Solar power in the United States

Solar power in the United States includes utility-scale solar power plants as well as local distributed generation, mostly from rooftop photovoltaics.
As of the end of 2020, the United States had 97,275 megawatts (MW) of installed photovoltaic and concentrated solar power capacity combined. In 2018, utility scale solar power generated 66.6 terawatt-hours (TWh), 1.66% of total U.S. electricity. During the same time period total solar generation, including estimated small scale photovoltaic generation, was 96.1 TWh, 2.30% of total U.S. electricity. In terms of total cumulative installed capacity, by year end 2017 the United States ranked 2nd in the world behind China.
In 2016, 39% of all new electricity generation capacity in the country came from solar, more than any other source and ahead of natural gas (29%). By 2015, solar employment had overtaken oil and gas as well as coal employment in the United States. In 2016, more than 260,000 Americans were employed in the solar industry.
The United States conducted much early research in photovoltaics and concentrated solar power.
It is among the top countries in the world in electricity generated by the Sun and several of the world's largest utility-scale installations are located in the desert Southwest. The oldest solar power plant in the world is the 354-megawatt (MW) SEGS thermal power plant, in California. The Ivanpah Solar Electric Generating System is a solar thermal power project in the California Mojave Desert, 40 miles (64 km) southwest of Las Vegas, with a gross capacity of 392 MW. The 280 MW Solana Generating Station is a solar power plant near Gila Bend, Arizona, about southwest of Phoenix, completed in 2013. When commissioned it was the largest parabolic trough plant in the world and the first U.S. solar plant with molten salt thermal energy storage.
There are plans to build many other large solar plants in the United States. Many states have set individual renewable energy goals with solar power being included in various proportions. Hawaii plans 100% renewable-sourced electricity by 2045. Governor Jerry Brown has signed legislation requiring California's utilities to obtain 100 percent of their electricity from zero-carbon sources by the end of 2045 (including 60% renewable energy sources by 2030).
Solar potential.
A 2012 report from the National Renewable Energy Laboratory (NREL) described technically available renewable energy resources for each state and estimated that urban utility scale photovoltaics could supply 2,232 TWh/year, rural utility scale PV 280,613 TWh/year, rooftop PV 818 TWh/year, and CSP 116,146 TWh/year, for a total of almost 400,000 TWh/year, 100 times current consumption of 3,856 TWh in 2011.
For comparison, onshore wind potential is estimated at 32,784 TWh/year, and offshore wind at 16,976 TWh/year, while the total available from all renewable resources is estimated at 481,963 TWh/year.
History.
Solar energy deployment increased at a record pace in the United States and throughout the world in 2008, according to industry reports. The Solar Energy Industries Association's "2008 U.S. Solar Industry Year in Review" found that U.S. solar energy capacity increased by 17% in 2007, reaching the total equivalent of 8,775 megawatts (MW). The SEIA report tallies all types of solar energy, and in 2007 the United States installed 342 MW of solar photovoltaic (PV) electric power, 139 thermal megawatts (MWth) of solar water heating, 762 MWth of pool heating, and 21 MWth of solar space heating and cooling.
Another report in 2008 by research and publishing firm Clean Edge and the nonprofit Co-op America found that solar power's contribution could grow to 10% of the nation's power needs by 2025, with nearly 2% of the nation's electricity coming from concentrating solar power systems, while solar photovoltaic systems would provide more than 8% of the nation's electricity.
Those figures correlate to nearly 50,000 megawatts of solar photovoltaic systems and more than 6,600 megawatts of concentrating solar power. The report noted that the cost per kilowatt-hour of solar photovoltaic systems had been dropping, while electricity generated from fossil fuels was becoming more expensive.
As a result, the report projects that solar power was expected to reach cost parity with conventional power sources in many U.S. markets by 2015.
To reach the 10% goal, solar photovoltaic companies would need to make solar power a "plug-and-play technology", or simplify the deployment of solar systems.
The report also underlines the importance of future "smart grid" technologies.
Solar Energy Industries Association and GTM Research found that the amount of new solar electric capacity increased in 2012 by 76 percent from 2011, raising the United States’ market share of the world's installations above 10 percent, up from roughly 5 to 7 percent in the past seven years.
According to the U.S. Energy Information Administration, as of September 2014 utility-scale solar had sent 12,303 gigawatt-hours of electricity to the U.S. grid. This was an increase of over 100% versus the same period in 2013 (6,048 GWh).
The number of homes with solar systems installed had been increasing rapidly; from 30,000 in 2006 to 1.3 million in 2016 with a study by the U.S. Department of Energy predicting the figure could reach 3.8 million homes by 2020.
In 2015 an article reported that Utilities in the United States have led a largely unsuccessful campaign to slow the growth of solar.
Solar photovoltaic power.
Solar PV installed capacity.
In the United States, 14,626 MW of PV was installed in 2016, a 95% increase over 2015 (7,493 MW).
During 2016, 22 states added at least 100 MW of capacity.
Just 4,751 MW of PV installations were completed in 2013. The U.S. had approximately 440 MW of off-grid photovoltaics as of the end of 2010. Through the end of 2005, a majority of photovoltaics in the United States was off-grid.
Solar PV generation.
The amount of electricity a unit is capable of producing over an extended period of time is determined by multiplying the capacity by the capacity factor.
The capacity factor for solar photovoltaic units is largely a function of climate and latitude and so varies significantly from state to state.
The National Renewable Energy Laboratory has calculated that the highest statewide average solar voltaic capacity factors are in Arizona, New Mexico, and Nevada (each 26.3 percent), and the lowest is Alaska (10.5 percent). The lowest statewide average capacity factor in the contiguous 48 states is in West Virginia (17.2 percent).
Solar PV by type.
The table above gives an indication of the spread of solar PV between the different types at the end of 2018. Capacity figures may seem smaller than those quoted by other sources and it is likely that the capacities are measured in MW AC rather than MW DC, the former of which gives a lower reading due to conversion losses during the process by which power is transformed by inverters from direct current to alternating current. Utility scale PV accounted for the largest figure at 30.17 GW and 63 TWh of generation. Next came small scale PV with 19.52 GW capacity and 29.54 TWh of generation. The proportion of residential and commercial solar to utility scale solar varies greatly between states (see distributed generation section below). Finally solar thermal generation was the smallest deployment by power rating at 1.76 GW capacity and 3.59 TWh generation.
The first floating solar array in the US was a 160 kW array installed next to Miami International Airport by Florida Power and Light in partnership with Miami-Dade County in 2020.
Large-scale PV facilities.
Current situation.
Large-scale photovoltaic power plants in the United States often consist of two or more units which correspond to construction stages and/or technology-improvement phases of a particular development project. Typically these units are co-located in the vicinity of the same high-capacity transmission substation, and may also feed that substation with other large PV plants which are adjacently sited but separately developed. As of 2018, the ten largest operating plants in the United States, based on development grouping and total AC power capacity, are:
1) The 579 megawatt (MWAC) Solar Star plant (Units I and II) in California was the world's largest photovoltaic power station when completed in 2015. It was superseded later that year by the Longyangxia Dam Solar Park in China.
2) The Copper Mountain Solar Facility is a 552 MWAC solar power plant in Eldorado Valley, Nevada that consists of four units. Sempra Generation completed the first unit in 2010, and the latest came online in late 2016.
3) The Topaz Solar Farm is a 550 MWAC photovoltaic power plant near San Luis Obispo County, California that has been fully operational since November 2014.
4) The Desert Sunlight Solar Farm is a 550 MWAC solar power station located in the Sonoran Desert of California and completed in January 2015.
5) The 460 MWAC Mount Signal Solar reached its current capacity when unit III came online in late 2018; the project will reach 600 MW when unit II is completed around 2020.
6) The 400 MWAC Mesquite Solar project in Arizona consists of three units at the end of 2016 and is still being expanded.
7) The Agua Caliente Solar Project is a 290 MWAC facility in Yuma County, Arizona operating at full capacity since April 2014.
8) The California Flats Solar Project in Monterey County, California reached a capacity of 280 MWAC when a second unit came online at the end of 2018.
9) The Springbok Solar Farm is a 260 MWAC facility in Kern County, California with two units completed. It is expected to reach 350 MW with completion of the third unit in 2019.
10) At 250 MWAC each, there are five plants: McCoy Solar Energy Project, Silver State South Solar Project, California Valley Solar Ranch, Desert Stateline Solar Facility, and Moapa Southern Paiute Solar Project
Planned PV plants.
SolarStrong is SolarCity's five-year plan to build more than $1 billion in solar photovoltaic projects for privatized military housing communities across the United States. SolarCity plans to work with the country's leading privatized military housing developers to install, own and operate rooftop solar installations and provide solar electricity at a lower cost than utility power. SolarStrong is ultimately expected to create up to 300 megawatts of solar generation capacity that could provide power to as many as 120,000 military housing units, making it the largest residential photovoltaic project in American history. In November 2011, SolarCity and Bank of America Merrill Lynch announced that they have agreed to terms on financing for SolarStrong.
Distributed generation.
Within the cumulative PV capacity in the United States, there has been growth in the distributed generation segment, which are all grid-connected PV installations in the residential and non-residential markets. Non-residential market includes installations on commercial, government, school and non-profit organization properties.
Between 2000 and 2013 there had been 2,261 MW of residential solar and 4,051 MW non-residential solar installed. After years of cost reduction, the average US price per watt was between $2.51 to $3.31 in 2020.
An example of a large scale PV installations in schools was the solar project of San Diego Unified School District with total of 48 sites and aggregated installed capacity of 9.17 MW. One of the largest rooftop installations for commercial properties was the 9 MW system of Holt Logistics refrigerated warehouse at the Gloucester Marine Terminal in New Jersey.
Another type of distributed generation implemented by a utility company was the world's first grid-connected pole-attached solar panels of Public Service Enterprise Group in New Jersey. More than 174,000 PV panels are mounted on utility poles along streets of New Jersey with aggregated capacity of 40 MW.
, there were nearly 5,500 schools in the United States that had solar installations with the total capacity of approximately 910 MW. The top five states were Nevada, California, Hawaii, Arizona, and New Jersey with 23.10%, 14.50%, 14.50%, 14.10% and 13.00% of the schools in the respective states that had installations. , there were total capacity of 2,562 MW of commercial solar installations from more than 4,000 companies in 7,400 locations. Top five corporations were Target, Walmart, Prologis, Apple, and Kohl's.
Solar cell manufacturing.
In late September 2008, Sanyo Electric Company, Ltd. announced its decision to build a manufacturing plant for solar ingots and wafers (the building blocks for silicon solar cells) in Salem, Oregon. The plant was scheduled to begin operating in October 2009 and scheduled to reach its full production capacity of 70 megawatts (MW) of solar wafers per year by April 2010. In April 2013 the plant closed its wafer slicing operation. In February 2016 the parent company, Panasonic, announced it would lay off 37% of the remaining workforce.
In early October 2008, First Solar, Inc. broke ground on an expansion of its Perrysburg, Ohio, planned to add enough capacity to produce another 57 MW per year of solar modules at the facility, bringing its total capacity to roughly 192 MW per year. In November 2016 the company reduced the workforce in the Perrysburg plant by 20% as part of a worldwide restructuring.
In mid-October 2008, SolarWorld AG opened a manufacturing plant in Hillsboro, Oregon. In 2016 the Hillsboro plant was the largest photovoltaic technology manufacturing plant in the Western Hemisphere. It maintains 500 megawatts of cell-manufacturing capacity and 350 MW of module-assembly capacity.
Rapidly decreasing photovoltaic prices put General Electric's planned factory in Colorado on hold, and led to the bankruptcy of Konarka Technologies, which had expected to produce 1,000 MW of solar modules per year by 2011, and Solyndra, which defaulted on a $535 million loan guarantee, prompting Republican members of the Energy and Commerce committee to vote to cease accepting new applications to the loan program.
