- Email: [email protected]
04721 Ultrasonically treated LiV3O8 as a cathode material for secondary lithium batteries
07
structure of the transfer function of the stabilizers has been chosen a priori. A usual phase lead characteristic has been included in the constraints, Numerical results are presented for a three-machine power system.
07
Alternative energy sources (bioconversion
ALTERNATIVE SOURCES
energy)
ENERGY
Ultrasonically treated LiVBOe as a cathode material lithium batteries Kumagai, N. and Yu, A. J. EIecfrorhemical Sm.. 1997, 144, (3) 830-835.
97104721
for secondary
LiVIOx was ultrasonically treated to improve its electrochemical behaviour as a cathode material for secondary lithium batteries. The treated products in water were characterized by X-ray diffractometry, thermogravimetric analysis, SEM, and specific surface area measurements. These measurements showed that the ultrasonic treatment process of crystallized LiVIOx causes a decrease in crystallinity and considerable increase in specific surface area and inter-layer spacing. The product was ultrasonically treated in water for 3 h and then heat treated at 250°C for 6 h. It showed a high initial discharge capacity of 283 mA-h/g active material, which was 62% higher than that of the starting material, and was charge-discharge cycled without a large capacity loss during 40 cycles. Both the specific capacity and the cycling hehaviour can improve with ultrasonic treatment of LiV70x
On undervoltage
97104722
load shedding
in power systems
Arnhorg, S. cr ol. Electri~rl Porter nrrd Errerm Systems, 1997, 19, (2). 14l149. An analytical hasis and criterion for undervoltage load shedding in power systems ts discussed. If the voltage is unstable, the proposed undervoltage load shed criterion can he used to calculate the amount of load must he shed to stabilise the voltage magnitude. Using a dynamic load model facilitated the forming of criterion which gives the amount of load which must he shed to stabilize the system in each point in time. The criterion is general and can be applied to any power system.
Bioconversion
Energy
97104727 Advantages and disadvantages of biomass fuels on a fundamental combustion basis in fluidized beds Wartha, C. et 01. Biomass Enera Em+ron., Proc. Eur. Bioenrrg) Conf., 9th., 1996, 2, 1215-1220. Edited by Chartier, P.. Elsevier, Oxford, UK. An evaluation of biomass fuels is presented on a fundamental combustion basis. Their combustion characteristics and emission hehaviour in relation to various other fuels such as bituminous and sub-hituminous coals, pressboard and hardhoard chips, sewage sludge pellets and plastics. The experiments are performed in a laboratoryscale multi-mode fluidized bed comhustor made of quartz glass which is exclusively electrically heated. The oxygen partial pressure is varied between 0 and 21 kPa, and the bed temperature between 600 and 900°C the superficial gas velocity hetween 0.2 and 3 m/s. The emissions of the single fuel particles are quantified and a carbon mass balance is performed. A classification system based on the carbon release rate is used. The conversion rates of fuel nitrogen to the gaseous species NO, NzO, and HCN are given and used for comparison of the biomass fuels with fossil fuels and fuels from industrial processes.
97104726 Agriculture-based vey of economic issues
Economics,
Policy, Supplies,
Forecasts
The 97104723 molten carbonate
influence of low operating temperature fuel cells decay processes lnr. J. Ener~ Rex., 1997, 21. (12), 1061-1070.
on
Freni, S. el al. This paper describes studies carried out to investigate the influence of low operating temperature (873 K) on the decay mechanisms that affect the endurance of a molten carbonate fuel cell.
Optimal 97104724 tion networks
planning
of rural medium voltage
distribu-
Nahman. .I. and Sniric, .I. Electr&rl Power& Etter~)’ Systenrs, 1997, 19. (8). 549-556. The proposed model could select the main initial parameters and timing of the reconstructions of rural distribution networks in long-term planning to meet the increasing load demands with minimum total-present-worth cost. The model incorporates capital and exploitation costs as well as the costs due to undelivered energy and load curtailments. The optimal investment policy is determined using a constrained dynamic programming technique which indicates the hest choice among possible options.
