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03873 Biomass yield and energy value of some fast-growing multipurpose trees in Nigeria
07 Strategies to address transition costs in a restruc97103866 turing electricity industry Baxter, L. er al. Energy Policy, 1997, 25, (5). 481-490. The potential financial consequences, or transition costs, of transforming electricity generation from a regulated to a competitive market in the US are evaluated. Industry-wide estimates suggest potential monetary losses could exceed $100 billion as a result of the move to competition. The paper discusses the most prominent strategies suggested to address these potential losses. For each strategy, the paper identifies the parties most likely to bear the financial consequences. Most strategies do nothing to reduce the total costs to society, but instead shift costs from one set of economic actors to another. The exceptions are those strategies that result in economic-efficiency gains, which can then be used to offset the transition costs. Most of the strategies examined require the co-operation of several parties, including regulators to achieve successful implementation. Time-of-use rates vs. Hopkinson tariffs redux: an 97103669 analysis of the choice of rate structures in a regulated electricity distribution company Seeto, D. ef al. Energy Economics, 1997, 19, (2) 169-185. Electricity industry restructuring proposals in North America may effect the disintegration of a vertically integrated company into several smaller entities, including distribution companies (DISCOS). The paper explores whether time-of-use (TOU) pricing or a Hopkinson tariff would be more suitable for a regulated DISCO. Focusing on the economic efficiency of these alternative rate structures, it is argued that a Hopkinson tariff with demand subscription is superior to TOU rates, as it can better handle the limited load diversity of local transmission and distribution (TD) demands made on the contemporary DISCO, while finessing the problem of endogenous marginal costs of local TD capacity. The US Department of Energy’s Combustion 2000 97103670 Program: clean, efficient electricity from coal Ruth, L. A. Energy Conver.s. Manage., 1997, 38, (10-13) 1249-1257. In co-operation with private industry, the US Department of Energy’s under its Combustion 2000 Pittsburgh Energy Technology Center, programme, is working to develop two types of advanced, coal-fired electrical power generation systems. These will incorporate significantly higher thermal efficiency, superior environmental performance, and a lower cost of electricity than current coal-fired plants. The low emission boiler system (LEBS) is a highly advanced pulverized-coal-fired power plant which will be ready for commercial introduction before the year 2001. LEBS uses supercritical steam conditions and substantial low-level heat recovery to achieve an efficiency of 42%. Very low emissions are achieved using advanced combustion technology and pollution controls integrated with the boiler. The high performance power system (HIPPS) is based on indirectly-fired, combined-cycle technology capable of 47-508 efficiency. This system uses a gas turbine driven by a clean air working fluid separate heated in a novel high-temperature furnace. Energy recovered from the turbine exhaust drives a steam cycle. HIPPS should be commercially available by 2005.
