- Email: [email protected]
04737 Drying of biomass particles in fixed and moving beds
07
Alternative
energy sources (bioconversion
A biomass energy 97104731 example of the methodology
flow
energy)
chart
for
Zimbabwe:
an
So/or E;,?er&~.1997. SY, (I-3). 49-57. Hemstock. S. L. and Hall, D. 0. If biomass energy is to he used on a sustainable hasis, analysis of the availability and use of the biomass resource is crucial. Detailed biomass energy flow charts for Kenya and Zimbabwe have been produced. hoth taking an average of 18 months to complete because of the difficulty in obtaining and analysing detailed and good quality data. In view of this, a flexible spreadsheet methodology has been developed which applies a common methodology to the drafting of biomass energy flow charts as a useful initial guide to more detailed studies. The FAOSTAT PC database was chosen as the primary data source as it accounts for forestry and agricultural production in well-defined and comparable categories for each country. Users can incorporate their own data, energy values, and energy ratios in an attempt to produce more accurate biomass energy flow charts than could be drafted from the FAOSTAT PC database and default settings alone.
Biomass 97104732 and the net influence
energy production: the global on the CO2 concentration
potential
Ahamer. G. Biomuss Ener, Environ., Proc. Eur. Bioerrerg)) Corrf.. 9th, 1996, 3, 1742-1747. Edited by Chartier, P., Elsevier, Oxford. UK. Fossil fuel combustion and its resultant carbon dioxide emissions represent the most important anthropogenic disturbance of the natural global carbon cycle. A promising suhstitute for fossil energy carriers is the ‘carhonneutral’ renewable energy carrier hiomass. The ‘Combined Energy and Biosphere Model’ CEBM has been developed as a tool for calculation of the atmospheric CO? content as a result of an intensive use of biomass for energy purposes. The CEBM comprises a hiospheric part hased on the ‘Osnahruck Biosphere Model, which calculates the annual carbon cycle in the atmosphere. plant matter and soil in 24.13 grid elements covering the earth’s surface. The theoretical global potential of woody biomass fuels grown equals today’s global demand for primary energy. The energy related part of the CEBM (the ‘energy strategy module’) integrates the annual CO: emissions from fossil and hiomass fuels and leads tn the final conclusion that ‘biomass for energy’ is still a very important strategy, due to its CO? mitigation potential. hut that first priority in the struggle against the greenhouse effect has to be attributed to lowering the increase of global energy demand.
97104733 Biomass growing multipurpose
yield and energy trees in Nigeria
value
of some
fast-
Fuwape, J. and Akindele, S. Biomass and Bioenergy, 1997. 12, (2). IOI106. The authors performed an assessment on the above-ground biomass yield of seven-year-old trees of Gliricidiu sepium, Gmelitza arborea and Leucaena letrumphala grown for fuel production. The combustion properties of the fuelwood and charcoal produced from the trees were determined. Significant differences in the above-ground biomass and the charcoal yield from the various species were discovered. The stand hiomass was 37.4 t/ha for Gliricidia .sepium, H.i.6 t/ha for Gmelinu arhorea and 46.2 t/ha tor Lerccaena lettcocephula. The charcoal yield (range 2S-42%) was highest in Leucaena leucocephalu. The average heat of combustion of charcoal, 33.25 MJikg. was higher than that of wood, 21.6 MJikg. Gme/irza arhorca gave the greatest energy yield per hectare.
97104734 problems
Co-firing
of coal
and
biomass.
Advantages
and
Kartak. .I. et al. Pm-. Anntc. Ittt. Pittsburgh Coal Cmf., 1996, 1.1, (2), 1487-1492. Among the feasible contenders for new generation resources, biomass power is a viable candidate. It already accounts for about 12% of world primary energy consumption. The great difference between the large potential of energetic biomass exploitation and current utilization status shows that the high cost of biomass explains low biomass usage.
