Showing papers in "Biomass & Bioenergy in 2000"
TL;DR: Jatropha curcas is a tropical plant that can be grown in low to high rainfall areas and can be used to reclaim land, as a hedge and/or as a commercial crop.
Abstract: Jatropha curcas is a multipurpose plant with many attributes and considerable potential. It is a tropical plant that can be grown in low to high rainfall areas and can be used to reclaim land, as a hedge and/or as a commercial crop. Thus, growing it could provide employment, improve the environment and enhance the quality of rural life. The establishment, management and productivity of jatropha under various climatic conditions are not fully documented. This is discussed and the gaps in the knowledge elucidated, especially its fertilizer requirements. The plant produces many useful products, especially the seed, from which oil can be extracted; this oil has similar properties to palm oil. The costs and returns of growing the plant and producing the plant oil are discussed and tabulated. Because it can be used in place of kerosene and diesel and as a substitute for fuelwood, it has been promoted to make rural areas self sufficient in fuels for cooking, lighting and motive power. This strategy is examined and found not viable. Oil for soap making is the most profitable use. It is concluded that all markets for jatropha products should be investigated. If the full potential of the plant is to be realized, much more research is required into the growing and management of Jatropha curcas and more information is needed on the actual and potential markets for all its products.
1,213 citations
TL;DR: Miscanthus is a tall perennial rhizomatous grass with C4 photosynthesis which originated in East Asia and has been successfully grown in Europe over the past 10 years as discussed by the authors.
Abstract: Miscanthus is a tall perennial rhizomatous grass with C4 photosynthesis which originated in East Asia. This article provides an overview of the most important results and experience gained with miscanthus in Europe over the past 10 years. Field trials have been established throughout Europe from the Mediterranean to southern Scandinavia. Most reported trials have used a vigorous sterile clone Miscanthus x giganteus, which has been propagated vegetatively either by rhizome cutting or in vitro culture. Yields in autumn have been reported in excess of 30 t ha−1 (12 t acre−1) for irrigated trials in southern Europe. Without irrigation autumn yields of 10–25 t ha−1 (dry matter) can be expected. The quality of miscanthus biomass for combustion is in some respect comparable to woody biomass and normally improves by delaying harvesting until the spring, although harvestable yields are thus reduced by 30–50% compared with autumn yields. Different technical options for establishment, harvesting and handling of miscanthus have been developed and these significantly effect production costs. Miscanthus production is characterized by low fertilizer and pesticide requirements making it a relatively benign crop environmentally. The main limitations to miscanthus production from M. x giganteus are the high establishment costs, poor over-wintering at some sites and insufficient water supply in southern regions of Europe. New agronomic techniques and new genotypes with improved characteristics are being developed and screened over the wide range of ecological conditions in Europe. Against this background of European experience the prospects for growing miscanthus in North America are discussed.
874 citations
TL;DR: In this paper, the catalytic behavior of olivine, a common, naturally occurring mineral containing magnesium, iron oxides and silica, was investigated in a laboratory scale, biomass gasification unit.
Abstract: Naturally occurring catalytic substances are employed in biomass steam-gasification processes to enhance the yield of fuel gas and reduce its tar content by cracking and reforming the high molecular weight organic components. Calcined dolomite is widely used for this purpose; it exhibits good catalytic activity under the operating conditions of the gasifier. However, due to its poor mechanical strength, it gives rise to a large production of fines in a fluidised-bed environment. This work reports an investigation into the catalytic behaviour of olivine, a common, naturally occurring mineral containing magnesium, iron oxides and silica: iron is known to play a positive role in tar decomposition reactions. The gasification runs, performed with a laboratory scale, biomass gasification unit, show that the olivine activity is close to that exhibited by dolomite under comparable operating conditions. Olivine has the additional advantage, however, that its resistance to attrition in the fluidised bed is much greater, similar to that of sand. Parametric sensitivity studies of a gasification process, utilising olivine as the fluidised-bed inventory, indicate an optimum gasification temperature of just above 800°C, and little influence of the steam/biomass ratio in the range 0.5–1.
