- Email: [email protected]
fossil energy hybridization
07 Alternative increased opportunities for farmers and land owners in supplying biomass raw material. In order to achieve these renewable energy and environmental benefits, the industry urgently needs to advance the technologies through large-scale demonstrations. These demonstrations will cost significantly more (40-50%) than subsequent installations. The industry has developed a partnership with the DOE to advance these technologies. DOE participation will not only make the demonstrations possible, it will also accelerate deployment of the technologies in the pulp and paper industry and ensure that results will be shared with other industries and the public. This paper will describe the background, vision and shared national and industry objectives. Subsequent papers in this session will describe the specific projects that are part of ‘The Forest Products Industry Gasification Combined Cycle Initiative’. 02/00497 Biomass gasification revision and technology description Ibanez, P.G., De Becerra, J.O. Energia (Madrid), 2000, 26, (I), 61-70. (In Spanish) Pyrolysis, combustion and gasification of biomass for fuel gas or synthesis gas production and power generation are discussed, including the state of the technology and useful reactors and scrubbers. 02/00498 Cereal chaff: a renewable fuel for generating electricity Bustamante, J.A. er al. Energiu (Madrid), 2000, 26, (I), 71-77. Spanish) Properties of cereal chaff (e.g. K, Cl content) and its combustion gasification for power generation are discussed.
(In or
02/00499 Energy applications of olive-oil industry by-products: - I. The exhaust foot cake Masghouni, M., Hassairi, M. Biomass Bioenergy, 2000, 18, (3), 257-262. The energy characteristics of the exhaust foot cake (EFC) from the olive-oil extraction industry are described in this paper. This biomass has proved to be an interesting energy source. The use of this solidwaste as a combustible in brick manufacture is economically profitable: 1100 tons of EFC yearly substitute 420 EOT of No. 2 heavy fuel containing 4% of sulphur. The use of this solid-waste as an energy source is environment friendly, as it reduces the nuisance of solid-waste and gas emissions to the atmosphere, particularly sulphur oxides. 02lOO500 Energy conversion from biomass Kitani, 0. T&o Enerugi, 2000, 26, (I), 3-1. (In Japanese) A review with 12 references. 02/00501 Energy production from contaminated biomass. Progress of on-going collaboration projects Grebenkov, A. et al. Impact Miner. Impurities Solid Fuel Cornbust., [Proc. Eng. Found. Conf. Miner. Matter Fuelsj, 1997, 635-643. Edited by Gupta R.P., Wall T.F., Baxter L. Feasibility study results are presented on the use of contaminated forests as sustainable renewable fuel resources. The bench-scale experiment was carried out to testify aerosol modelling and combustion properties of forest litter and duff. The results showed that: a conventional type boiler can effectively burn the new biofuel, radionuclide emission may not exceed the permissible concentration, ash residues can be effectively stabilized and handled, proposed action will reduce risk and doses to pupulation, and use of contaminated forest will lead to termination of its deterioration and improve social activity of local communities. 02/00502 Method and apparatus for gasification and incineration of biomass with manufacture of a tar-free gas Kiefer, C. Ger. Offen. DE 19,846,805 (Cl. ClOB53/00), 13 Apr 2000, Appl. 19,846,805, 10 Ott 1998. 6. (In German) The biomass, either agricultural materials or wastes: are first pyrolysed to form a pyrolysis gas and coke, the coke is comminuted, and the coke and gas mixture is then pyrolysed over a bed of glowing coke to form a synthesis gas. The synthesis gas and the coke are recycled to maintain high incineration levels. Excess synthesis gas and coke are recovered. 02100503 Power production from wood - comparison of the Rankine cycle to concepts using gasification and fast pyrolysis Solantausta, Y., Huotari, J. VTT Tied., 2000, 2024, Part3/l-Part3/46. A study of small scale power production from woody biomass was carried out within the IEA Bioenergy Task ‘Techno-Economic Assessments for Bioenergy Applications’. The task had the following objectives: to compare the common steam boiler power plant (the Rankine cycle) to two alternative new power plant concepts, to assess the uncertainties within these new concepts, to estimate the development potential of these concepts. The study was carried out comparing production of electricity at 2 MWe. The scale was selected to study:
