- Email: [email protected]
Carbon—carbon composite as anodes for lithiumion battery systems
06 Electrical power supply and utilization (scientific, technical) conditions, thermal limits calculated by the process computer and instruments readings from the travelling in-core probes (TIP) and the local power range monitor (LPRM). Results show an improvement compared with those obtained with the previous methodology based on RECORD/PRESTO-B.
02/01478 Validation of an MCNP4B whole-reactor model for LWR-PROTEUS using ENDF/B- V, ENDF/B- VI and JEF-2.2 cross-section libraries Joneja, O.P. et at. Annals of Nuclear Energy, 2001, 28, (7), 701-713. A detailed three-dimensional, continuous-energy MCNP4B model of the LWR-PROTEUS critical facility has been developed for the analysis of whole-reactor characteristics using ENDF/B-V, ENDF/B-VI and JEF-2.2 cross-section sets. The model has been applied to the determination of the critical loading, as well as the evaluation of reactivity worths for safety/shutdown rods, control rods, and individual driver-region fuel rods. The initially obtained results for the first configuration investigated (Core 1B) indicated that, for the same geometrical and materials specifications, the ENDF/B-V data library yields the closest critical prediction (discrepancy of 640+40 peru), followed by ENDF/B- VI (980+40 pcm) and JEF-2.2 (1340:t:40 peru). The differences in results between the three data libraries were studied by considering the contributions of individual materials to the neutron balance. 235U and 23Su cross-sections from JEF-2.2, for example, explain an effect of ~400 pcm. Refinement of the materials specifications in the MCNP4B whole-reactor model, in particular the impurities assumed for the graphite driver of the driver and reflector regions, has been shown to reduce the final discrepancy of the ENDF/B-V based Kerr result to ~0.2%. The MCNP4B results for relative reactivity effects, such as control rod worths, are found to agree within experimental errors with the measured values.
Economics, policy, supplies, forecasts 02/01479 Assimilation of public opinions in nuclear decision-making using risk perception Sohn, K.Y. et al. Annal.~ of Nuclear Energy, 2001, 28, (6), 553-563. A method of assimilating public opinions in the decision-making process has been developed in this study. The proposed method will resolve the major shortcomings of existing decision-making models, which are deficient in, or missing public participation during the process. In the nuclear-related decision-making process, a particular concern of the public is nuclear safety, which is numerically characterized by risk. In reality, it is the risk that each individual perceives that is very important. Hence, the public perception of risk has been employed as a key decision-making element in representing public opinions. To quantify the public perception of risk, the psychometric model is used. Psychological risk dimensions are first assessed using factor analysis and a set of factors is identified for optimized computation. Expert opinions formulated by a group of selected professionals and experts are then aggregated with the public opinions. To gather public and expert opinions, separate polls were conducted in this study. In the aggregation, the analytic hierarchy process (AHP) and multiattribute utility analysis (MAUA) were employed, and for uncertainty analysis, a fuzzy set based approach was adopted. This method has been applied to analyse six options for spent fuel management in Korea for a case study. As expected, the results of the case study show that public risk perception is an important element in nuclear-related decision-making processes.
02/01480 Economic feasibility of heat supply from simple and safe nuclear plants Tian, J. Annals of Nuclear Energy, 2001, 28, (11), 1145-1150. Use of nuclear energy as a heating source is greatly'challenged by the economic factor since the nuclear heating reactors have relative small size and often the lower plant load factor. However, use of very simple reactor could be a possible way to economically supply heat. A deep pool reactor (DPR) has been designed for this purpose. The DPR is a novel design of pool type reactor for heat only supply. The reactor core is put in a deep pool. By only putting light static water pressure on the core coolant, the DPR will be able to meet the temperature requirements of heat supply for district heating. The feature of simplicity and safety of DPR makes a decrease of investment cost compared to other reactors for heating only purposes. According to the economical assessments, the capital investment to build a DPR plant is much less than that of a pressurized reactor with pressure vessels. For the DPR with 120 or 200 MW output, it can bear the economical comparison with a usual coal-fired heating plant. Some special means taken in DPR design make an increase of the burn-up level of spent fuel and a decrease of fuel cost. The feasibility studies of DPR in some cities in China show that heating cost using nuclear energy is only one
190 Fuel and Energy Abstracts May 2002
third of that by coal and only one tenth of that by nature gas. Therefore, the DPR nuclear heating system provides an economically attractive solution to satisfy the demands of district heating without contributing to increasing green-house gas emissions.