657 citations
TL;DR: Bamboo is the common term applied to a broad group (1250 species) of large woody grasses, ranging from 10 cm to 40 cm in height as discussed by the authors, and it shares a number of desirable fuel characteristics with certain other bioenergy feedstocks, such as low ash content and alkali index.
Abstract: Bamboo is the common term applied to a broad group (1250 species) of large woody grasses, ranging from 10 cm to 40 m in height. Already in everyday use by about 2.5 billion people, mostly for fiber and food within Asia, bamboo may have potential as a bioenergy or fiber crop for niche markets, although some reports of its high productivity seem to be exaggerated. Literature on bamboo productivity is scarce, with most reports coming from various parts of Asia. There is little evidence overall that bamboo is significantly more productive than many other candidate bioenergy crops, but it shares a number of desirable fuel characteristics with certain other bioenergy feedstocks, such as low ash content and alkali index. Its heating value is lower than many woody biomass feedstocks but higher than most agricultural residues, grasses and straws. Although non-fuel applications of bamboo biomass may be actually more profitable than energy recovery, there may also be potential for co-production of bioenergy together with other bamboo processing. A significant drawback is the difficulty of selective breeding, given the lack of knowledge of flowering physiology. Further research is also required on propagation techniques, establishment and stand management, and mechanized harvesting needs to be developed.
626 citations
TL;DR: In this article, a technical evaluation of stillage characterization, treatment, and byproduct recovery in the ethanol industry was performed through a review of the scientific literature, with particular emphasis on solutions pertinent to a cellulosic-based ethanol production system.
Abstract: A technical evaluation of stillage characterization, treatment, and by-product recovery in the ethanol industry was performed through a review of the scientific literature, with particular emphasis on solutions pertinent to a cellulosic-based ethanol production system. This effort has generated substantial information supporting the viability of anaerobic digestion for stillage treatment followed by land application on biomass crops for nutrient recovery. Generally, the characteristics of stillage from cellulosic materials appear comparable to those of conventional sugar- and starch-based feedstocks. However, the data on cellulosic stillage characteristics and treatment parameters are extremely limited and highly variable. This has significant impacts on the capital costs and biogas recovery of anaerobic treatment systems predicted from these data. In addition, technical questions remain unanswered with regard to stillage toxicity from untested feedstocks and the impact of heavy metal leaching when acid hydrolysis reactors are fabricated from corrosion-resistant alloys. Thermophilic anaerobic digestion of ethanol stillage achieves similar treatment efficiencies and methane yields compared to mesophilic treatment, but at almost twice the organic loading rate. Therefore, application of thermophilic anaerobic digestion would improve process economics, since smaller digesters and less stillage cooling are required. Downstream processes for stillage utilization and by-product recovery considered worthy of continued investigation include the production of feed (from single cell protein and/or algae production), color removal, and production of calcium magnesium acetate. This study finds that sustainable and economically viable solutions are available for mitigating the environmental impacts which result from large-scale biomass-to-ethanol conversion facilities. However, further research in some areas is needed to facilitate successful implementation of appropriate technology options.
599 citations
TL;DR: There has been considerable emphasis on cofiring biomass opportunity fuels with coal in pulverized coal (PC) and cyclone boilers owned and operated by electricity generating utilities in order to address such issues as potential portfolio standards, voluntary actions to reduce fossil CO2 emissions, customer service, and the generation of green power within the context of deregulation.