energy sources (solar energy)
how well the common steam boiler power plant competes with the new power plant concepts especially in the small scale, what is the future estimates for cost and performance of the new concepts. The systems compared were: the Rankine steam boiler power plant, the gas engine power plant using gasification fuel gas. The gasifier and the engine are integrated, the diesel power plant using fast pyrolysis liquid as a fuel. Liquid production and the power plant are de-coupled. Overall efficiencies for these systems are: the Rankine cycle 17.5%, gasification-gas engine 23.9%, and pyrolysis-diesel engine 24.7%. Potential improved efficiencies for the three technologies are 23,32.4, and 31.5%, respectively. Estimated specific investment costs for the base power plants are 2300, 4200, and 3600 US$/kWe, respectively. It is shown that the Rankine cycle is superior compared to the gasification-gas engine and pyrolysis-diesel engine with current cost data. Increasing fuel cost 50% from the base value FIM 45/MWh (USD 2.3/GJ) improves the competitiveness of new concepts, but the Rankine is continuously more economic over the whole annual operation time. At high fuel costs, the difference between the diesel and the Rankine is negligible below 4000 h/a. In a very long-term operation time, the gas engine is not much more expensive than the Rankine power plant. Differences between the alternatives are fairly small over the whole range, where improvements for technologies are assumed valid. The range of variation with the Rankine and the least-cost new cycle is about lo%, which is not a significant difference within the accuracy of the study. It is shown that co-generation improves the economics of small-scale power production considerably. The Rankine cycle remains as the least-cost option in all cases studied. It is concluded that for the new power plant technologies to be competitive compared to the Rankine cycle, especially capital costs have to be reduced. Without such reductions it is hard to compete with the Rankine cycle in a small scale either in power-only or cogeneration mode of operation.
Geothermal
energy
02/00504 Paleotemperature analysis of Aliaga (Izmir, Turkey) geothermal field Senguler, I. et al. Energy Sources, 2000, 22, (4), 357-362. Mineralogical and organopetrography analysis were carried out on core samples of four geothermal wells from the Aliaga geothermal field located in western Turkey. Whole rock mineralogy and clay minerals were determined, and thermal maturity of the different levels of the formation was defined by means of vitrinite reflectance measurements. The measured maturity gradients complied from analysis data for four wells and outcrops ranged from low to very high values. 02/00505 The status of world geothermal power generation 1995-2000 Huttrer, G.W. Geothermics, 2001, 30, l-27. In order to assess the current status of international geothermal power generation, the author has reviewed the Country Update (CIJ) papers submitted to the World Geothermal Conference 2000 in Japan from nations generating or planning to generate electricity. Salient facts in these papers have been synthesized and summary descriptions of geothermally-related activities written. Finally, following a brief discussion, conclusions are drawn and appropriate tables and graphs presented. The CU reviews revealed that: (1) geothermally-fuelled electric power is being generated in 21 nations as of February 2000; (2) the installed capacity has reached 7974 MWe, which is a 16.7% increase since 1995; the total energy generated during the past 5 years has been at least 49,261 GWh; about 1165 wells more than 100 m deep have been drilled, and at least 13,621 person-years of professional geothermists’ time has been expended in the nations that reported this statistic.