06
ELECTRICAL POWER SUPPLY A N D UTILIZATION Scientific, technical
02/01481 A neuro-fuzzy program approach for evaluating electric power generation systems Mamlook, R. et or. Energy, 2001, 26, (6), 619-632. This paper uses neuro-fuzzy programming to perform a comparison between the different electricity power generation options for Jordan. Different systems are considered: in addition to fossil fuel power plants, nuclear, solar, wind, and hydropower systems are evaluated. Based on cost-to-benefit ratios, results show that solar, wind, and hydropower are considered to be the best systems for electricity power generation. On the other hand, nuclear electricity turns out to be the worst choice, followed by fossil fuel electric power.
02/01482 A study on a thermally regenerative fuel cell utilizing low-temperature thermal energy Ando, Y. et al. Energy Conversion and Management, 2001, 42, (15--17), 1807-1816. This paper examines a thermally regenerative fuel cell operated by lowtemperature thermal energy such as solar thermal energy and lowtemperature waste heat. It consists of the chemical reaction of 2proponol dehydrogenation at the negative electrode and the acetone hydrogenation at the positive electrode by using the principle of a fuel cell. As the first step of this research, the acetone hydrogenation w a s investigated. Activity of ruthenium and platinum composite catalyst (3 wt%) supported on a carbon plate for the reaction was much higher than that of ruthenium catalyst or platinum catalyst at 90°C. Activity of ruthenium and platinum composite catalyst was much higher when it was supported on carbon felt or cloth than a plate. A ruthenium and platinum composite catalyst supported on carbon cloth as electrodes of the cell was adopted and examined its characteristics. First, a molecular hydrogen was used instead of 2-proponal as a proton source. Under this condition, the open-circuit voltage and the short-circuit current were 104.6 mV and 8.98 mA, respectively. As loading of the catalyst became higher, the short-circuit current also became larger. The shortcircuit currents were 11.5 and 26.7 mA when loading of the catalyst was 5 and 30 wt%, respectively. Then we used 2-propanol as a proton source. Effects of 2-propanol concentration, catalyst loading and reaction temperature on the cell efficiency were investigated. When 2-propanol was diluted with water and supplied to the negative electrode, it was shown that 2-propanol concentration of 50-70 vol% was the best for cell efficiency. The cell efficiency was improved with increasing catalyst loading. As for reaction temperature, 80°C was better to improve the efficiency.
02/01483 plants.
Advanced automation offers new life to coal-fired
McFarland, G. Power, 2001, 145, (4), 62--64. The impact of new technologies on the operation of coal-fired power plants is examined in this paper. These technologies include openarchitecture distributed control system and process-optimization software, along with more comprehensive approaches to instrumentation and control. These advances in process control and automation c a n reduce emissions, increase thermal efficiency, and cut operation and maintenance costs. For a typical process-control modernization, a coalfired plant can anticipate up to a 40% reduction in maintenance labour effort-hours and material costs.