HelioVolt Corporation opened a manufacturing facility in Austin, Texas that will have an initial capacity to produce 20 MW of solar cells per year. Starting with solar "inks" developed at DOE's National Renewable Energy Laboratory that are deposited with ink jets, HelioVolt employs a proprietary "printing" process to produce solar cells consisting of thin films of copper indium gallium selenide, or CIGS. The technology won an R&D 100 Award in 2008 and it earned an Editor's Choice Award for Most Revolutionary Technology. HelioVolt's "FASST" reactive transfer printing process is 10–100 times faster than other CIGS production processes and can also be combined with vacuum evaporation or ultrasonic spray deposition techniques. At its new Austin manufacturing plant, HelioVolt plans to produce both solar modules and next-generation building-integrated solar products using its FASST process.
In 2012 the U.S. Department of Commerce placed a 31% tariff on solar cells made in China. In 2018, the Trump administration placed a 30% tariff on all imported solar equipment. In September 2014, SolarCity broke ground on a solar panel manufacturing plant in Buffalo, New York.
Upon its completion in 2016, it was projected to be the largest solar manufacturing facility in the Western hemisphere, with an annual manufacturing capacity of 1 gigawatt (GW). However, as of 2019 the facility has not met the projections on production or job creation.
Concentrated solar power (CSP).
History.
One of the first applications of concentrated solar was the solar powered motor made by H.E. Willsie and John Boyle in 1904.
An early solar pioneer of the 19th and 20th century, Frank Shuman, built a demonstration plant that used solar power to pump water using an array of mirrors in a trough to generate steam. Located in Philadelphia, the solar water pump station was capable of pumping an hour at that latitude, corresponding to . After seven weeks of testing the plant was disassembled and shipped to Egypt for testing as an irrigation plant.
In 1973, Karl Böer of the University of Delaware built an experimental house called the Solar One, the first house to convert sunlight into energy.
Solar One, the first pilot solar power tower design was completed in 1981. The parabolic trough Solar Energy Generating Systems opened its first unit in 1984, the first major solar thermal plant in the world.
Selected list of plants.
The United States pioneered solar tower and trough technologies. A number of different solar thermal technologies are in use in the U.S.:
The rapidly falling price of PV solar had led to several projects being abandoned or converted to PV technology. Blythe Solar Power Project converted to a PV project, Rice Solar Energy Project was put on indefinite hold, Palen Solar Project tried to convert to PV but its permits were denied, Hidden Hills Solar Project was suspended in 2013 and later canceled. No major CSP plants remain under construction in the United States.
CSP capacity and generation.
Abengoa's 280 MWac of CSP project was brought online in the 3rd quarter and Genesis Solar's first phase of 125 MWac was brought online in the 4th quarter of 2013 bringing the total to 410 MWac for the year and 918 MWac total. Ivanpah is already completed during the first quarter of 2014 the current world's largest CSP power plant is 392 MWac and brings the total to 1310 MWac.
The 110 MWac Crescent Dunes project started commissioning during February.
The 250 MWac Mojave solar, second phase 125 MWac Genesis Solar, and Tooele Army Depot Solar's 1.5 MWac power plant are all expected to come online in 2014. A total of around 9.5 GW of solar PV and CSP capacity is expected to come online in 2016, more than any other source.
Government support.
A complete list of incentives is maintained at the Database of State Incentives for Renewable Energy (DSIRE) (see external link).
Most solar power systems are grid connected and use net metering laws to allow use of electricity in the evening that was generated during the daytime.
New Jersey leads the nation with the least restrictive net metering law, while California leads in total number of homes which have solar panels installed. Many were installed because of the million solar roof initiative. In some states, such as Florida, solar power is subject to legal restrictions that discourage its use.
Federal.
The federal tax credit for solar was extended for eight years as part of the financial bail out bill, H.R. 1424, until the end of 2016. It was estimated this will create 440,000 jobs, 28 gigawatts of solar power, and lead to a $300 billion market for solar panels. This estimate did not take into account the removal of the $2,000 cap on residential tax credits at the end of 2008. A 30% tax credit is available for residential and commercial installations. For 2009 through 2011 this was a 30% grant, not a tax credit, known as the 1603 grant program.
The federal Residential Energy Efficient Property Credit (income tax credit on IRS Form 5695) for residential PV and solar thermal was extended in December 2015 to remain at 30% of system cost (parts and installation) for systems put into service by the end of 2019, then 26% until the end of 2020, and then 22% until the end of 2021. It applies to a taxpayer's principal and/or second residences, but not to a property that is rented out. There is no maximum cap on the credit, and the credit can be applied toward the Alternative Minimum Tax, and any excess credit (greater than that year's tax liability) can be rolled into the following year. The solar industry and utilities clashed extensively on renewal, but the solar industry prevailed. The renewal is expected to add $38 billion of investment for 20 GigaWatts of solar.
Section 1603 grants.
President Obama's stimulus bill in 2009 created a program known as Section 1603 grants. The program was designed to give federal grants to solar companies for 30 percent of investments into solar energy. Since 2009, the federal government has given solar companies $25 billion in grant money through this program. The Section 1603 grant program expired in 2011.
On June 9, 2016, Senator Orrin Hatch requested from Department of Treasury, the Internal Revenue Service (IRS) and the Treasury Inspector General for Tax Administration (TIGTA) details about how companies use Section 1603 grants and tax credits. In March 2016, Hatch asked the IRS and Treasury Department to demonstrate that the agencies use safeguards and coordinate with each other when reviewing applications for Section 1603 grants.
Solar America Initiative.
The United States Department of Energy (DOE) announced on September 29, 2008 that it will invest $17.6 million, subject to annual appropriations, in six company-led, early-stage photovoltaic (PV) projects under the Solar America Initiative's "PV Incubator" funding opportunity, designed to fund prototype PV components and systems with the goal of moving them through the commercialization process by 2010 and make it cost-competitive with conventional forms of electricity by 2015 (grid parity).
SunShot Initiative.
The SunShot Initiative aimed to reduce the cost of solar power by 75% from 2010 to 2020. The name is based on "moon shot", Kennedy's target of reaching the moon within the decade.
Goals:
Trump administration.
In 2018, as part of a trade war between the U.S. and China, US President Trump imposed tariffs on imported solar cells. The push for tariffs to protect American manufacturing and jobs in the solar power industry began in April 2017, when a bankrupt Georgia-based solar cell maker filed a trade complaint that a flood of cheap imports put them at a severe disadvantage. In response, the President imposed 30% tariffs of solar imports in January 2018. The solar industry is currently one of the fastest growing in the United States, employing more than 250,000 people as of 2018. On one hand, these tariffs forced the cancellation or scaling down of many projects and restrict the ability of companies to recruit more workers. On the other hand, they have the intended effect of incentivizing domestic manufacturing. Many solar power companies are transitioning towards automation and consequently will become less dependent on imports, especially from China. Analysts believe Trump's tariffs have made a clear impact. Without them, the manufacturing capacity for solar cells in the United States would likely not have increased significantly, from 1.8 gigawatts in 2017 to at least 3.4 gigawatts in 2018, they argue. However, because of the increasing reliance on automation, not that many new jobs will be created, while profits will flow to other countries, as many firms are foreign. By 2019, the solar power industry has recovered from the initial setbacks due to Trump's tariffs, thanks to initiatives from various states, such as California. Moreover, it is receiving considerable support from the Department of Energy. The National Renewable Energy Laboratory (NREL) launched the "American-made Solar Prize" competition in June 2018 and has handed out tens to hundreds of thousand of dollars in cash prizes for the most promising solar cell designs. Prices of solar cells continue to decline.
State and local.
Feed-in Tariffs.
Experience has demonstrated that a feed-in tariff is both the least expensive and the most effective means of developing solar power. Investors need certainty, which they receive from a feed-in tariff. California enacted a feed-in tariff which began on February 14, 2008. Washington state has a feed-in tariff of 15 ¢/kWh which increases to 54 ¢/kWh if components are manufactured in the state. Hawaii, Michigan, and Vermont also have feed in tariffs. In 2010, the Federal Energy Regulatory Commission (FERC) ruled that states were able to implement above-market feed-in tariffs for specific technologies.
Solar Renewable Energy Certificates.
In recent years, states that have passed Renewable Portfolio Standard (RPS) or Renewable Electricity Standard (RES) laws have relied on the use of Solar renewable energy certificates (SRECs) to meet state requirements. This is done by adding a specific solar carve-out to the state Renewable Portfolio Standard (RPS). The first SREC program was implemented in 2005 by the state of New Jersey and has since expanded to several other states, including Maryland, Delaware, Ohio, Massachusetts, North Carolina and Pennsylvania.
An SREC program is an alternative to the feed-in tariff model popular in Europe. The key difference between the two models is the market-based mechanism that drives the value of the SRECs, and therefore the value of the subsidy for solar. In a feed-in tariff model, the government sets the value for the electricity produced by a solar facility. If the level is higher, more solar power is built and the program is more costly. If the feed-in tariff is set lower, less solar power is built and the program is ineffective. The problem with SRECs is a lack of certainty for investors. A feed-in tariff provides a known return on investment, while an SREC program provides a possible return on investment.
Power Purchase Agreements.
In 2006 investors began offering free solar panel installation in return for a 25-year contract, or Power Purchase Agreement, to purchase electricity at a fixed price, normally set at or below current electric rates. By 2009 over 90% of commercial photovoltaics installed in the United States were installed using a power purchase agreement. Approximately 90% of the photovoltaics installed in the United States is in states that specifically address power purchase agreements.
New construction mandates.
In March 2013, Lancaster, California became the first U.S. city to mandate the inclusion of solar panels on new homes, requiring that "every new housing development must average 1 kilowatt per house."
PACE.
An innovative financing arrangement pioneered in Berkeley, California, and Palm Springs, lends money to a homeowner for a solar system, to be repaid via an additional tax assessment on the property for 20 years. This allows installation of the solar system at "relatively little up-front cost to the property owner." Now known as PACE, for Property Assessed Clean Energy, it is available in 28 states. Freddie Mac and Fannie Mae have objected to the repayment of solar loans being senior to mortgage loans, and some states have relegated PACE loans to junior loans. HR 2599 was introduced to prevent interference with the PACE program by other lenders. The principal feature of the program is that the balance of the loan is transferred to the new owners in the event the property is sold, and the loan is paid for entirely through electric bill savings. Unlike a mortgage loan, no funds are transferred when the property is sold - only the repayment obligation is transferred. PACE programs are currently operating in eight states, California, Colorado, Florida, Maine, Michigan, Missouri, New York, and Wisconsin, and are on hold in many others, pending resolution of the Freddie Mac, Fannie Mae objection.
Controversy and congressional investigation.
In 2016, the Senate Finance Committee and the House Ways and Means Committee ran a formal investigation into billions of dollars in tax incentives that solar-energy companies received. The investigation also focused on whether the Obama administration improperly gave out solar tax credits. The investigational probe was led by Senator Orrin Hatch (R-Utah), the chairman of the Senate Finance Committee, and U.S. Representative Kevin Brady (R-Texas), the chairman of the Ways and Means Committee.
Generation (PV and CSP).
Source: NREL EIA.
NREL includes distributed generation, EIA, including the monthly data above, includes only utility generation. "EIA % of total" is the percent of all electricity produced that is generated by utility solar.


