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Energy Conversion and Management 45 (2004) 3075–3092 www.elsevier.com/locate/enconman Environmental benefits of domestic solar energy systems Soteris A. Kalogirou * Department of Mechanical Engineering, Higher Technical Institute, P.O. Box 20423, Nicosia 2152, Cyprus Received 1 May 2003; received in revised form 10 October 2003; accepted 26 December 2003 Available online 27 February 2004 Abstract All nations of the world depend on fossil fuels for their energy needs. However the obligation to reduce CO2 and other gaseous emissions in order to be in conformity with the Kyoto agreement is the reason behind which countries turn to non-polluting renewable energy sources. In this paper the pollution caused by the burning of fossil fuels is initially presented followed by a study on the environmental protection offered by the two most widely used renewable energy systems, i.e. solar water heating and solar space heating. The results presented in this paper show that by using solar energy, considerable amounts of greenhouse polluting gasses are avoided. For the case of a domestic water heating system, the saving, compared to a conventional system, is about 80% with electricity or Diesel backup and is about 75% with both electricity and Diesel backup. In the case of space heating and hot water system the saving is about 40%. It should be noted, however, that in the latter, much greater quantities of pollutant gasses are avoided. Additionally, all systems investigated give positive and very promising financial characteristics. With respect to life cycle assessment of the systems, the energy spent for manufacture and installation of the solar systems is recouped in about 1.2 years, whereas the payback time with respect to emissions produced from the embodied energy required for the manufacture and installation of the systems varies from a few months to 9.5 years according to the fuel and the particular pollutant considered. Moreover, due to the higher solar contribution, solar water heating systems have much shorter payback times than solar space heating systems. It can, therefore, be concluded that solar energy systems offer significant protection to the environment and should be employed whenever possible in order to achieve a sustainable future. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Solar water heating; Solar space heating; Environmental impact; Embodied energy * Tel.: +357-22-406-466; fax: +357-22-494-953. E-mail address: firstname.lastname@example.com (S.A. Kalogirou). 0196-8904/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.enconman.2003.12.019 3076 S.A. Kalogirou / Energy Conversion and Management 45 (2004) 3075–3092 1. Introduction Energy is considered a prime agent in the generation of wealth and a significant factor in economic development. The importance of energy in economic development is recognized universally, and historical data verify that there is a strong relationship between the availability of energy and economic activity. Although in the early seventies, after the oil crises, the concern was on the cost of energy, during the past two decades, the risk and reality of environmental degradation have become more apparent. The growing evidence of environmental problems is due to a combination of several factors, since the environmental impact of human activities has grown dramatically. This is due to the increase of the world population, energy consumption and industrial activities. Achieving solutions to the environmental problems that humanity faces today requires long term potential actions for sustainable development. In this respect, renewable energy resources appear to be one of the most efficient and effective solutions. A few years ago, most environmental analysis and legal control instruments concentrated on conventional pollutants, such as sulphur dioxide (SO2 ), nitrogen oxides (NOx ), particulates and carbon monoxide (CO). Recently however, environmental concern has extended to the control of hazardous air pollutants, which are usually toxic chemical substances that are harmful even in small doses, as well as to other globally significant pollutants such as carbon dioxide (CO2 ). Additionally, developments in industrial processes and structures have led to new environmental problems. A detailed description of these gaseous and particulate pollutants and their impacts on the environment and human life is presented by Dincer [1,2]. One of the most widely accepted definitions of sustainable development is: ''development that meets the needs of the present without compromising the ability of future generations to meet their own needs''. There are many factors that can help to achieve sustainable development. Today, one of the main factors that must be considered in discussions of sustainable development is energy, and one of the most important issues is the requirement for a supply of energy that is fully sustainable [3,4]. A secure supply of energy is generally agreed to be a necessary but not a sufficient requirement for development within a society. Furthermore, for a sustainable development within a society, it is required that a sustainable supply of energy and effective and efficient utilization of energy resources be secured. Such a supply in the long term should be readily available at reasonable cost, be sustainable and be able to be utilized for all the required tasks without causing negative societal impacts. This is why there is a close connection between renewable sources of energy and sustainable development. Today the world daily oil consumption is 76 million barrels. Despite the well known consequences of fossil fuel combustion on the environment, this is expected to increase to 123 million barrels per day by the year 2025 [5]. In developed countries, energy consumption in the building sector represents a major part of the total energy budget. In the European Union, this is approximately equal to 40% of the total energy consumption [6]. Most of this amount is spent for hot water production and space heating. One way to reduce this amount of energy is to employ solar energy. The principal objective of this paper is to discuss the environmental impacts of energy utilization and to analyze the environmental benefits resulting from the use of solar water and space heating systems. Additionally, the amount of pollution saved because of the use of solar energy against the pollution caused for the manufacture of the systems is examined. S.A. Kalogirou / Energy Conversion and Management 45 (2004) 3075–3092 3077 2. Environmental impact of conventional energy sources Pollution depends on energy consumption. There are a large number of factors that are significant in the determination of the future level of energy consumption and production. Such factors include population growth, economic performance, consumer tastes and technological developments. Furthermore, governmental policies concerning energy and developments in the world energy markets will certainly play a key role in the future level and pattern of energy production and consumption [7]. During the last two decades, environmental considerations have been given increasing attention by energy industries and the public, and the concept that due to irrational use, consumers share responsibility for pollution and its cost has been increasingly accepted. In some cases, the prices of some energy resources have increased over the last one to two decades in order to account for environmental costs [7]. Another parameter to be considered is world population. This is expected to double by the middle of this century, and as economic development will certainly continue to grow, the global demand for energy is expected to increase. At the same time, concern regarding energy related environmental pollution will increase. Problems associated with energy supply and use are related not only to global warming but also to other environmental impacts such as air pollution, acid precipitation, ozone depletion, forest destruction and emission of radioactive substances [7]. Today, much evidence exists which suggests the future of our planet and of the generations to come will be negatively impacted if humans keep degrading the environment. A summary of the pollutants and their environmental impact is tabulated in Table 1 [8]. The three major environmental problems that are internationally known are analyzed in more detail below. 2.1. Acid rain This is a form of pollution in which SO2 and NOx produced by the combustion of fossil fuels, such as industrial boilers and transportation vehicles, are transported over great distances through the atmosphere and deposited via precipitation on the earth, causing damage to ecosystems that Table 1 Main gaseous pollutants and their impact on the environment [8] Gaseous pollutant Carbon monoxide (CO) and carbon dioxide (CO2 ) Methane (CH4 ) Nitric oxide (NO) and nitrogen dioxide (NO2 ) Nitrous oxide (N2 O) Sulfur dioxide (SO2 ) Chlorofluorocarbons (CFCs) Ozone (O3 ) Greenhouse effect + + Ozone depletion +/) +/) +/) + + ) + + +/) + + + + Acid rain Smog Note: + stands for positive contribution, ) stands for variation with conditions and chemistry. 3078 S.A. Kalogirou / Energy Conversion and Management 45 (2004) 3075–3092 are exceedingly vulnerable to excessive acidity. Therefore, it is obvious that the solution to the issue of acid rain deposition requires an appropriate control of SO2 and NOx pollutants. These pollutants cause both regional and transboundary problems of acid precipitation. Recently, attention is also given to other substances, such as volatile organic compounds (VOCs), chlorides, ozone and trace metals that may participate in a complex set of chemical transformations in the atmosphere, resulting in acid precipitation and the formation of other regional air pollutants. A number of evidences that show the damages of acid precipitation are reported by Dincer and Rosen [4]. It is well known that some energy related activities are major sources of acid precipitation. Additionally, VOCs are generated by a variety of sources and comprise a large number of diverse compounds. Obviously, the more energy we spend the more we contribute to acid precipitation, and therefore, the easiest way to reduce acid precipitation is by reducing energy consumption. Other possible methods to reduce this type of pollution include the cleaning of coal before combustion, with respect to electricity generation, and the use of three way catalytic converters, with respect to transport vehicles [7]. 2.2. Ozone layer depletion The ozone present in the stratosphere at altitudes between 12 and 25 km plays a natural equilibrium maintaining role for the earth through absorption of ultraviolet (UV) radiation (240– 320 nm) and absorption of infrared radiation [1]. A global environmental problem is the depletion of the stratospheric ozone layer, which is caused by the emissions of CFCs, halons (chlorinated and brominated organic compounds) and NOx . Ozone depletion can lead to increased levels of damaging UV radiation reaching the ground, causing increased rates of skin cancer and eye damage to humans and is harmful to many biological species. It should be noted that energy related activities are only partially (directly or indirectly) responsible for the emissions which lead to stratospheric ozone depletion. The most significant factor in ozone depletion has been CFCs, which are mainly used in air conditioning and refrigerating equipment as refrigerants, and NOx emissions, which are produced by fossil fuel and biomass combustion processes, natural denitrification and nitrogen fertilizers. In 1998, the size of the ozone hole over Antarctica was 25 million km2 . It was about 3 million km2 in 1993 [5]. Researchers expect the Antarctic ozone hole to remain severe in the next 10–20 years, followed by a period of slow healing. Full recovery is predicted to occur in 2050; however, the rate of recovery is affected by climate change [7]. 