02/01484 Carbon-carbon composite as anodes for lithiumion battery systems Hossain, S. et al. Journal of Power Sources, 2001, 96, (1), 5-13. Carbon-carbon (C-C) composite has been investigated as an anode f o r lithium-ion battery systems. The composite electrode delivers high reversible capacity and very low irreversible capacity loss. The test results of lithium-ion cells made with the C-C composite anode show
06 Electrical power supply and utilization (scientific, technical) many advantages, such as excellent performance and enhanced safety. The performance improvement is achieved because of strong mechanical integrity (cycle life) and absence of binder (shelf life) in C-C composite. The enhancement in safety comes from high thermal conductivity, fire retardant characteristics and an acceptable ability to overcharge and overdischarge.
02/01485 Coal utilization and dust collection technology. (Part 2). High temperature duet collection technology on new type high efficiency power generation Makino, H. Funtai Kogaku Kaishi, 2001, 38, (9), 652-658. (In Japanese) A review on power generation by combustion of coals using gas turbines, fuel cells. High dust collection technology is an important factor in promoting these methods.
02/01486 Contingency rankingfor voltage collapse using parallel self-organizing hierarchical neural network Pandit, M. et al. Electrical Power and Energy Systems, 2001, 23, (5), 369-379. On-line monitoring of the power system voltage security has become a vital factor electric utilities. This paper proposes a voltage contingency ranking approach based on parallel self-organizing hierarchical neural network (PSHNN). Loadability margin to voltage collapse following a contingency has been used to rank the contingencies. PSHNN is a multi-stage neural network where the stages operate in parallel rather than in series during testing. The number of ANNs required is drastically reduced by adopting a clustering technique to group contingencies of similar severity into one cluster. Entropy based feature selection has been employed to reduce the dimensionality of the ANN. Once trained, the proposed ANN model is capable of ranking the voltage contingencies under varying load conditions, on line. The effectiveness of the proposed method has been demonstrated by applying it for contingency ranking of IEEE 30-bus system and a practical 75-bus Indian system.
02/01487
CO2 conversion system and economic evaluation
Niwa, S. C02 Koteika, Kakuri no Saishin Gijutsu, 2000, 247-259. (In Japanese) Edited by Inui T. Conceptual design of natural-energy-based power generation systems is described, in which CO2 from coal-fired power plants is liquefied and hydrogenated to form MeOH for power generation systems. H2 needed for the above MeOH synthesis process is produced by water electrolysis with power supply from natural energy power generation systems using hydraulic or solar power. The system's economic feasibility is evaluated.
02/01488 Direct methanol-air fuel cells with membranes plus circulating electrolyte Kordesch, K. et al. Journal of Power Sources, 2001, 96, (1), 200-203. A new approach for direct methanol-air fuel cells (DMFC), with the advantage of reduced crossover is discussed in this paper. Methanol traces in the circulated electrolyte are recovered and COz bubbles in the cells are removed due to the forced methanol-electrolyte stream through the cell. Degradation of the catalyst is reduced since fuel cell electrodes degrade on activated stand without load to a higher extent than under load because high voltage on open circuit promotes carbon oxidation, catalyst changes, etc. Therefore, life expectancy increases with circulating electrolyte by removing the electrolyte from the cells between operating periods.
02/01489
Distributed generation: a definition
Ackermann, T. et al. Electric Power Systems Research, 2001, 57, (3), 195-204. Distributed generation (DG) is expected to become more important in the future g.eneration system. The current literature, however, does not use a cons:stent definition of DG. This paper discusses the relevant issues and aims at providing a general definition for distributed power generation in competitive electricity markets. In general, DG can be defined as electric power generation within distribution networks or on the customer side of the network. In addition, the terms distributed resources, distributed capacity and distributed utility are discussed. Network and connection issues of distributed generation are presented, tOO.