Pentode

A pentode is an electronic device having five active electrodes. The term most commonly applies to a three-grid amplifying vacuum tube (thermionic valve), which was invented by Gilles Holst and Bernhard D.H. Tellegen in 1926. The pentode consists of an evacuated glass envelope containing five electrodes in this order: a filament for indirectly heating a cathode, a control grid, a screen grid, a suppressor grid, and a plate (anode). The pentode (called a "triple-grid amplifier" in some early literature) was developed from the tetrode tube by the addition of a third grid, the suppressor grid. This served to prevent secondary emission electrons emitted by the plate from reaching the screen grid, which caused instability and parasitic oscillations in the tetrode. The pentode is closely related to the beam tetrode. Pentodes were widely used in industrial and consumer electronic equipment such as radios and televisions until the 1960s, when they were replaced by transistors. Their main use now is in high power industrial applications such as radio transmitters. The obsolete consumer tubes are still used in a few legacy and specialty vacuum tube audio devices.
Advantages over the tetrode.
The simple tetrode or "screen-grid tube" offered a larger amplification factor, more power and a higher frequency capability than the earlier triode. However, in the tetrode "secondary electrons" knocked out of the anode (plate) by the electrons from the cathode striking it (a process called secondary emission) can flow to the screen grid due to its relatively high potential. This current of electrons leaving the anode reduces the net anode current "I"a. As the anode voltage "V"a is increased, the electrons from the cathode hit the anode with more energy, knocking out more secondary electrons, increasing this current of electrons leaving the anode. The result is that in the tetrode the anode current "I"a is found to "decrease" with increasing anode voltage "V"a, over part of the characteristic curve. This property (Δ"V"a/Δ"I"a < 0) is called negative resistance. It can cause the tetrode to become unstable, leading to parasitic oscillations in the output, called dynatron oscillations in some circumstances.
The pentode, as introduced by Tellegen, has an additional electrode, or third grid, called the suppressor grid, located between the screen grid and the anode, which solves the problem of secondary emission. The suppressor grid is given a low potential—it is usually either grounded or connected to the cathode. Secondary emission electrons from the anode are repelled by the negative potential on the suppressor grid, so they can't reach the screen grid but return to the anode. The primary electrons from the cathode have a higher kinetic energy, so they can still pass through the suppressor grid and reach the anode.
Pentodes, therefore, can have higher current outputs and a wider output voltage swing; the anode/plate can even be at a lower voltage than the screen grid yet still amplify well.
Usage.
Pentode tubes were first used in consumer-type radio receivers. A well-known pentode type, the EF50, was designed before the start of World War II, and was extensively used in radar sets and other military electronic equipment. The pentode contributed to the electronic preponderance of the Allies.
The Colossus computer and the Manchester Baby used large numbers of EF36 pentode tubes. Later on, the 7AK7 tube was expressly developed for use in computer equipment.
After World War II, pentodes were widely used in TV receivers, particularly the successor to the EF50, the EF80. Vacuum tubes were replaced by transistors during the 1960s. However, they continue to be used in certain applications, including high-power radio transmitters and (because of their well-known valve sound) in high-end and professional audio applications, microphone preamplifiers and electric guitar amplifiers. Large stockpiles in countries of the former Soviet Union have provided a continuing supply of such devices, some designed for other purposes but adapted to audio use, such as the GU-50 transmitter tube.
Triode-strapped pentode circuits.
A pentode can have its screen grid (grid 2) connected to the anode (plate), in which case it reverts to an ordinary triode with commensurate characteristics (lower anode resistance, lower mu, lower noise, more drive voltage required). The device is then said to be "triode-strapped" or "triode-connected". This is sometimes provided as an option in audiophile pentode amplifier circuits, to give the sought-after "sonic qualities" of a triode power amplifier. A resistor may be included in series with the screen grid to avoid exceeding the screen grid's power or voltage rating, and to prevent local oscillation. Triode-connection is a useful option for audiophiles who wish to avoid the expense of 'true' power triodes.


Hitomi Kamanaka

 (born 11 June 1958, Toyama Prefecture, Japan) is a Japanese documentary filmmaker known particularly for her films on nuclear power and radiation.
Career.
Graduating from Waseda University in 1984, Kamanaka began working as an assistant director for documentaries at Group Gendai, Iwanami Productions, and other companies. She directed her first film in 1990 and between 1990 and 1995, worked and studied in Canada and the United States, first on a grant from Japan's Agency for Cultural Affairs. Returning to Japan, she worked as a freelance director for television and film. Her film, "Hibakusha at the End of the World" (also known as "Radiation: A Slow Death"), was the first of several she has made on the problems of nuclear radiation. It won several awards, including one from the Agency for Cultural Affairs for excellence in documentary. Her next film on nuclear issues, "Rokkasho Rhapsody", covered the problems surrounding the Rokkasho Reprocessing Plant. Her most recent work, "Ashes to Honey", about residents fighting the construction of a nuclear power plant in Yamaguchi Prefecture, opened in theaters only a month before the Fukushima Daiichi nuclear disaster. After the disaster, her work has garnered increased attention and she has been asked to present her work at numerous venues at home and abroad.


Active tip-clearance control

Active clearance control (ACC) is a method used in gas turbines to improve fuel efficiency. This is achieved by dynamically controlling the turbine tip clearance.
During normal cruise flight, the engine is exposed to many loads such as intense heat and centrifugal force. This causes expansion of certain components and alters the gap between the turbine casing and tips of the spinning turbine blades. The amount of air leaking around, past the edge of the blades without passing through them is critical to engine performance and fuel efficiency. For this reason since the late 1960s, blade tip sealing has taken on a prominent role in aircraft engine design. The ACC system dynamically controls the high pressure turbine (HPT) blade clearance. This can be achieved in numerous ways.
Background.
HPT (high pressure turbine) blade tip clearance has a significant impact on fuel burn and emissions.
Blade tip sealing has been a challenging problem since the development of the gas turbine engine. It is such because the clearance between the blade tips and surrounding casing (shroud) tends to vary due primarily to changes in thermal and mechanical loads on the rotating (turbine wheel) and stationary (stator, turbine casing) structures.
Using ACC gives significant benefits in cruise fuel burn, range, and payload capability for long range aircraft.
Basic system overview.
One common active clearance control consists of the ACC valve which mixes hot and cold air from the compressor exit and the bypass duct, respectively, to a desired temperature. The air is routed to flow through tubes surrounding the casing at each turbine stage. This air expands or contracts the turbine case and in doing so, it maintains the accurate clearance between the turbine case and the blade tip. This clearance should be maintained accurately which is essential for the engine efficiency and its performance. The ACC valve opening is adjusted automatically by the FADEC system depending on the thrust lever position.
Categories.
HPT clearance control systems can be categorized as passive and active, active being controlled via a hydro-mechanical control or via FADEC (full authority digital engine control). The systems can be further classified as either thermal or mechanical.