2.3. Global climate change The term greenhouse effect has generally been used for the role of the whole atmosphere (mainly water vapour and clouds) in keeping the surface of the earth warm. Recently however, it has been increasingly associated with the contribution of CO2 , which is estimated to contribute about 50% to the anthropogenic greenhouse effect. Additionally, several other gasses, such as CH4 , CFCs, halons, N2 O, ozone and peroxyacetylnitrate (also called greenhouse gasses), produced by industrial and domestic activities can also contribute to this effect, resulting in a rise of the earthÕs temperature [7]. Increasing atmospheric concentrations of greenhouse gasses increase the amount S.A. Kalogirou / Energy Conversion and Management 45 (2004) 3075–3092 3079 of heat trapped (or decrease the heat radiated from the earthÕs surface), thereby raising the surface temperature of the earth. According to Colonbo [9], the earthÕs surface temperature has increased by about 0.6 °C over the last century, and as a consequence, the sea level is estimated to have risen by perhaps 20 cm. These changes can have a wide range of effects on human activities all over the world. The role of various greenhouse gasses is summarized in Ref. [4]. Humans contribute through many of their economic and other activities to the increase in the atmospheric concentrations of various greenhouse gasses. For example, CO2 releases from fossil fuel combustion, methane emissions from increased human activity and CFC releases all contribute to the greenhouse effect. Scientists today agree that there is a cause and effect relationship between the emissions of greenhouse gasses and global warming. Furthermore, predictions show that if atmospheric concentrations of greenhouse gasses, mainly due to fossil fuels combustion, continue to increase at the present rates, the earthÕs temperature may increase by another 2–4 °C in the next century. If this prediction is realized, the sea level could rise by between 30 and 60 cm before the end of this century [9]. The impacts of such sea level increase could easily be understood and include flooding of coastal settlements, displacement of fertile zones for agriculture toward higher latitudes and decrease in the availability of fresh water for irrigation and other essential uses. Thus, such consequences could put in danger the survival of entire populations. 3. Renewable energy technologies Renewable energy technologies produce marketable energy by converting natural phenomena into useful forms of energy. These technologies use the sunÕs energy and its direct and indirect effects on the earth (solar radiation, wind and falling water), gravitational forces (tides) and the heat of the earthÕs core (geothermal) as the resources from which energy is produced. These resources have massive energy potential, however, they are generally diffuse and not fully accessible, and most of them are intermittent and have distinct regional variabilities. These characteristics give rise to difficult, but solvable, technical and economical challenges. Nowadays, significant progress is made by improving the collection and conversion efficiencies, lowering the initial and maintenance costs and increasing the reliability and applicability. Several potential solutions to the current environmental problems associated with harmful pollutant emissions from the burning of fossil fuels have evolved, including renewable energy and energy conservation technologies. Many countries consider today solar, wind and other renewable energy technologies as the key to a clean energy future. Worldwide research and development in the field of renewable energy resources and systems have been conducted during the last two decades. Energy conversion systems that are based on renewable energy technologies appear to be cost effective compared to the projected high cost of oil. Examples are given in Refs. [10,11]. Furthermore, renewable energy systems can have a beneficial impact on the environmental, economic and political issues of the world. The benefits arising from the installation and operation of renewable energy systems can be distinguished into three categories: energy saving, generation of new working posts and decrease of environmental pollution [12]. The energy saving benefit derives from the reduction in consumption of electricity and/or Diesel that are used conventionally to provide energy. This benefit can be directly translated into 3080 S.A. Kalogirou / Energy Conversion and Management 45 (2004) 3075–3092 monetary units according to the corresponding production or avoided capital expenditure for the purchase of imported fossil fuels. Additionally, another point that makes countries interested is the economic development potential of exporting renewable energy technology expertise. One area that seems to be of considerable importance in many countries is the ability of renewable energy technologies to generate jobs as a means of economic development to a country. The penetration of a new technology leads to the development of new production activities, contributing to the production, market distribution and operation of the pertinent equipment. Specifically in the case of solar energy, the collector job creation mainly relates to the construction and installation of the collectors. The latter is a decentralized process, since it requires the installation of equipment in every building or every individual consumer. The most important benefit of renewable energy systems is the decrease of environmental pollution. This is achieved by reduction of the air emissions due to the substitution of electricity and conventional fuels. The most important effects of air pollutants on the human and natural environment are their impact on public health, on agriculture, on buildings and historical monuments and on forests and ecosystems [12]. It is relatively simple to measure the financial impact of these effects when they relate to tradable goods, such as agricultural crops, however, when it comes to non-tradable goods, like human health and ecosystems, things become more complicated. It should be noted that the level of environmental impact and, therefore, the social pollution cost largely depends on the geographical location of the emission sources. Contrary to the conventional air pollutants, the social cost of CO2 does not vary with the geographical characteristics of the source, as each unit of CO2 contributes equally to the climate change thread and the resulting cost [12]. In this paper, emphasis is given to solar energy systems and in particular, to solar water heating and space heating systems. These are very popular systems used extensively in many countries with good sunshine potential, such as the Mediterranean countries. 4. Solar systems considered Two types of solar systems are considered in this study; a solar water heating (SWH) system and a solar space and water heating (SSWH) system. Flat plate collectors are used in both systems, which are, by far, the most used type of collectors. The instantaneous efficiency of the collector considered is given by the equation: 2 DT DT À 0:06 ; ð1Þ n ¼ 0:792 À 6:65 I I where DT is the temperature difference between the collector inlet (Ti ) and ambient (Ta ) temperatures, i.e. DT ¼ ðTi À Ta Þ and I is the global solar radiation. A schematic diagram of the solar water heating system is shown in Fig. 1 and a schematic of the solar central heating and water heating system is shown in Fig. 2. In both cases, active solar systems are used, i.e. a pump is employed to transfer the solar thermal energy to storage, which is operated by means of a differential thermostat. The thermostat compares the temperature at the outlet of the solar collectors and the storage tank and whenever the collector temperature is higher than the storage temperature by more than 8 °C, the pump is S.A. Kalogirou / Energy Conversion and Management 45 (2004) 3075–3092 Hot water Mixing supply Power supply device 3081 Relief valve Collector array 2-panels Storage tank (160 l) Auxiliary heater Differential thermostat Burner Solar pump Make-up water Fig. 1. Schematic diagram of the solar water heating (SWH) system. Relief valve Collector array 10-panels 150 liter Hot water Mixing supply device Auxiliary heater Burner Differential thermostat Storage tank (1500 l) House heating system Solar pump Make-up water Fig. 2. Schematic diagram of the solar heating and water heating (SSWH) system. switched on. It switches off whenever this difference is lower than 4 °C. The storage tank is well insulated to reduce thermal losses to the environment and is equipped with heat exchangers for both the solar system and the auxiliary system. In the case of SWH systems, the auxiliary can vary from electricity, Diesel or both, whereas in the case of SSWH systems, only Diesel is considered. In the cases where Diesel is considered, this is used in a central heating boiler, which supplies the energy for the heating needs of a house and is not used only as the solar system backup. No details of the house heating system are given in Fig. 2. What is of interest to note is that the water from the hot water storage tank is mixed with that returning from the heating appliances to provide the required temperature. The building considered has an insulated roof and walls and has a floor area of 150 m2 , and its solar system satisfies, in addition to the heating load (part), the hot water requirements of a 4 persons family. As can be seen from Fig. 2, a secondary hot water cylinder is used in the heating and hot water system installed within the primary tank (tank-in-tank system). The hot water storage tank of the system has a capacity of 1500 l, 150 l of which are used for hot water. The specifications of the various components of the two solar systems are shown in Table 2. 3082 S.A. Kalogirou / Energy Conversion and Management 45 (2004) 3075–3092 Table 2 Specifications of the solar systems considered Parameter Type of system Collector area (m2 ) Collector slope (°) Storage capacity (l) Auxiliary capacity (kW) Heat exchanger Heat exchanger area (m2 ) House area (m2 ) Hot water demand (lt) House construction Domestic hot water system Active 3.8 (2-panels) 40 160 3 Internal 3.6 – 120 (4 persons) – Space heating + hot water system Active 19 (10-panels) 31 1500 (150 l for SWH) 7 Internal 10 150 120 (4 persons) Insulated walls and roof Traditional hot water systems comprise a hot water cylinder powered either by electricity or by Diesel oil through the central heating boiler. Therefore, the extra equipment required for the solar system are the solar collectors, piping to connect the collectors with the storage tank and differential thermostat. Central heating systems are usually of the direct type, i.e. there is no storage. Therefore, the extra equipment required by the solar system are the solar collectors, storage tank, piping and controls. 