Abstract: Cofiring, the practice of supplementing a base fuel with a dissimilar fuel, is an extension of fuel blending practices common to the solid fuels community. Recently, there has been considerable emphasis on cofiring biomass opportunity fuels with coal in pulverized coal (PC) and cyclone boilers owned and operated by electricity generating utilities in order to address such issues as potential portfolio standards, voluntary actions to reduce fossil CO2 emissions, customer service, and the generation of green power within the context of deregulation. Biomass fuels considered for cofiring include wood waste, short rotation woody crops, short rotation herbaceous crops (e.g., switchgrass), alfalfa stems, various types of manure, landfill gas and wastewater treatment gas. Of these, the solid biofuels such as sawdust, urban wood waste and switchgrass have received the most attention. The Electric Power Research Institute (EPRI), along with the Tennessee Valley Authority (TVA), GPU Genco, Northern Indiana Public Service Company (NIPSCO), Central and South West Utilities (CS this agreement was extensively supported by the energy efficiency and renewable energy (EERE) element of USDOE. European cofiring programs also have been extensive and include gasification-based cofiring in Lahti, Finland and straw cofiring in Denmark. Three general techniques comprise the cofiring technology family: blending the biomass and coal in the fuel handling system and feeding that blend to the boiler; preparing the biomass fuel separately from coal, and injecting it into the boiler without impacting the conventional coal delivery system; and gasifying the biomass with subsequent combustion of the producer gas in either a boiler or a combined cycle combustion turbine (CCCT) generating plant. Commercialization has proceeded on the direct combustion approaches to cofiring, beginning with engineering and economic studies, parametric testing and the construction of demonstration projects. The direct combustion cofiring techniques are now ready for commercial deployment. This paper reviews the key projects, and details some of the influences of cofiring on the combustion process.
505 citations
TL;DR: In this article, three fatty materials, soy-bean oil, used frying oil and tallow, were transformed into two different types of biodiesel, by transesterification and amidation reactions with methanol and diethylamine respectively.
Abstract: Three fatty materials, soy-bean oil, used frying oil and tallow, were transformed into two different types of biodiesel, by transesterification and amidation reactions with methanol and diethylamine respectively. The ignition properties of these types of biodiesel were evaluated calculating the cetane index of the transesterification products, and the blending cetane number of the amide biodiesel blended with conventional diesel. Amide biodiesel enhances the ignition properties of the petrochemical diesel fuel, and it could account for the 5% market share that should be secured to biofuels by 2005.
443 citations
TL;DR: In this article, the most efficient means to produce fermentable sugars from corn stover is by enzymic hydrolysis, which is facilitated by thermochemical pretreatment of the corn Stover.
Abstract: Corn stover is an abundant, potential fermentation substrate. The most efficient means to produce fermentable sugars from corn stover is by enzymic hydrolysis, which is facilitated by thermochemical pretreatment of the corn stover. Pretreatment with slake lime (calcium hydroxide) increased the enzymic hydrolysis of corn stover nine times compared to untreated corn stover. The recommended pretreatment conditions are: lime loading 0.075 g Ca(OH)2 (g dry biomass)−1; water loading 5 g H2O (g dry biomass)−1; and heating for 4 h at 120°C. The recommended enzyme loading for the enzymic saccharification of pretreated corn stover is 10 FPU (g dry biomass)−1 and the recommended hydrolysis temperature is 40°C. The enzymic conversion of the corn stover to monosaccharides, when pretreated and saccharified as prescribed for 72 h, was about 60% cellulose, 47% xylan, and 53% total available polysaccharide. Increasing the enzyme loading to 25 FPU (g dry biomass)−1 and the hydrolysis time to 7 days produced conversions of 88.0, 87.7, and 92.1% for the glucan, xylan and arabinan, respectively. These high conversions indicate that pretreatment with lime can lead to corn stover polysaccharide conversions approaching 100%; the success of the saccharification after lime pretreatment depends on the enzyme loading.
388 citations
TL;DR: In this article, a comparison of the performance of fixed-bed and fluidized-bed nuclear power plants is presented, and it is shown that the advantages of one of the two types are marginal.
Abstract: Gasification as a thermochemical process is defined and limited to combustion and pyrolysis. A systematic overview of reactor designs categorizes fixed bed and fluidized bed reactors. Criteria for a comparison of these reactors are worked out, i.e. technology, use of material, use of energy, environment and economy. A utility analysis for thermochemical processes is suggested. It shows that the advantages of one of the reactor types are marginal. An advantage mainly depends on the physical consistency of the input. As a result there is no significant advantage for the fixed bed or the fluidized bed reactor.
