- Email: [email protected]
h laboratory scale boiler burner
07 Alternative energy sources (bioconversion energy) non-commercial energy to a period of commercial energy being the main source of energy. This article discusses the effect of the discharge of noxious gases caused by the consumption of biofuel.
04/01362 Biomass gasification for heat application
-
a substitute to fossil fuel
Dasappa, S. et al. Biomass and Bioenergy, 2003, 25, (6), 637-649. The paper addresses case studies of a low temperature and a high temperature industrial heat requirement being met using biomass gasification. The gasification system for these applications consists of an open top down draft reburn reactor lined with ceramic. Necessary cooling and cleaning systems are incorporated in the package to meet the end use requirements. The other elements included are the fuel conveyor, water treatment plant for recirculating the cooling water and adequate automation to start, shut down and control the operations of the gasifier system. Drying of marigold flower, a low temperature application is considered to replace diesel fuel in the range of 125150 1 h -1. Gas from the 500 kg h -1, gasifier system is piped into the producer gas burners fixed in the combustion chamber with the downstream process similar to the diesel burner. The high temperature application is for a heat treatment furnace in the temperature range of 873-1200 K. A 300 kg h a of biomass gasifier replaces 2000 1 of diesel or LDO per day completely. The novelty of this package is the use of one gasifier to energize 16 burners in the eight furnaces with different temperature requirements. The system operates over 140 h per week on a nearly nonstop mode and over 4000 h of operation replacing fossil fuel completely. The advantage of bioenergy package towards the economic and environmental considerations is presented.
04/01363 Brazil
Biomass resources for energy in North-Eastern
Filho, P. A. and Badr, O. Applied Energy, 2004, 77, (1), 51 67. Due to the high dependency on hydroelectric power generation, Brazil faced a power shortage in 2001. In order to remedy the situation and avoid more severe power crises in the future, the Brazilian Government launched incentive programmes to encourage thermal and renewable power generation. The Programme of Incentives to Alternative Sources (PROINFA) is mainly devoted to the utilization of biomass. The success of P R O I N F A depends on the availability of reliable studies for assessing existing biomass resources and the viability of their utilization for power generation. In this study, energy potentials of the main biomass resources in the north-eastern region of Brazil have been assessed. The economy of the north-eastern region of Brazil is heavily dependent on its sugar industry. Biomass available from sugarcane cultivation and processing represents an annual regional energy resource of 40.5 TWh at an average cost of US$0.005/kWh. Bamboo, cultivated as a dedicated energy crop, has the second largest annual energy potential of 30.8 TWh at an average cost of US$0.009/kWh. Municipal solid waste, generated in the region, has an annual energy potential of about 16.7 TWh.
04•01364 Brassica carinata as an alternative oil crop for the production of biodiesel in Italy: agronomic evaluation, fuel production by transesterification and characterization Cardone, M. et al. Biomass and Bioenergy, 2003, 25, (6), 623-636. In this study, the non-food use of Brassica carinata oil for biodiesel production was investigated. B. carinata, a native plant of the Ethiopian highlands and widely used as food by the Ethiopians, has recently become the object of increasing interest. This is due to its better agronomic performances in areas such as Spain, California and Italy that are characterized by unfavourable environmental conditions for the cultivation of Brassica napus (by far the most common rapeseed cultivated in continental Europe). The agronomic performance and the energetic balance described here confirmed that B. carinata adapted better and was more productive both in adverse conditions (clay- and sandy-type soils and in semi-arid temperate climate) and under low cropping system when compared with B. napus. The biodiesel, produced by transesterification of the oil extracted from the B. carinata seeds, displayed physical-chemical properties suitable for the use as diesel car fuel. A comparison of the performance of B. carinata oilderived biodiesel with a commercial biodiesel and petroleum diesel fuel was conducted as regards engine performance, regulated and unregulated exhaust emissions. These results make B. carinata a promising oil feedstock for cultivation in coastal areas of central-southern Italy, where it is more difficult to achieve the productivity potentials of B. napus, and could offer the possibility of exploiting the Mediterranean marginal areas for energetic purposes.
04•01365 Cellulosic fuel ethanol. Alternative fermentation process designs with wild-type and recombinant Zymomonas mobilis Lawford, H. G. and Rousseau, J. D. Applied Biochemistry and Biotechnology, 2003, 105-108, 457-469.
