- Email: [email protected]
03920 Evaluation of an integrated renewable energy system for electricity generation in rural areas
07
Performance of a solar tunnel dryer with micro97103910 computer control Fuller, R. J. and Charters, W. W. S. Solar Energy, 1997, 59, (4-6) 151154. Construction and subsequent testing of a solar tunnel dryer in the Sunraysia district of Northern Victoria, Australia, is detailed. The dryer features a novel microprocessor system control the exhaust fan. A tray containing a small sample of the crop is suspended from a load cell, and the output from this is used to continuously calculate the moisture content of the crop. Using this estimation and inputs from sensors measuring the relative humidity of the air inside and outside the dryer, it is possible to decide whether to activate the exhaust fan. Reduced fan operation has been found to maximize the air temperatures achieved in the dryer.
Performance testing and evaluation of solid absorption solar cooling unit
97103911
Bansal, N. K. et al. Solar Enemy, 1997, 61, (2) 127-140. A solar cooling unit utilizing thermal energy supplied by heat pipe vacuum tube solar collectors through thermosyphonic flow of water designed and manufactured by DORNIER, a German firm. It is based on a solid-vapour intermittent absorption system and uses ammonia as a refrigerant and IMPEX material as absorbent, has no moving parts requiring no auxiliary energy. Detailed experiments were performed on a unit in Delhi under real field conditions followed by theoretical analysis. Theoretical maximum overall COP of the unit is 0.143, and it depends upon the climatic conditions. In practical tests, however, the overall COP reached only 0.081. The automatic control valve based on mechanical/thermal principles however has defects and the problem of corrosion of the sealings needs to be solved. In climates where day time temperatures are high and solar radiation relatively low, it is most unlikely that pressure in the ammonia circuit can reach values at which ammonia vapours start to condense. Consequently, the unit requires modifications for such conditions.
A review of the photovoltaic 97103912 development in Africa
energy sources (wind energy)
generation technology. These results were used to develop total fuel cycle emission rates for planned electric capacity additions in the USA. These rates are compared with the emission rates that would occur if solar technologies were substituted for fossil generation capacity additions. It is found that even by doubling the planned additions of solar technologies produces less than a 1% reduction in annual CO? and CHI emissions from new generation. However, lifetime greenhouse gas savings can be substantial: up to six million tons of COz savings could be realized with only 25% solar deployment up to the year 2010, over the lifetime of the solar installations.
97103916 Thermodynamic analysis of the performance of a solar absorption heat transformer at maximum coefficient of performance Chen, J. Int. .I. Energy Res., 1997, 21, (11). 975-984. A solar absorption heat transformer affected by the irreversibility of finiterate heat transfer may be modelled as an equivalent combined system consisting of a solar collector and an endoreversible absorption heat transformer. The latter is treated as a combined cycle having an endoreversible heat pump driven by an endoreversible heat engine. The maximum coefficient of performance of the system is determined, based on the linear heat loss model for solar collectors and the general optimum relation for endoreversible absorption heat transformers. The optimality problems concerning the primary performance parameters of the system are discussed. The results obtained here may serve as a good guide for the evaluation of existing real solar absorption heat transformers or provide some theoretical bases for the optimal design of future solar absorption heat transformers.
Wind Energy
industry and its
Gope, G. et ul. Solar Energy, 1997, 59, (4-6), 217-225. Photovoltaic commercialization experiences are studied for application in the future. African development of this industry is of particular concern in this work and is examined to identity the areas of strength and potential as well as the necessary infrastructure for production, distribution and installation in order to support its growth. The question of capital requirement versus the efficiency of photovoltaics is highlighted and the reliability factor is analysed. Three issues seem crucial for the future development of photovoltaics, especially in Africa: (1) technology development; (2) education; (3) finance. These issues are addressed and their interdependence and impact on the use of photovoltaics are explored. Finally, a method of co-operation between research in photovoltaics at the universities and local industry is proposed as part of the Research and Development (R&D) infrastructure required for the technical support of this field.