348 citations
TL;DR: In this paper, a case study of rice straw production in the Sacramento Valley was conducted, which illustrates that 550 t d−1 of straw can be accessed at an estimated net delivered cost of about US $20/t (dry), which is generally considered attractive for an ethanol feedstock.
Abstract: As open-field burning of rice straw is being phased out in California, rice growers and government agencies are looking for new rice straw uses. The amount of rice straw that may be available as a feedstock ranges from 1.0 to 1.4 million t yr−1. Irrespective of its actual use as a source of raw material for liquid fuel, fiber, or power generation, a study of issues dealing with its harvest is needed. This paper reviews possible harvesting systems and provides an analysis of operating parameters such as straw moisture, density, storage, and optimal number of transport units. A case study of rice straw production in the Sacramento Valley was conducted, which illustrates that 550 t d−1 of straw can be accessed at an estimated net delivered cost of about US $20/t (dry), which is generally considered attractive for an ethanol feedstock. Gainfully utilizing this residue can ease the disposal problem facing agricultural operations in the State. Furthermore, the potential environmental benefits of diverting rice straw from open-field burning will be to significantly reduce criteria air pollutants such as VOC, SOx, NOx, and PM10, and also silica emissions, which are not specifically monitored but can be a health hazard.
314 citations
TL;DR: In this paper, a piston-and-mold (punch and die) process was used to produce densified logs (slugs) under room temperature and at pressures ranging from 34 to 138 MPa.
Abstract: High-pressure binderless compaction of wood processing residues and other biomass waste materials, including hardwood, softwood, and bark in the forms of sawdust, mulches, and chips, were studied. A piston-and-mold (punch-and-die) process was used to produce densified logs (slugs) under room temperature and at pressures ranging from 34 to 138 MPa. The properties of the logs including density, abrasion resistance, impact resistance, compressive strength, water resistance, and long-term performance were tested. The effects of moisture content, compaction pressure, compaction speed, pressure holding time, particle size and particle shape were studied. It was found that the necessary moisture for producing good-quality logs ranges from 5 to 12% for all the woody materials studied, and the optimum moisture content is in the neighborhood of 8%. It was also found that mulch is the easiest form to be compacted into dense and strong logs, sawdust is the second, and chips the last. For the mulches, a compaction pressure of 70 MPa can produce high-quality logs. For sawdust, a minimum pressure of 100 MPa is needed to form good logs. And for chips, no good logs can be made even at pressure as high as 138 MPa. The logs produced under optimal conditions had dry densities near or higher than 1 g / cm 3 . Such high density facilitates storage, handling and transportation of biomass. The dense logs also have high-energy content per unit volume, making it easier to be co-fired with coal in power plants.
TL;DR: In this paper, the use of Geographic Information Systems (GIS) for understanding the geographic context of bioenergy supplies is discussed and a regional-scale, GIS-based modeling system for estimating potential biomass supplies from energy crops is described.
Abstract: The use of Geographic Information Systems (GIS) for understanding the geographic context of bioenergy supplies is discussed and a regional-scale, GIS-based modeling system for estimating potential biomass supplies from energy crops is described. While GIS models can capture geographic variation that may influence biomass costs and supplies, GIS models are not likely to handle uncertainty well and are often limited by the lack of spatially explicit data. The presented modeling system estimates the costs and environmental implications of supplying specified amounts of energy crop feedstock across a state. The system considers where energy crops could be grown, the spatial variability in their yield, and transportation costs associated with acquiring feedstock for an energy facility. The modeling system was used to estimate potential switchgrass costs and supplies in eleven US states. Transportation costs increased with increased facility demand and were lowest in Iowa, North Dakota and South Dakota and highest in South Carolina, Missouri, Georgia, and Alabama. Farmgate feedstock costs were lowest in Alabama, North Dakota and South Dakota and highest in Iowa and Nebraska. Across the eleven states, delivered feedstock costs ranged from $33 to $55/dry tonne to supply a facility requiring 100,000 tonne/yr. Delivered feedstock costs for a 630,000 tonne/yr facility ranged from $36 to $58/dry tonne.