02/01490 Effects of a cogeneration plant on the system imbalance of a distribution feeder connected with It Chen, T. and Yang, W. Electrical Power and Energy Systems, 2001, 23, (5), 381-388. This paper has evaluated the effects of a cogeneration plant on the system imbalances of a radial three-phase four-wire distribution feeder connected with it. A three-phase four-wire distribution feeder is often operated under unbalanced circumstances by reason of unequal individual phase loads. The degree of voltage and current imbalances in a three-phase four-wire feeder might be significantly enlarged while
a cogeneration plant is operating in parallel. In this paper, a sample distribution feeder with a cogeneration plant connected at its end was simulated. The effects of the cogeneration plant on the voltage imbalances, current imbalances, and system loss of the specific distribution feeder were evaluated based on the simulation results. The simulation results and conclusion are of value to distribution engineers for planning and operating such a system.
02/01491 Electric power units operating on solid oxide fuels cells. Results and prospects Dudnik, O.M. et al. Energy. Elektrif. (Kiev), 2001, 4, 27--44. (In Ukrainian) A review with refs. on the world-wide achievements in developing new hybrid cogeneration power plants operating on solid oxide fuels cells (SOFCs) with 1 MW electric power. A brief description of the main structural and operating characteristics of contemporary SOFCs and their advantages is given along with measures for a further increase of their electricity efficiency. The effectiveness of integrating of high-rpm gas turbine units in the SOFC-based power plants in Germany and USA for increasing the electricity efficiency is demonstrated. The method of the calculation of the hybrid SOFC-based power plants is introduced. The design of a new ecologically pure SOFC-based plant employing the technology of gasification of Ukrainian high-ash coal in a circulating fluidized bed under pressure is developed with the prospect of 500 kW power under appropriate conditions.
02/01492 Electrochemical power sources for unmanned underwater vehicles used in deep sea survey operations Hasvold, ~. and Stcrkersen, N. Journal o[Power Sources, 2001, 96, (1), 252-258. A comparison of available energy from different power sources for unmanned underwater vehicles, discharged at atmospheric pressure or at ambient pressure, has been undertaken. The basis for the comparison has been a neutrally buoyant power source with a total volume of 300 lires. For deep diving vehicles, the use of batteries that can operate at ambient pressure is advantageous. This advantage increases as the mean density of the battery decreases and as the mean density of the pressure hull increases. A fuel cell using spherical gas containers is also an attractive power source for deep diving survey underwater vehicles.
02/01493 Evolution of power sources for implantable cardioverter defibrillators Crespi, A.M. et al. Journal of Power Sources, 2001, 96, (1), 33-38. The evolution of seven generations of power sources for implantable cardioverter defibrillators (ICD) is presented. The packaging efficiency of the power sources has steadily increased, resulting in smaller, lighter batteries while maintaining the required electrical characteristics. The main areas for improvement were reduction of headspace volume, reduction of separator volume, and a change from a two-cell battery to a single cell.
02/01494 Experimental study on the dynamic characteristics of kW-scale molten carbonate fuel cell systems Kang, B.S. et al. Journal of Power Sources, 2001, 94, (1), 51-62. The aim of this work is to develop dynamic models for two types of kWscale molten carbonate fuel cell (MCFC) systems of the basis of experimental data. the dynamic models are represented as a 3 x 3 transfer function matrix for a multi-input and multi-output (MIMO) system with three inputs and three outputs. The three controlled variables which severely affect the stack performance and lifetime are the temperature difference in the stack and the pressure drop at the anode and the cathode. Three manipulated variables, namely, current load, fuel and oxidant utilization, are selected to keep the three controlled variables within their safety limits for the reliable operation and protection of the system in case of emergency. Each element in the transfer function matrix is in the form of a first-order model using a simple, unit step, response test during operation. The non-zero offdiagonal elements in the transfer function matrix show that some interactions exist among the operating variables, and two zeros show no interaction between fuel and oxidant flow without gas cross-over. The stability of both dynamic models is analysed using the relative gain array (RGA) method. Large diagonal elements in the RGA matrix show that the pairing between the manipulated and controlled variable is appropriate. Proper pairing is also proven by the singular value analysis (SVA) method with a smaller singular value in each system.