5. Thermal and economic analysis of solar systems All systems are simulated with the Polysun [13] program (version 3.3.5g) with the weather conditions of Nicosia, Cyprus. The monthly solar radiation and mean ambient air temperature for Nicosia, as derived from the typical meteorological year [14], are shown in Table 3. The program provides dynamical annual simulations of solar thermal systems and helps to optimize them. It operates with dynamic time steps from 1 s to 1 h, thus simulation can be more stable and exact. The program is user friendly and the graphic user interface permits a comfortable and clear input of all system parameters. All aspects of the simulation are based on physical models that work without empirical correlation terms. In addition, the program performs economic viability analysis and ecological balance, which includes emissions from the eight most significant greenhouse gasses, thus the emissions of systems working only with conventional fuel and systems employing solar energy can be compared. The program Polysun was validated by Gantner [15] and it was found that the mean accuracy of the program is within 5–10%. The optimum slope of the solar collectors, shown in Table 2, was calculated with a special routine of the Polysun program. Three types of solar water heating systems were considered, one with electric heating backup, one with a combination of electricity and boiler backup and one with only a boiler backup. In houses where a central heating system exists, the two last options are preferred as the price of Diesel is much lower than that of electricity and the owners prefer to use their central heating boiler to produce hot water, as a solar system backup, irrespective of the requirement for heating. The second case where both electricity and boiler are used is a case that occurs S.A. Kalogirou / Energy Conversion and Management 45 (2004) 3075–3092 Table 3 Mean monthly solar radiation and ambient air temperature for Nicosia Month January February March April May June July August September October November December Year Horizontal global radiation (kW h/m2 ) 74.8 97.9 145.3 172.3 212.9 227.4 229.0 206.9 168.9 134.7 95.8 70.0 1840.1 3083 Mean ambient air temperature (°C) 10.7 11.3 13.4 16.7 19.8 23.3 25.9 26.5 24.7 21.0 16.4 12.5 18.5 frequently when in intermediate periods with no heating requirement, the users may prefer to use electricity as a backup instead of using the central heating boiler. The annual energy balance and the monthly solar contribution of the systems considered are shown in Tables 4 and 5, respectively. As can be seen from Table 5, all variations of the domestic hot water systems considered cover all the requirements during the summer time and a large percentage during the winter time. The annual figure is also high. In the case of space heating, as the system is oversized for the case of summer where no heating load is required, the solar contribution is 100%, i.e. all the hot water needs are covered by solar energy. In this case, a large number of collectors can be discontinued or shaded to avoid overheating. It should be noted that in domestic hot water systems, by adjusting slightly the consumption profile, contributions of 100% could be obtained in the months from May to October, which is what actually happens in practice. The program, however, considers a standard consumption throughout all months and that is why values slightly below 100% are Table 4 Annual energy balance of the systems considered Parameter Solar water heating (SWH) Electricity backup Solar system yield (kW h) Total auxiliary energy (kW h) Hot water demand (kW h) Space heating demand (kW h) Solar fraction 2046.4 269.3 1780.0 – 88.4 Electricity and Diesel backup 2054.7 211.4 (Diesel) 40.9 (electricity) 1780.0 – 89.1 Diesel backup 2063.1 238.5 1780.0 – 89.6 Space heating + SWH Diesel backup 6205.1 4616.0 2034.3 6768.4 57.3 Note: Solar fraction ¼ solar yield/(solar yield + auxiliary). 3084 S.A. Kalogirou / Energy Conversion and Management 45 (2004) 3075–3092 Table 5 Monthly solar contribution of the systems considered Month Solar water heating (SWH) Electricity backup January February March April May June July August September October November December Year 61.1 75.8 86.5 90.8 96.0 96.5 97.0 98.8 98.5 94.9 87.3 72.0 88.4 Electricity + Diesel backup 61.8 76.5 88.6 90.3 96.9 96.5 97.0 98.8 98.5 95.0 89.5 73.5 89.1 Diesel backup 61.7 76.5 88.7 91.2 98.2 97.3 98.5 99.4 99.9 94.9 89.0 74.5 89.6 Space heating + SWH Diesel backup 22.9 36.0 60.0 86.5 100.0 100.0 100.0 100.0 100.0 100.0 72.6 32.0 57.3 Note: All values are expressed in percentage. given. All the systems presented here are optimized with respect to their economic viability, i.e. lowest pay back time. The results of the economic analysis are shown in Table 6. These were obtained by using the current fuel and electricity rates, a 20 years period [16] and a market discount rate of 4%. No subsidies were considered. As can be seen, in all cases, the solar systems give much lower specific energy costs than conventional systems, and the pay back times are reasonable especially in the cases of solar water heating (SWH) systems. It should be noted that the cost of the boiler and other necessary auxiliary equipment is not taken into account in the economic analysis, i.e. only the cost of the extra equipment required for the solar installation is considered. Table 6 Results of the economic analysis Parameter System (backup fuel) SWH (electricity) Total system cost (solar) Annual fuel savings (C£) Pay-back time (years) Energy costs Solar energy only (C£/kW h) Solar + conventional (C£/kW h) Conventional (C£/kW h) Note: 1C£ ¼ 1.84US$ (January 2003). 550 95 4.2 0.0253 0.0332 0.105 SWH (electricity + Diesel) 550 71 5.6 0.0252 0.0301 0.0739 SWH (Diesel) 550 74 5.4 0.0251 0.0293 0.0739 Space heating + SWH (Diesel) 2690 228 9.8 0.0361 0.0623 0.0864 S.A. Kalogirou / Energy Conversion and Management 45 (2004) 3075–3092 3085 6. Environmental benefits of solar energy systems To investigate the environmental benefit of utilizing solar energy instead of conventional sources of energy, the different emissions resulting from the solar system operation are estimated and compared to those of a conventional fuel system. These are given directly from the software employed, which is unique in this respect [13]. The emissions reported are those that are responsible for the most important environmental problems as outlined in the previous sections. The environmental interventions are expressed in physical units of the emitted substances per year. The quantities of the emissions depend on the solar collector size and the required auxiliary energy and are compared to a non-solar system, which is using conventional fuel. The environmental analysis of the above systems, which includes the different pollutants as calculated by the program is tabulated in Tables 7–10. In the tables, the eight most important greenhouse gasses are compared. For the case of electricity backup (Table 7), Polysun considers a mixture of European power stations (coal based, nuclear, hydroelectric, etc.) in order to estimate the emissions of the conventional system [13]. As can be seen in all cases, by using solar energy instead of conventional fuel, a very large amount of pollutants are avoided. In the case of SWH systems, the amount of emissions depends on the type of fuel used as auxiliary. The percentage saving obtained in the cases where electricity or Diesel backup is used is about 80% whereas in the case that both electricity and Diesel are employed, this is 74.2%. It should be noted, however, that the quantities of emissions in all these cases are completely different, and the proximity of the percentage numbers obtained is due to the generation efficiency of each system. Electrical energy is produced at a maximum efficiency of about 35%, whereas in the case of Diesel backup, a boiler efficiency of 85% is considered. The size of SWH system considered is the usual type encountered in Cyprus but operated in thermosyphon mode, i.e., without pump and differential thermostat. Cyprus began manufacturing solar water heaters in the early sixties. Today, more than 93% of all houses have solar water heating systems installed and operating. The total number of systems is equal to 190,000 units. In fact, the number of units in operation today corresponds to one heater for every 3.7 people in the island, which is a Table 7 Environmental impact of the SWH system with electricity backup Emissions Carbon dioxide (CO2 ) Carbon monoxide (CO) Nitrogen oxides (NOx ) Nitrous oxide (N2 O) Methane (CH4 ) Hydrocarbons Sulfur dioxide (SO2 ) Dust Savings in GHG Units tons/year g/year g/year g/year g/year g/year g/year g/year % Conventional 1.982 496 74 7 12 50 743 248 – Solar system 0.40 100 15 2 3 10 150 50 – Savings (%) 79.8 79.8 79.8 79.8 79.8 79.8 79.8 79.8 79.8 Equation y y y y y y y y – ¼ 0:0009x þ 0:1635 ¼ 0:2173x þ 40:86 ¼ 0:0328x þ 5:9127 ¼ 0:0026x þ 1:3075 ¼ 0:0054x þ 0:9851 ¼ 0:0219x þ 4:0365 ¼ 0:3266x þ 61:042 ¼ 0:1093x þ 20:182 R2 -value 0.9994 0.9995 0.9996 0.9892 0.9988 0.9992 0.9994 0.9992 – Note: In equations, y represents pollutant emission and x represents system annual energy requirements in kW h. 3086 S.A. Kalogirou / Energy Conversion and Management 45 (2004) 3075–3092 Table 8 Environmental impact of the SWH system with both electricity and Diesel backup Emissions Carbon dioxide (CO2 ) Carbon monoxide (CO) Nitrogen oxides (NOx ) Nitrous oxide (N2 O) Methane (CH4 ) Hydrocarbons Sulfur dioxide (SO2 ) Dust Savings in GHG Units tons/year g/year g/year g/year g/year g/year g/year g/year % Conventional 0.964 796 728 7 15 60 770 90 – Solar system 0.299 280 228 1 3 11 148 51 – Savings (%) 69.0 64.9 68.7 80.2 81.5 81.9 80.9 44.1 74.2 Table 9 Environmental impact of the SWH system with Diesel backup Emissions Carbon dioxide (CO2 ) Carbon monoxide (CO) Nitrogen oxides (NOx ) Nitrous oxide (N2 O) Methane (CH4 ) Hydrocarbons Sulfur dioxide (SO2 ) Dust Savings in GHG Units tons/year g/year g/year g/year g/year g/year g/year g/year % Conventional 0.766 1615 1615 7 15 62 775 136 – Solar system 0.259 363 324 1 3 11 145 52 – Savings (%) 66.3 77.5 80.0 80.7 82.8 82.8 81.3 61.7 80.0 Equation y y y y y y y y – ¼ 0:0004x þ 0:1662 ¼ 635:34 lnðxÞ À 307:7 ¼ 626:96 lnðxÞ À 3065:2 ¼ 0:0033x þ 0:1759 ¼ 0:0069x þ 1:1017 ¼ 0:0267x þ 4:4069 ¼ 0:3231x þ 67:577 ¼ 61:172 lnðxÞ À 278:73 R2 -value 0.9970 0.9973 0.9971 0.9999 0.9962 0.9999 0.9987 0.9964 – Note: In equations, y represents pollutant emission and x represents system annual energy requirements in kW h. world record [17]. Therefore, for the Cyprus case, if the above numbers are considered, one can understand the magnitude of the environmental pollution reduction per year, just for water heating. A smaller percentage saving is obtained in the case of space heating but the absolute quantities of emissions saved are much bigger. This leads to the conclusion that solar space heating should also be promoted as much as possible. It is believed that similar results can be obtained for other countries with a good solar resource. In the above tables, regression equations are given to enable the interested reader to estimate the emission from the systems according to the auxiliary