97104735 CO2 neutral carbonization Klose, W. and Wiest. W. Process.
S,vmp.,
6th,
carbon
Changing
1996.
4X5-488.
production
Scopes
Mirwr.
Edited
from
Process.,
by Kemal,
biomass Proc.
M.,
Int.
by
Miner.
Balkema,
Rotterdam, The Netherlands. In carbon production, biomass, in its various modifications, can serve as a substitute for fossil carbonaceous materials. As usual, coal standard methods are employed for biomass characterization. Results of an investigation with air-dried maize as the feedstock are presented in comparison to the results of the pyrolysis of the same material in a rotary kiln. The rotary kiln experimental set-up is briefly described. The influence of pyrolysis temperature on product composition and quality is discussed. The differences in gas and tar formation clearly indicate the limits of laboratory-scale analysis and the dependence of pyrolysis results on the temperature-time-history, As an example for the next step, the pilot plant close to technical scale, a new process type for charcoal production is presented. By indirectly heating several reaction tubes continuous highly automated operation combined with very low emissions and a high quality charcoal product are achieved. A Clausius-Rankine process is also included, driven by the surplus energy of the combustion of the volatiles.
410
Fuel and Energy Abstracts
November
1997
Concentrations of inorganic elements 97104736 fuels and recovery in the different ash fractions
et al. Biomuscand
in biomass
12. (3). 21 l-224. Obernberger, I. The combustion process and the composition of the ashes produced arc influenced by the inorganic elements and compounds in biomass fuels. Consequently, knowledge about the material fluxes of inorganic elements and compounds during biomass combustion for different kinds of biofuels and their influencing variables is of great importance. Future design and control of biomass furnaces and boilers will be greatly influenced hy this research, in order to prevent slagging, fouling and corrosion and to assist in the definition of quality requirements for hiofuels as well as the possibilities of a sustainable ash utilization. For this reason, comprehensive teht runs were carried out in several biomass combustion plants equipped with different combustion technologies and using various biomass fuels. Over at least two-day observation periods. samples of the biomass and the different ash fractions were take.n and analysed and the operating data nf the plants were recorded. The results show a major requirement for a hustainahlc ash utilization is a fractionated heavy metal separation. distinguishing hrtween different fly-ash fractions and taking the temperature of tly-ash precipit;!. tion into consideration for new furnace technologic\. Research has al\n shown that straw and cereals, as well as their ashes, contain significantly lower amounts of heavy metals than woody hiofuels and wood aThe\. The same principles pointed out for environmentally relevant heavy metals arc also valid for K. Na, Cl and S.
97104737 beds
Drying
Biomerp,
of biomass
1997,
particles
in fixed
and moving
Saastamoinen. J. and Impala. R. Dnirrg Tech&.. 1007. 15. (h-8). IYIO1929. Experimental and theoretical drying of biomass fuel particles in fixed and moving beds with hot gas or steam is addressed in this work. A \ingle particle drying model is coupled with a model describing heat and moisture transfer in the gas phase of the bed. To reach a certain degree of drying, the following parameters are influential: particle size. particle moisture content, gas inlet temperature, gas inlet moisture content and gas mass flow rate.
97104738
The economics
of forest-based
biomass
supply
Sedjo. R. A. Energy Policy, 1997, 25, (6). SS9-566. A preliminary exploration into the economics of generating energy from forest-based biomass is conducted. The study assesses the feasibility of greatly expanding the share of total energy consumption in developed countries that could be economically satisfied by biomass without fiscal subsidy support, given current technologies, and with plausible potential technologies ten years into the future. The study briefly considers the environmental effects of biomass usage compared with fossil fuels. Since wood has uses both as fuelwood for energy and as industrial wood for wood products, the comparative economics of these alternative uses are examined.