186
Fuel and Energy Abstracts May 2004
Iogen (Canada) is a major manufacturer of industrial cellulase and hemicellulase enzymes for the textile, pulp and paper, and poultry feed industries. Iogen has recently constructed a 40 t/d biomass-to-ethanol demonstration plant adjacent to its enzyme production facility. The integration of enzyme and ethanol plants results in significant reduction in production costs and offers an alternative use for the sugars generated during biomass conversion. Iogen has partnered with the University of Toronto to test the fermentation performance characteristics of metabolically engineered Zymomonas mobilis created at the National Renewable Energy Laboratory. This study focused on strain AX101, a xylose- and arabinose-fermenting stable genomic integrant that lacks the selection marker gene for antibiotic resistance. The 'Iogen Process' for biomass depolymerization consists of a dilutesulfuric acid-catalysed steam explosion, followed by enzymic hydrolysis. This work examined two process design options for fermentation, first, continuous co-fermentation of C5 and C6 sugars by Zm AX101, and second, separate continuous fermentations of prehydrolysate by Zm AX101 and cellulose hydrolysate by either wild-type Z. mobilis ZM4 or an industrial yeast commonly used in the production of fuel ethanol from corn. Iogen uses a proprietary process for conditioning the prehydrolysate to reduce the level of inhibitory acetic acid to at least 2.5 g/L. The pH was controlled at 5.5 and 5.0 for Zymomonas and yeast fermentations, respectively. Neither 2.5 g/L of acetic acid nor the presence of pentose sugars (C6:Cs = 2:1) appreciably affected the highperformance glucose fermentation of wild-type Z. mobilis ZM4. By contrast, 2.5 g/L of acetic .acid significantly reduced the rate of pentose fermentation by strain AX101. For single-stage continuous fermentation of pure sugar synthetic cellulose hydrolysate (60 g/L of glucose), wild-type Zymomonas exhibited a four-fold higher volumetric productivity compared with industrial yeast. Low levels of acetic acid stimulated yeast ethanol productivity. The glucose-to-ethanol conversion efficiency for Zm and yeast was 96 and 84%, respectively.
04/01366 Changes in various physical/chemical parameters of Pinus pinaster wood after steam explosion pretreatment Negro, M. J. et al. Biomass and Bioenergy, 2003, 25, (3), 301-308. Steam-explosion process can be satisfactorily used as a pretreatment in ethanol production from lignocellulosic biomass. Traditionally, pretreatment effectiveness is evaluated in terms of hemicellulose solubilization, enzymatic convertibility of cellulose fraction, and recovery of both polysaccharides. In this study some parameters different from composition (main components) have been evaluated as an alternative tool to characterize the effect of steaming pre-treatment on lignocellulosie materials. The effect of the most important variables in steam explosion pre-treatment (temperature, residence time and chip size) on various physical/chemical parameters of pine biomass were investigated. Changes in O/C and H/C atomic ratios, colour analysis, elementary composition, water drop penetration time, organic soluble content, cellulose cristallinity index, and thermogravimetric analysis after the pre-treatment were evaluated. Furthermore the influence of operational pre-treatment variables on all such parameters and their interactions were examined with the Yates' algorithm.
04/01367 Co-firing of coal and cattle feedlot biomass (FB) fuels, Part II. Performance results from 30 kWt (100 000) BTU/ h laboratory scale boiler burner Annamalai, K. et al. Fuel, 2003, 82, (10), 1183-1193. The use of cattle manure (referred to as feedlot biomass, FB) as a fuel source has the potential to both solve waste disposal problems and reduce fossil fuel based CO2 emissions. A co-firing technology is proposed where FB is ground, mixed with coal, and then fired in existing, pulverized coal-fired boiler burner facilities. A research programmewas undertaken in order to determine (i) fuel characteristics, (if) combustion characteristics when fired along with coal in a small scale 30-kWt (100000 BTU/h) boiler burner facility, and (iii) combustion and fouling characteristics when fired along with coal in a large pilot scale 150-kWt (500 000 BTU/h) DOE-NETL boiler-burner facility. Part I presented a methodology for fuel collection, fuel characteristics of the FB, its relation to ration fed, and the change in fuel characteristics and volatile oxides due to composting. Part II addresses the pyrolysis characteristics of coal, FB, and blend and presents results on the performance of 90:10 coal:FB (PC) blend as fired in a 30-kW t boiler-burner unit. The boiler-burner unit is made of steel and lined with a cast ceramic liner for long duration operation and a commercial feeding system is used for firing the coal and the blend. Thermogravimetric analyses (TGA) performed on coal, FB, and 90:10 coal:FB blend reveal that biomass will start releasing gases at 273°C (523°C) which is about 100°C (212°C) lower than that of coal. The maximum rate of volatile release is about 0.000669 kg/s kg for FB while that of coal is 0.000425 kg/s kg. The experiments revealed that the 90:10 blend burns more completely in the boiler, due to the earlier release of biomass volatiles and higher amount of volatile matter in FB. The NOx emission for coal was 290 ppm, 0.162 kg/GJ (0.3768 lb/mm BTU) and 260 ppm, 0.1475 kg/GJ (0.343 lb/mm BTU) for the 90:10 blend at 10% excess air. Even though the effective N content of the
07 Alternative energy sources (bioconversion energy) blend increased by 18%, compared to coal the NOx emission decreased which is attributed to the higher VM of FB and more N in the form of NH3. However, due to limited residence time and higher VM, the CO emission increased from 15 582 ppm, 5.29 kg/GJ (12.305 Ib/mm BTU) to 22669 ppm, 7.81 kg/GJ (18.16 lb/mm BTU) when fuel was switched from coal to 90:10 blend. Large-scale pilot plant tests performed at the 150-kWt facility (DOE-NETL) reveal increased falling potential for the blend compared to coal (Part III), emissions were negligible.