energy required. These were obtained by running the program Polysun with a number of collector areas and recording the emissions. As the accuracy of these equations, represented by the R2 -value, is quite acceptable, these equations can be used with confidence to estimate the emissions of systems of similar configuration. The R2 value is known as the coefficient of determination. It indicates how closely the values estimated correspond to the actual data. An exception to the above is the case where both electricity and Diesel are considered (Table 8), as the program can give emissions for only one fuel at a time. In this case, the emissions are estimated by the ratio of the quantity of each fuel requirement as given in Table 4. S.A. Kalogirou / Energy Conversion and Management 45 (2004) 3075–3092 Table 10 Environmental impact of the SSWH system with Diesel backup Emissions Carbon dioxide (CO2 ) Carbon monoxide (CO) Nitrogen oxides (NOx ) Nitrous oxide (N2 O) Methane (CH4 ) Hydrocarbons Sulfur dioxide (SO2 ) Dust Savings in GHG Units tons/year g/year g/year g/year g/year g/year g/year g/year % Conventional 3.406 3168 3168 32 69 276 3445 203 – Solar system 1.481 2384 2378 14 30 118 1476 194 – Savings (%) 56.5 24.7 24.9 57.1 57.2 57.2 57.1 4.6 39.5 Equation y y y y y y y y – ¼ 0:0003x ¼ 0:1293x þ 1787:1 ¼ 0:1273x þ 1789:7 ¼ 0:03x ¼ 0:0064x ¼ 0:0256x ¼ 0:3205x ¼ 0:0028x þ 181:07 3087 R2 -value 0.9999 1.0 1.0 0.9999 0.9994 1.0 1.0 0.9992 – Note: In equations, y represents pollutant emission and x represents system annual energy requirements in kW h. Electricity Dust Sulfur dioxide (SO2) Hydrocarbons Methane (CH4) Nitrous oxide (N2O) Nitrogen oxides (NOx) Carbon monoxide (CO) Carbon dioxide (CO2) 0 20 Electricity+diesel Diesel 40 60 Percentage savings 80 100 Fig. 3. Comparison of the percentage emissions of the three SWH systems considered. A comparison of the percentage savings of emissions obtained from the three solar water heating systems is shown in Fig. 3. As can be seen, considerable amounts of polluting gases are saved by all types of systems considered, which implies that the solar water heating is environmentally friendly irrespective of the backup fuel used or the mode of operation. 7. Pollution created from solar systems The negative environmental impact of solar energy systems includes land displacement and possible air and water pollution resulting from manufacturing, normal maintenance operations and demolition of the systems. However, land use is not a problem when collectors are mounted on the roof of a building, the maintenance required is minimal and the pollution caused by demolition is not greater than the pollution caused from demolition of a conventional system of the same capacity. The pollution created for the manufacture of the solar collectors is estimated 3088 S.A. Kalogirou / Energy Conversion and Management 45 (2004) 3075–3092 by calculating the embodied energy invested in the manufacture and assembly of the collectors and estimating the pollution produced by this energy. Initially, the embodied energy of one solar collector panel, 1.9 m2 in area is determined. This is the same collector considered in the performance analysis of the systems. The analysis is based on the primary and intermediate embodied energy of the components and materials as illustrated in Fig. 4. In the present analysis, no allowance is made for unit packing, transportation and maintenance, as these have insignificant contributions compared to the total. The total embodied energy required to produce a complete flat plate collector is calculated using the primary and intermediate production stages. The primary stage is established from an assessment of the various materials used and their corresponding mass. Using the embodied energy index (MJ/kg) defined in Ref. [18], the material embodied energy content within the unit is determined. Table 11 summarizes the unit materials used and lists their corresponding mass and embodied energy content. The total embodied energy content for the production of one flat plate collector panel is calculated at 3540 MJ. This comprises the primary embodied energy of materials and the intermediate embodied energy, i.e. the amount of energy used in the production and assembly of the component parts during the construction stage and was determined through a stage by stage appraisal of the power sources used. Inherent within this intermediate stage is the fabrication of purchased components, like screws, glass and insulation. An analysis of the embodied energy content of a complete solar hot water system is shown in Table 12 and for the complete solar central heating system in Table 13. It should be noted that only the extra components of the solar system are considered in this analysis, as the other components are standard and are also present in the conventional system. Here, the objective is to compare the pollution created for the manufacture and installation of the solar systems against its PRIMARY PRODUCTION Paint, sealant, coatings Primary raw materials extraction and production Glass Copper pipes INTERMEDIATE PRODUCTION Absorber Copper Sheet Insulation Casing Galvanized sheet Packing Transportation Installation Maintenance Demolition Disposal/recycling Fig. 4. Factors considered in the calculation of embodied energy of a flat plate collector. S.A. Kalogirou / Energy Conversion and Management 45 (2004) 3075–3092 Table 11 Embodied energy content of one flat plate collector 1.9 m2 in area Description 1.9 · 1 · 0.05 m insulation 1.9 · 1 · 0.005 m glass 2 m, 22 mm copper pipe 20 m, 15 mm copper pipe 2.3 · 1.3 · 0.005 m galvanized steel sheet 6 m sealant Black paint Casing paint 20 No. screws 1.9 · 1 · 0.003 m copper absorber Mass (kg) 6 13.4 2.4 12.4 11.7 0.6 0.3 0.9 0.00125 5 Embodied energy index (MJ/kg) 117 15.9 70.6 70.6 34.8 110 44 44 34.8 70.6 Embodied energy content (MJ) 702 213.3 169.5 875.5 408.4 66 13.2 39.6 Ignored 353 2840.5 284.1 415.4 3540 3089 Total Add 10% for contingencies Unit manufacture using a net to gross value of conversion rate of 27% Grand total Table 12 Embodied energy content for the construction and installation of the complete solar hot water system Description 2 No. solar panels 4 m, 22 mm copper pipe 4 m, pipe insulation Steel frame Total Installation Grand total Mass (kg) – 3.8 1 30 Embodied energy index (MJ/kg) – 70.6 120 34.8 Embodied energy content (MJ) 7080 268.3 120 1044 8512.3 187.7 8700 benefits due to the lower emissions realized during the operation of the systems. As can be seen, the total embodied energy for the complete system is 8700 and 82554 MJ for the two types of systems, respectively. For the life cycle assessment of the systems considered, the useful energy supplied by solar energy per year, shown in Table 4, is compared with the total embodied energy of the systems, shown in Tables 12 and 13. As can be seen, the total energy used in the manufacture and installation of the systems is recouped in about 1.2 years for both the solar water heating systems, and solar space heating systems, which is considered as very satisfactory. The emissions created from the total embodied energy for the two types of systems considered are presented in Tables 14 and 15. Additionally, these emissions are compared with the emissions saved because solar energy is used instead of auxiliary energy, according to the type of fuel used in the various cases of solar systems investigated, in order to estimate the payback period for each pollutant. In all cases, the emissions are estimated by considering that all embodied energy was produced from electricity. This is not quite correct, but electricity is chosen, as it is the most 3090 S.A. Kalogirou / Energy Conversion and Management 45 (2004) 3075–3092 Table 13 Embodied energy content for the construction and installation of the complete solar central heating system Description 19 No. solar panels 24 m, 22 mm copper pipe 22 m, 28 mm copper pipe 20 m, 35 mm copper pipe 24 m, 22 mm pipe insulation 22 m, 28 mm pipe insulation 20 m, 35 mm pipe insulation Supports Total Installation Grand total Mass (kg) – 22.9 27.5 30.9 6 7.3 7.6 100 Embodied energy index (MJ/kg) – 70.6 70.6 70.6 120 120 120 34.8 Embodied energy content (MJ) 67260 1616.7 1941.5 2181.5 720 876 912 3480 78,987.7 3566.3 82,554 Table 14 Pollution created for the construction and installation of the solar hot water system and payback for the three types of backup fuels considered Emission Pollution created from solar system embodied energy 1.934 tons 483 g 72.5 g 7.3 g 12.1 g 48.3 g 725 g Savings and payback of solar system Electricity 1.582 (1.2) 396 (1.2) 59 (1.2) 5 (1.5) 9 (1.3) 40 (1.2) 593 (1.2) Electricity and Diesel 0.665 (2.9) 516 (0.9) 500 (0.15) 6 (1.2) 12 (1.0) 49 (1.0) 622 (1.2) Diesel 0.517 (3.7) 1252 (0.4) 1291 (0.06) 6 (1.2) 12 (1.0) 51 (0.9) 630 (1.2) Carbon dioxide (CO2 ) Carbon monoxide (CO) Nitrogen oxides (NOx ) Nitrous oxide (N2 O) Methane (CH4 ) Hydrocarbons Sulfur dioxide (SO2 ) Note: (1) Number in parenthesis represent payback in years. (2) The units of savings are in g/year except carbon dioxide which is tons/year. Table 15 Pollution created for the construction and installation of the solar central heating system and payback of system with Diesel backup Emission Carbon dioxide (CO2 ) Carbon monoxide (CO) Nitrogen oxides (NOx ) Nitrous oxide (N2 O) Methane (CH4 ) Hydrocarbons Sulfur dioxide (SO2 ) Pollution created from solar system embodied energy 18.34 tons 4586 g 688 g 68.8 g 114.7 g 458.6 g 6880 g Savings and payback of solar system with Diesel backup 1.925 (9.5) 784 (5.8) 790 (0.9) 18 (3.8) 39 (2.9) 158 (2.9) 1969 (3.5) Note: (1) Number in parenthesis represent payback in years. (2) The units of savings are in g/year except carbon dioxide which is tons/year. S.A. Kalogirou / Energy Conversion and Management 45 (2004) 3075–3092 3091 polluting fuel. Therefore, it gives the worst possible results. As can be seen from Tables 14 and 15, the payback periods for the cases investigated vary from a few months to 9.5 years according to the fuel and the particular pollutant considered. It can also be seen from the results presented in Tables 14 and 15 that the payback times for the various pollutants emitted by SWH systems are much lower than those of SSWH systems. This is due to the fact that the solar contribution of SWH systems is much higher than that of SSWH, and thus, higher amounts of pollution gases are avoided (much lower auxiliary is required) because of the utilization of solar energy. 