02/01495 Highly efficient electricity generation through a hybrid molten carbonate fuel cell-closed loop gas turbine plant Lunghi, P. et al. Energy Conversion and Management, 2001, 42, (14), 1657-1672.
Fuel and Energy Abstracts May 2002
191
02/01478 Validation of an MCNP4B whole-reactor model for LWR-PROTEUS using ENDF/B- V, ENDF/B- VI and JEF-2.2 cross-section libraries Joneja, O.P. et at. Annals of Nuclear Energy, 2001, 28, (7), 701-713. A detailed three-dimensional, continuous-energy MCNP4B model of the LWR-PROTEUS critical facility has been developed for the analysis of whole-reactor characteristics using ENDF/B-V, ENDF/B-VI and JEF-2.2 cross-section sets. The model has been applied to the determination of the critical loading, as well as the evaluation of reactivity worths for safety/shutdown rods, control rods, and individual driver-region fuel rods. The initially obtained results for the first configuration investigated (Core 1B) indicated that, for the same geometrical and materials specifications, the ENDF/B-V data library yields the closest critical prediction (discrepancy of 640+40 peru), followed by ENDF/B- VI (980+40 pcm) and JEF-2.2 (1340:t:40 peru). The differences in results between the three data libraries were studied by considering the contributions of individual materials to the neutron balance. 235U and 23Su cross-sections from JEF-2.2, for example, explain an effect of ~400 pcm. Refinement of the materials specifications in the MCNP4B whole-reactor model, in particular the impurities assumed for the graphite driver of the driver and reflector regions, has been shown to reduce the final discrepancy of the ENDF/B-V based Kerr result to ~0.2%. The MCNP4B results for relative reactivity effects, such as control rod worths, are found to agree within experimental errors with the measured values.
Economics, policy, supplies, forecasts 02/01479 Assimilation of public opinions in nuclear decision-making using risk perception Sohn, K.Y. et al. Annal.~ of Nuclear Energy, 2001, 28, (6), 553-563. A method of assimilating public opinions in the decision-making process has been developed in this study. The proposed method will resolve the major shortcomings of existing decision-making models, which are deficient in, or missing public participation during the process. In the nuclear-related decision-making process, a particular concern of the public is nuclear safety, which is numerically characterized by risk. In reality, it is the risk that each individual perceives that is very important. Hence, the public perception of risk has been employed as a key decision-making element in representing public opinions. To quantify the public perception of risk, the psychometric model is used. Psychological risk dimensions are first assessed using factor analysis and a set of factors is identified for optimized computation. Expert opinions formulated by a group of selected professionals and experts are then aggregated with the public opinions. To gather public and expert opinions, separate polls were conducted in this study. In the aggregation, the analytic hierarchy process (AHP) and multiattribute utility analysis (MAUA) were employed, and for uncertainty analysis, a fuzzy set based approach was adopted. This method has been applied to analyse six options for spent fuel management in Korea for a case study. As expected, the results of the case study show that public risk perception is an important element in nuclear-related decision-making processes.
02/01480 Economic feasibility of heat supply from simple and safe nuclear plants Tian, J. Annals of Nuclear Energy, 2001, 28, (11), 1145-1150. Use of nuclear energy as a heating source is greatly'challenged by the economic factor since the nuclear heating reactors have relative small size and often the lower plant load factor. However, use of very simple reactor could be a possible way to economically supply heat. A deep pool reactor (DPR) has been designed for this purpose. The DPR is a novel design of pool type reactor for heat only supply. The reactor core is put in a deep pool. By only putting light static water pressure on the core coolant, the DPR will be able to meet the temperature requirements of heat supply for district heating. The feature of simplicity and safety of DPR makes a decrease of investment cost compared to other reactors for heating only purposes. According to the economical assessments, the capital investment to build a DPR plant is much less than that of a pressurized reactor with pressure vessels. For the DPR with 120 or 200 MW output, it can bear the economical comparison with a usual coal-fired heating plant. Some special means taken in DPR design make an increase of the burn-up level of spent fuel and a decrease of fuel cost. The feasibility studies of DPR in some cities in China show that heating cost using nuclear energy is only one
190 Fuel and Energy Abstracts May 2002
third of that by coal and only one tenth of that by nature gas. Therefore, the DPR nuclear heating system provides an economically attractive solution to satisfy the demands of district heating without contributing to increasing green-house gas emissions.