97104739 Effect of magnesium and silver oxides on the heat values of biofuels determined by differential scanning calorimetrv Pratt, B. C. >nd Kumar, J. V. Am. Lah. 1997, 29, (l6), 12-16. In order to achieve more efficient conversion of carbon monoxide to carbon dioxide, metal oxides were applied as combustion aids to supply additional oxygen at the sample metal oxide interface. Among the metal oxides experimented as additives, the MgO/AgzO mixture proved to hc the mo\t effective. The heat values for the ANL premium coal samples arc hettcr than the deviation of +X37 J/g adopted by ASTM and the same effect was noticed for the biofuels. The results were generated at the optimized conditions for differential scanning calorimetry DSC.
97104740 Energy efficiency based energy systems
and competitiveness
of biomass-
Gustavsson, L. Energy, 1997, 22, (IO), 959-967. Seventeen per cent of the total Swedish energy supply comes from biomass and the potential increase in annual domestic biomass production is considerable. The costs and primary energy use required for producing one unit of electricity and one unit of heat, as well as the CO? emissions involved, were analysed for different biomass- and fossil-fuel-hased \ystemh, Supply systems based on cogeneration plants are more energy- and co%tefficient than those based either on heat pumps and condensing plants or on boilers and condensing plants. Less efficient systems lead to greater CO? emissions, except for biomass systems involving a COz-neutral fuel cycle. They also lead to an increase in primary energy use. In Sweden. significant reductions in the price of forest fuel over the past two decades and increases in fossil fuel taxes have made hioenergy competitive with fossil fuels for heat production. From 1990 to 1994. the use of wood fuels for district-heat production increased from 3.6 TWh to IO.7 TWh and further increase is expected. Expanded use of hiomasa-based boilers may prove an obstacle to future cogeneration investments. From 1990 to lY94, use of biofuels for the cogeneration of electricity in district heating systems was less than 0.5 TWhiyr. Low electricity prices in Sweden have limited the competitiveness of cogeneration. The tax advantages of biomass-based electricity production are slight since carbon and fuel taxes are only applied to heat production. Such taxation increases the tax disadvantages for more energy-efficient systems.
Alternative
energy sources (bioconversion
A biomass energy 97104731 example of the methodology
flow
energy)
chart
for
Zimbabwe:
an
So/or E;,?er&~.1997. SY, (I-3). 49-57. Hemstock. S. L. and Hall, D. 0. If biomass energy is to he used on a sustainable hasis, analysis of the availability and use of the biomass resource is crucial. Detailed biomass energy flow charts for Kenya and Zimbabwe have been produced. hoth taking an average of 18 months to complete because of the difficulty in obtaining and analysing detailed and good quality data. In view of this, a flexible spreadsheet methodology has been developed which applies a common methodology to the drafting of biomass energy flow charts as a useful initial guide to more detailed studies. The FAOSTAT PC database was chosen as the primary data source as it accounts for forestry and agricultural production in well-defined and comparable categories for each country. Users can incorporate their own data, energy values, and energy ratios in an attempt to produce more accurate biomass energy flow charts than could be drafted from the FAOSTAT PC database and default settings alone.
Biomass 97104732 and the net influence
energy production: the global on the CO2 concentration
potential
Ahamer. G. Biomuss Ener, Environ., Proc. Eur. Bioerrerg)) Corrf.. 9th, 1996, 3, 1742-1747. Edited by Chartier, P., Elsevier, Oxford. UK. Fossil fuel combustion and its resultant carbon dioxide emissions represent the most important anthropogenic disturbance of the natural global carbon cycle. A promising suhstitute for fossil energy carriers is the ‘carhonneutral’ renewable energy carrier hiomass. The ‘Combined Energy and Biosphere Model’ CEBM has been developed as a tool for calculation of the atmospheric CO? content as a result of an intensive use of biomass for energy purposes. The CEBM comprises a hiospheric part hased on the ‘Osnahruck Biosphere Model, which calculates the annual carbon cycle in the atmosphere. plant matter and soil in 24.13 grid elements covering the earth’s surface. The theoretical global potential of woody biomass fuels grown equals today’s global demand for primary energy. The energy related part of the CEBM (the ‘energy strategy module’) integrates the annual CO: emissions from fossil and hiomass fuels and leads tn the final conclusion that ‘biomass for energy’ is still a very important strategy, due to its CO? mitigation potential. hut that first priority in the struggle against the greenhouse effect has to be attributed to lowering the increase of global energy demand.