8. Conclusions In the present study, the environmental impact of energy utilization has been investigated and the potential benefits that solar systems offer are discussed in detail. From the analysis presented in this paper, it can be concluded that the environmental impact of any energy system is an important factor, and solar systems have the potential to reduce environmental pollution. Crucial to discussions on prevention of global climate change are thorough evaluations of the costs of reducing emissions. Many countries through several national and international institutes and agencies have started taking actions to reduce (or eliminate) the pollutant emissions and to attain a sustainable supply of energy [7]. One way to achieve this is by using solar energy as much as possible. This is in compliance with the agreement reached in the December 1997 International Kyoto Conference on climate change, where a list of fifteen concrete proposals emerged for the reduction of global greenhouse gas emissions. The list includes, among others, the use of solar energy [7]. Additionally, in this study, the environmental protection offered by the two most widely used renewable energy systems, i.e. solar water heating and solar space heating is presented. The results show that by using solar energy, considerable amounts of greenhouse polluting gasses are saved. For the case of domestic hater heating systems with electricity or Diesel backup, the saving, compared to a conventional system, is about 80%, whereas for the case that both electricity and Diesel backup are used, it is about 75%. For the case of solar space heating and hot water system, the saving is about 40%. It should be noted, however, that in the latter, much greater quantities of pollutant gasses are saved. Additionally, all systems investigated give positive and very promising financial characteristics. With respect to life cycle assessment of the systems, the energy spent for the manufacture and installation of the solar systems is recouped in about 1.2 years, whereas the payback time with respect to emissions produced from the embodied energy required for the manufacture and installation of the systems varies from a few months to 9.5 years according to the fuel and the particular pollutant considered. Moreover, due to the higher solar contribution, solar water heating systems have much shorter payback times than solar space heating systems. It can, therefore, be concluded that solar energy systems are friendlier to the environment and offer significant protection of the environment. The reduction of greenhouse gasses pollution is the main advantage of utilizing solar energy. Therefore, solar energy systems should be employed whenever possible in order to achieve a sustainable future, thus applying the slogan ''THINK GLOBALLY––ACT LOCALLY''. 3092 S.A. Kalogirou / Energy Conversion and Management 45 (2004) 3075–3092 References [1] Dincer I. Energy and environmental impacts: present and future perspectives. Energy Sources 1998;20(4/5):427–53. [2] Dincer I. Renewable energy, environment and sustainable development. In: Proceedings of the World Renewable Energy Congress, Florence, Italy, 1998. p. 2559–62. [3] Rosen MA. The role of energy efficiency in sustainable development. Technol Soc 1996;15(4):21–6. [4] Dincer I, Rosen MA. A worldwide perspective on energy, environment and sustainable development. Int J Energy Res 1998;22(15):1305–21. [5] www.worldwatch.org. [6] Argiriou A, Klitsikas C, Balaras C, Asimakopoulos D. Active solar space heating of residential buildings in northern Hellas––a case study. Energy Buildings 1997;26(2):215–21. [7] Dincer I. Environmental impacts of energy. Energy Policy 1999;27(14):845–54. [8] Speight JG. Environmental technology handbook. Washington, DC: Taylor and Francis; 1996. [9] Colonbo U. Development and the global environment. In: Hollander JM, editor. The energy-environment connection. Washington: Island Press; 1992. p. 3–14. [10] Kalogirou S, Lloyd S. Use of solar parabolic trough collectors for hot water production in Cyprus––a feasibility study. Renew Energy 1992;2(2):117–24. [11] Kalogirou S, Papamarcou C. Modelling of a thermosyphon solar water heating system and simple model validation. Renew Energy 2000;21(3–4):471–93. [12] Diakoulaki D, Zervos A, Sarafidis J, Mirasgedis S. Cost benefit analysis for solar water heating systems. Energy Convers Manage 2001;42(14):1727–39. [13] Polysun, 2000. UserÕs manual for Polysun 3.3, SPF, Switzerland. [14] Kalogirou S. Generation of typical meteorological year (TMY-2) for Nicosia, Cyprus. Renew Energy 2003;28(15):2317–34. [15] Gantner M. Dynamische Simulation thermischer Solaranlagen. Diploma thesis, Hochschule f€r Technik u Rapperswil (HSR), Switzerland, 2000. [16] Statistical Abstract 2001, Statistical Service, Republic of Cyprus, Report No. 44, 2001. [17] Kalogirou S. 2001. The sun island: solar energy in Cyprus. ReFocus, The International Renewable Energy Magazine of ISES, March 2001. p. 30–2. [18] Alcorn J. Embodied energy coefficients of building materials. Centre for Building Performance Research, Victoria University of Wellington, New Zealand, 1995.
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Page 1 of 4
The skin on lips lack oil glands and hence they tend to get dry and cracked easily, especially in winters. You have to take special care of your lips to maintain their moisture level.
Here are some tips to prevent chapped and cracked lips.
- Apply a thin coat of lip balm before applying lipstick
- Every night before going to sleep, apply petroleum jelly on moist lips. Also make sure that you remove lipstick before going to bed
- Dip a black tea bag in warm water and put it on your lips for three to four minutes. This helps increase their moisture level
- Dip some cotton in warm ghee and place it on your lips for 20 minutes
- Don't lick your lips too much. It provides temporary relief but has a drying effect in the long run
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Design & Living
MUJI is Making Us Want to Live the Simple Life
Remember all those years ago, when you were living in London, and a trip to MUJI was like to a trip to IKEA without the epic hike to some far away suburb at the end of tube li ...Read more
How to Add Luxury to Your Everyday
You know those people who hide their best stuff in a cupboard and only bring them out on special occasions? We don't get them. Why save your most prized and pretty things fo ...Read more
Coveting Everything kate spade new york
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Etsy Enters the Real World & Sets Up Shop at The Cullen
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5 Days of the Most Beautiful Flowers You've Ever Seen
The Melbourne International Flower & Garden Show is back. But this isn't just any year; this is the year the show turns 20. And we think that's a pretty neat number t ...Read more
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Google's Chrome Passes Firefox to Become Top IE Rival
Microsoft's Internet Explorer browser is still the most popular in the world, but a new number two has emerged: Google Chrome. According to StatCounter, Chrome now commands a fraction of a percentage point more share than Firefox on a global basis.
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Bullying in North American Schools
Dorothy L. Espelage, Susan M. Swearer
Taylor & Francis, Oct 15, 2010 - Education - 316 pages
Bullying in North American Schools is an exciting compilation of research on bullying in school-aged youth by a representative group of researchers, including developmental, social, counseling, school, and clinical psychologists across North America.
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Tsinghua University School of Economics & Management: Beijing
Space available for Spring 2016!
Program Dates:
The academic calendar at Tsinghua will differ from the University of Minnesota and all exchange students are expected to be at their host campus on the first day of orientation and through the last day of final exams.
Fall Semester 2015:
Orientation: September 7
Semester Dates: September 7 - Decemeber 26
Spring Semester 2016:
March - July 2016
Tsinghua University
Tsinghua University
Tsinghua University
Tsinghua University
The Great Wall of China
Beijing, China
Beijing, China
Location details
With over one billion people and unique natural resources, China is the world's largest emerging economy. Since opening its economy to the world over 30 years ago, China has undergone a profound transformation, recently spurred by the award of the 2008 Olympic games in Beijing and the 2010 World Expo in Shanghai. With over 17 million inhabitants, Beijing is China's second largest city and recognized as the political, educational and cultural center of the country.
Learn more about the city and surrounding area by visiting the Beijing Tourism Site.
Founded in 1911, Tsinghua University is one of the leading universities directly affiliated with the Ministry of Education of China and is known as the prominent center for higher education and scientific research. The School of Economics and Management offers bachelor's degrees in Management and Economics, with additional courses in Information Systems, Economics and Finance, and Accounting. Tsinghua welcomes exchange students from 73 partner schools in 26 countries.
Located in Haidian District of Beijing, formerly known as a royal garden of Qing Dynasty, Tsingua University's campus is famous for its beautiful surroundings and is listed as one of the world's top 14 most beautiful college campuses by Forbes Magazine in 2010, the only one from Asia.
- Incoming exchange students can apply for the international student dorm, the Zinjing Foreign Student Dormitory, however, it is not guaranteed.
- Singles rooms, AB rooms, and double rooms are available in the apartments, with costs varying across options.
- Students who are not able to obtain on-campus housing make their own arrangements upon arrival in Beijing.
Academics and credits
- Students on exchange programs take a full semester courseload at their host university (13-18 UMN credits/semester).
- Courses transfer back as S/N on UMN transcript.
- Business courses taught in English and Chinese are available to exchange students.
- The undergraduate program provides Chinese languague courses for incoming exchange students.
- Students participating in CGI semester exchange programs are strongly encouraged to enroll in the 1-credit Global Identity course for business students. This course helps you to develop your intercultural skills and articulate the value of your experience to future employers. It offers an additional layer of support through one-on-one interactions with your instructor that complements the independent structure of the exchange program.
- For information about specific courses available to exchange students please meet with an adviser.
- No host country language skills required
- UMN student who has successfully completed the I-Core curriculum or equivalent coursework
- Preference is given to Carlson School of Management students
- Preferred minimum GPA of 3.0
- Additional criteria may apply
- The University of Minnesota is committed to the policy that all persons shall have equal access to its programs, facilities and employment without regard to race, color, creed, religion, national origin, sex, age, marital status, disability, public assistance status, veteran status, or sexual orientation
Visa and Passport
- All Carlson students are responsible for obtaining a passport before they participate on a study abroad program
- All students participating on an exchange program will be responsible for obtaining a visa or residence permit if requried by their host country. The Carlson Global Institute does not process visa applications for students participating on exchange programs
- The Carlson Global Institute and the host university will provide resources for visa and residence permit applications if necessary, but students will need to work with the consulate and/or visa processing company directly as well
- Visa and passport requirements are always subject to change by the host country and students are expected to check with the consulate for up-to-date information
What is a Business Exchange Program?