Solar energy 02/00508 Coal gasification by CO2 gas bubbling in molten salt for solar/fossil energy hybridization Matsunami, J. et al. Sol. Energy, 2000, 68, (3), 257-261. Coal gasification with COz (the Boudouard reaction: C + CO2 = 2C0, A,H” = 169.2 kJ/mol at 1150 K), which can be applied to a solar thermochemical process to convert concentrated solar heat into chemical energy, was conducted in the molten salt medium (eutectic mixture of NazCOs and KzCOs, weight ratio = l/l) to provide thermal storage. When COz gas was bubbled through the molten salt, higher reaction rates were observed compared to the case without COz gas bubbling (CO* gas was streamed over the surface of the molten salt). Thus the coke formed by coal pyrolysis was well suspended in the Fuel and Energy
Abstracts
January 2002
51
07 Alternative
energy sources (wind energy)
molten salt by COz gas bubbling. When the COz flow rate was increased from 15 to 60 pmol/s, the CO evolution rate was increased (15 to 26 pmol/s). However, COz conversion efficiency was decreased (50 to 22%). Based on the maximum CO evolution rate 126 pmolls), solar thermal energy from a solar farm (300 x 300 m ) could be converted to chemical energy at a rate of 50000 kJ/s by the coal (23 ton as C) gasification process studied here. This assumes 50% solar heat to chemical energy conversion efficiency which can be generally obtained by the actual solar experiments.
The solar thermochemical production of H from water or synthesis gas from natural gas using metal oxide redox cycles represent promising alternatives to the well known conventional technologies. The thermodynamic mechanisms and kinetics of the concomitant reaction steps have been and are still examined. The obtained results are promising with respect to two features: the experimental studies conducted in the solar furnaces demonstrate the technical feasibility of the relevant processes and (as surplus) interesting chemical commodities such as metals or metal compounds are obtained.
02/00507 Feasibility study of a district energy system with seasonal water thermal storage Tanaka, H. er al. Solar Energy, 2000, 69, (6) 535-547. In this paper, performance of three types of district heating/cooling and hot water supply system with natural and unused energy utilization were examined by using system simulation. An area zoned for both commercial and residential buildings was chosen for this study. The first system is the conventional system in which an electric driven turbo chiller and a gas-fired boiler are installed as the heat source. This is considered as the reference system. Two alternative systems utilize waste heat from space cooling and heating. One is designed-based on short-term heat recovery and the other employs the concept of an annual cycle energy system (i.e. seasonal heat recovery). All of the three systems use solar thermal energy for hot water supply to the residential zone. The index for evaluation is the coefficient of performance of the overall system, based on primary energy. As a result, it was found that the seasonal storage system could decrease the energy consumption by about 26% and the short-term heat recovery system could decrease it by about 16% compared with the reference system. In designing the heat recovery system, a balance of cooling/ heating demand is an important factor. Therefore a sensitivity analysis of performance of the overall system and the seasonal thermal storage for several load patterns was performed. From these results, it was found that if the amount of heating/cooling demand were well balanced, an improvement of energy performance could be achieved and the utilization factor of the seasonal tank would become higher. Furthermore, the volume of the seasonal storage tank could be reduced.
02/00511 Solar-assisted district heating plants: status of the German programme solarthermie-2000 Lottner, V. ef al. Solar Energy, 2000, 69, (6), 449459. Within the IO-year programme ‘Solarthermie-2000’ of the German Federal Ministry for Economics and Technology (BMWi), large-scale solar-assisted heating plants have been funded in Germany. Long-term monitoring programmes are carried out to prove the technical and economic feasibility of various solar system concepts with and without seasonal storage. The paper presents a summary and review of the present status and results of the activities in the Programme. Longterm monitoring programmes have shown that the design data of the solar plants can be achieved if realistic assumptions are made. The main obstacle for the implementation of the concepts on a broader scale without public subsidies is the high investment costs of the solar systems. The main goal of the Programme is the further improvement of the cost-effectiveness of the solar concept.