IFA-2

IFA-2 (Interconnexion France-Angleterre 2) is a subsea electrical interconnector, running beneath the English Channel between France and the United Kingdom. The high voltage DC (HVDC) cable operates at +/-320kV with the capacity to transmit 1,000 MW of power. IFA-2 is the second interconnector built between France and Great Britain, after the HVDC Cross-Channel link.
Route.
The cable connects to the French grid at the Tourbe 400 kV substation. From there, a 300 m high voltage alternating current (HVAC) underground cable runs to the converter station nearby. A long underground HVDC cable runs from the converter station to the landfall point east of Merville-Franceville-Plage, near Caen in Normandy.
On the British side, the landfall point is located at Monks Hill Beach, at the southern end of Solent Airfield, near Portsmouth. The converter station is located to the north east of Solent Airfield. From there, a long HVAC cable runs underwater to the point of connection to the grid at Chilling 400 kV substation, near Warsash, Hampshire.
Project history.
The project was developed by IFA2 SAS, a joint venture between the UK's National Grid and RTE of France.
In 2015, the European Commission identified IFA-2 as one of key energy infrastructure projects.
In 2017, contract for IFA-2 was awarded to the Prysmian Group and ABB.
In October 2019, the project completed the external construction of the UK convertor building.
 Cable laying works in the eastern Solent took place at the end of 2019.
The cable was energised for the first time on 15 Oct 2020, in preparation for testing before going live. It was placed into live operation on 22 January 2021 with an opening flow from France to the UK. The connector tripped in the morning of January 29, causing a loss of 900 MW, and grid batteries compensated some of the loss to keep frequency drop at 0.25 Hz.


Augustin Mouchot

Augustin Mouchot (; ; 7 April 1825 – 4 October 1912) was a 19th-century French inventor of the earliest solar-powered engine, converting solar energy into mechanical steam power.
Background.
Mouchot was born in Semur-en-Auxois, France on 7 April 1825. He first taught at the primary schools of Morvan (1845–1849) and later Dijon, before attaining a degree in Mathematics in 1852 and a Bachelor of Physical Sciences in 1853. Subsequently, he taught mathematics in the secondary schools of Alençon (1853–1862), Rennes and Lycée de Tours (1864–1871). It was during this period that he undertook research into solar energy, which led eventually to his obtaining government funding for full-time research.
Solar research.
Mouchot was drawn to the idea of finding new alternative energy sources, believing that the coal which fueled the Industrial Revolution would eventually run out. In 1860 he began exploring solar cooking, drawing on the work of Horace-Bénédict de Saussure and Claude Pouillet. Further experiments involved a water-filled cauldron enclosed in glass, which would be exposed to the heat of the sun until the water boiled; the steam thus produced would provide motive power for a small steam engine. By August 1866, Mouchot had developed the first parabolic trough solar collector, which was presented to the emperor Napoleon III in Paris. Mouchot continued development and increased the scale of his solar experiments. The publication of his book on solar energy, "La Chaleur solaire et ses Applications industrielles" ("Solar Heat and its Industrial Applications") (1869), coincided with the unveiling of the largest solar steam engine he had yet built. This engine was displayed in Paris until the city fell under siege during the Franco-Prussian War in 1871, and was not found after the siege ended.
In 1861 M. Mouchot gave the name of Heliopompe to one of his invention, and in 1865 he had several small engines of this description at work at Tours, Indre-et-Loire. M. Mouchot avoided the use of parabolic mirrors and added a glass jacket to retain the heat.
In September 1871, Mouchot received financial assistance from the General Council of Indre-et-Loire to install an experimental solar generator at the Tours library. He presented a paper on the generator to the Academy of Sciences on 4 October 1875, and in December of the same year he presented to the Academy a device he claimed would, in optimal sunshine, provide a steam flow of 140 liters per minute. Later the following year he sought permission from the ministry to take leave from his teaching position in order to develop an engine for the Universal Exhibition of 1878, and in January 1877 obtained a mission and a grant for the purchase of materials and execution of his solar engines in French Algeria, where sunlight was in abundance. The director of science missions recommended Mouchot to the Governor of Algeria, stressing the importance of his mission to France, "for science and for the glory of the University".
Universal Exhibition, Paris 1878.
 Returning to metropolitan France in 1878, Mouchot and his assistant Abel Pifre displayed Mouchot's engine at the Universal Exhibition in Paris, and won a Gold Medal in Class 54 for his works, most notably the production of ice using concentrated solar heat. However, the continuing economic benefits of the Cobden-Chevalier Treaty, combined with a more efficient internal transportation for coal delivery, meant that coal became increasingly cheaper in France, reducing the necessity for research into alternative energy. The French government assessed in a report that solar energy was uneconomical, deeming Mouchot's research no longer important and ending his funding.
Mouchot subsequently went back to teaching. He was not completely forgotten however, and was named Lauréat de l'Institut by the Institut de France in 1891 and 1892, receiving prizes for work of the imagination. He died in 1912 in Paris.


Radisson Substation

Radisson Substation is a large electrical substation located near Radisson on the Route de la Baie James highway. The switching station, owned by Hydro-Québec, is the largest substation in its power grid, covering an area of a massive 100 football fields. Electrical power heading into the switchyard is collected via several relatively short alternating current (AC) 735 kilovolt (kV) and AC 315 kV power lines coming from hydroelectric plants like the Robert-Bourassa power station, part of the James Bay Project, located away. The power from these lines is either raised to AC 735 kV from AC 315 kV, statically inverted to high-voltage direct current (HVDC) +/- 450 kV, or unchanged (735 kV to 735 kV). The amount of electrical energy passing through the substation is 6,600 megawatts (MW). Two AC 735 kV lines and one HVDC +/- 450 kV line, part of the James Bay transmission system, transfer this electrical energy over a distance of to Montreal and Northeast United States.


Joel Makower

Joel Makower (born 19 February 1952 in Oakland, California) is an American entrepreneur, writer and strategist on sustainable business, clean technology, and green marketing. His work has focused on three principal topics: how companies of all sizes and sectors are integrating environmental thinking into their operations in a way that produces business value; the creation of new companies and markets for clean energy, clean water, and advanced materials; and the strategies and tactics that companies use in order to communicate and market their environmental efforts and leadership, especially to consumers.
Makower has written more than a dozen books, including "Strategies for the Green Economy", "The Green Consumer", "The E-Factor: The Bottom Line Approach to Environmentally Responsible Business" and "Beyond the Bottom Line: Putting Social Responsibility to Work for Your Business and the World". In 2010, Makower was awarded the Hutchens Medal by the American Society for Quality. In 2014, he was inducted into the Hall of Fame of the International Society of Sustainability Professionals.
Makower also writes and speaks on the environmental impact of consumerism. Makower writes a blog on these topics, “Two Steps Forward” and contributes to Worldchanging and other blogs on progressive business topics.


HT (vacuum tube)

In vacuum tube technology, HT or high tension describes the main power supply to the circuit, which produces the current between anode and cathode. It is also known as the plate supply or voltage, B battery supply, or simply labeled ->B on circuit diagrams, from the days of battery powered circuitry.
The HT supply circuit most commonly provides a positive voltage of some hundreds of volts to the anode (or "plate") and in later circuits also to the screen grid, with the cathode running at near ground or chassis potential. The main exception to this was in the case of tubes with water-cooled anodes, once used for radio transmission, electric furnaces and similar applications. These tubes used a negative HT supply to the cathode, so that the anode could run near ground DC potential (but typically at many hundreds of volts of RF).
Other power supplies to vacuum tube circuits include:
Typical circuits.
HT.
The HT supply was usually obtained from a full wave rectifier circuit similar to the one shown. In those sets that had no mains transformer (the so-called AC/DC design), the HT was obtained directly from the mains supply, either with a simple half wave rectifier or with a voltage doubler circuit.
EHT.
In very early vacuum tube television sets, the EHT was derived directly from a high voltage winding on the mains transformer using a half wave rectifier. In later television sets, the EHT supply was invariably generated by rectifying the flyback pulses from the scanning circuitry rather than directly from the mains supply (a practice that survived the transition to transistor circuits). Although this provided a greater degree of safety, the reason for the change was that the mains transformer had been eliminated from sets produced from the 1940s onwards.


Electricity Corporation of New Zealand

The Electricity Corporation of New Zealand Ltd (ECNZ) is a New Zealand state-owned enterprise (SOE) formed on 1 April 1987, as a transition entity in the process of deregulating the New Zealand electricity market. Most of ECNZ's remaining liabilities were resolved in the late 2000s, and ECNZ is a residual entity with the sole remaining task of winding up a series of land title issues.
Formation.
In the 1980s the New Zealand Electricity Department (NZED), a government department, controlled and operated almost all New Zealand electricity generation and operated the electricity transmission grid. The first phase of deregulation saw the New Zealand Government corporatise the NZED and form the state-owned enterprise ECNZ.
Division.
In 1994, Transpower was separated from ECNZ and created as an SOE to own and operate the national grid. In 1996, ECNZ was split into two SOEs, ECNZ and Contact Energy, and on 1 April 1999 ECNZ was split into three electricity generation SOEs:
All three remain in existence, along with Contact Energy and Transpower.
ECNZ was originally proposed to be wound up by 2009, but resolving the few remaining land title issues has taken years longer than originally expected.