04101368 Combined effect of bottom reflectivity and water turbidity on steady state thermal efficiency of salt gradient solar pond Husain, M. et al. Energy Conversion and Management, 2004, 45, (l), 7381. In salt gradient solar ponds, the clarity of water and absorptivity of the bottom are important concerns. However, both are practically difficult to maintain beyond a certain limit. The reflectivity of the bottom causes the loss of a fraction of the incident radiation flux, resulting in lower absorption of flux in the pond. Turbidity hinders the propagation of radiation. Thereby it decreases the flux reaching the storage zone. Both these factors lower the efficiency of the pond significantly. However, the same turbidity also prevents the loss of radiation reflected from the bottom. Hence, the combined effect is compensatory to some extent. The present work is an analysis of the combined effect of the bottom's reflectivity and water turbidity on the steady state efficiency of solar ponds. It is found that in the case of a reflective bottom, turbidity, within certain limits, improves the efficiency of pond. This is apparently contradictory to the conventional beliefs about the pond. Nevertheless, this conclusion is of practical importance for design and maintenance of solar ponds.
04•01369 Combined molten carbonate fuel cell and gas turbine systems for efficient power and heat generation using biomass Jurado, F. and Valverde, M. Electric Power Systems Research, 2003, 65, (3), 223-232. When used in combination with turbines, fuel cells can produce from 55 to 90% of the electricity of the system while turbines produce the remainder. Fuel flexibility enables the use of low-cost indigenous fuels, renewables, and waste materials. The characteristics of gas from biomass gasification may vary significantly. Most real systems cannot be modelled exactly. Errors arise from un-modelled or unknown parameters. From another point of view, robust control incorporates the varying or uncertain parameters of the model. The advantage of this uncertainty representation is that it provides a good representation of the uncertainty arising in many real control problems.
04101370 Combustion efficiency and emissions in the combustion of biomass in stoves Machnikova, E. et al. Chemicke Listy, 2003, 97, (3), 171-178. (In Czech) The paper presents mass and enthalpy balances in the combustion of biomass in stoves. The first part of the paper concerns the biomass as an alternative source of energy, the combustion processes, formation of emissions and the method of calculation of mass and enthalpy balances. In the second part, experimental data are presented involving four types of fuels: foliate pellets, mixed pellets, 'American' pellets and sludge pellets of the bituminous coal type. The efficiency of the stove was calculated for all the fuels by using mass and enthalpy balances. In addition, analysis of products of incomplete combustion, such as C~Hy, volatile organic compounds, persistent organic pollutants (polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polychlorinated dibenzodioxines and dibenzofurans) was performed.
04•01371 Energy feedstock characteristics of willow and hybrid poplar clones at harvest age Tharakan, P. J. et al. Biomass and Bioenergy, 2003, 25, (6), 571-580. Woody biomass feedstock produced from willow and hybrid poplar can be converted into bioenergy via thermochemical and biochemical processes. Variation in key properties that relate to the quality of biomass feedstock and determine its value for energy conversion were determined at rotation age (3 years), in 30 willow and seven hybrid poplar clones, grown in a short-rotation intensive culture (SRIC) system in central NY. Substantial clonal variation in the concentrations of nitrogen (2.9-5.0 g k g - 1 ), phosphorus (0.4-0.8 g kg 1 ) potassium (1.2-2.4 g kg-l), sodium (0.09-0.20 g kg-1), calcium (3.9-8.9 g kg 1), magnesium (0.2-0.6 g k g - 1 ), ash (13.2-27.2 g k g - 1 ) and bark percentage (3.6-8.1%) was found in stem (bark+wood) samples. A lower amount of variation was documented for specific gravity (0.330.48 g c m -3) and percent moisture (49-56%). Bark had a higher concentration of inorganic elements and ash, relative to wood. Willow clones as a group had a higher specific gravity, bark percentage and calcium concentration relative to hybrid poplar clones, which had a higher potassium concentration. The two groups were similar in terms
of the concentrations of other elements and ash. Clonal variation in these characteristics present opportunities for manipulating feedstock quality through selection, breeding and plantation management.