02/00508 Solar cells based on carbon thin films Krishna, K.M. et al. Solar Energy Marerials & Solar Cells, 2001, 65, (l4) 163-170. Carbon as an alternative material for low-cost and high-efficiency solar cell is attempted. Thin films of semiconducting n- (p-doped) and p(un-doped) type carbon have been deposited on various substrates by ion beam sputtering and pyrolysis, using camphor as a natural carbon precursor. The optical gap of carbon has been found to be around 1.05 and <0.5 eV for n- and p-type films, respectively. Studies dealing with the temperature dependence of conductivity reveal semiconducting behaviour of both the films and Hall measurements indicate n-type conducting of p-doped ion beam sputtered films and p-type conduction of un-doped pyrolysed films. Photovoltaic solar cells of configurations n-C/p-Si and n-C/p-Si have been fabricated and their photoresponse characteristics under AM 0 and 1 SUN illumination conditions have been studied. An enhanced efficiency of 1.52% has been obtained for the n-C/p-C/p-Si solar cell with the insertion of a p-C layer. 02/00509 Solar energy technologies and stabilizing atmospheric COP concentrations Kim, S.H. et al. hog. Phofovoltaics, 2000, 8, (l), 3-15. In this analysis, we explore the role of solar energy, specifically utilityscale photovoltaic (PV) technology, in supplying the world’s growing demand for energy while limiting the impact of climate change by reducing carbon dioxide emissions. We present a range of cost paths for the technology and examine the role of solar energy in the global energy system under these paths and a reference scenario. We also assess the impacts of these cost paths on the role of solar power under carbon constraint scenarios designed to stabilize the concentration of atmospheric carbon dioxide over the next century. Our analysis shows that solar energy can play a significant role in the future global energy system and that the benefit of the solar energy option increases as the limitation on carbon emissions becomes more stringent. However, lowering the cost of power production to the point at which solar is competitive with other options is critical if solar power is to become a core generation technology Aggressively lowering the cost of solar energy in the next few decades will ensure that solar energy technologies are a prominent part of any global energy system, so the potential value of research in solar energy is great. 02/00510 Solar thermochemical production of hydrogen using metal oxide redox systems Steinfeld, A., Reller,’ A. Hydrogen Energy Prog. XII. Proc. World Hydrogen Energy Conf, 12rh, 1998, 1, 793-799. Edited by Bolcich, J.C., Veziroglu, T.N.
52
Fuel and Energy Abstracts
January 2002
02/00512 Surface passivation in high efficiency silicon solar cells Wenham, S.R. et al. Solar Energy Materials & Solar Cells, 2001, 65, (l4), 377-384.
Surface passivation for crystalline silicon solar cells is particularly important for devices with open-circuit voltages in excess of 650 mV. Thick passivating thermal oxides, originally developed for use with buried contact solar cells, are shown to produce the most effective and stable surface passivation particularly in conjunction with lightly phosphorus diffused surfaces. However, for improved optical performance, antireflection coatings are0 only effective with surface oxide thicknesses reduced to 100-200 A. Thinner passivating oxides cause significant voltage loss, most of which can be recovered through hydrogen passivation. Throughout this study, variation in surface passivation approaches has produced open-circuit voltages ranging from 620 mV to record voltages of 720 mV. 02lOO513 The case for a 40% efficiency goal for photovoltaic cells in 2005 Rannels, J.E. Solar Energy Material.7 & Solar Cells, 2001, 65, (l-4),
3-
8.
The creation of 40% efficient, multijunction laboratory cells under 500x concentrations is a reasonable, important near-term goal for the US photovoltaic (PV) program. A renewed focus on high-performance PV device research is justified by the large-scale market potential it creates for PV. Promising research results on multijunction III-V devices have established the technical fesibility of this goal. DOE is working to expand the resources available for high-performance research, while continuing to accomplish breakthroughs in thin-films, manufacturing, and balance of systems that will pave the way for commercial deployment of new high-efficiency PV devices. This paper explains why 40% efficiency is important to achieving PV’s potential, the research results that have led to this conclusion and how this research complements the overall PV program; and discusses how the US program intends to accomplish this challenging - but realistic goal.