Oncor Electric Delivery

Oncor Electric Delivery Company is Texas's largest transmission and distribution electric utility, Owned by M. Elledge, the 5th largest in the US, serving more than 10 million Texans in 420 cities and 120 counties in the state. Their service territory includes east, west and north-central Texas, including Dallas, Fort Worth, Irving, Plano, Arlington, Beeville, Midland, Odessa, Killeen, Waco, Wichita Falls, and Tyler and other surrounding cities in Texas. In 2018, Sempra Energy acquired a majority stake in Oncor for US$9.45 billion.
History.
It was formerly known as TXU Electric Delivery and TU Electric. Predecessor companies include Dallas Power & Light (DP&L), which served the city of Dallas; Texas Electric Service Company (TESCO), which served areas surrounding Fort Worth and west Texas; and Texas Power and Light (TP&L), which served other areas of northern and east-central Texas.
Oncor is privately held by a limited number of investors including Energy Future Holdings Corporation ("EFH"). Oncor is separate from its owners and separately managed by a majority independent board of directors. While a majority owner, EFH was not involved in the management of Oncor. On March 24, 2016, the Texas Public Utility Commission (PUC) granted the request to convert Oncor into a real estate investment trust (REIT) with the reservation that the PUC would consider the treatment of potential tax savings, which could account to $250M, from the REIT structure in a separate proceeding to be held at a future date. The subsequent proceeding's focus was to determine how the potential tax savings attributable to the REIT format would be shared with utility ratepayers.
On July 7, 2017, it was announced that Berkshire Hathaway had agreed a deal to buy the whole of Energy Future Holdings and ultimately Oncor. This bid was ultimately surpassed by Sempra Energy, which bid $9.45 billion in cash and the assumption of debt on August 21, 2017. The acceptance of the Sempra bid effectively terminated the Berkshire bid. The Sempra bid subsequently received court approval on September 6, 2017. On March 8, 2018, regulators in Texas approved Sempra Energy's purchase of a majority stake in Oncor for $9.45 billion.
Major projects.
As of 2014, Oncor Electric Delivery Company was working in partnership with Siemens Power Technologies to build a smart grid in an exploration of the use of storage batteries and micro-grids. The Competitive Renewable Energy Zone (CREZ) project was intended to improve the transmission of wind power to Oncor's grid.
Oncor Electric Delivery Company works with private and public utilities throughout the country through organizations called Mutual Assistance Groups. Oncor is a member of Texas Mutual Assistance Group, Midwest Mutual Assistance Group, and the Southeastern Electric Exchange. The mutual partnerships are part of a larger network of utilities that meet throughout the year to share best practices and improve upon safety methods. Members are able to quickly access and deploy resources and personnel across long distances to communities impacted by severe weather. For example, Oncor crews were sent to Florida and Georgia to assist in Hurricane Matthew aftermath in 2016. Additionally, crews were sent to California to assist in restoring power to areas devastated by the region's wildfires in 2018, and to Florida to assist in preparing for Hurricane Dorian in 2019.
Environmental Impact.
Oncor Electric Delivery Company's Take A Load Off Texas provides a variety of energy efficiency programs for residences and businesses in an effort to reduce energy and save people money on their electric bill. Oncor budgeted more than $50 million for its programs in 2019; in the last ten years, Take A Load Off Texas has helped more than 250,000 customers reduce their energy usage.
Oncor assisted with the adoption of larger, commercial electric vehicles in Texas. The company worked with electric vehicle original equipment manufacturers and other utilities to monitor the use of electric vehicles in its service territory, to provide power supply to vehicles and homes; it has helped install and plan locations for charging stations.
For nine consecutive years, Oncor has partnered with the Arbor Day Foundation's Energy-Saving Trees Program to give away thousands of free trees to customers. The program is designed to help customers better understand where to plant trees for maximum energy savings and the protection of electrical equipment.
Oncor's transmission system is planned to connect to a $104 million solar farm in Falls County. San Antonio-based OCI Solar Power is planning the project where 800 acres will be leased from private landowners in the reinvestment zone where it plans to build the 100-megawatt farm.
Oncor partnered with IBM Oncor to predict for preventative maintenance where vegetative growth is most likely to interfere with power lines, which can cause blackouts and wildfires.
Corporate Social Responsibility.
In April 2020, Oncor donated $1.7 million to community non-profit organizations across its service territory that serve those most affected by the COVID-19 pandemic.


Concentrated photovoltaic thermal system

The combination of photovoltaic (PV) technology, solar thermal technology, and reflective or refractive solar concentrators has been a highly appealing option for developers and researchers since the late 1970s and early 1980s. The result is what is known as a concentrated photovoltaic thermal (CPVT) system which is a hybrid combination of concentrated photovoltaic (CPV) and photovoltaic thermal (PVT) systems.
A Concentrated Photovoltaic Thermal system (CPVT) consists of four parts including the absorber, concentrator, solar radiation tracker and thermal absorber.
As the CPVT works with the beam radiation, the absorber and concentrator should follow the position of the sun to maximize the incident beam radiation. In order to concentrate the radiation, two major technologies of Fresnel lens, and parabolic concentrators can be used.
The difference between CPV and CPVT.
In Concentrating Photovoltaic (CPV) systems differs from PV system is the solar radiation is concentrated on the PV cells to generate additional electricity than a normal flat panel. The disadvantages of CPV system is as the intensity of the radiation increases, so does the temperature and hence decreases the electrical efficiency of the cell. The other limitations of the CPV system includes limited application scope and requirement of efficient cooling of the PV cells. To overcome the above limitations the CPV systems were modified to utilize the thermal energy and are termed as Concentrated Photovoltaic Thermal (CPVT) systems. Like CPV system, CPVT also uses low cost optical elements and compatible with multijunction cells. The area of the PV cell is reduced due to the concentration of the optical element. The heat generated on the PV cell due to the concentration of radiation is utilized for a thermal process. The utilized thermal energy in CPVT system can increase the overall system (electrical and thermal) efficiency to around 90%.
CPVT system components.
CPVT systems comprise four parts which are as below:
Solar trackers.
A solar tracker is a device that changes the position of the solar module so that the radiation can be perpendicular to the surface. In the design of the solar tracker, the position of the sun and the earth in a year period should be evaluated.
Reflectors.
The conventional material for reflectors is Anodized Aluminum. However, one of the disadvantages of this is that when a large reflector is constructed, the aluminum structure begins to deviate from its main characteristic which causes a depression in the surface of the reflector.
Solar cells.
Multi-junction PV cells have been proven to be particularly well suited for a concentrating system where sunlight can be focused through lenses or mirrors into a much smaller cell.
Ventilation.
Two major procedures of ventilation of solar collectors are active ventilation and passive ventilation. With passive ventilation, the heat generated in the surface of the collector is transmitted to the air by heat sink. With active ventilation, the heat can be used for cooling or heating purposes. So, active ventilation converts a CPV system to a CPVT system.


Malakoff (power company)

Malakoff Corporation Berhad () ("Malakoff") is an independent water and power producer (“IWPP”) with core focus on power generation, water desalination, operation & maintenance and waste management and environmental services. In Malaysia, Malakoff is the largest independent power producer (“IPP”) with a net generating capacity of 5,822 MW from its six power plants.
International assets include power and water ventures in Saudi Arabia, Bahrain and Oman, with an effective capacity of 588 MW of power and 472,975 m3/day of water desalination. Malakoff is also actively looking to venture further in the fast growing Middle East and North African region as well as the South-East Asian markets.
Through its wholly owned subsidiary, Teknik Janakuasa Sdn Bhd, Malakoff has involvements in operation & maintenance services locally and in Saudi Arabia, Algeria, Kuwait, Oman and Indonesia.
Malakoff completed the acquisition of a 97.37% interest in Alam Flora Sdn Bhd from DRB-Hicom with a price tag of RM869 million.
Malakoff believes in working together with all stakeholders in productive partnerships. As such, the Group takes pride in being a responsible operator and a good corporate citizen in all communities where it operates.
Malakoff is a member of the MMC Group.
Power generation capacity.
Malakoff generates electricity mainly from two major types of plant; steam turbine thermal plants and gas turbine plants.
The company owns and operates four power plants:
The company's total effective generation capacity is 5,822 MW.


WEC Energy Group

WEC Energy Group, based in Milwaukee, Wisconsin, provides electricity and natural gas to 4.4 million customers across four states.
Primergy merger.
On May 3, 1995, Wisconsin Energy Corporation and Northern States Power Company ( each filed a Securities and Exchange Commission Form 8-K to combine in a merger-of-equals transaction to form Primergy Corporation. It would have been the 10th largest investor-owned electric and gas utility company in the United States, based on market capitalization at that time of about US$6.0 billion. NSP would have been the nominal survivor, and the merged company would be headquartered in Minneapolis (headquarters of the old NSP), but the merged company would have been registered in Wisconsin.
On May 16, 1997, both CEOs announced that the boards of directors of both companies had terminated the merger plan because of approval delays by the U.S. Department of Justice, the SEC, and state regulators in Minnesota and Wisconsin. They also stated that regulatory agencies were changing their merger policies as they were considering the companies' filing and that further delay would reduce the benefits of the Primergy transaction.
The delay already had put the merger five months behind schedule and had reduced earnings for both utilities by a total of US$58 million to that point. In addition, Wisconsin Energy's stock had fallen about 13% since early 1995 when the deal had been announced, while NSP's stock had risen by 6%. The case was considered to be a bellwether in the utilities industry, putting an end to the rapid pace of mergers and acquisitions that had been ongoing up to then.


SunShare

SunShare is a clean energy company that is based in Denver, Colorado. Founded by David Amster-Olszewski in 2011, SunShare designs, builds, and installs community solar farms or gardens. This allows businesses, nonprofit groups, and residents to benefit from solar energy without having to build their own systems on the roof.
To serve customers, SunShare builds its solar gardens "...on the edge of the community on large pieces of land, working with the local utility [to] sell customers the energy from the panels." Customers who subscribe to the solar gardens receive credits on their utility bill based on the amount of solar power produced.
SunShare developed its first two solar gardens in Colorado Springs, partnering with Colorado Springs Utilities. SunShare moved its headquarters to Denver in 2013 where it developed several more solar gardens across Colorado's Front Range under Xcel Energy. With Xcel Energy's predominant position as a utility in Minnesota, SunShare moved into the Minnesota market as well, opening an office in downtown Minneapolis in 2014.
In February 2015, NRG Energy and SunShare signed an agreement to finance and build five solar projects throughout metro Denver and Colorado Springs.