TL;DR: In this article, the effect of methanol and/or a pyrolytic aqueous phase on the physicochemical properties of bio-oils was investigated, and the results indicated that the bio-oil sample investigated is a valuable gas turbine fuel: it has a relatively low Na+K+Ca content (21ppm), a low viscosity ( 5.3 cSt @90°C ), a high net heating value (32MJ/kg, as-received basis) and a low solid content (0.34 wt%).
Abstract: The objective of this study was to provide background information on biomass pyrolysis oils (bio-oils) regarding their use as a liquid fuel for gas turbine applications. The bio-oil was obtained by vacuum pyrolysis of softwood bark residues. Alkali metal content, viscosity, solid content, heating value, surface tension, moisture content and density of the bio-oil were investigated. The effect of the addition of methanol and/or a pyrolytic aqueous phase on the physicochemical properties of the bio-oils was also investigated. The pyrolytic aqueous phase is the sum of the water contained in form of moisture in the feedstock plus the water formed during biomass pyrolysis reactions. The results indicated that the bio-oil sample investigated is a valuable gas turbine fuel: it has a relatively low Na+K+Ca content (21 ppm), a low viscosity ( 5.3 cSt @90° C ), a high net heating value (32 MJ/kg, as-received basis) and a low solid content (0.34 wt%). The addition of methanol to the oil was beneficial. It was also found that the pyrolytic aqueous phase addition had no significant effect on the viscosity, but that its “flowability” effect was beneficial for other properties. A concentration of 10–15% of the aqueous phase in the bio-oil seemed to be optimal. The second phase of this study investigated the storage and thermal stability of bio-oils and their mixtures. This was carried out using a method performed in our laboratory. The results are presented in Part II of this study.
TL;DR: In this article, the effect of particle size on the yields of the products was investigated and the results showed the potential of rapeseed as an important source of liquid hydrocarbon fuels.
Abstract: Brassica napus L. pyrolysis experiments were performed in a Heinze reactor under static atmosphere at a pyrolysis temperature of 500°C at 40°C/min of heating rate. The effect of particle size on the yields of the products was investigated. The particle size of rapeseed was varied in the range of 0.224–1.8 mm. Pyrolysis oil and char yields from rapeseed were found to be largely independent of particle size in the experimental conditions. Oil yield shows a maximum of ca 46 wt% with a particle size range of 0.85–1.8 mm. The various characteristics of pyrolysis oil obtained under these conditions were identified on the basis of standard test methods. The empirical formula of pyrolysis oil with a heating value of 38.4 MJ/kg was established as CH 1.67 O 0.12 N 0.046 . The results from the pyrolysis of rapeseed showed the potential of rapeseed as an important source of liquid hydrocarbon fuels. Rapeseed oil was also evaluated for fatty acid composition.
TL;DR: In this paper, the stability and ageing of the bio-oil and mixtures thereof were evaluated and it was found that the molecular weight increase after heating the biooil for one week at 80°C was equivalent to keeping the sample for one year at room temperature.