Wind energy 02/00514 The economic feasibility of producing hydrogen from sunlight, wind, and biomass energy Mann, M.K., Spath, P.L. Proc. Renewable Adv. Energy Sysf. 21~1 Century, 1999, 405-417. Edited by Hogan, R. Studies have been made to determine the economic feasibility of photoelectrochemical (PEC), electrolytical, and thermochemical technologies to convert solar and wind energy and biomass into hydrogen. The analyses that have been conducted can essentially be broken up into three blocks: an analysis of PEC conversion of sunlight, analyses of photovoltaic (PV)- and wind-based systems, and analyses of thermochemical biomass systems. PEC, by combining a semiconductor and an electrocatalyst into a single monolithic device, is an alternative to PV/ electrolysis. In studying PV- and wind-based electrolysis systems, opportunities to reduce hydrogen production costs through interaction with the electric utility grid were explored. The thermochemical routes
(In or
02/00499 Energy applications of olive-oil industry by-products: - I. The exhaust foot cake Masghouni, M., Hassairi, M. Biomass Bioenergy, 2000, 18, (3), 257-262. The energy characteristics of the exhaust foot cake (EFC) from the olive-oil extraction industry are described in this paper. This biomass has proved to be an interesting energy source. The use of this solidwaste as a combustible in brick manufacture is economically profitable: 1100 tons of EFC yearly substitute 420 EOT of No. 2 heavy fuel containing 4% of sulphur. The use of this solid-waste as an energy source is environment friendly, as it reduces the nuisance of solid-waste and gas emissions to the atmosphere, particularly sulphur oxides. 02lOO500 Energy conversion from biomass Kitani, 0. T&o Enerugi, 2000, 26, (I), 3-1. (In Japanese) A review with 12 references. 02/00501 Energy production from contaminated biomass. Progress of on-going collaboration projects Grebenkov, A. et al. Impact Miner. Impurities Solid Fuel Cornbust., [Proc. Eng. Found. Conf. Miner. Matter Fuelsj, 1997, 635-643. Edited by Gupta R.P., Wall T.F., Baxter L. Feasibility study results are presented on the use of contaminated forests as sustainable renewable fuel resources. The bench-scale experiment was carried out to testify aerosol modelling and combustion properties of forest litter and duff. The results showed that: a conventional type boiler can effectively burn the new biofuel, radionuclide emission may not exceed the permissible concentration, ash residues can be effectively stabilized and handled, proposed action will reduce risk and doses to pupulation, and use of contaminated forest will lead to termination of its deterioration and improve social activity of local communities. 02/00502 Method and apparatus for gasification and incineration of biomass with manufacture of a tar-free gas Kiefer, C. Ger. Offen. DE 19,846,805 (Cl. ClOB53/00), 13 Apr 2000, Appl. 19,846,805, 10 Ott 1998. 6. (In German) The biomass, either agricultural materials or wastes: are first pyrolysed to form a pyrolysis gas and coke, the coke is comminuted, and the coke and gas mixture is then pyrolysed over a bed of glowing coke to form a synthesis gas. The synthesis gas and the coke are recycled to maintain high incineration levels. Excess synthesis gas and coke are recovered. 02100503 Power production from wood - comparison of the Rankine cycle to concepts using gasification and fast pyrolysis Solantausta, Y., Huotari, J. VTT Tied., 2000, 2024, Part3/l-Part3/46. A study of small scale power production from woody biomass was carried out within the IEA Bioenergy Task ‘Techno-Economic Assessments for Bioenergy Applications’. The task had the following objectives: to compare the common steam boiler power plant (the Rankine cycle) to two alternative new power plant concepts, to assess the uncertainties within these new concepts, to estimate the development potential of these concepts. The study was carried out comparing production of electricity at 2 MWe. The scale was selected to study:
energy sources (solar energy)