An options model for electric power markets 97104725 Ghosh, K. and Ramesh, V. C. Electrical Power and Energy Sysiems, 1997, 19, (2). 75-85. On an international scale, the once regulated and monopolistic electric utility industry is facing deregulation and competition on the world market. This paper investigates the development of an options market for hulk power trading in a market set-up, while considering power system planning and operational constraints and/or requirements. The different market based financial derivative instruments which can be used to trade electrical power in bulk are examined and the role of established tools such as Optimal Power Flow (OPF) in developing a price for bulk power transactions under a market based set-up is discussed. 97104726 combination
Short term method
load
forecasting
using
a Bayesian
Kiartzis. S. (‘I ul. Electrical Powrr und Energy S_ystems. 1997, 19. (3) 165-170. Based on the combination of an artificial neural network (ANN) predictor and two linear regression (LR) predictors, the Bayesian Combined Predictor (BCP). a prohahilistically motivated predictor for Short Term Load Forecasting (STLF) is presented. The method is applied to STLF for the Greek Pubhc Power Corporation dispatching centre of Crete, using 1994 data, and daily load profiles are obtained. Statistical analysis of prediction errors reveals that during given time periods the ANN predictor consistently produces better forecasts for certain hours of the day, while the LR predictor produces better forecasts for the rest. The combined prediction is a weighted sum of the ANN and LR predictions, where the weights are computed using an adaptive update of the Bayesian posterior probability of each predictor, based on their past predictive performance. Results of testing reveals that the proposed method outperforms both ANN and LR predictions.
biomass
energy
supply-a
sur-
Lunnan, A. Energy Policy. 1997. 25. (6) 573-582. There is a large potential for the production of energy crops on agricultural land. Most of the biomass produced has alternative use as food, feed or fibre. In most cases, energy utilization of the biomass is far from competitive given today’s prices. If dedicated energy crops are to he more competitive in the future, fossil energy prices must increase relative to the price of food, feed and fihre. Considerable spread exists among puhlished future fossil fuel price forecasts. From currently available evidence, there is small hope that fossil energy prices will increase relative to the price of food and feed. The impact on the greenhouse gas balance is the most important positive factor for biomass energy, compared with fossil energy. For the time being there is no consensus among economists about the magnitude of the environmental costs of greenhouse gas emissions. Reasonable values on the external effects are in most cases not enough to make agriculture-based biomass energy competitive. Considerable government subsidies are needed. There is, however, no economic justification for such suhsidies. Biomass energy systems using low quality biomass, originating as a hyproduct from the production of food, feed and/or fihre. is the most promising niche for energy from agricultural biomass.
Analysis of combustion 97104729 of coal with biomass fuels
products
from the cofiring
Belle-Oudry,
D. A. and Dayton, D. C. Pre/>r. Pup. Am. Chem. Sot., flit,. 1997, 42, (4) 1096-l 100. The amounts of NO and SOz during the combustion of the coahhiomass blends were detected using molecular beam mass spectrometry. The results indicated that any decrease in the amounts of these compounds was the result of diluting the nitrogen and sulfur present in the fuel blend. A hypothesis was advanced suggesting the chlorine released during the combustion of the coal/biomass blends may have been affected by mending the two fuels beyond a dilution effect. Furl
Chem.,
Behavior of trace elements 97104730 biomass and sewage sludge
during the pyrolysis
of
Storm, C. et al. DGMK Tugzqshrr., 1997, 9703, (Proceedings ICCS ‘Y7, Volume 2) 721-724. Increasing interest in biomass and sewage sludge has been noted in power plant technology as sources of COz-neutral fuels. Besides using solid pulverized biomass or sewage sludge as an additional fuel in coal-fired boilers, a further possibility to run a combined coal and biomass/sewage sludge process is to pre-pyrolyse or pre-gasify biomass or sewage sludge and to use the generated gas as reburn fuel in the coal-fired boiler. The separation of coal and biomass/sewage sludge ash within this cocomhustion process enables a specialized use of the residuals. The advantage of this pre-treatment process is that undesired components like inorganic compounds can be kept away from the coal-fired boiler. Investigations on the pyrolysis behaviour of biofuels continue with regard on the path of trace elements, like heavy metals, and alkali compounds, during the pyrolysis process varying different parameters. Detailed analysis of char samples, collected from two locations of the test facility with drfferent characteristic particle sizes, illustrate the behaviour of trace elements during pyrolysis at different temperatures. The investigation of biomass pyrolysis shows a specific behaviour of the most important elements depending on the pyrolysis temperature and the particle size of the pyrolysed char. During the pyrolysis of sewage sludge there is no distinct influence of the temperature on the release of the investigated components.