97103913
Alternative
The solar-driven coal/Fe304 redox system
Tamaura, T. et al. .I. Phys. IV., 1997, 7, (Cl, 7th International Conference on Ferrites, 1996) C1/685-Cl/686. The paper studies the solar-driven endothermic reaction of coal and magnetite for mixing solar and fossil energies. The overall reaction can be represented by CH, + Fez04 = CO + 3FeO + l/2HZ where x depends on the coal. Solar-driven experiments were conducted using a high-flux solar furnace. Samples were directly exposed for short time intervals to a solar flux irradiation of 300 W/cm’. The carbon content decreased rapidly after suggesting efficient heat transfer and chemical only 1 s exposure, conversion by direct absorption of concentrated solar energy at the reaction site. The proposed solar thermochemical process offers the possibility of simultaneously performing the gasification of coal and reduction of iron oxide, and for producing a fuel with an upgraded calorific value.
Territorial competitiveness of the stand alone photovoltaic systems versus grid electricity supply. A method and a study based on geographical Information systems
97103914
Lopez, F. J. A. et al. Solar Energy, 1997, 61, (2), 107-118. In remote areas, stand alone photovoltaic power systems (SAPPS) are a natural option for electrification outside the grid-connected electricity supply system (GCESS). Three areas are taken into account in the proposed method: photovoltaic and grid sizing. economic analysis, and the integration of information and development of models within geographical information systems (GIS). The results of a case study carried out in the south of Spain show that SAPPS are economically more competitive for a domestic electricity consumption (5 kW h/day) in 69% of this region.
A total fuel cycle approach to reducing greenhouse gas emissions: solar generation technologies as greenhouse gas offsets in U.S. utility systems
9710397 5
Martin, J. A. Solar Energy, 1997, 59, (4-6). 195-203. A total fuel cycle approach is used to evaluate the potential greenhouse gas savings that could result from the deployment of solar generation technologies in utility systems in the US. Total fuel cycle analyses were completed for several renewable and conventional generation technologies to estimate the total greenhouse gas emission contribution from each
‘ARES-a refined simulation program for the sizing and optfmisation of autonomous hybrid energy systems
97103917
Morgan, T. R. et al. Solar Energy, 1997, 59, (4-6) 195-203. Enhancements made to autonomous renewable energy systems (ARES)-I, the Cardiff School of Engineering’s hybrid photovoltaic and wind energy simulation program are presented. The resulting program, ARES-II predicts the battery state of voltage (SoV) rather than its state of charge (SoC). ARES-II is able to predict the occurrence of loss of load thus giving a direct measure of the system autonomy. The enhanced model also predicts the effect of different battery temperatures on the LoL. Incorporating battery temperature effects into the battery algorithm is a novel advancement in hybrid system voltage simulation. Further refinements have also been made to the voltage controller algorithms, Accurate modelling of the non-linear action of the low voltage controller is of paramount importance when predicting loss of load probability for hybrid systems. Combining all the above features and incorporating them into ARES-II produces a simple, accurate and reliable method for hybrid system design and LoL prediction.
97103916 Assessing the maximum fuel savings obtainable in simple wind-diesel systems Beyer, H. G. and Degner, T. Solar Energy, 1997, 61, (1) 5-10. A new statistical method is introduced for determining the upper limit of the obtainable fuel savings in simple wind-diesel systems, applying fixed control rules. When using the optimal control, fuel savings may be estimated from the statistical properties of the time series of the power balance: wind turbine power-load. A time step simulation of the system is compared with the method to confirm its validity. Fuel savings from a simple persistence based control are close to the optimal values. Using this method, the dependence of the fuel savings on the wind climate and the turbulence characteristics at the site may be easily obtained. These results are also compared to the performance data of systems with energy storage.
Electromechanical converters associated to wind turbines and their control
97103919
Sadre, M. Solar Energy, 1997, 61, (2), 119-125. Potential converters to be associated to wind turbines are subject to classification in this work. A detailed classification of electromechanical converters is given. Different methods of converter control are discussed, among which the maximum power point tracking method is of particular interest. It responds well to various criteria such as precision, stability, rapidity and auto-adaptability.