04/01372
Ester fuels and chemicals from biomass
Olson, E. S. et al. Applied Biochemistry and Biotechnology, 2003, 105108, 843 851. Bench-scale research demonstrated that using an efficient esterification step to integrate an ethanol with a carboxylic acid fermentation stream offers potential for producing valuable ester feedstocks and fuels. Polar organic acids from bacterial fermentations are difficult to extract and purify, but formation of the ammonium salts and their conversion to esters facilitates the purifications. An improved esterification procedure gave high yields of esters, and this method will lower the cost of ester production. Fuel characteristics have been detected for a number of ester-gasoline blends with promising results for lowering Reid vapour pressure and raising octane numbers.
04/01373 Estimation of biomass and sequestered carbon on farm forest plantations in northern New South Wales, Australia Specht, A. and West, P. W. Biomass and Bioenergy, 2003, 25, (4), 363 379. Tree stem diameters were measured in a stratified random sample of plots in each of 19 forest plantation estates in northern New South Wales. The estates were 0.2-170 ha in area and the plantations were 110 years old, growing eucalypts, sub-tropical rainforest species or an exotic conifer, both in single-species and mixed-species plantations. A sample of trees was measured also for biomass and estate- and regionspecific allometric relationships developed to predict tree biomass from tree diameter. With the stratified random sample data, the allometric relationships were used to predict the total amount of carbon sequestered in tree biomass, and its 95% confidence limit, across each estate. These results were compared with estimates made using an allometric relationship from Nova Scotia, Canada, and a stand-based relationship from Australia. Bias in estimates made using the regionspecific or Nova Scotia relationships appeared to be unimportant if the confidence limit was >10% of the estimate. Bias was greater using the stand-based relationship and was unimportant only if the confidence limit was >30% of the estimate. It was concluded that using sampling intensities of around 2-4% of the estate area, the total carbon sequestered by an individual small plantation estate in the region could generally be estimated satisfactorily with a 95% confidence limit of about 30-40% of the estimate or better, with a minimum of about 10%. Generally, the younger the plantation estate, the higher was the sampling intensity necessary to achieve the same precision of estimate as in older estates. If small plantation owners in the region are intending to offer sequestered carbon for sale as carbon credits, it appeared it will be difficult for them to estimate carbon sequestration by their trees with a 95% confidence limit as low as the present Australian recommendation of 10% of the estimate. If owners pooled their estates in a cooperative, they should be better able to achieve the required confidence limit from the much larger, pooled estate. Analysis of organic carbon contents of soil below plantations and adjacent pasture paddocks suggested there was a decline in soil carbon with time following plantation establishment. Growers will need to account for these losses when estimating the total carbon sequestered by their plantations ecosystems.
04/01374 Experimental investigation of the decomposition and calcinations of calcium-enriched bio-oil Sotirchos, S. and Smith, A. R. Industrial & Engineering Chemistry Research, 2003, 42, (10), 2245-2255. The subject of this study is the experimental investigation of the decomposition of calcium-enriched bin-oil (CEB), the product of the reaction of bin-oil with calcium hydroxide, at high temperatures and of the calcination of the CaCO3 material that is obtained when the decomposition is carried out in the presence of CO2. Decomposition and calcination experiments are conducted in a thermogravimetric analysis system, and the pore structures of dried, decomposed, and calcined samples are characterized using nitrogen adsorptiondesorption, mercury intrusion-extrusion, and photomicrographical examination. The calcinations results for CEB-derived CaCO3 are compared with those for two naturally occurring calcitic solids of high CaCO3 content. The pore structure characterization results show that the decomposition and calcinations products of CEB have very high porosities, higher than 80-90%. Because of its high porosity, the calcinations product exhibits a much higher calcinations rate than particles of limestones and calcitics with a characteristic size similar to that of the CEB layer. This indicates that calcium-enriched bin-oil might perform as a more efficient sorbent than limestones for S O 2 capture in fossil fuel combustors.