Duquesne Light Company

Duquesne Light Holdings, Inc. (“DLH”) is an energy services holding company formed in 1989 to serve as the holding company for Duquesne Light Company and to engage in certain unregulated energy and related businesses. After a 2007 acquisition, DLH is a wholly owned subsidiary of parent company DQE Holdings LLC, with principal executive offices located in Pittsburgh, Pennsylvania.
Through its chief subsidiary, Duquesne Light Company, the corporation provides energy to over 588,000 homes and businesses.
Historic incorporation.
Duquesne Light was one of the dozens of companies founded by inventor George Westinghouse and for its first 75 years of operation (1870s-1940s) was a subsidiary of the holding company known as the "Philadelphia Company". Other such companies also founded by Westinghouse such as the Equitable Gas company and other "Equitable" energy/electronic companies were equal subsidiaries with DQE when it was a subsidiary of the 'Philadelphia Company'.
In 1997, Duquesne and Allegheny Energy agreed to a $4.3 billion merger with headquarters remaining in Hagerstown, Maryland. However DQE backed out of the deal by 1998.
In May 2007, Duquesne was acquired by a consortium led by affiliates of the Australian-based Macquarie Group Limited. The consortium consists of several institutional investors which own all of the common equity of parent company, DQE Holdings, LLC. This classifies it as an investor-owned utility. In 2010, GIC Private Limited acquired a 29% stake from original investor DUET Group.
In 2018, Duquesne Light began offering $3,000 rebates for the purchase of electric vehicles in an effort to promote adoption of electric vehicles and increase the number on the road. The company partnered with Nissan North America to execute the program. People in Pennsylvania who purchase electric vehicles, in addition to the rebate, get up to $7,500 in federal tax credits and a $1,750 rebate from the state. In 2019, the company named Steve Malnight as CEO, replacing Rich Riazzi, who had held the post since 2010.


Cape Hatteras Electric Cooperative

Cape Hatteras Electric Cooperative (CHEC) is a utility cooperative that distributes electricity to Hatteras and Ocracoke islands in the Outer Banks region of the state of North Carolina. The electric cooperative was founded in 1945 and is headquartered in Buxton.
Electricity.
Cape Hatteras Electric Cooperative distributes electricity to 7,000 members on Hatteras and Ocracoke islands, both of which are barrier islands that are situated between the Atlantic Ocean and the Pamlico Sound in the Outer Banks region of the state of North Carolina. As an electric cooperative, Cape Hatteras Electric Cooperative is owned by the members who it provides electricity to. Cape Hatteras Electric Cooperative is a Touchstone Energy Cooperative and a member of the North Carolina Electric Membership Corporation (NCEMC), an electric generation and transmission cooperative that supplies electricity to most of North Carolina's electric cooperatives. Cape Hatteras Electric Cooperative receives its electricity supply from underground cables attached to the Herbert C. Bonner Bridge over the Oregon Inlet that connect to the Dominion North Carolina Power electric system. A diesel generation plant operated by the NCEMC is located in Buxton and is used during peak demand times and also to provide limited backup power to Cape Hatteras Electric Cooperative during times of transmission maintenance or emergencies.
History.
Cape Hatteras Electric Cooperative was founded in 1945 to provide electricity to Hatteras Island, most of which lacked electricity at the time as investor-owned utilities did not find it profitable to serve the island. Prior to 1945, the only place on the island that had electricity was Hatteras Village. Originally, generators were the only power source on Hatteras Island, resulting in frequent power outages. In the 1960s, electric lines were constructed across the Herbert C. Bonner Bridge. A new cable across the bridge was built in 1995 at a cost of $10 million. In recent years, utility poles have been raised and new substations have been constructed. A new power line will be installed after the new Herbert C. Bonner Bridge is completed.
On July 27, 2017, a crew working on constructing a new Herbert C. Bonner Bridge severed the underground cable serving Cape Hatteras Electric Cooperative, causing a widespread power outage on Hatteras and Ocracoke islands. The power outage resulted in tourists being evacuated from Hatteras and Ocracoke islands during the peak of the summer vacation season. During the outage, a state of emergency was declared while residents were mandated to conserve their energy use, with emergency generators serving the islands. Power to Hatteras and Ocracoke islands was restored on August 3, with tourists allowed to return the next day. A $10.53 million settlement was reached, with PCL Civil Constructors denying guilt.
The new bridge was completed and opened to traffic on February 25, 2019, although some minor work remained to be performed, and a dedication ceremony was held on April 2, 2019 with NC Governor Roy Cooper as the keynote speaker. However, it was not Herbert C. Bonner, but long-time NC state senator and leader Marc Basnight who was recognized in the naming ceremony. Despite some objection from Hatteras Island residents and officials, and a NC BOT rule requiring unanimous consent by Dare County, the NC Board of Transportation made an exception and voted to name it after Senator Basnight, thus it is now the Marc Basnight Bridge over Oregon Inlet.


SaskPower

Saskatchewan Power Corporation, operating as SaskPower, is the principal electric utility in Saskatchewan, Canada. Established in 1929 by the provincial government, it serves more than 538,000 customers and manages over $11.8 billion in assets. SaskPower is a major employer in the province with over 3,100 permanent full-time staff located in approximately 70 communities.
Legal status.
SaskPower was founded as the Saskatchewan Power Commission in 1929, becoming the Saskatchewan Power Corporation in 1949 with the passage of "The Rural Electrification Act". The abbreviated name SaskPower was officially adopted as a trade name in 1987.
Owned by the government through its holding company, the Crown Investments Corporation, SaskPower is governed by a Board of Directors who are accountable to the provincial government Minister Responsible for Saskatchewan Power Corporation.
SaskPower has the exclusive right and the exclusive obligation to supply electricity in the province, except in the city of Swift Current and most of the city of Saskatoon. The Swift Current Department of Light and Power provides electrical services within the municipal boundary of Swift Current. Saskatoon Light & Power provides service to the customers within the 1958 boundaries of Saskatoon while SaskPower has responsibility for areas annexed after 1958.
Customers.
SaskPower serves more than 538,000 customers through more than 157,000 kilometres of power lines throughout the province and covers a service territory that includes Saskatchewan's geographic area of approximately . This relatively low customer density means that while most North American electrical utilities supply an average of 12 customers per circuit kilometre, SaskPower supplies about three. In fiscal year 2018-19, SaskPower sold 23,559 GWh of electricity for $2,583 million (CAD).
Facilities.
SaskPower has a generating capacity of 3,542 megawatts (MW) from 17 generating facilities, including three coal-fired power stations, five natural gas stations, seven hydroelectric stations, and two wind power facilities.
In 2019, SaskPower purchased full ownership in Cory Cogeneration Station, which was previously owned and operated as a joint venture between Canadian Utilities (an ATCO Power subsidiary) and SaskPower international. The cogeneration facility supplies both electricity and steam to Nutrien’s Cory Potash Mine and also supplies electricity to the SaskPower grid.
SaskPower also buys power from various independent power producers (IPPs) including the North Battleford Generating Station, Spy Hill Generating Station, Morse Wind Energy Facility, Red Lily Wind Power Facility and SunBridge Wind Energy Facility. When all SaskPower and IPP facilities are counted, the total available generation capacity is 4,437 MW.
The Chinook Power Station is a 350MW combined-cycle natural gas power station near Swift Current that is expected to come online in 2019. This will increase SaskPower's generating capacity to 3,892 MW, and the total generation capacity controlled by SaskPower to 4,881 MW.
The SaskPower transmission system utilizes lines carrying 230,000 volts, 138,000 volts and 72,000 volts. There are 56 switching stations and 197 distribution stations on the transmission system.
SaskPower has four interconnections to Manitoba, one interconnection to North Dakota, and one interconnection to Alberta. Manitoba and North Dakota are on the same grid frequency as Saskatchewan, which means interconnections can be made directly using a normal AC transmission line. Alberta is part of WECC, so the interconnection relies on an AC/DC-AC link via the McNeill HVDC Back-to-back station.
Rural areas.
Incorporated under "The Power Corporation Act" (1949), SaskPower purchased the majority of the province's small, independent municipal electrical utilities and integrated them into a province-wide grid. It was also responsible under "The Rural Electrification Act" (1949) for the electrification of the province's rural areas, bringing electricity to over 66,000 farms between 1949 and 1966. To manage the high costs of electrifying the province's sparsely populated rural areas, SaskPower used a large-scale implementation of a single wire ground return distribution system, claimed to be a pioneering effort (although some utilities in the USA had been using such a system on its rural lines). It was at the time one of the largest such systems in the world. One of the last cities in the province added to SaskPower's system was North Portal in 1971 (which had been served up to this point from Montana-Dakota Utilities' distribution system in Portal, ND just across the border).
Rural electrification.
SaskPower was founded by an Act of the provincial legislature as the "Saskatchewan Power Commission" in 1929. The purpose of the Commission was to research how best to create a provincial power system which would provide the province's residents with safe, reliable electric service.
A provincial power system was desirable for many reasons. In the early days of electricity in the province of Saskatchewan, electricity was largely unavailable outside of larger centres. Most electrical utilities were owned either privately or by municipalities, and none of them were interconnected. Because each utility operated independently, rates often varied significantly between communities – anywhere from 4 to 45 cents per kilowatt hour in the mid-1920s. The rapid growth in the province's population in the first decades of the century – from 91,279 to 757,510 within 20 years – had led to a sharp increase in the demand for electricity. Finally, the provincial government had determined that the lack of inexpensive power was hampering the development of industry in the province.
While the Commission began purchasing independently owned electrical utilities with the goal of interconnecting them, the economic situation of the 1930s and the labour shortage caused by the Second World War delayed the creation of a provincial power system for nearly two decades.
By 1948, the Commission operated 35 generating stations and more than 8,800 km of transmission lines. However, most farm families who had electricity generated it themselves using battery systems charged by wind turbines or gasoline- or diesel-powered generators. Across the province, only 1,500 farms were connected to the electrical grid, most of them because of their proximity to the lines that linked cities and larger towns.
In 1949, by an Act of the Provincial Legislature, the Commission became the Saskatchewan Power Corporation. The first task of the new Corporation was to purchase what remained of the province's small, independent electrical utilities and to begin integrating them into a province-wide electrical grid.
The final step in creating a truly province-wide grid was to electrify the province's vast rural areas. The primary hurdle to rural electrification was the very low customer density in the province – approximately one farm customer per network mile (1.6 km) – and the extremely high cost of a network of the scale required by the vast distances between customers. After much study, the Corporation adopted a single wire ground return distribution scheme, which lowered the cost of rural electrification significantly.
The first year of the program set the goal of connecting 1200 rural customers to the network. The experience gained during the first years led to an increased rate of connections every year, leading to a peak yearly connection rate in 1956 of 7,800 customers. By 1961, 58,000 farms were connected, and by 1966 when the program concluded, the Corporation had provided power to a total of 66,000 rural customers. In addition, hundreds of schools, churches and community halls received electrical service during this period.
Corporate governance.
SaskPower is governed by a Board of Directors that is responsible to the Minister Responsible for Saskatchewan Power Corporation. The board gets appointed by the Lieutenant Governor of Saskatchewan. Current directors of the corporation include: Chief Darcy Bear (Chair), Bryan Leverick (Vice-Chair), Dale Bloom (Corporate Secretary), Terry Bergan, Bevra Fee, Jim Hopson, Karri Howlett, Cherilyn Jolly-Nagel, Phil Klein, Fred Matheson, Rob Nicolay, Marvin Romanow, and Tammy van Lambalgen.
Emissions Reductions.
By 2030, SaskPower plans to reduce their greenhouse gas emissions by 40% compared to 2005.
In 2012, the Harper government introduced regulations to start phasing out coal-fired power plants in Canada. These regulations set an emissions limit for coal-fired generating units of 420 tonnes of CO2 per GWh. The limit was to be imposed in 2015 on all new coal units, and would also apply to units built before 1975 starting in 2020, and to units built before 1986 starting in 2030, and would also apply to all units once they reach 50 years of age regardless of the aforementioned dates.
In 2014, SaskPower rebuilt Boundary Dam unit 3 with a CCS system capable of capturing 90% of the CO2 emissions of the unit, and 100% of the SO2 emissions.
In 2018, the Trudeau government accelerated the coal phase-out by mandating that all coal units must shut down by 2030, regardless of the year they were built. The Trudeau government also implemented a nationwide carbon tax that made it more-expensive for SaskPower to operate both coal and natural gas plants in comparison to hydro, wind, and solar facilities.
The federal coal regulations mentioned above would have meant that Boundary Dam units 4 and 5 would need to close at the end of 2019. However, in 2019 the Moe government was able to negotiate an equivalency agreement with the Trudeau government that allowed Boundary Dam unit 4 to run until the end of 2021 and Boundary Dam unit 5 until the end of 2024 due to SaskPower's investments into CCS technology on unit 3.
As coal units close, SaskPower plans to replace the lost capacity with low-emissions generation sources such as combined-cycle natural gas, wind, and solar, and they also plan to import more hydroelectricity from Manitoba. In particular, a new 350MW combined-cycle natural gas generating station is expected to come online in 2019 and a total of 340MW of hydro imports from Manitoba will be available by 2022.
In addition to building new generators and interconnections to reduce emissions, SaskPower is implementing energy efficiency and demand-side management (DSM) programs to reduce electricity use per-capita. Their DSM program has reduced peak demand by 11.4MW as of 2019.
Further reading.
Print:
Online:


