostructured piezolelectric arrays embedded in an environmental-responsive polymer matrix, which can self-generate electrical power by scavenging energy from the environment. A proof of principle device is designed, fabricated, and tested using vertically aligned ZnO nanowires and heat as the local energy source. The device layout takes advantage of the collective stretching motion of piezoelectric ZnO NWs, induced by the shape-change of the matrix polymer, to convert the thermal energy into direct current with output power densities of ?20 nW/cm(2) at a heating temperature of ?65 �C. The responsive nature of polymeric matrices to various stimuli makes this nanostructured piezoelectric architecture a highly versatile approach to scavenging energy from a multitude of environments including fluid-based and chemical-rich systems. PMID:21062047
Wang, Xianying; Kim, Kanguk; Wang, Yinmin; Stadermann, Michael; Noy, Aleksandr; Hamza, Alex V; Yang, Junhe; Sirbuly, Donald J
Vibration Based Electromagnetic Energy Harvesting - Microgenerator, Power Conversion and Control
NASA Astrophysics Data System (ADS)
Energy harvesting has been a research focus for many years. The idea that energy can be harvested from ambient environment and a device can operate without a battery is very attractive for low power electronic applications. The slow growth of battery technology and development of low power semiconductor technology has positioned energy harvesting as a feasible power source for low power applications. The present work emphasizes on microgenerator design and power processing circuits for electromagnetic energy harvesting. The main objective is to develop a complete system for low voltage electromagnetic energy harvesting. The thesis work has been designed and developed in consecutive stages - (a) novel converter topologies for low voltage microgenerators, (b) unified design of microgenerators and converter topologies, (c) design of efficient auxiliary circuits, (d) optimal energy harvesting control. A number of suitable converter topologies are first presented for low voltage, low power energy harvesting. Their operation, analysis and modeling are discussed in detail. The loss analysis is developed to properly characterize the performance of different converters developed in this thesis. Multiple methods to interface the microgenerator with the converters are presented. Based on the interface mechanism, a suitable unified design approach is also formulated for both the microgenerator and the converters. To realize a self-sufficient energy harvesting system, design of auxiliary circuits like start-up circuits, controller and gate driver circuits is very important. In this work, they are fabricated to consume very low power while satisfying the converter requirements. Finally, a new low power control system is developed to maximize the output of the energy harvesting system. Two types of control are envisaged in this work. The first type is a simpler voltage regulation mechanism. The second, more interesting type of control is based on controlling the converter to maximize the harvested energy from the source.
Dayal, Rohan
Energy Conversion Alternatives Study (ECAS), General Electric Phase 1. Volume 3: Energy conversion subsystems and components. Part 3: Gasification, process fuels, and balance of plant
NASA Technical Reports Server (NTRS)
Results are presented of an investigation of gasification and clean fuels from coal. Factors discussed include: coal and coal transportation costs; clean liquid and gas fuel process efficiencies and costs; and cost, performance, and environmental intrusion elements of the integrated low-Btu coal gasification system. Cost estimates for the balance-of-plant requirements associated with advanced energy conversion systems utilizing coal or coal-derived fuels are included.
Boothe, W. A.; Corman, J. C.; Johnson, G. G.; Cassel, T. A. V.
Relativistic fireballs - Energy conversion and time-scales
NASA Technical Reports Server (NTRS)
The expansion energy of a relativistic fireball can be reconverted into radiation when it interacts with an external medium. For expansion with Lorentz factors greater than or approximately equal to 1000 into a typical galactic environment, the corresponding time-scale in the frame of the observer is of the order of seconds. This mechanism would operate in any cosmological scenario of gamma-ray bursts involving initial energies of order a percent of a stellar rest mass, and implies photon energies and time-scales compatible with those observed in gamma-ray bursts.
Rees, M. J.; Meszaros, P.