Fuel and Energy Abstracts
November
1997
409
structure of the transfer function of the stabilizers has been chosen a priori. A usual phase lead characteristic has been included in the constraints, Numerical results are presented for a three-machine power system.
07
Alternative energy sources (bioconversion
ALTERNATIVE SOURCES
energy)
ENERGY
Ultrasonically treated LiVBOe as a cathode material lithium batteries Kumagai, N. and Yu, A. J. EIecfrorhemical Sm.. 1997, 144, (3) 830-835.
97104721
for secondary
LiVIOx was ultrasonically treated to improve its electrochemical behaviour as a cathode material for secondary lithium batteries. The treated products in water were characterized by X-ray diffractometry, thermogravimetric analysis, SEM, and specific surface area measurements. These measurements showed that the ultrasonic treatment process of crystallized LiVIOx causes a decrease in crystallinity and considerable increase in specific surface area and inter-layer spacing. The product was ultrasonically treated in water for 3 h and then heat treated at 250°C for 6 h. It showed a high initial discharge capacity of 283 mA-h/g active material, which was 62% higher than that of the starting material, and was charge-discharge cycled without a large capacity loss during 40 cycles. Both the specific capacity and the cycling hehaviour can improve with ultrasonic treatment of LiV70x
On undervoltage
97104722
load shedding
in power systems
Arnhorg, S. cr ol. Electri~rl Porter nrrd Errerm Systems, 1997, 19, (2). 14l149. An analytical hasis and criterion for undervoltage load shedding in power systems ts discussed. If the voltage is unstable, the proposed undervoltage load shed criterion can he used to calculate the amount of load must he shed to stabilise the voltage magnitude. Using a dynamic load model facilitated the forming of criterion which gives the amount of load which must he shed to stabilize the system in each point in time. The criterion is general and can be applied to any power system.
Bioconversion
Energy
97104727 Advantages and disadvantages of biomass fuels on a fundamental combustion basis in fluidized beds Wartha, C. et 01. Biomass Enera Em+ron., Proc. Eur. Bioenrrg) Conf., 9th., 1996, 2, 1215-1220. Edited by Chartier, P.. Elsevier, Oxford, UK. An evaluation of biomass fuels is presented on a fundamental combustion basis. Their combustion characteristics and emission hehaviour in relation to various other fuels such as bituminous and sub-hituminous coals, pressboard and hardhoard chips, sewage sludge pellets and plastics. The experiments are performed in a laboratoryscale multi-mode fluidized bed comhustor made of quartz glass which is exclusively electrically heated. The oxygen partial pressure is varied between 0 and 21 kPa, and the bed temperature between 600 and 900°C the superficial gas velocity hetween 0.2 and 3 m/s. The emissions of the single fuel particles are quantified and a carbon mass balance is performed. A classification system based on the carbon release rate is used. The conversion rates of fuel nitrogen to the gaseous species NO, NzO, and HCN are given and used for comparison of the biomass fuels with fossil fuels and fuels from industrial processes.
97104726 Agriculture-based vey of economic issues
Economics,
Policy, Supplies,
Forecasts
The 97104723 molten carbonate
influence of low operating temperature fuel cells decay processes lnr. J. Ener~ Rex., 1997, 21. (12), 1061-1070.
on
Freni, S. el al. This paper describes studies carried out to investigate the influence of low operating temperature (873 K) on the decay mechanisms that affect the endurance of a molten carbonate fuel cell.
Optimal 97104724 tion networks
planning
of rural medium voltage
distribu-
Nahman. .I. and Sniric, .I. Electr&rl Power& Etter~)’ Systenrs, 1997, 19. (8). 549-556. The proposed model could select the main initial parameters and timing of the reconstructions of rural distribution networks in long-term planning to meet the increasing load demands with minimum total-present-worth cost. The model incorporates capital and exploitation costs as well as the costs due to undelivered energy and load curtailments. The optimal investment policy is determined using a constrained dynamic programming technique which indicates the hest choice among possible options.