- Successful exchange students demonstrate a high degree of independence, adaptability, and flexibility because support and services will be different from a US university
- You are enrolled as an exchange student at a host university and take business courses in English
- You take courses with students from the host university as well as other exchange students from around the world
- You attend the host university according to their term dates which differ from the University of Minnesota
- A small group of Carlson students are selected to study at each partner university per semester and are fully immersed in another country, culture, and education system
- You will work closely with both Carlson School advisers and advisers from the host university for support pre-departure and during your semester abroad
Application and Admissions
To apply for an exchange program you must first apply through the Carlson Global Institute on the Apply page. You will be charged a $50 application fee for each term that you apply for a program. If you apply for two programs in Fall semester you will be charged $50. If you apply for one program in Fall semester and one in Spring semester you will be charged $100. The priority deadline for Fall 2016 and Spring 2017 is February 1, 2016. Applications for Fall 2016 and Spring 2017 will open on September 8th, 2015. Applications for programs that do not fill by the priority deadline will be accepted on a rolling basis until full. Applications will be reviewed and students will be informed of their status within 6 weeks of the priority deadline. Once accepted into an exchange program, you will also complete an application to the host university.
Financial Aid and Scholarships
Most financial aid may be applied to study abroad. University of Minnesota students are eligible for education abroad scholarships. Please visit "Financial Aid" and "Scholarships" for more information.
Cost estimate (Summary)
These estimates will vary based on student preference and exchange rates. All details subject to change based on economic and international factors. Most financial aid may be applied to study abroad programs. Students should also maintain their U.S.-based health insurance plan while abroad. Visa and passport costs are subject to change. Please verify current documentation costs with the host country consulate.
Cost table
|Estimated Expenses 2014-2015
|Carlson School Tuition (charged to UMN student account)
|Program Fee (charged to UMN student account)
|Transportation (to and from program site)
|Documentation (passport, visa, immunizations)
|Books and Materials
|Room and/or Board
|Essential Daily Living Expenses
|Global Identity Course - strongly recommended (charged to UMN student account)


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Fla. cop shoots, kills 16-year-old gunman
The shooting comes as Miami police begin a five-day operation to flood the streets with extra officers, in uniform and plainclothes
Miami Herald
LIBERTY CITY, Fla. — Police have identified a 16-year-old youth shot and killed by an undercover officer during a robbery sting on Wednesday in Overtown as Joell Lee Johnson.
The teen pointed a gun at an officer posing as a delivery man, police union president Armando Aguilar said.
A second officer fired around 8:30 p.m., fatally wounding Johnson in the parking lot of the Town Park Plaza South apartment complex, 1798 NW Fifth Ave.
Read more on The Miami Herald.
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Wandering, All Right, but on Harleys; Jewish Bikers Band Together to Enjoy the Company and Their Cycles
By GLENN COLLINS
Published: February 28, 2003
ARMONK, N.Y.— Their T-shirt motto? ''My hog is kosher.'' Their slogan? ''We're loud, we're proud, we're Hebrew.'' But relax already. The members of the Star of Davidson Motorcycle Club will not be rattling windows here as March roars in like a lion.
Instead, the guys with the mezuzas on their Harley-Davidsons will be riding for the first time as a group in Daytona, Fla., during Bike Week, the annual bikers' Woodstock for half a million motorcyclists.
''It's the place to go vroom vroom,'' said Drew Rayman, the club's founder and leader. ''When I was at Daytona last year, I was offended that there weren't any Jewish bikers, though they had every conceivable group: Christian bikers, Hells Angels, Neo-Nazis. We are the silent minority. We are devoid of any organized presence.''
Star of Davidson -- Star of David meets Harley-Davidson -- is only a little more than a year old. In the two months since it put up its Web site (www.starofdavidson.com), the club has attracted 60 new members from around the country, to bring its membership to 100.
And the group hopes to use the Web site to organize more members. The goal, Mr. Rayman said, is ''to make the Jewish riding heritage more apparent.''
The, um, Jewish riding heritage?
''I know, I know, good Jewish boys aren't supposed to ride bikes or get their hands dirty,'' Mr. Rayman said, laughing. ''But there are a lot of us out there who like to get their hands dirty.''
To Mark Starr, the 47-year-old owner of Hunting Ridge Motors in neighboring Bedford who describes himself as ''a gearhead,'' ''a lot of people think of the typical Jewish guy as the doctor, the lawyer, the guy behind the desk.'' He smiled. ''Well, I'm not the typical Jewish guy.''
This is hardly a group of schleppers. Most Star of Davidson members own their own businesses and have the time and wherewithal to indulge their hobby. ''I'm a nice Jewish boy who likes motorcycles, shoots guns from time to time, and kills things for a living,'' said Seth Tokson, 43, of Armonk, owner of Absolute Pest Management Inc.
They are suspicious of the angst explanation. ''There are many reasons we ride,'' Mr. Rayman said, ''and the idea that we're rebelling against our parents after a protected childhood is not one of them.''
Howard Rozins, 47, co-owner of the Bagel Emporium on Main Street in Armonk, likes the rush. ''The speed, the freedom, the openness of it,'' he said. ''You can't believe the beauty of riding up here.''
The Armonk Biker Boyz fire up their motorcycles almost every week there isn't snow and ice ''and just pick a direction,'' Mr. Tokson said, usually toward scenic beauty, culinary payoff, or both.
Astride one of his Harleys, Mr. Rayman, 43, bears a passing resemblance to the pre-''Adaptation'' Nicolas Cage. Mr. Rayman sold I33, his Web site and marketing business, in 1998, before the virtual bubble burst. He found himself with enough money and, he said, ''enough time on my hands to start tinkering with motorcycles,'' and began hanging out at Puff's Auto Salon (carwash $13, window tinting $200) on Main Street.
''I told Drew that if he wanted to hang here, he'd better have a bike,'' said Kurt Puff, the salon's 43-year-old owner, a motorcycle enthusiast. ''I think Star of Davidson started as a gag, but pretty soon I could see Drew was very serious.''
Soon Mr. Rayman, who had ridden motorcycles sporadically since college, bought a Harley, and then another. Like-minded bikers began hanging out at Puff's as well. Star of Davidson is not limited to Harley owners, and even those who don't own motorcycles can join the, er, gang (they borrow others' bikes).
The club welcomes goyim, too, like Mr. Puff and Bill Knudsen, 39, owner of Knudsen Plumbing and Heating here. ''It's a great group of friends,'' Mr. Knudsen said. ''We've taken some long rides together, and all of us have gotten a sore butt.''
Star of Davidson is even joined from time to time by a Muslim biker who rides his cherished Indian motorcycle.
Women have signed up, thanks to the Internet, but so far, there are no regular female riders. ''Of course, a girl could ride with us,'' Mr. Rayman said expansively, then laughed. ''But we're not asking! It's guys' night out!''
Which they say does not always go over so wonderfully with their wives. ''The guys say they're going out riding for a couple of hours and then they take the whole day,'' Mr. Puff said, not terribly remorsefully.
The wives can speak for themselves, thank you. ''I didn't want my husband to have a motorcycle, and now he has two,'' said Laurie Rayman, Drew's wife of 11 years. ''But look, he loves this. These guys still need their toys. And they can afford bigger toys -- I mean, what's more fun than a toy you can ride around on? I just wonder where is it ever going to end?'' (But she has been known to ride with her husband on the back of his Harley Fat Boy.)
Mr. Rayman admitted that ''no Jewish mother wants her kids to ride a motorcycle.'' He himself is not sure he wants his three children to ride. ''I am an overprotective Jewish father,'' he said.


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33 year old man | Bergen, NY, USA | Seeking women 25-36 within 50 miles
what color's your favorite number in the alphabet?
hmm... I work weird hours. I think breakfast for dinner is totally acceptable. I do not have a DVD player hooked up to my TV...I have a VHS player..true story Anything that has to do with Jersey shore makes me want to punch people. I think I was supposed to be born in the 40's. My morals are apparently too high for this day in age. If you tell me your going to be here at 5..by 5:03 Im wondering why your late. My mind wanders....a lot, and goes to far off lands with wild thoughts. I think I watched to many cartoons as a kid. I love training for races. Triathlons, marathons and 5-10K's are amazing places to throw up in front of a crowd. (If you don't understand that last part..well. never mind) My dog is almost as weird as I am and possibly makes even weirder faces I am very simple, very low key, and apparently very transparent. I don't try to hide much, feelings included. I say "wicked" and "super" too much. If your deciding factor on dating a guy is his ability to spell correctly 100% of the time, I might not be the guy for you. I try, but there is more important things in life and if THAT is your major concern..I am sorry. I think bicycles are sexy. don't judge me. carbon fiber wrapped with titanium is amazing to me...which is why I'm also a car guy. I ramble...a lot. I tend to start on a given subject and 5 min later have no clue how I ended up talking about sloths. Family is important to me. Everyone says that but I don't think to many people really feel that way. I just passed up a job making 12K more a year because it would take me away from my grandmother. She was there for me so many times in my life that it seems wrong to leave when she needs me. It's the memories of my family that is worth more then any job could pay me. Like most people on this site...there is a lot to me..trying to type something in this little box could never orchestrate the kind of person I am in real life. which is a loyal, kind hearted guy that is ready to find that some one. which apparently is harder then I thought. Oh yeah...did I mention my dog? he is a goofball...and like all dogs, he has hair. wearing black into my house is a death sentence, and while the two of us try to agree on things..his ability to spread water from his dish to the living room makes shoes, flip flops, or a towel to dry your feet off with a mandatory item. anything else, just ask!!! OK, here we go...we're going to play "this for that". So pull up a seat, pour some wine, and lets do this! Girls say:"If you have a profile pic with your shirt off you are a pig" ME: If half your pics are with your jumblies hanging out to show how hot you are.. get a better bra and cover up. your mom would be ashamed Girls say:"don't message me one word emails. I will not respond" ME:.....ok I agree with you there. total lack of effort and I assume you didn't even read my profile Girls say: "If you message me asking for sex, don't bother" ME: one polite female emailed me asking if I wanted to make babies with her...no, but thank you I have to leave now...in other words, I don't appreciate it either Girls say: "If your profile pic is of you flexing your muscles, move on" ME: I have a hard time wrapping my head around HOW the preferred animal to mimic on a photographic adventure is a DUCK!!! STOP WITH THE DUCK FACES!!!!! I mean WHAT is with that? you look like you took a pic holding a vacuum just a little too close to your face! stop that. Are you still reading this? I'm impressed!