how well the common steam boiler power plant competes with the new power plant concepts especially in the small scale, what is the future estimates for cost and performance of the new concepts. The systems compared were: the Rankine steam boiler power plant, the gas engine power plant using gasification fuel gas. The gasifier and the engine are integrated, the diesel power plant using fast pyrolysis liquid as a fuel. Liquid production and the power plant are de-coupled. Overall efficiencies for these systems are: the Rankine cycle 17.5%, gasification-gas engine 23.9%, and pyrolysis-diesel engine 24.7%. Potential improved efficiencies for the three technologies are 23,32.4, and 31.5%, respectively. Estimated specific investment costs for the base power plants are 2300, 4200, and 3600 US$/kWe, respectively. It is shown that the Rankine cycle is superior compared to the gasification-gas engine and pyrolysis-diesel engine with current cost data. Increasing fuel cost 50% from the base value FIM 45/MWh (USD 2.3/GJ) improves the competitiveness of new concepts, but the Rankine is continuously more economic over the whole annual operation time. At high fuel costs, the difference between the diesel and the Rankine is negligible below 4000 h/a. In a very long-term operation time, the gas engine is not much more expensive than the Rankine power plant. Differences between the alternatives are fairly small over the whole range, where improvements for technologies are assumed valid. The range of variation with the Rankine and the least-cost new cycle is about lo%, which is not a significant difference within the accuracy of the study. It is shown that co-generation improves the economics of small-scale power production considerably. The Rankine cycle remains as the least-cost option in all cases studied. It is concluded that for the new power plant technologies to be competitive compared to the Rankine cycle, especially capital costs have to be reduced. Without such reductions it is hard to compete with the Rankine cycle in a small scale either in power-only or cogeneration mode of operation.
Geothermal
energy
02/00504 Paleotemperature analysis of Aliaga (Izmir, Turkey) geothermal field Senguler, I. et al. Energy Sources, 2000, 22, (4), 357-362. Mineralogical and organopetrography analysis were carried out on core samples of four geothermal wells from the Aliaga geothermal field located in western Turkey. Whole rock mineralogy and clay minerals were determined, and thermal maturity of the different levels of the formation was defined by means of vitrinite reflectance measurements. The measured maturity gradients complied from analysis data for four wells and outcrops ranged from low to very high values. 02/00505 The status of world geothermal power generation 1995-2000 Huttrer, G.W. Geothermics, 2001, 30, l-27. In order to assess the current status of international geothermal power generation, the author has reviewed the Country Update (CIJ) papers submitted to the World Geothermal Conference 2000 in Japan from nations generating or planning to generate electricity. Salient facts in these papers have been synthesized and summary descriptions of geothermally-related activities written. Finally, following a brief discussion, conclusions are drawn and appropriate tables and graphs presented. The CU reviews revealed that: (1) geothermally-fuelled electric power is being generated in 21 nations as of February 2000; (2) the installed capacity has reached 7974 MWe, which is a 16.7% increase since 1995; the total energy generated during the past 5 years has been at least 49,261 GWh; about 1165 wells more than 100 m deep have been drilled, and at least 13,621 person-years of professional geothermists’ time has been expended in the nations that reported this statistic.
Solar energy 02/00508 Coal gasification by CO2 gas bubbling in molten salt for solar/fossil energy hybridization Matsunami, J. et al. Sol. Energy, 2000, 68, (3), 257-261. Coal gasification with COz (the Boudouard reaction: C + CO2 = 2C0, A,H” = 169.2 kJ/mol at 1150 K), which can be applied to a solar thermochemical process to convert concentrated solar heat into chemical energy, was conducted in the molten salt medium (eutectic mixture of NazCOs and KzCOs, weight ratio = l/l) to provide thermal storage. When COz gas was bubbled through the molten salt, higher reaction rates were observed compared to the case without COz gas bubbling (CO* gas was streamed over the surface of the molten salt). Thus the coke formed by coal pyrolysis was well suspended in the Fuel and Energy
Abstracts
January 2002
51
07 Alternative
energy sources (wind energy)
molten salt by COz gas bubbling. When the COz flow rate was increased from 15 to 60 pmol/s, the CO evolution rate was increased (15 to 26 pmol/s). However, COz conversion efficiency was decreased (50 to 22%). Based on the maximum CO evolution rate 126 pmolls), solar thermal energy from a solar farm (300 x 300 m ) could be converted to chemical energy at a rate of 50000 kJ/s by the coal (23 ton as C) gasification process studied here. This assumes 50% solar heat to chemical energy conversion efficiency which can be generally obtained by the actual solar experiments.