Fuel and Energy Abstracts
May 2004
187
04/01362 Biomass gasification for heat application
-
a substitute to fossil fuel
Dasappa, S. et al. Biomass and Bioenergy, 2003, 25, (6), 637-649. The paper addresses case studies of a low temperature and a high temperature industrial heat requirement being met using biomass gasification. The gasification system for these applications consists of an open top down draft reburn reactor lined with ceramic. Necessary cooling and cleaning systems are incorporated in the package to meet the end use requirements. The other elements included are the fuel conveyor, water treatment plant for recirculating the cooling water and adequate automation to start, shut down and control the operations of the gasifier system. Drying of marigold flower, a low temperature application is considered to replace diesel fuel in the range of 125150 1 h -1. Gas from the 500 kg h -1, gasifier system is piped into the producer gas burners fixed in the combustion chamber with the downstream process similar to the diesel burner. The high temperature application is for a heat treatment furnace in the temperature range of 873-1200 K. A 300 kg h a of biomass gasifier replaces 2000 1 of diesel or LDO per day completely. The novelty of this package is the use of one gasifier to energize 16 burners in the eight furnaces with different temperature requirements. The system operates over 140 h per week on a nearly nonstop mode and over 4000 h of operation replacing fossil fuel completely. The advantage of bioenergy package towards the economic and environmental considerations is presented.
04/01363 Brazil
Biomass resources for energy in North-Eastern
Filho, P. A. and Badr, O. Applied Energy, 2004, 77, (1), 51 67. Due to the high dependency on hydroelectric power generation, Brazil faced a power shortage in 2001. In order to remedy the situation and avoid more severe power crises in the future, the Brazilian Government launched incentive programmes to encourage thermal and renewable power generation. The Programme of Incentives to Alternative Sources (PROINFA) is mainly devoted to the utilization of biomass. The success of P R O I N F A depends on the availability of reliable studies for assessing existing biomass resources and the viability of their utilization for power generation. In this study, energy potentials of the main biomass resources in the north-eastern region of Brazil have been assessed. The economy of the north-eastern region of Brazil is heavily dependent on its sugar industry. Biomass available from sugarcane cultivation and processing represents an annual regional energy resource of 40.5 TWh at an average cost of US$0.005/kWh. Bamboo, cultivated as a dedicated energy crop, has the second largest annual energy potential of 30.8 TWh at an average cost of US$0.009/kWh. Municipal solid waste, generated in the region, has an annual energy potential of about 16.7 TWh.
04•01364 Brassica carinata as an alternative oil crop for the production of biodiesel in Italy: agronomic evaluation, fuel production by transesterification and characterization Cardone, M. et al. Biomass and Bioenergy, 2003, 25, (6), 623-636. In this study, the non-food use of Brassica carinata oil for biodiesel production was investigated. B. carinata, a native plant of the Ethiopian highlands and widely used as food by the Ethiopians, has recently become the object of increasing interest. This is due to its better agronomic performances in areas such as Spain, California and Italy that are characterized by unfavourable environmental conditions for the cultivation of Brassica napus (by far the most common rapeseed cultivated in continental Europe). The agronomic performance and the energetic balance described here confirmed that B. carinata adapted better and was more productive both in adverse conditions (clay- and sandy-type soils and in semi-arid temperate climate) and under low cropping system when compared with B. napus. The biodiesel, produced by transesterification of the oil extracted from the B. carinata seeds, displayed physical-chemical properties suitable for the use as diesel car fuel. A comparison of the performance of B. carinata oilderived biodiesel with a commercial biodiesel and petroleum diesel fuel was conducted as regards engine performance, regulated and unregulated exhaust emissions. These results make B. carinata a promising oil feedstock for cultivation in coastal areas of central-southern Italy, where it is more difficult to achieve the productivity potentials of B. napus, and could offer the possibility of exploiting the Mediterranean marginal areas for energetic purposes.
04•01365 Cellulosic fuel ethanol. Alternative fermentation process designs with wild-type and recombinant Zymomonas mobilis Lawford, H. G. and Rousseau, J. D. Applied Biochemistry and Biotechnology, 2003, 105-108, 457-469.