07
ALTERNATIVE SOURCES Bioconversion
ENERGY
Energy
Biological fossil CO2 mitigation 97103871 Hughes, E. and Benemann, J. R. Energy Convers. Manage., 1997, 38, (Suppl., Proceedings of the Third International Conference on Carbon Dioxide Removal, 1996) S467-S473. Management of even a small fraction of the biological carbon cycle would make a major contribution to mitigation of this greenhouse gas, as it produces ten times the level of COz than fossil fuels combustion. Electrical power generation is responsible for roughly one third of fossil COz emissions. Direct COz mitigation processes reduce fossil COz emissions from specific power plants, while biological COz mitigation processes include the cultivation of microalgae on flue-gas or captured COz, and the co-firing of wood with fossil fuels. Indirect biological processes, such as growing trees for carbon storage or for fuelling dedicated biomass power plants, recapture COz that already has entered the atmosphere. Both indirect and direct processes have the same overall effect in reducing global warming potential. Reducing global COz emissions from forest destruction and unsustainable agricultural and land use practices is one of the most cost-effective, and environmentally beneficial actions that can be taken now to arrest global climate change. The substitution of fossil fuels with biofuels provides another short-term option; biofuels could globally replace a substantial fraction of current fossil fuel usage. Co-firing biomass wastes and residues with coal is one of the lowest-cost, nearest-term options for reducing fossil COz emissions at existing power plants. Long-term
Alternative
energy sources
(bioconvetsion
energy)
demonstrations of biomass co-firing are required to address technical issues. Biomass fuel resources for co-firing can be expanded in the nearterm through greater recovery of wastes and residues in forestry and agriculture, and in the mid-term through systems that produce biomass specifically for use as fuels. 97103672 Biomass and natural gas as co-feedstocks for production of fuel for fuel-ceil vehicles Borgwardt, R. H. Biomass and Bioenergy, 1997, 12, (5). 333-345. Renewable energy crops are examined as a source of liquid fuel to mitigate greenhouse gas emissions from mobile sources and reduce dependence on imported petroleum. Fuel-cell vehicles would provide a promising technology for coping with the environmental and economic effects of an expanding vehicle fleet and a decreasing petroleum supply. Fuelled with methanol or hydrogen derived from biomass, fuel cells could help CO? emissions mitigation. The influence on petroleum displacement depends on the amount of biomass that could be produced and the efficiency of its conversion to a fuel compatible with fuel cells. Reduction of net COz emissions by the best current bio-fuel technology will be limited by biomass supply. Biomass conversion efficiency, petroleum displacement and overall net COz emission reduction can be improved, and the cost of fuel minimized, by use of natural gas as a co-feedstock. A thermochemical process utilizing both biomass and natural gas as co-feedstocks is compared with other options for methanol production and COz mitigation using either biomass or natural gas alone. Use of natural gas as co-feedstock makes the use of waste methane from landfills and waste-water treatment facilities, as well as the carbonaceous solid wastes and sludge from those facilities for conversion to clean transportation fuel possible. Greenhouse gas emissions from these important municipal sources can thus be reduced. 97103673 Biomass yield and energy value of some fastgrowing multipurpose trees in Nigeria Fuwape, .I. A. and Akindele, S. Biomass Bioenergy, 1997, 12, (2) 101-106. The paper assesses the above-ground biomass yield of 7-year-old trees of Gliricidia sepium, Gmelina arborea and Leucaena leucocephala grown for fuel production. The combustion properties of the fuel wood and charcoal produced from the trees were determined. There were significant differences in the above-ground biomass and the charcoal yield from the various species. The stand biomass was 37.4 t/ha for GIiricidia sepium, 85.6 t/ha for Gmelina arborea and 46.2 t/ha for Leucaena leucocephala. The charcoal yield was highest in Leucaena leucocephala. The average heat of combustion of charcoal, 33.25 MJikg, was higher than that of wood, 21.6 MJ/kg. Gmelina arborea gave the greatest energy yield per ha due to its high stand biomass. 97103674 Carbohydrate biofueis. iii. Consumptive-use and root yield of buffalo gourd (Cucufbita foetidissima HBK) Smeal, D. et al. Proc. Biomass Conf. Am.: Energy, Environ., Agric. Ind., 2nd, 1995, 333-342. Cucurbita foetidissima
produces a potential, cleaner burning alternative to other biofuels currently used for cooking and heating an the Navajo Indian Reservation. However, no information is available regarding the plant water requirements for growth and viable root production on the Colorado Plateau in north-western New Mexico where the Navajo Indian Irrigation Project is located. The study principally aimed to evaluate the relationship between buffalo gourd root production and evapotranspiration under variable irrigation as provided by a line-source design. Results of this study indicate that buffalo gourd can be successfully grown in north-western New Mexico when irrigated. Other observations during this study suggest that planting rates for optimum root production need to be established. 97103676 North, B. C.
Cofiring
coal and biomass
Proc. Int. Tech. Conf
waste in an FB boiler.
Coal Util. Fuel Syst., 1995, 20, 467-476.