97104733 Biomass growing multipurpose
yield and energy trees in Nigeria
value
of some
fast-
Fuwape, J. and Akindele, S. Biomass and Bioenergy, 1997. 12, (2). IOI106. The authors performed an assessment on the above-ground biomass yield of seven-year-old trees of Gliricidiu sepium, Gmelitza arborea and Leucaena letrumphala grown for fuel production. The combustion properties of the fuelwood and charcoal produced from the trees were determined. Significant differences in the above-ground biomass and the charcoal yield from the various species were discovered. The stand hiomass was 37.4 t/ha for Gliricidia .sepium, H.i.6 t/ha for Gmelinu arhorea and 46.2 t/ha tor Lerccaena lettcocephula. The charcoal yield (range 2S-42%) was highest in Leucaena leucocephalu. The average heat of combustion of charcoal, 33.25 MJikg. was higher than that of wood, 21.6 MJikg. Gme/irza arhorca gave the greatest energy yield per hectare.
97104734 problems
Co-firing
of coal
and
biomass.
Advantages
and
Kartak. .I. et al. Pm-. Anntc. Ittt. Pittsburgh Coal Cmf., 1996, 1.1, (2), 1487-1492. Among the feasible contenders for new generation resources, biomass power is a viable candidate. It already accounts for about 12% of world primary energy consumption. The great difference between the large potential of energetic biomass exploitation and current utilization status shows that the high cost of biomass explains low biomass usage.
97104735 CO2 neutral carbonization Klose, W. and Wiest. W. Process.
S,vmp.,
6th,
carbon
Changing
1996.
4X5-488.
production
Scopes
Mirwr.
Edited
from
Process.,
by Kemal,
biomass Proc.
M.,
Int.
by
Miner.
Balkema,
Rotterdam, The Netherlands. In carbon production, biomass, in its various modifications, can serve as a substitute for fossil carbonaceous materials. As usual, coal standard methods are employed for biomass characterization. Results of an investigation with air-dried maize as the feedstock are presented in comparison to the results of the pyrolysis of the same material in a rotary kiln. The rotary kiln experimental set-up is briefly described. The influence of pyrolysis temperature on product composition and quality is discussed. The differences in gas and tar formation clearly indicate the limits of laboratory-scale analysis and the dependence of pyrolysis results on the temperature-time-history, As an example for the next step, the pilot plant close to technical scale, a new process type for charcoal production is presented. By indirectly heating several reaction tubes continuous highly automated operation combined with very low emissions and a high quality charcoal product are achieved. A Clausius-Rankine process is also included, driven by the surplus energy of the combustion of the volatiles.
410
Fuel and Energy Abstracts
November
1997
Concentrations of inorganic elements 97104736 fuels and recovery in the different ash fractions
et al. Biomuscand
in biomass
12. (3). 21 l-224. Obernberger, I. The combustion process and the composition of the ashes produced arc influenced by the inorganic elements and compounds in biomass fuels. Consequently, knowledge about the material fluxes of inorganic elements and compounds during biomass combustion for different kinds of biofuels and their influencing variables is of great importance. Future design and control of biomass furnaces and boilers will be greatly influenced hy this research, in order to prevent slagging, fouling and corrosion and to assist in the definition of quality requirements for hiofuels as well as the possibilities of a sustainable ash utilization. For this reason, comprehensive teht runs were carried out in several biomass combustion plants equipped with different combustion technologies and using various biomass fuels. Over at least two-day observation periods. samples of the biomass and the different ash fractions were take.n and analysed and the operating data nf the plants were recorded. The results show a major requirement for a hustainahlc ash utilization is a fractionated heavy metal separation. distinguishing hrtween different fly-ash fractions and taking the temperature of tly-ash precipit;!. tion into consideration for new furnace technologic\. Research has al\n shown that straw and cereals, as well as their ashes, contain significantly lower amounts of heavy metals than woody hiofuels and wood aThe\. The same principles pointed out for environmentally relevant heavy metals arc also valid for K. Na, Cl and S.