The solar thermochemical production of H from water or synthesis gas from natural gas using metal oxide redox cycles represent promising alternatives to the well known conventional technologies. The thermodynamic mechanisms and kinetics of the concomitant reaction steps have been and are still examined. The obtained results are promising with respect to two features: the experimental studies conducted in the solar furnaces demonstrate the technical feasibility of the relevant processes and (as surplus) interesting chemical commodities such as metals or metal compounds are obtained.
02/00507 Feasibility study of a district energy system with seasonal water thermal storage Tanaka, H. er al. Solar Energy, 2000, 69, (6) 535-547. In this paper, performance of three types of district heating/cooling and hot water supply system with natural and unused energy utilization were examined by using system simulation. An area zoned for both commercial and residential buildings was chosen for this study. The first system is the conventional system in which an electric driven turbo chiller and a gas-fired boiler are installed as the heat source. This is considered as the reference system. Two alternative systems utilize waste heat from space cooling and heating. One is designed-based on short-term heat recovery and the other employs the concept of an annual cycle energy system (i.e. seasonal heat recovery). All of the three systems use solar thermal energy for hot water supply to the residential zone. The index for evaluation is the coefficient of performance of the overall system, based on primary energy. As a result, it was found that the seasonal storage system could decrease the energy consumption by about 26% and the short-term heat recovery system could decrease it by about 16% compared with the reference system. In designing the heat recovery system, a balance of cooling/ heating demand is an important factor. Therefore a sensitivity analysis of performance of the overall system and the seasonal thermal storage for several load patterns was performed. From these results, it was found that if the amount of heating/cooling demand were well balanced, an improvement of energy performance could be achieved and the utilization factor of the seasonal tank would become higher. Furthermore, the volume of the seasonal storage tank could be reduced.
02/00511 Solar-assisted district heating plants: status of the German programme solarthermie-2000 Lottner, V. ef al. Solar Energy, 2000, 69, (6), 449459. Within the IO-year programme ‘Solarthermie-2000’ of the German Federal Ministry for Economics and Technology (BMWi), large-scale solar-assisted heating plants have been funded in Germany. Long-term monitoring programmes are carried out to prove the technical and economic feasibility of various solar system concepts with and without seasonal storage. The paper presents a summary and review of the present status and results of the activities in the Programme. Longterm monitoring programmes have shown that the design data of the solar plants can be achieved if realistic assumptions are made. The main obstacle for the implementation of the concepts on a broader scale without public subsidies is the high investment costs of the solar systems. The main goal of the Programme is the further improvement of the cost-effectiveness of the solar concept.