Evaluation of an integrated renewable system for electricity generation in rural areas
97103920
energy
Rozakis, S. et al. Energy Policy, 1997, 25, (3), 337-347. The combination of renewable energy sources for electricity generation at local level, and in particular the case of an isolated area of South Crete, the Frangocastello area has been examined. This study employed F-Cast, a computerized model that has been developed for the simulation of the operation of an integrated system. The energy supply side includes three renewable energy sources, namely wind, micro-hydraulic and biomass, and conventional high-cost electricity supplied by the National Grid. The model is the economic counterpart of an electronic control system that dispatches
Fuel and Energy Abstracts
September 1997
329
08
Steam raising (boiler operation/design)
electricity on an hourly basis. Wind energy introduces uncertainty to the system. Relations among variables are based on three states of the world depending upon the hourly speed of the wind. Biomass is a balancing factor in the supply-demand interaction, as the production of biomass is itself at the same time consuming electricity, as an input. Conclusions are drawn on (a) the optimal combination of renewable energy sources to achieve economic viability of the system (b) effects on agricultural income and local development. and (c) evaluation of renewable energy policies. Time series models to simulate and forecast hourly 97103921 averaged wind speed in Quetta, Pakistan Kamal, L. and Jafri, Y. Z. Solar Energy, 1997, 61, (1) 23-32. Hourly average wind speeds were calculated using stochastic simulation and forecast models. Time series models take into account several basic features of wind speed data including autocorrelation, non-Gaussian distribution and diurnal non-stationarity. An ARMA @, q) process is fitted to wind speed data transformed to make their distribution approximately Gaussian and standardized to remove scattering of transformed data, for a positive correlation of consecutive wind speed observations, Diurnal variations are used to observe forecasts and its dependence on lead times. The ARMA (p, 4) model is suitable for prediction intervals and probability forecasts.
Others, including Economics
Development,
Hydropower and environment in India 97103922 Ranganathan, V. Energy Policy, 1997, 25, (4) 435-438. Renewable and harmless to the environment during operation, hydroelectric power is the cheapest source of energy. Yet environmental activism has obstructed hydrodevelopment throughout the world, and more so in India. The paper calls for a realistic economic-environmental trade-off and improvements in environmental decision making apparatus. Low-temperature ftlterability properties of alterna97103923 tive diesel fuels from vegetable oils Dunn, R. 0. and Bagby, M. 0. Liq. Fuel Ind. Prod. Renewable Resow., Edited by Cundiff, John S. Proc. Liq. Fuel Con& 3rd, 1996, 95-103. American Society of Agricultural Engineers, St. Joseph, MI. Me esters from vegetable oils are an attractive option for combustion in compression ignition (diesel) engines. Recent research has shown that the issue of cold flow properties should be resolved before Me esters are appropriate as an alternative fuel in moderate temperature climates. In North America, fuel systems powered by petroleum middle distillates develop operability problems when overnight ambient temperature drop below -15°C. In contrast, Me esters from soybean oil develop similar problems at temperature near 0°C. This work examines expected operability limits for Me esters through evaluation of their low-temperature filterabilities. Overall, the results of this work demonstrate that emphasis on reducing cloud point (CP) remains the key to developing Me ester diesel fuels with improved low-temperature flow properties. Production technology of refuse-derived fuel (RDF) 97103924 Furuhayashi, K. Kagaku Kogaku, 1997, 61, (7). 502-505. (In Japanese) RDF classification, characteristics of RDF, the manufacturing processes of RDF. and its uses are discussed. A survey: internatfonal aid for renewable energy in 97/03925 the Pacific Islands since the 1970s Yu, X. and Taplin, R. Energy Policy, 1997, 25, (5) 501-516. A survey was conducted between November 1995 and May 1996, to review the situation regarding international aid for renewable energy in the Pacific Island region,. The survey has provided some interesting information regarding bilateral and multilateral aid for renewable energy in the region from the late 70s to 1996. In this paper, the main findings of the survey are presented and discussed. In the future, international aid for renewable energy in the region could be enhanced with further financial assistance, human resources and institutional development, local community involvement, joint ventures and aid efficiency. A winning coalition of advocacy: climate research, 97103926 bureaucracy and ‘alternative’ fuels. Who is driving climate change policy? Boehmer-Christiansen, S. Energy Policy, 1997, 25, (4) 439-444. With regard to global warming, anti-coal and some investment policies are largely justified. Political analysis suggests that these policies are supported by the reinforcing interests of three powerful lobbies: scientific institutions engaged in atmospheric research and earth observation, energy corporations harmed by low fossil fuel prices or supplying ‘clean’ technologies, and numerous interlocking bureaucracies. Together they have succeeded in maintaining momentum in current climate negotiations. The scientific consensus which underpins the climate treaty is examined critically. It is argued that support for emission abatement policies is better explained with
330
Fuel and Energy Abstracts
September
1997
reference to diplomatic interest in the globalisation of energy related investments and trade than understood causality between average global surface warming and fossil fuel combustion.