06
ELECTRICAL POWER SUPPLY A N D UTILIZATION Scientific, technical
02/01481 A neuro-fuzzy program approach for evaluating electric power generation systems Mamlook, R. et or. Energy, 2001, 26, (6), 619-632. This paper uses neuro-fuzzy programming to perform a comparison between the different electricity power generation options for Jordan. Different systems are considered: in addition to fossil fuel power plants, nuclear, solar, wind, and hydropower systems are evaluated. Based on cost-to-benefit ratios, results show that solar, wind, and hydropower are considered to be the best systems for electricity power generation. On the other hand, nuclear electricity turns out to be the worst choice, followed by fossil fuel electric power.
02/01482 A study on a thermally regenerative fuel cell utilizing low-temperature thermal energy Ando, Y. et al. Energy Conversion and Management, 2001, 42, (15--17), 1807-1816. This paper examines a thermally regenerative fuel cell operated by lowtemperature thermal energy such as solar thermal energy and lowtemperature waste heat. It consists of the chemical reaction of 2proponol dehydrogenation at the negative electrode and the acetone hydrogenation at the positive electrode by using the principle of a fuel cell. As the first step of this research, the acetone hydrogenation w a s investigated. Activity of ruthenium and platinum composite catalyst (3 wt%) supported on a carbon plate for the reaction was much higher than that of ruthenium catalyst or platinum catalyst at 90°C. Activity of ruthenium and platinum composite catalyst was much higher when it was supported on carbon felt or cloth than a plate. A ruthenium and platinum composite catalyst supported on carbon cloth as electrodes of the cell was adopted and examined its characteristics. First, a molecular hydrogen was used instead of 2-proponal as a proton source. Under this condition, the open-circuit voltage and the short-circuit current were 104.6 mV and 8.98 mA, respectively. As loading of the catalyst became higher, the short-circuit current also became larger. The shortcircuit currents were 11.5 and 26.7 mA when loading of the catalyst was 5 and 30 wt%, respectively. Then we used 2-propanol as a proton source. Effects of 2-propanol concentration, catalyst loading and reaction temperature on the cell efficiency were investigated. When 2-propanol was diluted with water and supplied to the negative electrode, it was shown that 2-propanol concentration of 50-70 vol% was the best for cell efficiency. The cell efficiency was improved with increasing catalyst loading. As for reaction temperature, 80°C was better to improve the efficiency.
02/01483 plants.
Advanced automation offers new life to coal-fired
McFarland, G. Power, 2001, 145, (4), 62--64. The impact of new technologies on the operation of coal-fired power plants is examined in this paper. These technologies include openarchitecture distributed control system and process-optimization software, along with more comprehensive approaches to instrumentation and control. These advances in process control and automation c a n reduce emissions, increase thermal efficiency, and cut operation and maintenance costs. For a typical process-control modernization, a coalfired plant can anticipate up to a 40% reduction in maintenance labour effort-hours and material costs.
02/01484 Carbon-carbon composite as anodes for lithiumion battery systems Hossain, S. et al. Journal of Power Sources, 2001, 96, (1), 5-13. Carbon-carbon (C-C) composite has been investigated as an anode f o r lithium-ion battery systems. The composite electrode delivers high reversible capacity and very low irreversible capacity loss. The test results of lithium-ion cells made with the C-C composite anode show
06 Electrical power supply and utilization (scientific, technical) many advantages, such as excellent performance and enhanced safety. The performance improvement is achieved because of strong mechanical integrity (cycle life) and absence of binder (shelf life) in C-C composite. The enhancement in safety comes from high thermal conductivity, fire retardant characteristics and an acceptable ability to overcharge and overdischarge.