02/00508 Solar cells based on carbon thin films Krishna, K.M. et al. Solar Energy Marerials & Solar Cells, 2001, 65, (l4) 163-170. Carbon as an alternative material for low-cost and high-efficiency solar cell is attempted. Thin films of semiconducting n- (p-doped) and p(un-doped) type carbon have been deposited on various substrates by ion beam sputtering and pyrolysis, using camphor as a natural carbon precursor. The optical gap of carbon has been found to be around 1.05 and <0.5 eV for n- and p-type films, respectively. Studies dealing with the temperature dependence of conductivity reveal semiconducting behaviour of both the films and Hall measurements indicate n-type conducting of p-doped ion beam sputtered films and p-type conduction of un-doped pyrolysed films. Photovoltaic solar cells of configurations n-C/p-Si and n-C/p-Si have been fabricated and their photoresponse characteristics under AM 0 and 1 SUN illumination conditions have been studied. An enhanced efficiency of 1.52% has been obtained for the n-C/p-C/p-Si solar cell with the insertion of a p-C layer. 02/00509 Solar energy technologies and stabilizing atmospheric COP concentrations Kim, S.H. et al. hog. Phofovoltaics, 2000, 8, (l), 3-15. In this analysis, we explore the role of solar energy, specifically utilityscale photovoltaic (PV) technology, in supplying the world’s growing demand for energy while limiting the impact of climate change by reducing carbon dioxide emissions. We present a range of cost paths for the technology and examine the role of solar energy in the global energy system under these paths and a reference scenario. We also assess the impacts of these cost paths on the role of solar power under carbon constraint scenarios designed to stabilize the concentration of atmospheric carbon dioxide over the next century. Our analysis shows that solar energy can play a significant role in the future global energy system and that the benefit of the solar energy option increases as the limitation on carbon emissions becomes more stringent. However, lowering the cost of power production to the point at which solar is competitive with other options is critical if solar power is to become a core generation technology Aggressively lowering the cost of solar energy in the next few decades will ensure that solar energy technologies are a prominent part of any global energy system, so the potential value of research in solar energy is great. 02/00510 Solar thermochemical production of hydrogen using metal oxide redox systems Steinfeld, A., Reller,’ A. Hydrogen Energy Prog. XII. Proc. World Hydrogen Energy Conf, 12rh, 1998, 1, 793-799. Edited by Bolcich, J.C., Veziroglu, T.N.
52
Fuel and Energy Abstracts
January 2002
02/00512 Surface passivation in high efficiency silicon solar cells Wenham, S.R. et al. Solar Energy Materials & Solar Cells, 2001, 65, (l4), 377-384.
Surface passivation for crystalline silicon solar cells is particularly important for devices with open-circuit voltages in excess of 650 mV. Thick passivating thermal oxides, originally developed for use with buried contact solar cells, are shown to produce the most effective and stable surface passivation particularly in conjunction with lightly phosphorus diffused surfaces. However, for improved optical performance, antireflection coatings are0 only effective with surface oxide thicknesses reduced to 100-200 A. Thinner passivating oxides cause significant voltage loss, most of which can be recovered through hydrogen passivation. Throughout this study, variation in surface passivation approaches has produced open-circuit voltages ranging from 620 mV to record voltages of 720 mV. 02lOO513 The case for a 40% efficiency goal for photovoltaic cells in 2005 Rannels, J.E. Solar Energy Material.7 & Solar Cells, 2001, 65, (l-4),
3-
8.
The creation of 40% efficient, multijunction laboratory cells under 500x concentrations is a reasonable, important near-term goal for the US photovoltaic (PV) program. A renewed focus on high-performance PV device research is justified by the large-scale market potential it creates for PV. Promising research results on multijunction III-V devices have established the technical fesibility of this goal. DOE is working to expand the resources available for high-performance research, while continuing to accomplish breakthroughs in thin-films, manufacturing, and balance of systems that will pave the way for commercial deployment of new high-efficiency PV devices. This paper explains why 40% efficiency is important to achieving PV’s potential, the research results that have led to this conclusion and how this research complements the overall PV program; and discusses how the US program intends to accomplish this challenging - but realistic goal.
Wind energy 02/00514 The economic feasibility of producing hydrogen from sunlight, wind, and biomass energy Mann, M.K., Spath, P.L. Proc. Renewable Adv. Energy Sysf. 21~1 Century, 1999, 405-417. Edited by Hogan, R. Studies have been made to determine the economic feasibility of photoelectrochemical (PEC), electrolytical, and thermochemical technologies to convert solar and wind energy and biomass into hydrogen. The analyses that have been conducted can essentially be broken up into three blocks: an analysis of PEC conversion of sunlight, analyses of photovoltaic (PV)- and wind-based systems, and analyses of thermochemical biomass systems. PEC, by combining a semiconductor and an electrocatalyst into a single monolithic device, is an alternative to PV/ electrolysis. In studying PV- and wind-based electrolysis systems, opportunities to reduce hydrogen production costs through interaction with the electric utility grid were explored. The thermochemical routes