08
STEAM RAISING Boiler Operation/Design
97103927 Achieving compliance with advanced coal-fired low-emission boiler systems Regan, J. W. et al. Proc. Inf. Tech. Conf: Coal Util. Fuel Syst., 1995, 20, 633-645.
The work undertaken in Phase I of the U.S. Department of Energy (DOE) project, ‘Engineering Development of Advanced Coal-Fired Low-Emissions Boiler Systems’ (LEBS), part of the DOE’s Combustion 2000 Programme, alongside descriptions for future work. The overall objective of the LEBS Project is to dramatically improve environmental performance of future coal-fired power plants without adversely impacting efficiency or the cost of electricity. Short-term technologies will be used to reduce NO, and SO2 emissions to one-third current NSPS limits and particulates to half current NSPS limits. Air toxics must be in compliance and waste must be reduced and made more disposable. The work in Phase I included concept development and evaluation of several subsystems for controlling the emission of SO*, NO,, and particulates. Evaluations were then conducted on potential technologies in various combinations, as part of complete advanced supercritical power generation systems. One system was selected for preliminary design of a commercial generating plant. Acid rain legislation challen es coal pulverizer 97103926 designers to minimize impact on boiler pe r?ormance Piepho, R. R. Proc. Int. Tech. Conf. Coal Uril. Fuel Syst., 1994. 19, 733741. Pulverizer operating flexibility to supply power stations was improved with the combined use of the dynamically controlled variable speed classifier with spring load adjuster. Alternative fuel advanced reburning 97103929 Maly, P. M. et al. Proc. Int. Tech. Conf Coal Ufil. Fuel Sysf., 1997, 22, 815826. Full scale boiler systems have successfully demonstrated reburning as a mature fuel staging NO, control technology. The Energy and Environmental Research Corporation has developed advanced reburning techniques in which reburning is coupled with injection of nitrogen agents and promoter compounds, showing potential for greater than 90% NO, reduction. Test work has shown that a wide range of fuels can effectively be used for reburning, including natural gas, pulverized coal. coal pond fines, biomass and Orimulsion. The test work was conducted at a 1 x 1Oh Btu/h boiler simulation facility. Both natural gas and bituminous coal were tested as main fuels. Efficiency of basic and advanced reburning were characterized as a function of key process variables. The amount of reburn fuel ranged from 10 to 28% of the total heat input. NO, reduction was found to increase both with increasing reburn heat input and reburn zone residence time. Reburn fuel properties found to control performance include fuel nitrogen content, volatiles, fixed carbon, and ash constituents. Advanced reburn tests were conducted in which reburning was coupled with injection of nitrogen agents and/or promoters. The most effective promoter compounds were found to he alkalis, most notably sodium compounds. While reburning with alternative fuels has the potential to cause boiler impacts, such as increased slagging with biomass, these impacts are generally minimized because the reburn fuel comprises only a small fraction of total boiler heat input. The advanced reburning techniques are flexible since they can be readily applied to a variety of waste products and off-specification fuels having low cost. By virtue of their NO, reduction capabilities and its economic efficiency, such techniques are attractive candidates for a wide range of new and retrofit power plant applications. 97103930 Anthracite firing in large utility arch fired boilers Winkin, J. P. and Garcia-Mallol, J. A. Proc. Am. Power Conf., 1997, 59, (2). 1166-1174. Foster Wheeler (FW) has sold 49 arch-fired utility type boilers for burning low volatile type coals including semi-anthracites, anthracites and blends. Forty-one of these boilers have been in operation for many years. Twentythree are in the size range over 100 MWe with a total equivalent capacity of 5130 MWe. Of particular interest to the utility industry are I2 large units in the size range from 250 to 500 MWe. Ten boilers are in operation and two are completing construction. Four of these units burn anthracite, with volatile matter as law as 5.5% on an as-received basis. These were designed to burn anthracite, but some are burning semi-anthracite blends. These boilers have up-to-date arch-firing systems and furnace designs. The boilers sustain the minimum load requirements without support fuel. The database obtained from the above operating experience over a wide range of coals is
Performance of a solar tunnel dryer with micro97103910 computer control Fuller, R. J. and Charters, W. W. S. Solar Energy, 1997, 59, (4-6) 151154. Construction and subsequent testing of a solar tunnel dryer in the Sunraysia district of Northern Victoria, Australia, is detailed. The dryer features a novel microprocessor system control the exhaust fan. A tray containing a small sample of the crop is suspended from a load cell, and the output from this is used to continuously calculate the moisture content of the crop. Using this estimation and inputs from sensors measuring the relative humidity of the air inside and outside the dryer, it is possible to decide whether to activate the exhaust fan. Reduced fan operation has been found to maximize the air temperatures achieved in the dryer.