Feasibility assessment of low temperature voltaic energy conversion
An experimental and theoretical investigation of the feasibility of thermo voltaic (TV) power generation in the temperature range 800{degrees}C - 1000{degrees}C has been performed. In this concept, voltaic cells of Indium-Galium-Arsenide (InGaAs) were employed to convert thermal radiation directly into electric power. The advantage of this concept over previous thermo photo voltaic concepts (TPV) is the reduced materials issues associated with a lower heat source temperature, and applicability to a wider range of fossil fuels. A numerical model was constructed and used to analyze test data, demonstrating good agreement and understanding of process physics. The key functional parameters were found to be dark current coefficient and spectral efficiency. A conversion efficiency of 25% was measured at 900{degrees}C, with potential for 30% in optimized devices. The limiting issue for a practical TV power converter below 900{degrees}C is the required power density, which is a strong function of heat source temperature.
Baldasaro, P.F.; Campbell, B.C.; Depoy, D.M.; Parrington, J.
Assessment of dynamic energy conversion systems for radioisotope heat sources
The use of dynamic conversion systems to convert the heat generated in a 7500 W(t) 90 Sr radioisotopic heat source to electricity is examined. The systems studies were Stirling; Brayton Cycle; three organic Rankines (ORCs) (Barber-Nichols/ORMAT, Sundstrand, and TRW); and an organic Rankine plus thermoelectrics. The systems were ranked for a North Warning System mission using a Los Alamos Multiattribute Decision Theory code. Three different heat source designs were used: case I with a beginning of life (BOL) source temperature of 640 C, case II with a BOL source temperature of 745/sup 0/C, and case III with a BOL source temperature of 945/sup 0/C. The Stirling engine system was the top-ranked system of cases I and II, closely followed by the ORC systems in case I and ORC plus thermoelectrics in case II. The Brayton cycle system was top-ranked for case III, with the Stirling engine system a close second. The use of /sup 238/Pu in heat source sizes of 7500 W(t) was examined and found to be questionable because of cost and material availability and because of additional requirements for analysis of safeguards and critical mass.
Thayer, G.R.; Mangeng, C.A.
Harvesting UV photons for solar energy conversion applications.
We report the synthesis and characterization of five new donor�?�spacer�acceptor dye molecules with a diphenylamine donor, fluorene�1,2,5-oxadiazole spacers and a range of acceptor/anchor groups (carboxylic acid 1, cyanoacrylic acid 2 and 3, alcohol 4 and cyano 5) to facilitate electron injection from the excited dye into the TiO2 photoanode in dye-sensitized solar cells (DSSCs). Detailed photophysical studies have probed the dyes' excited state properties and revealed structure�property relationships within the series. Density functional theory (DFT) and time dependent DFT (TDDFT) calculations provide further insights into how the molecular geometry and electronic properties impact on the photovoltaic performance. A special feature of these dyes is that their absorption features are located predominantly in the UV region, which means the dye-sensitized TiO2 is essentially colorless. Nevertheless, DSSCs assembled from 1 and 2 exhibit photovoltaic power conversion efficiencies of ? = 1.3 and 2.2%, respectively, which makes the dyes viable candidates for low-power solar cells that need to be transparent and colorless and for applications that require enhanced harvesting of UV photons. PMID:24343589
Wielopolski, Mateusz; Linton, Katharine E; Marsza?ek, Magdalena; Gulcur, Murat; Bryce, Martin R; Moser, Jacques E
Assessment of dynamic energy conversion systems for radioisotope heat sources
NASA Astrophysics Data System (ADS)
The use of dynamic conversion systems to convert the heat generated in a 7500 W(t) 90 Sr radioisotopic heat source to electricity is examined. The systems studies were: Stirling; Brayton cycle; three organic Rankines (ORCs) (Barber-Nichols/ORMAT, Sundstrand, and TRW); and an organic Rankine plus thermoelectrics. The systems were ranked for a North Warning System mission using a Los Alamos multiattribute decision theory code. Three different heat source designs were used: case 1 with a beginning of life (BOL) source temperature of 640 C, case 2 with a BOL source temperature of 745 C, and case 3 with a BOL source temperature of 945 C. The Stirling engine system was the top-ranked system of case 1 and 2, closely followed by the ORC systems in case 1 and ORC plus thermoelectrics in case 2. The Brayton cycle system was top-ranked for case 3, with the Stirling engine system a close second. The use of (238) Pu in heat source sizes of 7500 W(t) is examined and it is found to be questionable because of cost and material availability and because of additional requirements for anlaysis of safeguards and critical mass.