97103876 Combustion of residual biosoiids from a high solids anaerobic digestion/aerobic cornposting process Jenkins, B. M. ef al. Biomass and Bioenergy, 1997, 12, (5), 367-381. In order to evaluate possible problems in using humus as fuel in boilers, a humus consisting of aerobically stabilized anaerobic digester effluent was burned in two laboratory test facilities. An atmospheric circulating fluidized-bed combustor (FBC) was used to assess possible bed agglomeration when using alumina-silicate bed media. A multi-fuel capable entrained flow combustor (MFC) with electrically heated walls simulating a boiler was used with air-cooled tubular probes to evaluate potential ash deposition on heat exchangers. Low heating value of the humus led to poor temperature control in the FBC when burned alone. Tests of the humus blended 50% by weight with wood were also carried out in the FBC. No evidence of bed agglomeration was found in the FBC with either humus alone or blended with wood at temperatures up to 900°C. the maximum tested. Bed-drain rate was nearly equal to fuel-ash feed rate to maintain constant bed pressure drop due to the high sand fraction in the humus. Deposits collected on the probes in the MFC experiment were enriched in alkalisulfate, as were the fine fractions of fly-ash samples. Deposition rates were not established due to particle-induced abrasion of deposits from the heavy sand fraction of the fuel, but at least moderate alkali-sulfate deposition can be anticipated if humus is burned in commercial units.
Fuel and Energy Abstracts
September
1997
325
07
ALTERNATIVE SOURCES Bioconversion
ENERGY
Energy
Biological fossil CO2 mitigation 97103871 Hughes, E. and Benemann, J. R. Energy Convers. Manage., 1997, 38, (Suppl., Proceedings of the Third International Conference on Carbon Dioxide Removal, 1996) S467-S473. Management of even a small fraction of the biological carbon cycle would make a major contribution to mitigation of this greenhouse gas, as it produces ten times the level of COz than fossil fuels combustion. Electrical power generation is responsible for roughly one third of fossil COz emissions. Direct COz mitigation processes reduce fossil COz emissions from specific power plants, while biological COz mitigation processes include the cultivation of microalgae on flue-gas or captured COz, and the co-firing of wood with fossil fuels. Indirect biological processes, such as growing trees for carbon storage or for fuelling dedicated biomass power plants, recapture COz that already has entered the atmosphere. Both indirect and direct processes have the same overall effect in reducing global warming potential. Reducing global COz emissions from forest destruction and unsustainable agricultural and land use practices is one of the most cost-effective, and environmentally beneficial actions that can be taken now to arrest global climate change. The substitution of fossil fuels with biofuels provides another short-term option; biofuels could globally replace a substantial fraction of current fossil fuel usage. Co-firing biomass wastes and residues with coal is one of the lowest-cost, nearest-term options for reducing fossil COz emissions at existing power plants. Long-term
Alternative
energy sources
(bioconvetsion
energy)
demonstrations of biomass co-firing are required to address technical issues. Biomass fuel resources for co-firing can be expanded in the nearterm through greater recovery of wastes and residues in forestry and agriculture, and in the mid-term through systems that produce biomass specifically for use as fuels. 97103672 Biomass and natural gas as co-feedstocks for production of fuel for fuel-ceil vehicles Borgwardt, R. H. Biomass and Bioenergy, 1997, 12, (5). 333-345. Renewable energy crops are examined as a source of liquid fuel to mitigate greenhouse gas emissions from mobile sources and reduce dependence on imported petroleum. Fuel-cell vehicles would provide a promising technology for coping with the environmental and economic effects of an expanding vehicle fleet and a decreasing petroleum supply. Fuelled with methanol or hydrogen derived from biomass, fuel cells could help CO? emissions mitigation. The influence on petroleum displacement depends on the amount of biomass that could be produced and the efficiency of its conversion to a fuel compatible with fuel cells. Reduction of net COz emissions by the