Performance testing and evaluation of solid absorption solar cooling unit
97103911
Bansal, N. K. et al. Solar Enemy, 1997, 61, (2) 127-140. A solar cooling unit utilizing thermal energy supplied by heat pipe vacuum tube solar collectors through thermosyphonic flow of water designed and manufactured by DORNIER, a German firm. It is based on a solid-vapour intermittent absorption system and uses ammonia as a refrigerant and IMPEX material as absorbent, has no moving parts requiring no auxiliary energy. Detailed experiments were performed on a unit in Delhi under real field conditions followed by theoretical analysis. Theoretical maximum overall COP of the unit is 0.143, and it depends upon the climatic conditions. In practical tests, however, the overall COP reached only 0.081. The automatic control valve based on mechanical/thermal principles however has defects and the problem of corrosion of the sealings needs to be solved. In climates where day time temperatures are high and solar radiation relatively low, it is most unlikely that pressure in the ammonia circuit can reach values at which ammonia vapours start to condense. Consequently, the unit requires modifications for such conditions.
A review of the photovoltaic 97103912 development in Africa
energy sources (wind energy)
generation technology. These results were used to develop total fuel cycle emission rates for planned electric capacity additions in the USA. These rates are compared with the emission rates that would occur if solar technologies were substituted for fossil generation capacity additions. It is found that even by doubling the planned additions of solar technologies produces less than a 1% reduction in annual CO? and CHI emissions from new generation. However, lifetime greenhouse gas savings can be substantial: up to six million tons of COz savings could be realized with only 25% solar deployment up to the year 2010, over the lifetime of the solar installations.
97103916 Thermodynamic analysis of the performance of a solar absorption heat transformer at maximum coefficient of performance Chen, J. Int. .I. Energy Res., 1997, 21, (11). 975-984. A solar absorption heat transformer affected by the irreversibility of finiterate heat transfer may be modelled as an equivalent combined system consisting of a solar collector and an endoreversible absorption heat transformer. The latter is treated as a combined cycle having an endoreversible heat pump driven by an endoreversible heat engine. The maximum coefficient of performance of the system is determined, based on the linear heat loss model for solar collectors and the general optimum relation for endoreversible absorption heat transformers. The optimality problems concerning the primary performance parameters of the system are discussed. The results obtained here may serve as a good guide for the evaluation of existing real solar absorption heat transformers or provide some theoretical bases for the optimal design of future solar absorption heat transformers.
Wind Energy
industry and its
Gope, G. et ul. Solar Energy, 1997, 59, (4-6), 217-225. Photovoltaic commercialization experiences are studied for application in the future. African development of this industry is of particular concern in this work and is examined to identity the areas of strength and potential as well as the necessary infrastructure for production, distribution and installation in order to support its growth. The question of capital requirement versus the efficiency of photovoltaics is highlighted and the reliability factor is analysed. Three issues seem crucial for the future development of photovoltaics, especially in Africa: (1) technology development; (2) education; (3) finance. These issues are addressed and their interdependence and impact on the use of photovoltaics are explored. Finally, a method of co-operation between research in photovoltaics at the universities and local industry is proposed as part of the Research and Development (R&D) infrastructure required for the technical support of this field.