02/01485 Coal utilization and dust collection technology. (Part 2). High temperature duet collection technology on new type high efficiency power generation Makino, H. Funtai Kogaku Kaishi, 2001, 38, (9), 652-658. (In Japanese) A review on power generation by combustion of coals using gas turbines, fuel cells. High dust collection technology is an important factor in promoting these methods.
02/01486 Contingency rankingfor voltage collapse using parallel self-organizing hierarchical neural network Pandit, M. et al. Electrical Power and Energy Systems, 2001, 23, (5), 369-379. On-line monitoring of the power system voltage security has become a vital factor electric utilities. This paper proposes a voltage contingency ranking approach based on parallel self-organizing hierarchical neural network (PSHNN). Loadability margin to voltage collapse following a contingency has been used to rank the contingencies. PSHNN is a multi-stage neural network where the stages operate in parallel rather than in series during testing. The number of ANNs required is drastically reduced by adopting a clustering technique to group contingencies of similar severity into one cluster. Entropy based feature selection has been employed to reduce the dimensionality of the ANN. Once trained, the proposed ANN model is capable of ranking the voltage contingencies under varying load conditions, on line. The effectiveness of the proposed method has been demonstrated by applying it for contingency ranking of IEEE 30-bus system and a practical 75-bus Indian system.
02/01487
CO2 conversion system and economic evaluation
Niwa, S. C02 Koteika, Kakuri no Saishin Gijutsu, 2000, 247-259. (In Japanese) Edited by Inui T. Conceptual design of natural-energy-based power generation systems is described, in which CO2 from coal-fired power plants is liquefied and hydrogenated to form MeOH for power generation systems. H2 needed for the above MeOH synthesis process is produced by water electrolysis with power supply from natural energy power generation systems using hydraulic or solar power. The system's economic feasibility is evaluated.
02/01488 Direct methanol-air fuel cells with membranes plus circulating electrolyte Kordesch, K. et al. Journal of Power Sources, 2001, 96, (1), 200-203. A new approach for direct methanol-air fuel cells (DMFC), with the advantage of reduced crossover is discussed in this paper. Methanol traces in the circulated electrolyte are recovered and COz bubbles in the cells are removed due to the forced methanol-electrolyte stream through the cell. Degradation of the catalyst is reduced since fuel cell electrodes degrade on activated stand without load to a higher extent than under load because high voltage on open circuit promotes carbon oxidation, catalyst changes, etc. Therefore, life expectancy increases with circulating electrolyte by removing the electrolyte from the cells between operating periods.
02/01489
Distributed generation: a definition
Ackermann, T. et al. Electric Power Systems Research, 2001, 57, (3), 195-204. Distributed generation (DG) is expected to become more important in the future g.eneration system. The current literature, however, does not use a cons:stent definition of DG. This paper discusses the relevant issues and aims at providing a general definition for distributed power generation in competitive electricity markets. In general, DG can be defined as electric power generation within distribution networks or on the customer side of the network. In addition, the terms distributed resources, distributed capacity and distributed utility are discussed. Network and connection issues of distributed generation are presented, tOO.
02/01490 Effects of a cogeneration plant on the system imbalance of a distribution feeder connected with It Chen, T. and Yang, W. Electrical Power and Energy Systems, 2001, 23, (5), 381-388. This paper has evaluated the effects of a cogeneration plant on the system imbalances of a radial three-phase four-wire distribution feeder connected with it. A three-phase four-wire distribution feeder is often operated under unbalanced circumstances by reason of unequal individual phase loads. The degree of voltage and current imbalances in a three-phase four-wire feeder might be significantly enlarged while
a cogeneration plant is operating in parallel. In this paper, a sample distribution feeder with a cogeneration plant connected at its end was simulated. The effects of the cogeneration plant on the voltage imbalances, current imbalances, and system loss of the specific distribution feeder were evaluated based on the simulation results. The simulation results and conclusion are of value to distribution engineers for planning and operating such a system.