Camping , Coffee and conversation , Dining out , Hobbies and crafts , Movies/Videos , Museums and art , Music and concerts , Exploring new areas , Performing arts , Playing sports , Travel/Sightseeing , Video games , Watching sports , Wine tasting
Auto racing / Motorcross, Bowling, Cycling, Football, Golf, Hockey, Other types of exercise, Running, Skiing, Swimming, Walking / Hiking, Weights / Machines
I exercise 3-4 times per week.
I have Cats, Dogs
My dog is AWESOME....just a bit "energetic", but you wont find a more loving dog, and for being a rescue pup..I think I'm the lucky one!
Middle of the Road
State University of New York College of Technology at Alfred, Alfred, NY
The smell of leaves in the fall. Going with the family to cut down Christmas trees in the snow. OH!..and chocolate chip cookies. ADDICTED to chocolate chip cookies. mmmmmmm.....
I LOVE triathlon training. grabbin a beer at the bar with my boys. I like to target shoot a lot. play with my dog.
all the mortal instruments books, and the divergent series, Chris kyle American sniper.
Z{{Cta}} {{#if HasMoreInfo}} ?{{CtaSecondary}} {{/if}}
|What he is looking for
|5'11" (180cms)
|4'10" (147cms) to 6'1" (185cms)
|Body type:
|About average
|Slender, About average, Curvy, Athletic and toned
|No preference
|Dark blonde
|No preference
|No Way
|No Way
|Social Drinker
|No preference
|Law enforcement / Security / Military
|No preference
|$50,001 to $75,000
|No preference
|Never Married
|No preference
|Have kids:
|No preference
|Wants kids:
|No preference
|White / Caucasian
|White / Caucasian
|I'll tell you later
|No preference
|Associates degree
|No preference


text:
Logic circuitry in the form of an integrated circuit includes a number of scannable registers located at various locations of the logic circuitry to continuously sample signal states thereat. In response to signalling from a maintenance diagnostic processor the scannable registers can be commanded to freeze their content for extraction and observation to determining the operating condition of the logic circuitry.
1. An observable logic circuit formed on an integrated circuit chip, comprising:
internal logic circuitry operating to produce a plurality of data signals;
a number of scannable registers coupled to receive predetermined ones of the plurality of data signals, the number of scannable registers being responsive to a first test signal to sample first and second states of the predetermined ones of the plurality of data signals at first and second periods of time, respectively, and to a second test signal to form at least one serial shift register to shift out the sample first and second states; and
means for comparing the first and second states to one another to issue an indication of error when a mis-compare is not detected.
2. The observable logic circuit of claim 1, wherein the plurality of data signals includes a number of data output signals, and wherein the predetermined ones of the plurality of data signals includes selected ones of the number of data signals.
3. A method of performing real-time observation of a logic circuit having at least one output for providing data thereat, the method including the steps of:
sampling the output a first moment in time;
again sampling the output a subsequent moment in time;
comparing the sample of the first moment in time with the sample of the subsequent moment in time to determine if a change in state has occurred; and
providing an error indication if no change of state has occurred.
4. A method of performing real-time observation of a logic circuit operating to produce a number plurality of data signals, the method including the steps of:
sampling a first state of predetermined ones of the number of data signals at a first moment in time;
sampling a second state of the predetermined ones of the number of data signals at a successive moment in time;
comparing the first and second states; and
providing an error indication when predetermined ones of the first state match corresponding predetermined ones of the second state.
The present invention relates to observation of logic circuitry, and in particular to use of serial scan techniques to perform a real-time observation of the logic circuitry without the need of interrupting normal logic operation.
There are available today are a number of techniques for testing digital logic circuitry, but many if not all require normal operation to be interrupted for the test to proceed. There are also fault-tolerant designs that incorporate error checking circuitry for ensuring proper operation, and to halt operation or take some other action if an error is detected. Often, however, there are times when a digital system may not encounter an error, may be in proper operating condition, but stuck in an operating (e.g., hardware) loop, or hung, unable to exit. It is this type of condition that needs detection.
Thus, there is a need, not necessarily for testing a digital system, but merely to provide real-time observation of the on-going operation of the system to ensure that the system is operating correctly without interrupting operation of the system.
The present invention uses a scan technique to perform periodic observations, in real-time, of the continuing operation of a digital system or circuit without interrupting the normal on-going process of the system.
The invention employs scannable registers such as is employed by various scan test techniques, for example pseudo-random scan testing. A scannable register is one configured to selectively operate in one of two modes: a normal operating mode in which the register performs the function for which it was intended in the design of the digital system (e.g., as a stage in a counter, a multi-bit register, etc.); and, responsive to asserted test signals, in a test mode that causes the scannable registers to be coupled to one another to form one or more shift registers which can receive serial data or, as used with the present invention, from which serial data can be extracted.
Broadly, then, the invention is directed to locating scannable registers within the design of the digital system to sample various signal states within the system. At periodic intervals scan signals are asserted to cause the scannable registers to assume their shift register configuration, and the signal states sampled just prior to the scan signal being asserted scanned out and saved. The scannable registers are returned to their normal state, and allowed to continue their sampling function, until the scan signal is again asserted, and new sampled states extracted. The two sampled states retrieved from the system can then be compared to ensure that the digital system's operation is continuing by noting that certain of them (sampled states) have changed state in the period between samples.
There are a number of advantages achieved by the present invention. First is the ability of the invention to perform real-time monitoring of the digital system. Operation of the digital system need not be terminated, or interrupted even for a short period, to determine its continuing operability. Sampling of state is completely transparent to the ongoing operation of the digital system.
These and other features and advantages of the present invention will become apparent, and more fully appreciated, by those skilled in this art upon a reading of the following detailed description of the invention, which should be taken in conjunction with the accompanying drawings identified below.
FIG. 1 is a block diagram representation of the invention used in connection with logic circuitry formed on an integrated circuit chip;
FIGS. 2A and 2B show two different scannable register designs that may be used in connection with the present invention; and
FIG. 3 is a flow diagram that illustrates control of the invention for sampling the operating state of the associated logic circuitry.
Referring now to the Figures, and for the moment FIG. 1, there is broadly and diagrammatically illustrated a digital system designated generally with the reference numeral 10. The digital system 10 is shown in the form of a single integrated circuit 12 for ease of description and understanding of the invention. However, it will be evident to those skilled in this art that the invention can be used in association with a plurality of integrated circuits, or with discrete logic if so desired.
The digital system may either include, or have associated therewith, a maintenance diagnostic processor (MDP) 14 that is connected to internal logic 16 of the integrated circuit 12 by a test bus 18 that carries various test signals between the MDP 14 that the integrated circuit 12. Formed on the integrated circuit 12 are scannable registers 20 (20a, 20b, . . . , 20n) that are placed at strategic locations within the internal logic 16 to samples various signal states.
The integrated circuit 12 can form a part of a larger system, and for that purpose most likely will have assorted input/output (I/O) connections to that larger system. Such I/O connections are illustrated at 21 and 22 which represent bus or signal line connections that in FIG. 1 the integrated circuit 12 to carry I/O signals between the internal logic 16 to locations outside or external to the integrated circuit 12. Thus, certain of the scannable registers 20 (20a, 20b, 20c) are connected to sample the signals communicated on the I/O connections 21, 22. The scannable registers 20 are free-running in the sense that they operate in response to the clock signal (SYS-- CK) that is used by the internal logic 16 for synchronous operation; that is, the clock is not controlled when extracting data from the scannable registers. When in their normal mode of operation, i.e., no scan signals being asserted by the MDP 14, the scannable registers 20 operate to sample signal states with each pulse of the SYS-- CK clock signal. Thus, the sample changes with each period of SYS-- CK when the scannable registers are operating in their normal mode.
As FIG. 1 indicates, while some scannable registers 20 sample the states of I/O signals, other. Other scannable registers 20 are located to sample states occurring in the internal logic 16, such as the continuing operation of various state machines (not shown), counters (not shown), combinatorial logic outputs (not shown), and other synchronous devices. This is represented by the scannable registers 20m, . . . , 20n.
Two constructions of the scannable register 20 are illustrated in FIGS. 2A and 2B, although it will be obvious to those skilled in the art that other configurations can also be constructed. In FIG. 2a, a scannable register 20x is shown as including a D-type flip-flop 24 and a pair of multiplexers 26, 28. The multiplexers 26, 28 operate in response to test signals to select data from among three sources for application to the data (D) input of the flip-flop 24: scan data (S-- DATA), system data (SYS-- DATA), or the data output (Q) of the flip-flop 24 itself. FIG. 2B illustrates an alternate embodiment of the scannable register, designated with the reference numeral 20y, that also includes a D-type flip-flop 24'. In similar fashion as the flip-flop 24 of FIG. 2A, the data (D) input of the flip-flop 24' receives data selected from among the three sources of S-- DATA, SYS-- DATA, or the Q output of the flip-flop 24', via the combination of multiplexers 26', 28', and a negative input AND gate 30. Both implementations operate substantially in the same manner. The differences are primarily that the implementation shown in FIG. 2A may be constructed with less circuit components, whereas the implementation shown in FIG. 2b imposes less delay on the system data (SYS-- DATA). As mentioned, those skilled in this art will readily see that other configurations are available.