97103913
Alternative
The solar-driven coal/Fe304 redox system
Tamaura, T. et al. .I. Phys. IV., 1997, 7, (Cl, 7th International Conference on Ferrites, 1996) C1/685-Cl/686. The paper studies the solar-driven endothermic reaction of coal and magnetite for mixing solar and fossil energies. The overall reaction can be represented by CH, + Fez04 = CO + 3FeO + l/2HZ where x depends on the coal. Solar-driven experiments were conducted using a high-flux solar furnace. Samples were directly exposed for short time intervals to a solar flux irradiation of 300 W/cm’. The carbon content decreased rapidly after suggesting efficient heat transfer and chemical only 1 s exposure, conversion by direct absorption of concentrated solar energy at the reaction site. The proposed solar thermochemical process offers the possibility of simultaneously performing the gasification of coal and reduction of iron oxide, and for producing a fuel with an upgraded calorific value.
Territorial competitiveness of the stand alone photovoltaic systems versus grid electricity supply. A method and a study based on geographical Information systems
97103914
Lopez, F. J. A. et al. Solar Energy, 1997, 61, (2), 107-118. In remote areas, stand alone photovoltaic power systems (SAPPS) are a natural option for electrification outside the grid-connected electricity supply system (GCESS). Three areas are taken into account in the proposed method: photovoltaic and grid sizing. economic analysis, and the integration of information and development of models within geographical information systems (GIS). The results of a case study carried out in the south of Spain show that SAPPS are economically more competitive for a domestic electricity consumption (5 kW h/day) in 69% of this region.
A total fuel cycle approach to reducing greenhouse gas emissions: solar generation technologies as greenhouse gas offsets in U.S. utility systems
9710397 5
Martin, J. A. Solar Energy, 1997, 59, (4-6). 195-203. A total fuel cycle approach is used to evaluate the potential greenhouse gas savings that could result from the deployment of solar generation technologies in utility systems in the US. Total fuel cycle analyses were completed for several renewable and conventional generation technologies to estimate the total greenhouse gas emission contribution from each
‘ARES-a refined simulation program for the sizing and optfmisation of autonomous hybrid energy systems
97103917
Morgan, T. R. et al. Solar Energy, 1997, 59, (4-6) 195-203. Enhancements made to autonomous renewable energy systems (ARES)-I, the Cardiff School of Engineering’s hybrid photovoltaic and wind energy simulation program are presented. The resulting program, ARES-II predicts the battery state of voltage (SoV) rather than its state of charge (SoC). ARES-II is able to predict the occurrence of loss of load thus giving a direct measure of the system autonomy. The enhanced model also predicts the effect of different battery temperatures on the LoL. Incorporating battery temperature effects into the battery algorithm is a novel advancement in hybrid system voltage simulation. Further refinements have also been made to the voltage controller algorithms, Accurate modelling of the non-linear action of the low voltage controller is of paramount importance when predicting loss of load probability for hybrid systems. Combining all the above features and incorporating them into ARES-II produces a simple, accurate and reliable method for hybrid system design and LoL prediction.
97103916 Assessing the maximum fuel savings obtainable in simple wind-diesel systems Beyer, H. G. and Degner, T. Solar Energy, 1997, 61, (1) 5-10. A new statistical method is introduced for determining the upper limit of the obtainable fuel savings in simple wind-diesel systems, applying fixed control rules. When using the optimal control, fuel savings may be estimated from the statistical properties of the time series of the power balance: wind turbine power-load. A time step simulation of the system is compared with the method to confirm its validity. Fuel savings from a simple persistence based control are close to the optimal values. Using this method, the dependence of the fuel savings on the wind climate and the turbulence characteristics at the site may be easily obtained. These results are also compared to the performance data of systems with energy storage.
Electromechanical converters associated to wind turbines and their control
97103919
Sadre, M. Solar Energy, 1997, 61, (2), 119-125. Potential converters to be associated to wind turbines are subject to classification in this work. A detailed classification of electromechanical converters is given. Different methods of converter control are discussed, among which the maximum power point tracking method is of particular interest. It responds well to various criteria such as precision, stability, rapidity and auto-adaptability.