186
Fuel and Energy Abstracts May 2004
Iogen (Canada) is a major manufacturer of industrial cellulase and hemicellulase enzymes for the textile, pulp and paper, and poultry feed industries. Iogen has recently constructed a 40 t/d biomass-to-ethanol demonstration plant adjacent to its enzyme production facility. The integration of enzyme and ethanol plants results in significant reduction in production costs and offers an alternative use for the sugars generated during biomass conversion. Iogen has partnered with the University of Toronto to test the fermentation performance characteristics of metabolically engineered Zymomonas mobilis created at the National Renewable Energy Laboratory. This study focused on strain AX101, a xylose- and arabinose-fermenting stable genomic integrant that lacks the selection marker gene for antibiotic resistance. The 'Iogen Process' for biomass depolymerization consists of a dilutesulfuric acid-catalysed steam explosion, followed by enzymic hydrolysis. This work examined two process design options for fermentation, first, continuous co-fermentation of C5 and C6 sugars by Zm AX101, and second, separate continuous fermentations of prehydrolysate by Zm AX101 and cellulose hydrolysate by either wild-type Z. mobilis ZM4 or an industrial yeast commonly used in the production of fuel ethanol from corn. Iogen uses a proprietary process for conditioning the prehydrolysate to reduce the level of inhibitory acetic acid to at least 2.5 g/L. The pH was controlled at 5.5 and 5.0 for Zymomonas and yeast fermentations, respectively. Neither 2.5 g/L of acetic acid nor the presence of pentose sugars (C6:Cs = 2:1) appreciably affected the highperformance glucose fermentation of wild-type Z. mobilis ZM4. By contrast, 2.5 g/L of acetic .acid significantly reduced the rate of pentose fermentation by strain AX101. For single-stage continuous fermentation of pure sugar synthetic cellulose hydrolysate (60 g/L of glucose), wild-type Zymomonas exhibited a four-fold higher volumetric productivity compared with industrial yeast. Low levels of acetic acid stimulated yeast ethanol productivity. The glucose-to-ethanol conversion efficiency for Zm and yeast was 96 and 84%, respectively.
04/01366 Changes in various physical/chemical parameters of Pinus pinaster wood after steam explosion pretreatment Negro, M. J. et al. Biomass and Bioenergy, 2003, 25, (3), 301-308. Steam-explosion process can be satisfactorily used as a pretreatment in ethanol production from lignocellulosic biomass. Traditionally, pretreatment effectiveness is evaluated in terms of hemicellulose solubilization, enzymatic convertibility of cellulose fraction, and recovery of both polysaccharides. In this study some parameters different from composition (main components) have been evaluated as an alternative tool to characterize the effect of steaming pre-treatment on lignocellulosie materials. The effect of the most important variables in steam explosion pre-treatment (temperature, residence time and chip size) on various physical/chemical parameters of pine biomass were investigated. Changes in O/C and H/C atomic ratios, colour analysis, elementary composition, water drop penetration time, organic soluble content, cellulose cristallinity index, and thermogravimetric analysis after the pre-treatment were evaluated. Furthermore the influence of operational pre-treatment variables on all such parameters and their interactions were examined with the Yates' algorithm.
04/01367 Co-firing of coal and cattle feedlot biomass (FB) fuels, Part II. Performance results from 30 kWt (100 000) BTU/ h laboratory scale boiler burner Annamalai, K. et al. Fuel, 2003, 82, (10), 1183-1193. The use of cattle manure (referred to as feedlot biomass, FB) as a fuel source has the potential to both solve waste disposal problems and reduce fossil fuel based CO2 emissions. A co-firing technology is proposed where FB is ground, mixed with coal, and then fired in existing, pulverized coal-fired boiler burner facilities. A research programmewas undertaken in order to determine (i) fuel characteristics, (if) combustion characteristics when fired along with coal in a small scale 30-kWt (100000 BTU/h) boiler burner facility, and (iii) combustion and fouling characteristics when fired along with coal in a large pilot scale 150-kWt (500 000 BTU/h) DOE-NETL boiler-burner facility. Part I presented a methodology for fuel collection, fuel characteristics of the FB, its relation to ration fed, and the change in fuel characteristics and volatile oxides due to composting. Part II addresses the pyrolysis characteristics of coal, FB, and blend and presents results on the performance of 90:10 coal:FB (PC) blend as fired in a 30-kW t boiler-burner unit. The boiler-burner unit is made of steel and lined with a cast ceramic liner for long duration operation and a commercial feeding system is used for firing the coal and the blend. Thermogravimetric analyses (TGA) performed on coal, FB, and 90:10 coal:FB blend reveal that biomass will start releasing gases at 273°C (523°C) which is about 100°C (212°C) lower than that of coal. The maximum rate of volatile release is about 0.000669 kg/s kg for FB while that of coal is 0.000425 kg/s kg. The experiments revealed that the 90:10 blend burns more completely in the boiler, due to the earlier release of biomass volatiles and higher amount of volatile matter in FB. The NOx emission for coal was 290 ppm, 0.162 kg/GJ (0.3768 lb/mm BTU) and 260 ppm, 0.1475 kg/GJ (0.343 lb/mm BTU) for the 90:10 blend at 10% excess air. Even though the effective N content of the
07 Alternative energy sources (bioconversion energy) blend increased by 18%, compared to coal the NOx emission decreased which is attributed to the higher VM of FB and more N in the form of NH3. However, due to limited residence time and higher VM, the CO emission increased from 15 582 ppm, 5.29 kg/GJ (12.305 Ib/mm BTU) to 22669 ppm, 7.81 kg/GJ (18.16 lb/mm BTU) when fuel was switched from coal to 90:10 blend. Large-scale pilot plant tests performed at the 150-kWt facility (DOE-NETL) reveal increased falling potential for the blend compared to coal (Part III), emissions were negligible.