97104737 beds
Drying
Biomerp,
of biomass
1997,
particles
in fixed
and moving
Saastamoinen. J. and Impala. R. Dnirrg Tech&.. 1007. 15. (h-8). IYIO1929. Experimental and theoretical drying of biomass fuel particles in fixed and moving beds with hot gas or steam is addressed in this work. A \ingle particle drying model is coupled with a model describing heat and moisture transfer in the gas phase of the bed. To reach a certain degree of drying, the following parameters are influential: particle size. particle moisture content, gas inlet temperature, gas inlet moisture content and gas mass flow rate.
97104738
The economics
of forest-based
biomass
supply
Sedjo. R. A. Energy Policy, 1997, 25, (6). SS9-566. A preliminary exploration into the economics of generating energy from forest-based biomass is conducted. The study assesses the feasibility of greatly expanding the share of total energy consumption in developed countries that could be economically satisfied by biomass without fiscal subsidy support, given current technologies, and with plausible potential technologies ten years into the future. The study briefly considers the environmental effects of biomass usage compared with fossil fuels. Since wood has uses both as fuelwood for energy and as industrial wood for wood products, the comparative economics of these alternative uses are examined.
97104739 Effect of magnesium and silver oxides on the heat values of biofuels determined by differential scanning calorimetrv Pratt, B. C. >nd Kumar, J. V. Am. Lah. 1997, 29, (l6), 12-16. In order to achieve more efficient conversion of carbon monoxide to carbon dioxide, metal oxides were applied as combustion aids to supply additional oxygen at the sample metal oxide interface. Among the metal oxides experimented as additives, the MgO/AgzO mixture proved to hc the mo\t effective. The heat values for the ANL premium coal samples arc hettcr than the deviation of +X37 J/g adopted by ASTM and the same effect was noticed for the biofuels. The results were generated at the optimized conditions for differential scanning calorimetry DSC.
97104740 Energy efficiency based energy systems
and competitiveness
of biomass-
Gustavsson, L. Energy, 1997, 22, (IO), 959-967. Seventeen per cent of the total Swedish energy supply comes from biomass and the potential increase in annual domestic biomass production is considerable. The costs and primary energy use required for producing one unit of electricity and one unit of heat, as well as the CO? emissions involved, were analysed for different biomass- and fossil-fuel-hased \ystemh, Supply systems based on cogeneration plants are more energy- and co%tefficient than those based either on heat pumps and condensing plants or on boilers and condensing plants. Less efficient systems lead to greater CO? emissions, except for biomass systems involving a COz-neutral fuel cycle. They also lead to an increase in primary energy use. In Sweden. significant reductions in the price of forest fuel over the past two decades and increases in fossil fuel taxes have made hioenergy competitive with fossil fuels for heat production. From 1990 to 1994. the use of wood fuels for district-heat production increased from 3.6 TWh to IO.7 TWh and further increase is expected. Expanded use of hiomasa-based boilers may prove an obstacle to future cogeneration investments. From 1990 to lY94, use of biofuels for the cogeneration of electricity in district heating systems was less than 0.5 TWhiyr. Low electricity prices in Sweden have limited the competitiveness of cogeneration. The tax advantages of biomass-based electricity production are slight since carbon and fuel taxes are only applied to heat production. Such taxation increases the tax disadvantages for more energy-efficient systems.