Evaluation of an integrated renewable system for electricity generation in rural areas
97103920
energy
Rozakis, S. et al. Energy Policy, 1997, 25, (3), 337-347. The combination of renewable energy sources for electricity generation at local level, and in particular the case of an isolated area of South Crete, the Frangocastello area has been examined. This study employed F-Cast, a computerized model that has been developed for the simulation of the operation of an integrated system. The energy supply side includes three renewable energy sources, namely wind, micro-hydraulic and biomass, and conventional high-cost electricity supplied by the National Grid. The model is the economic counterpart of an electronic control system that dispatches
Fuel and Energy Abstracts
September 1997
329
08
Steam raising (boiler operation/design)
electricity on an hourly basis. Wind energy introduces uncertainty to the system. Relations among variables are based on three states of the world depending upon the hourly speed of the wind. Biomass is a balancing factor in the supply-demand interaction, as the production of biomass is itself at the same time consuming electricity, as an input. Conclusions are drawn on (a) the optimal combination of renewable energy sources to achieve economic viability of the system (b) effects on agricultural income and local development. and (c) evaluation of renewable energy policies. Time series models to simulate and forecast hourly 97103921 averaged wind speed in Quetta, Pakistan Kamal, L. and Jafri, Y. Z. Solar Energy, 1997, 61, (1) 23-32. Hourly average wind speeds were calculated using stochastic simulation and forecast models. Time series models take into account several basic features of wind speed data including autocorrelation, non-Gaussian distribution and diurnal non-stationarity. An ARMA @, q) process is fitted to wind speed data transformed to make their distribution approximately Gaussian and standardized to remove scattering of transformed data, for a positive correlation of consecutive wind speed observations, Diurnal variations are used to observe forecasts and its dependence on lead times. The ARMA (p, 4) model is suitable for prediction intervals and probability forecasts.
Others, including Economics
Development,
Hydropower and environment in India 97103922 Ranganathan, V. Energy Policy, 1997, 25, (4) 435-438. Renewable and harmless to the environment during operation, hydroelectric power is the cheapest source of energy. Yet environmental activism has obstructed hydrodevelopment throughout the world, and more so in India. The paper calls for a realistic economic-environmental trade-off and improvements in environmental decision making apparatus. Low-temperature ftlterability properties of alterna97103923 tive diesel fuels from vegetable oils Dunn, R. 0. and Bagby, M. 0. Liq. Fuel Ind. Prod. Renewable Resow., Edited by Cundiff, John S. Proc. Liq. Fuel Con& 3rd, 1996, 95-103. American Society of Agricultural Engineers, St. Joseph, MI. Me esters from vegetable oils are an attractive option for combustion in compression ignition (diesel) engines. Recent research has shown that the issue of cold flow properties should be resolved before Me esters are appropriate as an alternative fuel in moderate temperature climates. In North America, fuel systems powered by petroleum middle distillates develop operability problems when overnight ambient temperature drop below -15°C. In contrast, Me esters from soybean oil develop similar problems at temperature near 0°C. This work examines expected operability limits for Me esters through evaluation of their low-temperature filterabilities. Overall, the results of this work demonstrate that emphasis on reducing cloud point (CP) remains the key to developing Me ester diesel fuels with improved low-temperature flow properties. Production technology of refuse-derived fuel (RDF) 97103924 Furuhayashi, K. Kagaku Kogaku, 1997, 61, (7). 502-505. (In Japanese) RDF classification, characteristics of RDF, the manufacturing processes of RDF. and its uses are discussed. A survey: internatfonal aid for renewable energy in 97/03925 the Pacific Islands since the 1970s Yu, X. and Taplin, R. Energy Policy, 1997, 25, (5) 501-516. A survey was conducted between November 1995 and May 1996, to review the situation regarding international aid for renewable energy in the Pacific Island region,. The survey has provided some interesting information regarding bilateral and multilateral aid for renewable energy in the region from the late 70s to 1996. In this paper, the main findings of the survey are presented and discussed. In the future, international aid for renewable energy in the region could be enhanced with further financial assistance, human resources and institutional development, local community involvement, joint ventures and aid efficiency. A winning coalition of advocacy: climate research, 97103926 bureaucracy and ‘alternative’ fuels. Who is driving climate change policy? Boehmer-Christiansen, S. Energy Policy, 1997, 25, (4) 439-444. With regard to global warming, anti-coal and some investment policies are largely justified. Political analysis suggests that these policies are supported by the reinforcing interests of three powerful lobbies: scientific institutions engaged in atmospheric research and earth observation, energy corporations harmed by low fossil fuel prices or supplying ‘clean’ technologies, and numerous interlocking bureaucracies. Together they have succeeded in maintaining momentum in current climate negotiations. The scientific consensus which underpins the climate treaty is examined critically. It is argued that support for emission abatement policies is better explained with
330
Fuel and Energy Abstracts
September
1997
reference to diplomatic interest in the globalisation of energy related investments and trade than understood causality between average global surface warming and fossil fuel combustion.