best current bio-fuel technology will be limited by biomass supply. Biomass conversion efficiency, petroleum displacement and overall net COz emission reduction can be improved, and the cost of fuel minimized, by use of natural gas as a co-feedstock. A thermochemical process utilizing both biomass and natural gas as co-feedstocks is compared with other options for methanol production and COz mitigation using either biomass or natural gas alone. Use of natural gas as co-feedstock makes the use of waste methane from landfills and waste-water treatment facilities, as well as the carbonaceous solid wastes and sludge from those facilities for conversion to clean transportation fuel possible. Greenhouse gas emissions from these important municipal sources can thus be reduced. 97103673 Biomass yield and energy value of some fastgrowing multipurpose trees in Nigeria Fuwape, .I. A. and Akindele, S. Biomass Bioenergy, 1997, 12, (2) 101-106. The paper assesses the above-ground biomass yield of 7-year-old trees of Gliricidia sepium, Gmelina arborea and Leucaena leucocephala grown for fuel production. The combustion properties of the fuel wood and charcoal produced from the trees were determined. There were significant differences in the above-ground biomass and the charcoal yield from the various species. The stand biomass was 37.4 t/ha for GIiricidia sepium, 85.6 t/ha for Gmelina arborea and 46.2 t/ha for Leucaena leucocephala. The charcoal yield was highest in Leucaena leucocephala. The average heat of combustion of charcoal, 33.25 MJikg, was higher than that of wood, 21.6 MJ/kg. Gmelina arborea gave the greatest energy yield per ha due to its high stand biomass. 97103674 Carbohydrate biofueis. iii. Consumptive-use and root yield of buffalo gourd (Cucufbita foetidissima HBK) Smeal, D. et al. Proc. Biomass Conf. Am.: Energy, Environ., Agric. Ind., 2nd, 1995, 333-342. Cucurbita foetidissima
produces a potential, cleaner burning alternative to other biofuels currently used for cooking and heating an the Navajo Indian Reservation. However, no information is available regarding the plant water requirements for growth and viable root production on the Colorado Plateau in north-western New Mexico where the Navajo Indian Irrigation Project is located. The study principally aimed to evaluate the relationship between buffalo gourd root production and evapotranspiration under variable irrigation as provided by a line-source design. Results of this study indicate that buffalo gourd can be successfully grown in north-western New Mexico when irrigated. Other observations during this study suggest that planting rates for optimum root production need to be established. 97103676 North, B. C.
Cofiring
coal and biomass
Proc. Int. Tech. Conf
waste in an FB boiler.
Coal Util. Fuel Syst., 1995, 20, 467-476.
97103876 Combustion of residual biosoiids from a high solids anaerobic digestion/aerobic cornposting process Jenkins, B. M. ef al. Biomass and Bioenergy, 1997, 12, (5), 367-381. In order to evaluate possible problems in using humus as fuel in boilers, a humus consisting of aerobically stabilized anaerobic digester effluent was burned in two laboratory test facilities. An atmospheric circulating fluidized-bed combustor (FBC) was used to assess possible bed agglomeration when using alumina-silicate bed media. A multi-fuel capable entrained flow combustor (MFC) with electrically heated walls simulating a boiler was used with air-cooled tubular probes to evaluate potential ash deposition on heat exchangers. Low heating value of the humus led to poor temperature control in the FBC when burned alone. Tests of the humus blended 50% by weight with wood were also carried out in the FBC. No evidence of bed agglomeration was found in the FBC with either humus alone or blended with wood at temperatures up to 900°C. the maximum tested. Bed-drain rate was nearly equal to fuel-ash feed rate to maintain constant bed pressure drop due to the high sand fraction in the humus. Deposits collected on the probes in the MFC experiment were enriched in alkalisulfate, as were the fine fractions of fly-ash samples. Deposition rates were not established due to particle-induced abrasion of deposits from the heavy sand fraction of the fuel, but at least moderate alkali-sulfate deposition can be anticipated if humus is burned in commercial units.
Fuel and Energy Abstracts
September
1997
325