04101368 Combined effect of bottom reflectivity and water turbidity on steady state thermal efficiency of salt gradient solar pond Husain, M. et al. Energy Conversion and Management, 2004, 45, (l), 7381. In salt gradient solar ponds, the clarity of water and absorptivity of the bottom are important concerns. However, both are practically difficult to maintain beyond a certain limit. The reflectivity of the bottom causes the loss of a fraction of the incident radiation flux, resulting in lower absorption of flux in the pond. Turbidity hinders the propagation of radiation. Thereby it decreases the flux reaching the storage zone. Both these factors lower the efficiency of the pond significantly. However, the same turbidity also prevents the loss of radiation reflected from the bottom. Hence, the combined effect is compensatory to some extent. The present work is an analysis of the combined effect of the bottom's reflectivity and water turbidity on the steady state efficiency of solar ponds. It is found that in the case of a reflective bottom, turbidity, within certain limits, improves the efficiency of pond. This is apparently contradictory to the conventional beliefs about the pond. Nevertheless, this conclusion is of practical importance for design and maintenance of solar ponds.
04•01369 Combined molten carbonate fuel cell and gas turbine systems for efficient power and heat generation using biomass Jurado, F. and Valverde, M. Electric Power Systems Research, 2003, 65, (3), 223-232. When used in combination with turbines, fuel cells can produce from 55 to 90% of the electricity of the system while turbines produce the remainder. Fuel flexibility enables the use of low-cost indigenous fuels, renewables, and waste materials. The characteristics of gas from biomass gasification may vary significantly. Most real systems cannot be modelled exactly. Errors arise from un-modelled or unknown parameters. From another point of view, robust control incorporates the varying or uncertain parameters of the model. The advantage of this uncertainty representation is that it provides a good representation of the uncertainty arising in many real control problems.
04101370 Combustion efficiency and emissions in the combustion of biomass in stoves Machnikova, E. et al. Chemicke Listy, 2003, 97, (3), 171-178. (In Czech) The paper presents mass and enthalpy balances in the combustion of biomass in stoves. The first part of the paper concerns the biomass as an alternative source of energy, the combustion processes, formation of emissions and the method of calculation of mass and enthalpy balances. In the second part, experimental data are presented involving four types of fuels: foliate pellets, mixed pellets, 'American' pellets and sludge pellets of the bituminous coal type. The efficiency of the stove was calculated for all the fuels by using mass and enthalpy balances. In addition, analysis of products of incomplete combustion, such as C~Hy, volatile organic compounds, persistent organic pollutants (polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polychlorinated dibenzodioxines and dibenzofurans) was performed.
04•01371 Energy feedstock characteristics of willow and hybrid poplar clones at harvest age Tharakan, P. J. et al. Biomass and Bioenergy, 2003, 25, (6), 571-580. Woody biomass feedstock produced from willow and hybrid poplar can be converted into bioenergy via thermochemical and biochemical processes. Variation in key properties that relate to the quality of biomass feedstock and determine its value for energy conversion were determined at rotation age (3 years), in 30 willow and seven hybrid poplar clones, grown in a short-rotation intensive culture (SRIC) system in central NY. Substantial clonal variation in the concentrations of nitrogen (2.9-5.0 g k g - 1 ), phosphorus (0.4-0.8 g kg 1 ) potassium (1.2-2.4 g kg-l), sodium (0.09-0.20 g kg-1), calcium (3.9-8.9 g kg 1), magnesium (0.2-0.6 g k g - 1 ), ash (13.2-27.2 g k g - 1 ) and bark percentage (3.6-8.1%) was found in stem (bark+wood) samples. A lower amount of variation was documented for specific gravity (0.330.48 g c m -3) and percent moisture (49-56%). Bark had a higher concentration of inorganic elements and ash, relative to wood. Willow clones as a group had a higher specific gravity, bark percentage and calcium concentration relative to hybrid poplar clones, which had a higher potassium concentration. The two groups were similar in terms
of the concentrations of other elements and ash. Clonal variation in these characteristics present opportunities for manipulating feedstock quality through selection, breeding and plantation management.