08
STEAM RAISING Boiler Operation/Design
97103927 Achieving compliance with advanced coal-fired low-emission boiler systems Regan, J. W. et al. Proc. Inf. Tech. Conf: Coal Util. Fuel Syst., 1995, 20, 633-645.
The work undertaken in Phase I of the U.S. Department of Energy (DOE) project, ‘Engineering Development of Advanced Coal-Fired Low-Emissions Boiler Systems’ (LEBS), part of the DOE’s Combustion 2000 Programme, alongside descriptions for future work. The overall objective of the LEBS Project is to dramatically improve environmental performance of future coal-fired power plants without adversely impacting efficiency or the cost of electricity. Short-term technologies will be used to reduce NO, and SO2 emissions to one-third current NSPS limits and particulates to half current NSPS limits. Air toxics must be in compliance and waste must be reduced and made more disposable. The work in Phase I included concept development and evaluation of several subsystems for controlling the emission of SO*, NO,, and particulates. Evaluations were then conducted on potential technologies in various combinations, as part of complete advanced supercritical power generation systems. One system was selected for preliminary design of a commercial generating plant. Acid rain legislation challen es coal pulverizer 97103926 designers to minimize impact on boiler pe r?ormance Piepho, R. R. Proc. Int. Tech. Conf. Coal Uril. Fuel Syst., 1994. 19, 733741. Pulverizer operating flexibility to supply power stations was improved with the combined use of the dynamically controlled variable speed classifier with spring load adjuster. Alternative fuel advanced reburning 97103929 Maly, P. M. et al. Proc. Int. Tech. Conf Coal Ufil. Fuel Sysf., 1997, 22, 815826. Full scale boiler systems have successfully demonstrated reburning as a mature fuel staging NO, control technology. The Energy and Environmental Research Corporation has developed advanced reburning techniques in which reburning is coupled with injection of nitrogen agents and promoter compounds, showing potential for greater than 90% NO, reduction. Test work has shown that a wide range of fuels can effectively be used for reburning, including natural gas, pulverized coal. coal pond fines, biomass and Orimulsion. The test work was conducted at a 1 x 1Oh Btu/h boiler simulation facility. Both natural gas and bituminous coal were tested as main fuels. Efficiency of basic and advanced reburning were characterized as a function of key process variables. The amount of reburn fuel ranged from 10 to 28% of the total heat input. NO, reduction was found to increase both with increasing reburn heat input and reburn zone residence time. Reburn fuel properties found to control performance include fuel nitrogen content, volatiles, fixed carbon, and ash constituents. Advanced reburn tests were conducted in which reburning was coupled with injection of nitrogen agents and/or promoters. The most effective promoter compounds were found to he alkalis, most notably sodium compounds. While reburning with alternative fuels has the potential to cause boiler impacts, such as increased slagging with biomass, these impacts are generally minimized because the reburn fuel comprises only a small fraction of total boiler heat input. The advanced reburning techniques are flexible since they can be readily applied to a variety of waste products and off-specification fuels having low cost. By virtue of their NO, reduction capabilities and its economic efficiency, such techniques are attractive candidates for a wide range of new and retrofit power plant applications. 97103930 Anthracite firing in large utility arch fired boilers Winkin, J. P. and Garcia-Mallol, J. A. Proc. Am. Power Conf., 1997, 59, (2). 1166-1174. Foster Wheeler (FW) has sold 49 arch-fired utility type boilers for burning low volatile type coals including semi-anthracites, anthracites and blends. Forty-one of these boilers have been in operation for many years. Twentythree are in the size range over 100 MWe with a total equivalent capacity of 5130 MWe. Of particular interest to the utility industry are I2 large units in the size range from 250 to 500 MWe. Ten boilers are in operation and two are completing construction. Four of these units burn anthracite, with volatile matter as law as 5.5% on an as-received basis. These were designed to burn anthracite, but some are burning semi-anthracite blends. These boilers have up-to-date arch-firing systems and furnace designs. The boilers sustain the minimum load requirements without support fuel. The database obtained from the above operating experience over a wide range of coals is