Radial turbine

A radial turbine is a turbine in which the flow of the working fluid is radial to the shaft. The difference between axial and radial turbines consists in the way the fluid flows through the components (compressor and turbine). Whereas for an axial turbine the rotor is 'impacted' by the fluid flow, for a radial turbine, the flow is smoothly orientated perpendicular to the rotation axis, and it drives the turbine in the same way water drives a watermill. The result is less mechanical stress (and less thermal stress, in case of hot working fluids) which enables a radial turbine to be simpler, more robust, and more efficient (in a similar power range) when compared to axial turbines. When it comes to high power ranges (above 5 MW) the radial turbine is no longer competitive (due to its heavy and expensive rotor) and the efficiency becomes similar to that of the axial turbines.
Advantages and challenges.
Compared to an axial flow turbine, a radial turbine can employ a relatively higher pressure ratio (≈4) per stage with lower flow rates. Thus these machines fall in the lower specific speed and power ranges. For high temperature applications rotor blade cooling in radial stages is not as easy as in axial turbine stages. Variable angle nozzle blades can give higher stage efficiencies in a radial turbine stage even at off-design point operation. In the family of hydro-turbines, Francis turbine is a very well-known IFR turbine which generates much larger power with a relatively large impeller.
Components of radial turbines.
The radial and tangential components of the absolute velocity c2 are cr2 and cq2, respectively. The relative velocity of the flow and the peripheral speed of the rotor are w2 and u2 respectively. The air angle at the rotor blade entry is given by
Enthalpy and entropy diagram.
The stagnation state of the gas at the nozzle entry is represented by point 01. The gas expands adiabatically in the nozzles from a pressure p1 to p2 with an increase in its velocity from c1 to c2. Since this is an energy transformation process, the stagnation enthalpy remains constant but the stagnation pressure decreases (p01 > p02) due to losses.
The energy transfer accompanied by an energy transformation process occurs in the rotor.
Spouting velocity.
A reference velocity (c0) known as the isentropic velocity, spouting velocity or stage terminal velocity is defined as that velocity which will be obtained during an isentropic expansion of the gas between the entry and exit pressures of the stage.
Stage efficiency.
The total-to-static efficiency is based on this value of work.
Degree of reaction.
The relative pressure or enthalpy drop in the nozzle and rotor blades are determined by the degree of reaction of the stage. This is defined by
The two quantities within the parentheses in the numerator may have the same or opposite signs. This, besides other factors, would also govern the value of reaction. The stage reaction decreases as Cθ2 increases because this results in a large proportion of the stage enthalpy drop to occur in the nozzle ring.
Stage losses.
The stage work is less than the isentropic stage enthalpy drop on account of aerodynamic losses in the stage. The actual output at the turbine shaft is equal to the stage work minus the losses due to rotor disc and bearing friction.
Blade to gas speed ratio.
The blade-to-gas speed ratio can be expressed in terms of the isentropic stage terminal velocity c0.
for
Outward-flow radial stages.
In outward flow radial turbine stages, the flow of the gas or steam occurs from smaller to larger diameters. The stage consists of a pair of fixed and moving blades. The increasing area of cross-section at larger diameters accommodates the expanding gas.
This configuration did not become popular with the steam and gas turbines. The only one which is employed more commonly is the Ljungstrom double rotation type turbine. It consists of rings of cantilever blades projecting from two discs rotating in opposite directions. The relative peripheral velocity of blades in two adjacent rows, with respect to each other, is high. This gives a higher value of enthalpy drop per stage.
Nikola Tesla's bladeless radial turbine.
In the early 1900s, Nikola Tesla developed and patented his bladeless Tesla turbine. One of the difficulties with bladed turbines is the complex and highly precise requirements for balancing and manufacturing the bladed rotor which has to be very well balanced. The blades are subject to corrosion and cavitation. Tesla attacked this problem by substituting a series of closely spaced disks for the blades of the rotor. The working fluid flows between the disks and transfers its energy to the rotor by means of the boundary layer effect or adhesion and viscosity rather than by impulse or reaction. Tesla stated his turbine could realize incredibly high efficiencies by steam. There has been no documented evidence of Tesla turbines achieving the efficiencies Tesla claimed. They have been found to have low overall efficiencies in the role of a turbine or pump. In recent decades there has been further research into bladeless turbine and development of patented designs that work with corrosive/abrasive and hard to pump material such as ethylene glycol, fly ash, blood, rocks, and even live fish.


Conical screw compressor

The relatively recently developed conical screw compressor is a type of rotary-screw compressor using a different topology from the typical dual-screw type, in effect it is a conical spiral extension of a gerotor. Because of this it does not have the inherent "blow-hole" leakage path which in typical screw compressors is responsible for significant leakage through the assembly and makes low-speed operation impractical. This theoretically allows much smaller rotors to have practical efficiency since at smaller sizes the leakage area does not become as large a portion of the pumping area as in straight screw compressors. In conjunction with the decreasing diameter of the cone shaped rotor this may also allows much higher compression ratios to be achieved in a single stage.
A significant impediment to production is the challenging manufacturing process, although the inner rotor can be manufactured with precise CNC machines without much difficulty the outer rotor presents significant difficulties in production due to the restricted access to the interior for precision machining tooling, assembling the shell from easier to machine segments presents its own problems. The cost of units is currently very high, but development is ongoing, development is primarily being performed by VERT Rotors.


List of solar farms in Queensland

This is a list of solar farms in Queensland. There has been significant growth in this area recently, with an estimated 17298 MW of solar capacity either operational, planned or under construction.
Table.
Summary of capacity


States of India by installed power capacity

This is a list of states and territories of India by installed power generation capacity
Other Renewable Energy sources include SHP (Small Hydro Power - hydel plants ≤ 25 MW), Biomass Power, Urban & Industrial waste, Solar and Wind Energy


Auguste Rateau

Auguste Rateau (13 October 1863 – 13 January 1930) was an engineer and industrialist born in Royan, France, specializing in turbines.
Biography.
After studies, first at the École Polytechnique and then at the École des Mines de Paris, he began his career as a teacher at the École des Mines de Saint-Étienne from 1888 to 1897.
He then embarked on an industrial career exploiting turbines. He manufactured fans for mines, blowers for steel mills, water pumps, and steam turbines for ships. To this end, he created a design office in Paris and, in 1903, the "Société pour l’exploitation des appareils Rateau", which moved in 1917 to La Courneuve where he opened a factory two years later. The company has since been integrated into Alstom, and La Courneuve's premises are still operated by GE Power Service. This entity manages the maintenance of turbomachines, turbo-pumps and turbocompressors installed on nuclear, thermal and industrial sites in France and in some parts of the world.
In 1928 he founded the "Association Française de Normalisation", the French national organization for standardization, and served as president.
Rateau was a Commander of the Legion of Honour () and a member of the French Academy of Sciences ().