In the context of the present invention, the system data (SYS-- DATA) applied to the scannable register 20 (e.g., 20x or 20y of FIGS. 2A or 2B) is the state being sampled by the scannable register 20. The scan data (S-- DATA) is that data coupled from the output of another scannable register 20 when the scannable registers are in their shift register configuration as a result a scan enable signal (S-- EN) asserted by the MDP 14. The scannable register will be placed in a frozen state, so to speak, when the MDP 14 asserts a HOLD signal. It can now be seen that it is only the system clock (SYS-- CK), together with the S-- EN and HOLD signals alone control the operation; no attempt is made by the MDP 14 to control the clock applied to the flip-flops 24 of the scannable registers 20.
The scan signals HOLD and S-- EN are communicated from the MDP 14 to the scannable registers 20 (FIG. 1) by the bus 18. The S-- EN signal connects the scannable registers 20 in scan string configuration so that their contents can be extracted by the MDP 14 for examination. When operating in their normal configuration, i.e., with the HOLD and S-- EN signals not asserted, certain of the scannable registers 20 (e.g., those shown as scannable registers 20a, 20b, 20c, and others not shown) of the integrated circuit 12 are connected to sample the signal states (SYS-- DATA) of input and/or output signals applied at the connections 21 and 22 each clock period of the SYS-- CK clock signal. The sampled state at any moment in time can be extracted by asserting the S-- EN test signal to cause the scannable registers 20 to form a one or more shift registers ("scan chains") so that the MDP 14 can scan out and extract the sampled states.
With the scannable registers 20 connected at various points in the integrated circuit in the manner described, real-time observation of the integrated circuit 12 can be made to determine its continuing operation in the following manner. Before they are called into play by the MDP 14, each of the scannable registers 20 are continuously sampling the states of the various input and output signals and internal states of the integrated circuit 12. Referring to the flow diagram of FIG. 3, illustrated is the operation of the real-time observation routine, beginning with step 38: the continuous sampling of states. (The S-- EN and HOLD signals are held in their non-asserted states.) To extract a sample for observation the routine first moves to step 40 where the MDP 14 asserts the HOLD signal to freeze the scannable registers 20 with a sample. So long as the HOLD signal is asserted the sample will be retained.
Next, at step 42, the MDP 14 asserts the scan enable (S-- EN) signal, the effect of which is to connect the scannable registers 20 in the one or more shift register configurations. Then, at step 44, the MDP 14 de-asserts (drops) the HOLD signal and, at step 46, extracts the content of the scannable registers 20 by merely letting the SYS-- CK signal shift out that content for communication to the MDP 14 via the test bus 18. The extraction continues (step 46) until the content of each scannable register 20 has been retrieved.
In order to determine continuing operability of the integrated circuit 12, two such samples are needed, at different moments in time, and those two samples compared to see if state changes were made in the interim. If certain bits in one sample have states different from what they have in the other sample, it is assumed that the integrated circuit 12 is continuing operation, receiving data from, providing data to, and otherwise communicating with the rest of the system in which it may be included. Similarly, observation of the sampled internal states can also provide information as to the operation of the integrated circuit 12. Alternatively, if such a comparison shows that the states of the sampled signals did not change between samples it may safely be assumed that the integrated circuit 12 has somehow gone into an operating loop, or some idle condition from which it cannot escape. Accordingly, a second sample must be taken and compared to the first: thus, step 48 determines whether or not the scan completed in step 46 was the first sample or the second sample. If the second sample has not been obtained, the procedure returns to step 40, via step 50 where the MDP 14 deasserts the S-- EN to allow the scannable registers 20 to assume their normal configuration to again continuously sample signals of the integrated circuit 12 for a period of time. Returning to step 40, the second sample of the states is captured by asserting the HOLD test signal. Steps 42, 44, and 46 are repeated to withdraw the second sample, so that now when step 48 is reached, both samples have been obtained. Accordingly, at step 52 the comparison is made and, if as discussed above there is a change of state of any of the bits between the two samples, it is assumed that the integrated circuit 12 is continuing operation.
This comparing of the two samples of digital states may be nothing more than displaying the two samples to a test person, who can then make the necessary observation, and draw the relevant conclusions therefrom. Alternatively, the entire process can be automated, wherein the MDP 14 is configured to make the necessary comparison and provide an error indication when states of the two samples do match.
The present invention is advantageously used in connection with pseudo-random test techniques that also uses scannable registers such as used here. Thus, certain of the scannable registers may be used for both the pseudo-random tests, and later (or earlier) for the real-time observations of the present invention. This is mentioned because if that is the case, those scannable registers which do perform such dual functions will need to have special scan enable signals applied to them so that they can be included in the shift register(s) formed for the pseudo-random scan test environment, as well as the separate sampled observations of the present invention.
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text:
The Shishavac is an all-in-one narghile maintenance kit that would look absurdly out of place in most Middle Eastern cafes, but for home shisha enthusiasts, this espresso-machine-like device features an elegant brazier that uniformly lights the smoldering coals (promising perfectly heated coals within seconds) and easily clean the narghile hose... certainly the most nightmarish aspect of home shisha maintenance. At $249, though, The price is well beyond the budget of most narghile owners, who can usually manage to buy the most extravagant, multi-hosed shisha for about $50, but I'm entranced: I'd smoke my shisha a lot more often if I didn't have to deal with cleaning the bugger. Shishavac [Official Site]
All-in-one shisha maintenance kit
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14 Responses to "All-in-one shisha maintenance kit"
I'll let my ignorance of shisha hang out, I thought this was a combination vacuum/duster/housecleaner.
Can I use it as a bong? I don't need to know what shisha is to enjoy it that way.
Any time you are in Minneapolis/Saint Paul drop by for some shishah.
But will it scrape my lungs clean?
It cleans your tobacco? Oh, wait, you're just using some kind of non-standard terminology. For anyone as confused as I was the first time reading this, John is using both narghile and shisha to refer to the hookah. Actual shisha, the tobacco, is not mentioned in this post.
In regard to the device itself, evenly lighting a coal in seconds would make that thing worth the price.
You've fallen victim to the myth that because cigarettes are evil, cancerous things all tobacco is an evil, cancerous thing. It's not exactly *good* for you, but what you're implying is similar to saying that since you can get STDs having sex and it sometimes makes you smell funny afterward, all sex is bad and dangerous and only gross heathens do it.
A hookah smoker doesn't inhale smoke anyways. It's vapor formed from heating molasses and nicotine. If the tobacco actually starts to burn, it becomes very harsh and nearly impossible to inhale.
I read that as "All in one Shiksa vac".
I started to wonder what you have against non-Jewish women? Or why they need such attachments.
Actually what terminology is used depends on where you are from.
In the Levant (Palestine, Jordan, Lebanon, Syria) arghileh or narghileh is the most commonly used word.
In areas influenced by Persian (Iraq, the Arab Gulf states, Egypt) shishah is more common.
The tobacco soaked in glycerin and molasses is 'mo3assel' or honeyed tobacco.
The dry tobacco is tumbak (tobacco). One method of preparation usually take a wad of tobacco, soak it in water then squeeze and layer the head.
In the Levant a lot of the language to describe the water pipe comes from the Turkish, and in the Gulf it is Persian that loans out to Arabic.
Okay kids, I work in a tobacco shop/hookah lounge, so let's clear it up.
Actual Arabic People (specifically Jordanians) call the pipe a hookah, and the hookah tobacco is called shisha for short.
And no, you can't use it as a bong. Unless, of course, you're smoking hash, which is what the hookah was originally invented for.
Hashish for me please!
Bookmunkie's got it right.
The attitude that all forms of tobacco are evil is like "abstinence-only" sex ed.
The amount of nicotine you get from smoking a hookah or a regular pipe is minimal compared to what you get from cigarettes. Yes, it's relaxing; but so is a glass of wine or a pint of ale, and if all you want is to get drunk those are highly inefficient means of doing so.
I've been smoking a regular oldschool pipe since long before steampunk retro-cool came along. It's all about the oral gratification factor: taste and aroma (try the G.L. Pease blend called Montgomery: it's "better than sex"); and with hookahs, the social thing of people gathering around a bit of fire and making smoke like dragons.
And never discount the ancient archetypes when trying to figure out why people do apparently silly things like puff on smoke. Dragons, breathing fire, breath as spirit made visible, the campfire, the hearth, the four elements, and so on. These and others are more powerful in the human psyche than one might think.
By the way, the smoke from shisha isn't just nicotine and molasses, it's also got the various flavor elements of the tobacco in it, along with whatever fruit essences might have been added.
Oldschool pipe smokers also have our gadgets, though nothing quite as impressive as the Shishavac. A little metal three-way tool is quite sufficient for tamping down the tobacco in the bowl and loosening the ash when done, along with a supply of pipe cleaners for removing moisture and traces of ash from the stem; and a reamer for keeping the carbon layer in the bowl at the correct thickness. No electricity required:-)
I think the redeeming feature is the coal lighter. For the vacuum thing, couldn't you just make a house vacuum attachment or a handheld pump thing to cycle air or water through it? Hell, this is Boing Boing; where's the penis pump shisha cleaning attachment?
@ Razzabeth:
YES you can use it as a bong. Hookah = water pipe = bong. If you put drugs in the bowl it's basically a bong.
Wow I used to love smoking my favourite was double apple. I stopped however because I thought it was to bad on my health and since i box this can have a major effect.
According to this article the health community is still undecided as to whether it is harmful
I might just smoke every now and again
I own a
hooka lounge and I also own this device above! Saves a lot of time… Great piece of equipment. I highly recommend it!