Thayer, G. R.; Mangeng, C. A.
Thermionic Energy Conversion Research Analysis. Annual Progress Report.
National Technical Information Service (NTIS)
This progress report summarizes the major results presented in ''Preliminary Report on Plasma Arc-Drop in Thermionic Energy Converters,'' (COO-2533-1), and includes additional discussions on the magnitude of the normalized plasma resistance required to ac...
S. H. Lam
A review of impulse turbines for wave energy conversion
Oscillating Water Column based wave energy plants convert wave energy into low pressure pnuematic power in the form of bi-directional air flows. Air turbines which are capable of rotating uni-directionally in bi-directional air flow, otherwise also known as self-rectifying turbines, are used to extract mechanical shaft power which is further converted into electrical power by a generator. This paper reviews
T Setoguchi; S Santhakumar; H Maeda; M Takao; K Kaneko
Dipolar energy of Nd-Fe-B nanocrystalline magnets in magnetization reversal process
NASA Astrophysics Data System (ADS)
We analyzed the dipolar energy of Nd-Fe-B nanocrystalline magnets in magnetization reversal process through visualizing magnetic dipolar interaction. We obtained magnetization distribution images experimentally by using scanning transmission X-ray microscopy (STXM). The magnetic dipolar interaction was calculated by the interaction between the magnetization at each point and those at the other points on the STXM image. We showed the dipolar energy in the nanocrystalline Nd-Fe-B magnets and compared it with the exchange energy at various applied fields. Our results indicated the significance of the dipolar energy in magnetization reversal process.
Ohtori, Hiroyuki; Iwano, Kaoru; Mitsumata, Chiharu; Yano, Masao; Kato, Akira; Shoji, Tetsuya; Manabe, Akira; Ono, Kanta
Magnets for high energy colliders
The problem of producing, preserving and stably colliding low emittance bunches for long periods of time is a formidable problem involving questions of jitter, dynamic alignment and reproducibility associated with magnetic and mechanically hysteresis. Permanent magnets provide ideal solutions for lower capital and operating costs. Because they are light in weight, compact and require no power or cooling they are easy to use, stable and uniquely reliable. With their low permeability this implies a minimal impact on the surrounding environment and vice versa. For example, they are ideal for final focus systems embedded in particle detectors with strong solenoidal fields while their strength and compactness minimizes the solid angle they subtend around the interaction point (IP) as well as their target thickness along the beam line. We discuss calculations there /rvec B/ is a nonlinear, anisotropic function of /rvec H/. The results explain discrepancies observed measurement and calculation of permanent magnet systems and indicate good multipoles are possible with far higher strengths than previously obtained. We extend previous calculations on the obtainable gradients for different types of quadrupoles down to 1 mm bore radii where 2000 T/m appears possible with conventional designs and available materials. We discuss why much higher gradients are possible by the same means. Additional specifications for PM manufacturers are recommended. 14 refs., 5 figs.
Spencer, J.; Stucki, H.
Ionosphere/microwave beam interaction study. [satellite solar energy conversion
NASA Technical Reports Server (NTRS)
A solar power satellite microwave power density of 20mw sq cm was confirmed as the level where nonlinear interactions may occur in the ionosphere, particularly at 100 km altitude. Radio wave heating at this altitude, produced at the Arecibo Observatory, yielded negative results for radio wave heating of an underdense ionosphere. Overdense heating produced striations in the ionosphere which may cause severe radio frequency interference problems under certain conditions. The effects of thermal self-focusing are shown to be limited severely geographically. The aspect sensitivity of field-aligned striations makes interference-free regions above magnetic latitude ab