Abstract: This paper completes a study the ultimate objective of which was to provide background information on biomass pyrolysis oils (bio-oils) regarding their use as a gas turbine liquid fuel. The bio-oil was obtained by vacuum pyrolysis of softwood bark residues. The stability and ageing of the bio-oil and mixtures thereof were evaluated. The samples were stored at 40, 50 and 80°C for up to 168 h and at room temperature for up to one year, period after which the phase separation time, viscosity, solid and water content and average molecular weight were measured. The results indicated that the properties of the bio-oil were significantly altered when the bio-oil was heated at 80°C, but that the variations after heating at 40 and 50°C were not critical. It was found that the molecular weight increase after heating the bio-oil for one week at 80°C was equivalent to keeping the sample for one year at room temperature. The addition of aqueous phase to the bio-oil lowered its thermal stability significantly. A rapid phase separation occurred after heating at 80°C and, therefore, the total aqueous phase concentration in the bio-oil must be limited to 15%. Ageing of the raw bio-oil at room temperature resulted in a dramatic viscosity increase during the first 65 days, period after which a plateau was reached. The addition of methanol to the bio-oil was beneficial for the bio-oil properties as well as for the stability of the bio-oil and its mixtures. Methanol dissolved some structured components of the bio-oil and thus reduced the viscosity increase rate. Moreover, the addition of methanol to the bio-oil/pyrolytic aqueous phase mixtures delayed the phase separation process.
TL;DR: In this paper, the authors used the life cycle inventory (LCI) to investigate the environmental load of selected bioenergy transport chains and showed that emissions from long range transportation, 1200 km, performed with ships, is of minor importance compared to emissions from local bioenergy systems in a local market.
Abstract: Biomass for energy conversion is usually considered as a local resource. With appropriate logistic systems, access to biomass can be improved over a large geographical area. In this study, life cycle inventory (LCI) has been used as a method to investigate the environmental load of selected bioenergy transport chains. As a case study, chains starting in Sweden and ending in Holland have been investigated. Biomass originates from tree sections or forest residues, the latter upgraded to bales or pellets. The study is concentrated on production of electricity, hot cooling water is considered as a loss. Electricity is, in the case study, produced from solid biomass in the importing country. Electricity can also be produced in the country of origin and exported via the transnational grid as transportation medium. The results show that emissions from long range transportation, 1200 km, performed with ships, is of minor importance compared to emissions from local bioenergy systems in a local market. In bioenergy systems the use of fuels and electricity for operating machines and transportation carriers requires a net energy input which amounts to typically 7‐9% of delivered electrical energy from the system. Emissions of key substances such as NOx, CO, S, hydrocarbons, and particles are low in a perspective of sustainability. Emissions of CO2 from biocombustion are considered to be zero since there is approximately no net contribution of carbon to the biosphere in an energy system based on biomass. The results indicate that biomass for energy can be transported from Scandinavia to Holland without losing its environmental benefits. 7 2000 Elsevier Science Ltd. All rights reserved.
TL;DR: In this article, a series of CO2-char gasification tests were performed in a thermogravimetric analyzer (TGA) to evaluate the catalytic activity of alkali-rich biomass-derived materials.
Abstract: We are investigating catalytic gasification of coal char using biomass-derived potassium salts. Alkali metal salts, especially those containing potassium, are excellent promoters of gasification reactions but are generally considered too expensive for commercial use. Fast-growing biomass, which contains large quantities of potassium, may prove to be an excellent source of inexpensive gasification catalyst. A series of CO2-char gasification tests were performed in a thermogravimetric analyzer (TGA) to evaluate the catalytic activity of alkali-rich biomass-derived materials. Both switchgrass char and switchgrass ash displayed catalytic activity in mixtures with coal char produced from Illinois No. 6 coal. The results obtained with switchgrass ash were especially impressive, with an almost eight-fold increase in coal char gasification rate at 895°C in a 10:90 mixture of coal char and switchgrass ash. These results give encouragement that biomass could be the source of inexpensive, coal gasification catalysts.
TL;DR: In this paper, the effect of different cultural practices on soil carbon sequestration under switchgrass was investigated and the results showed that N application, row spacing, harvest frequency, and switchgrass cultivar did not change soil organic carbon in the short-term after switchgrass establishment.