Magnetic confinement fusion

Magnetic confinement fusion is an approach to generate thermonuclear fusion power that uses magnetic fields to confine fusion fuel in the form of a plasma. Magnetic confinement is one of two major branches of fusion energy research, along with inertial confinement fusion. The magnetic approach began in the 1940s and absorbed the majority of subsequent development.
Fusion reactions combine light atomic nuclei such as hydrogen to form heavier ones such as helium, producing energy. In order to overcome the electrostatic repulsion between the nuclei, they must have a temperature of tens of millions of degrees, creating a plasma. In addition, the plasma must be contained at a sufficient density for a sufficient time, as specified by the Lawson criterion (triple product).
Magnetic confinement fusion attempts to use the electrical conductivity of the plasma to contain it through interaction with magnetic fields. The magnetic pressure offsets the plasma pressure. Developing a suitable arrangement of fields that contain the fuel without excessive turbulence or leaking is the primary challenge of this technology.
History.
The development of magnetic fusion energy (MFE) came in three distinct phases. In the 1950s it was believed MFE would be relatively easy to achieve, setting off a race to build a suitable machine. By the late 1950s, it was clear that plasma turbulence and instabilities were problematic, and during the 1960s, "the doldrums", effort turned to a better understanding of plasma physics.
In 1968, a Soviet team invented the tokamak magnetic confinement device, which demonstrated performance ten times better than alternatives and became the preferred approach.
Construction of a 500-MW power generating fusion plant using this design, the ITER, began in France in 2007. Its most recent schedule is for it to begin operation in 2025.
Plasma.
When fuel is injected into a fusion reactor, powerful "rogue" waves might be created that can cause it to escape confinement. These waves can reduce the efficiency or even stop the fusion reaction. Mathematical models can determine the likelihood of a rogue wave and can be used to calculate the exact angle of a counter-wave to cancel it out.
Magnetic islands are anomalies where magnetic field lines separate from the rest of the field and form a tube, allowing fuel to escape. The presence of large magnetic islands disrupt fusion. Injecting frozen pellets of deuterium into the fuel mixture can cause enough turbulence to disrupt the islands.
Types.
Magnetic mirrors.
A major area of research in the early years of fusion energy research was the magnetic mirror. Most early mirror devices attempted to confine plasma near the focus of a non-planar magnetic field generated in a solenoid with the field strength increased at either end of the tube. In order to escape the confinement area, nuclei had to enter a small annular area near each magnet. It was known that nuclei would escape through this area, but by adding and heating fuel continually it was felt this could be overcome.
In 1954, Edward Teller gave a talk in which he outlined a theoretical problem that suggested the plasma would also quickly escape sideways through the confinement fields. This would occur in any machine with convex magnetic fields, which existed in the centre of the mirror area. Existing machines were having other problems and it was not obvious whether this was occurring. In 1961, a Soviet team conclusively demonstrated this flute instability was indeed occurring, and when a US team stated they were not seeing this issue, the Soviets examined their experiment and noted this was due to a simple instrumentation error.
The Soviet team also introduced a potential solution, in the form of "Ioffe bars". These bent the plasma into a new shape that was concave at all points, avoiding the problem Teller had pointed out. This demonstrated a clear improvement in confinement. A UK team then introduced a simpler arrangement of these magnets they called the "tennis ball", which was taken up in the US as the "baseball". Several baseball series machines were tested and showed much-improved performance. However, theoretical calculations showed that the maximum amount of energy they could produce would be about the same as the energy needed to run the magnets. As a power-producing machine, the mirror appeared to be a dead end.
In the 1970s, a solution was developed. By placing a baseball coil at either end of a large solenoid, the entire assembly could hold a much larger volume of plasma, and thus produce more energy. Plans began to build a large device of this "tandem mirror" design, which became the Mirror Fusion Test Facility (MFTF). Having never tried this layout before, a smaller machine, the Tandem Mirror Experiment (TMX) was built to test this layout. TMX demonstrated a new series of problems that suggested MFTF would not reach its performance goals, and during construction MFTF was modified to MFTF-B. However, due to budget cuts, one day after the construction of MFTF was completed it was mothballed. Mirrors have seen little development since that time.
Toroidal machines.
Z-pinch.
The first real effort to build a control fusion reactor used the pinch effect in a toroidal container. A large transformer wrapping the container was used to induce a current in the plasma inside. This current creates a magnetic field that squeezes the plasma into a thin ring, thus "pinching" it. The combination of Joule heating by the current and adiabatic heating as it pinches raises the temperature of the plasma to the required range in the tens of millions of degrees Kelvin.
First built in the UK in 1948, and followed by a series of increasingly large and powerful machines in the UK and US, all early machines proved subject to powerful instabilities in the plasma. Notable among them was the kink instability, which caused the pinched ring to thrash about and hit the walls of the container long before it reached the required temperatures. The concept was so simple, however, that herculean effort was expended to address these issues.
This led to the "stabilized pinch" concept, which added external magnets to "give the plasma a backbone" while it compressed. The largest such machine was the UK's ZETA reactor, completed in 1957, which appeared to successfully produce fusion. Only a few months after its public announcement in January 1958, these claims had to be retracted when it was discovered the neutrons being seen were created by new instabilities in the plasma mass. Further studies showed any such design would be beset with similar problems, and research using the z-pinch approach largely ended.
Stellarators.
An early attempt to build a magnetic confinement system was the stellarator, introduced by Lyman Spitzer in 1951. Essentially the stellarator consists of a torus that has been cut in half and then attached back together with straight "crossover" sections to form a figure-8. This has the effect of propagating the nuclei from the inside to outside as it orbits the device, thereby cancelling out the drift across the axis, at least if the nuclei orbit fast enough.
Not long after the construction of the earliest figure-8 machines, it was noticed the same effect could be achieved in a completely circular arrangement by adding a second set of helically-wound magnets on either side. This arrangement generated a field that extended only part way into the plasma, which proved to have the significant advantage of adding "shear", which suppressed turbulence in the plasma. However, as larger devices were built on this model, it was seen that plasma was escaping from the system much more rapidly than expected, much more rapidly than could be replaced.
By the mid-1960s it appeared the stellarator approach was a dead end. In addition to the fuel loss problems, it was also calculated that a power-producing machine based on this system would be enormous, the better part of a thousand feet long. When the tokamak was introduced in 1968, interest in the stellarator vanished, and the latest design at Princeton University, the Model C, was eventually converted to the Symmetrical Tokamak.
Stellarators have seen renewed interest since the turn of the millennium as they avoid several problems subsequently found in the tokamak. Newer models have been built, but these remain about two generations behind the latest tokamak designs.
Tokamaks.
In the late 1950s, Soviet researchers noticed that the kink instability would be strongly suppressed if the twists in the path were strong enough that a particle travelled around the circumference of the inside of the chamber more rapidly than around the chamber's length. This would require the pinch current to be reduced and the external stabilizing magnets to be made much stronger.
In 1968 Russian research on the toroidal tokamak was first presented in public, with results that far outstripped existing efforts from any competing design, magnetic or not. Since then the majority of effort in magnetic confinement has been based on the tokamak principle. In the tokamak a current is periodically driven through the plasma itself, creating a field "around" the torus that combines with the toroidal field to produce a winding field in some ways similar to that in a modern stellarator, at least in that nuclei move from the inside to the outside of the device as they flow around it.
In 1991, START was built at Culham, UK, as the first purpose-built spherical tokamak. This was essentially a spheromak with an inserted central rod. START produced impressive results, with β values at approximately 40% - three times that produced by standard tokamaks at the time. The concept has been scaled up to higher plasma currents and larger sizes, with the experiments NSTX (US), MAST (UK) and Globus-M (Russia) currently running. Spherical tokamaks have improved stability properties compared to conventional tokamaks and as such the area is receiving considerable experimental attention. However spherical tokamaks to date have been at low toroidal field and as such are impractical for fusion neutron devices.
Compact toroids.
Compact toroids, e.g. the spheromak and the Field-Reversed Configuration, attempt to combine the good confinement of closed magnetic surfaces configurations with the simplicity of machines without a central core.
An early experiment of this type in the 1970s was Trisops. (Trisops fired two theta-pinch rings towards each other.)
Other.
Some more novel configurations produced in toroidal machines are the reversed field pinch and the Levitated Dipole Experiment.
The US Navy has also claimed a "Plasma Compression Fusion Device" capable of TW power levels in a 2018 US patent filing:
""It is a feature of the present invention to provide a plasma compression fusion device that can produce power in the gigawatt to terawatt range (and higher), with input power in the kilowatt to megawatt range."
Magnetic fusion energy.
All of these devices have faced considerable problems being scaled up and in their approach toward the Lawson criterion. One researcher has described the magnetic confinement problem in simple terms, likening it to squeezing a balloon – the air will always attempt to "pop out" somewhere else. Turbulence in the plasma has proven to be a major problem, causing the plasma to escape the confinement area, and potentially touch the walls of the container. If this happens, a process known as "sputtering", high-mass particles from the container (often steel and other metals) are mixed into the fusion fuel, lowering its temperature.
In 1997, scientists at the Joint European Torus (JET) facilities in the UK produced 16 megawatts of fusion power. Scientists can now exercise a measure of control over plasma turbulence and resultant energy leakage, long considered an unavoidable and intractable feature of plasmas. There is increased optimism that the plasma pressure above which the plasma disassembles can now be made large enough to sustain a fusion reaction rate acceptable for a power plant. Electromagnetic waves can be injected and steered to manipulate the paths of plasma particles and then to produce the large electrical currents necessary to produce the magnetic fields to confine the plasma. These and other control capabilities have come from advances in basic understanding of plasma science in such areas as plasma turbulence, plasma macroscopic stability, and plasma wave propagation. Much of this
progress has been achieved with a particular emphasis on the tokamak.


Tube caddy

A tube caddy is a type of carrying case used for storing and transporting vacuum tubes. They were carried by repair technicians who performed home service calls in the days when radios and television sets were too large and heavy for the average homeowner to bring to a repair shop. Caddies varied in size and shape, some resembling large briefcases with others resembling tool chests with drawers on the front. Typically they would have rows of square compartments that fit the individually boxed tubes, and often had larger compartments for other components or tools. Most of the space in the caddies was afforded to vacuum tubes (gas-filled tubes were also kept as needed) as most repairs could be effected with the replacement of tubes, with them being some of the few active components in electronic equipment of the time and often being made of glass with sensitive seals they were most likely to break, and were installed in sockets from which they were easy to remove.
The use of tube caddies, along with home visits from repairmen, declined with the use of vacuum tubes themselves as televisions and radios became smaller and cheaper, eliminating a need for repair diagnoses from technicians.