04/01372
Ester fuels and chemicals from biomass
Olson, E. S. et al. Applied Biochemistry and Biotechnology, 2003, 105108, 843 851. Bench-scale research demonstrated that using an efficient esterification step to integrate an ethanol with a carboxylic acid fermentation stream offers potential for producing valuable ester feedstocks and fuels. Polar organic acids from bacterial fermentations are difficult to extract and purify, but formation of the ammonium salts and their conversion to esters facilitates the purifications. An improved esterification procedure gave high yields of esters, and this method will lower the cost of ester production. Fuel characteristics have been detected for a number of ester-gasoline blends with promising results for lowering Reid vapour pressure and raising octane numbers.
04/01373 Estimation of biomass and sequestered carbon on farm forest plantations in northern New South Wales, Australia Specht, A. and West, P. W. Biomass and Bioenergy, 2003, 25, (4), 363 379. Tree stem diameters were measured in a stratified random sample of plots in each of 19 forest plantation estates in northern New South Wales. The estates were 0.2-170 ha in area and the plantations were 110 years old, growing eucalypts, sub-tropical rainforest species or an exotic conifer, both in single-species and mixed-species plantations. A sample of trees was measured also for biomass and estate- and regionspecific allometric relationships developed to predict tree biomass from tree diameter. With the stratified random sample data, the allometric relationships were used to predict the total amount of carbon sequestered in tree biomass, and its 95% confidence limit, across each estate. These results were compared with estimates made using an allometric relationship from Nova Scotia, Canada, and a stand-based relationship from Australia. Bias in estimates made using the regionspecific or Nova Scotia relationships appeared to be unimportant if the confidence limit was >10% of the estimate. Bias was greater using the stand-based relationship and was unimportant only if the confidence limit was >30% of the estimate. It was concluded that using sampling intensities of around 2-4% of the estate area, the total carbon sequestered by an individual small plantation estate in the region could generally be estimated satisfactorily with a 95% confidence limit of about 30-40% of the estimate or better, with a minimum of about 10%. Generally, the younger the plantation estate, the higher was the sampling intensity necessary to achieve the same precision of estimate as in older estates. If small plantation owners in the region are intending to offer sequestered carbon for sale as carbon credits, it appeared it will be difficult for them to estimate carbon sequestration by their trees with a 95% confidence limit as low as the present Australian recommendation of 10% of the estimate. If owners pooled their estates in a cooperative, they should be better able to achieve the required confidence limit from the much larger, pooled estate. Analysis of organic carbon contents of soil below plantations and adjacent pasture paddocks suggested there was a decline in soil carbon with time following plantation establishment. Growers will need to account for these losses when estimating the total carbon sequestered by their plantations ecosystems.
04/01374 Experimental investigation of the decomposition and calcinations of calcium-enriched bio-oil Sotirchos, S. and Smith, A. R. Industrial & Engineering Chemistry Research, 2003, 42, (10), 2245-2255. The subject of this study is the experimental investigation of the decomposition of calcium-enriched bin-oil (CEB), the product of the reaction of bin-oil with calcium hydroxide, at high temperatures and of the calcination of the CaCO3 material that is obtained when the decomposition is carried out in the presence of CO2. Decomposition and calcination experiments are conducted in a thermogravimetric analysis system, and the pore structures of dried, decomposed, and calcined samples are characterized using nitrogen adsorptiondesorption, mercury intrusion-extrusion, and photomicrographical examination. The calcinations results for CEB-derived CaCO3 are compared with those for two naturally occurring calcitic solids of high CaCO3 content. The pore structure characterization results show that the decomposition and calcinations products of CEB have very high porosities, higher than 80-90%. Because of its high porosity, the calcinations product exhibits a much higher calcinations rate than particles of limestones and calcitics with a characteristic size similar to that of the CEB layer. This indicates that calcium-enriched bin-oil might perform as a more efficient sorbent than limestones for S O 2 capture in fossil fuel combustors.
Fuel and Energy Abstracts
May 2004
187