02/01491 Electric power units operating on solid oxide fuels cells. Results and prospects Dudnik, O.M. et al. Energy. Elektrif. (Kiev), 2001, 4, 27--44. (In Ukrainian) A review with refs. on the world-wide achievements in developing new hybrid cogeneration power plants operating on solid oxide fuels cells (SOFCs) with 1 MW electric power. A brief description of the main structural and operating characteristics of contemporary SOFCs and their advantages is given along with measures for a further increase of their electricity efficiency. The effectiveness of integrating of high-rpm gas turbine units in the SOFC-based power plants in Germany and USA for increasing the electricity efficiency is demonstrated. The method of the calculation of the hybrid SOFC-based power plants is introduced. The design of a new ecologically pure SOFC-based plant employing the technology of gasification of Ukrainian high-ash coal in a circulating fluidized bed under pressure is developed with the prospect of 500 kW power under appropriate conditions.
02/01492 Electrochemical power sources for unmanned underwater vehicles used in deep sea survey operations Hasvold, ~. and Stcrkersen, N. Journal o[Power Sources, 2001, 96, (1), 252-258. A comparison of available energy from different power sources for unmanned underwater vehicles, discharged at atmospheric pressure or at ambient pressure, has been undertaken. The basis for the comparison has been a neutrally buoyant power source with a total volume of 300 lires. For deep diving vehicles, the use of batteries that can operate at ambient pressure is advantageous. This advantage increases as the mean density of the battery decreases and as the mean density of the pressure hull increases. A fuel cell using spherical gas containers is also an attractive power source for deep diving survey underwater vehicles.
02/01493 Evolution of power sources for implantable cardioverter defibrillators Crespi, A.M. et al. Journal of Power Sources, 2001, 96, (1), 33-38. The evolution of seven generations of power sources for implantable cardioverter defibrillators (ICD) is presented. The packaging efficiency of the power sources has steadily increased, resulting in smaller, lighter batteries while maintaining the required electrical characteristics. The main areas for improvement were reduction of headspace volume, reduction of separator volume, and a change from a two-cell battery to a single cell.
02/01494 Experimental study on the dynamic characteristics of kW-scale molten carbonate fuel cell systems Kang, B.S. et al. Journal of Power Sources, 2001, 94, (1), 51-62. The aim of this work is to develop dynamic models for two types of kWscale molten carbonate fuel cell (MCFC) systems of the basis of experimental data. the dynamic models are represented as a 3 x 3 transfer function matrix for a multi-input and multi-output (MIMO) system with three inputs and three outputs. The three controlled variables which severely affect the stack performance and lifetime are the temperature difference in the stack and the pressure drop at the anode and the cathode. Three manipulated variables, namely, current load, fuel and oxidant utilization, are selected to keep the three controlled variables within their safety limits for the reliable operation and protection of the system in case of emergency. Each element in the transfer function matrix is in the form of a first-order model using a simple, unit step, response test during operation. The non-zero offdiagonal elements in the transfer function matrix show that some interactions exist among the operating variables, and two zeros show no interaction between fuel and oxidant flow without gas cross-over. The stability of both dynamic models is analysed using the relative gain array (RGA) method. Large diagonal elements in the RGA matrix show that the pairing between the manipulated and controlled variable is appropriate. Proper pairing is also proven by the singular value analysis (SVA) method with a smaller singular value in each system.
02/01495 Highly efficient electricity generation through a hybrid molten carbonate fuel cell-closed loop gas turbine plant Lunghi, P. et al. Energy Conversion and Management, 2001, 42, (14), 1657-1672.
Fuel and Energy Abstracts May 2002
191