An options model for electric power markets 97104725 Ghosh, K. and Ramesh, V. C. Electrical Power and Energy Sysiems, 1997, 19, (2). 75-85. On an international scale, the once regulated and monopolistic electric utility industry is facing deregulation and competition on the world market. This paper investigates the development of an options market for hulk power trading in a market set-up, while considering power system planning and operational constraints and/or requirements. The different market based financial derivative instruments which can be used to trade electrical power in bulk are examined and the role of established tools such as Optimal Power Flow (OPF) in developing a price for bulk power transactions under a market based set-up is discussed. 97104726 combination
Short term method
load
forecasting
using
a Bayesian
Kiartzis. S. (‘I ul. Electrical Powrr und Energy S_ystems. 1997, 19. (3) 165-170. Based on the combination of an artificial neural network (ANN) predictor and two linear regression (LR) predictors, the Bayesian Combined Predictor (BCP). a prohahilistically motivated predictor for Short Term Load Forecasting (STLF) is presented. The method is applied to STLF for the Greek Pubhc Power Corporation dispatching centre of Crete, using 1994 data, and daily load profiles are obtained. Statistical analysis of prediction errors reveals that during given time periods the ANN predictor consistently produces better forecasts for certain hours of the day, while the LR predictor produces better forecasts for the rest. The combined prediction is a weighted sum of the ANN and LR predictions, where the weights are computed using an adaptive update of the Bayesian posterior probability of each predictor, based on their past predictive performance. Results of testing reveals that the proposed method outperforms both ANN and LR predictions.
biomass
energy
supply-a
sur-
Lunnan, A. Energy Policy. 1997. 25. (6) 573-582. There is a large potential for the production of energy crops on agricultural land. Most of the biomass produced has alternative use as food, feed or fibre. In most cases, energy utilization of the biomass is far from competitive given today’s prices. If dedicated energy crops are to he more competitive in the future, fossil energy prices must increase relative to the price of food, feed and fihre. Considerable spread exists among puhlished future fossil fuel price forecasts. From currently available evidence, there is small hope that fossil energy prices will increase relative to the price of food and feed. The impact on the greenhouse gas balance is the most important positive factor for biomass energy, compared with fossil energy. For the time being there is no consensus among economists about the magnitude of the environmental costs of greenhouse gas emissions. Reasonable values on the external effects are in most cases not enough to make agriculture-based biomass energy competitive. Considerable government subsidies are needed. There is, however, no economic justification for such suhsidies. Biomass energy systems using low quality biomass, originating as a hyproduct from the production of food, feed and/or fihre. is the most promising niche for energy from agricultural biomass.
Analysis of combustion 97104729 of coal with biomass fuels
products
from the cofiring
Belle-Oudry,
D. A. and Dayton, D. C. Pre/>r. Pup. Am. Chem. Sot., flit,. 1997, 42, (4) 1096-l 100. The amounts of NO and SOz during the combustion of the coahhiomass blends were detected using molecular beam mass spectrometry. The results indicated that any decrease in the amounts of these compounds was the result of diluting the nitrogen and sulfur present in the fuel blend. A hypothesis was advanced suggesting the chlorine released during the combustion of the coal/biomass blends may have been affected by mending the two fuels beyond a dilution effect. Furl
Chem.,
Behavior of trace elements 97104730 biomass and sewage sludge
during the pyrolysis
of
Storm, C. et al. DGMK Tugzqshrr., 1997, 9703, (Proceedings ICCS ‘Y7, Volume 2) 721-724. Increasing interest in biomass and sewage sludge has been noted in power plant technology as sources of COz-neutral fuels. Besides using solid pulverized biomass or sewage sludge as an additional fuel in coal-fired boilers, a further possibility to run a combined coal and biomass/sewage sludge process is to pre-pyrolyse or pre-gasify biomass or sewage sludge and to use the generated gas as reburn fuel in the coal-fired boiler. The separation of coal and biomass/sewage sludge ash within this cocomhustion process enables a specialized use of the residuals. The advantage of this pre-treatment process is that undesired components like inorganic compounds can be kept away from the coal-fired boiler. Investigations on the pyrolysis behaviour of biofuels continue with regard on the path of trace elements, like heavy metals, and alkali compounds, during the pyrolysis process varying different parameters. Detailed analysis of char samples, collected from two locations of the test facility with drfferent characteristic particle sizes, illustrate the behaviour of trace elements during pyrolysis at different temperatures. The investigation of biomass pyrolysis shows a specific behaviour of the most important elements depending on the pyrolysis temperature and the particle size of the pyrolysed char. During the pyrolysis of sewage sludge there is no distinct influence of the temperature on the release of the investigated components.
Fuel and Energy Abstracts
November
1997
409