Abstract: Increased atmospheric carbon dioxide (CO2) could have negative impacts on the environment. Producing and creating bioenergy in the form of biofuels and electricity from crops is a practical approach to reducing CO2 buildup by displacing fossil fuels and sequestering carbon (C). The use of switchgrass (Panicum virgatum L.) as an energy crop can contribute to clean burning fuels, but no studies addressing soil C sequestration as influenced by use of switchgrass as an energy crop have been conducted. Our objective was to determine the effect of different cultural practices on soil C sequestration under switchgrass. Field experiments were designed to provide differences in row spacing, nitrogen (N) rate, switchgrass cultivar, and harvest frequency on a variety of soils. Our results showed that N application, row spacing, harvest frequency, and switchgrass cultivar did not change soil organic C in the short-term (2–3 yr) after switchgrass establishment. However, after 10 yr under switchgrass soil organic C was 45 and 28% higher at depths of 0–15 and 15–30 cm, respectively, compared with fallowed soil in an adjacent area. It appears that several years of switchgrass culture will be required to realize a soil C sequestration benefit.
TL;DR: In this article, a two-dimensional mathematical model for the combustion of straw in a cross-current, moving bed was developed as part of a tool for optimizing operating conditions and design parameters.
Abstract: A two-dimensional mathematical model for the combustion of straw in a cross-current, moving bed was developed as part of a tool for optimizing operating conditions and design parameters. To verify the model and to increase the understanding of straw bed combustion, laboratory fixed-bed experiments were performed in a 15 cm diameter and 137 cm long vertical reactor. Air was introduced through the bottom plate and the straw was ignited from the top with an electrical radiation source. The temperature was measured at eight positions within the bed and gas analysis was performed for O 2 , CO 2 , CO, C x H y , NO x , NH 3 and SO 2 . The inlet air flow rate and air preheat temperature were varied. The experimental data for ignition front temperatures and front propagation velocity compared reasonably well with the modelling results. A higher air inlet temperature resulted in lower maximum bed temperatures, which was successfully modelled. A limited parameter analysis study was performed. Measurement of NO from the bed showed that, within the air inlet flow rates investigated, the conversion of fuel nitrogen to NO decreased with increasing air flow rate during ignition front propagation, while the conversion increased during the char burnout phase.
TL;DR: In this article, sawdust, rice husks, peanut shells, coconut fibres and palm fruit fibres were densified into briquettes at modest pressures of 5-7 MPa using a piston and die type of press.
Abstract: Biomass material, including sawdust, rice husks, peanut shells, coconut fibres and palm fruit fibres, was densified into briquettes at modest pressures of 5–7 MPa using a piston and die type of press. The briquettes were tested to evaluate their relaxation behaviour, mechanical strength and burning characteristics. The sawdust briquettes were found to have better overall handling characteristics. But briquettes of different biomass materials required different optimum conditions of fabrication and generally showed a promising potential for further development.
TL;DR: The US Department of Energy (DOE), Electric Power Research Institute (EPRI) and utilities are evaluating, testing and applying technology that can give a new, and potentially profitable, mission to existing coal-fired power plants.
Abstract: The US Department of Energy (DOE), Electric Power Research Institute (EPRI) and utilities are evaluating, testing and applying technology that can give a new, and potentially profitable, mission to existing coal-fired power plants. The oldest of all fuels, wood, and the old original fuel of the industrial revolution, coal, are key to this move to a new mission. Technical issues that can lead to doubt about, or outright rejection of, wood (or biomass) cofiring are, in fact, being resolved through testing and experience. DOE, EPRI and utilities have joined to cosponsor tests in full-sized boilers and design/cost/supply studies related to these tests. Economic calculations, based on the measured performance and on cost estimates confirmed in purchases for the tests, are presented in this paper. The technical feasibility is proved. The constraints are identified. So far, the profits are in the future. Policy changes that produce stronger economic incentives could make profit possible today, and enable this low-cost form of renewable power to be deployed. But, without the policy, or market, change, the economic barrier is a strong one, when biomass cofiring must compete with low-cost coal at low fuel cost and with low-capital-cost gas turbine combined cycle power plants. The economics would not be a barrier at all if biomass cofiring were in competition against moderate-velocity wind power or solar PV power.
TL;DR: In this article, the influence of row spacing, nitrogen (N) rate, switchgrass cultivar, and soil type on switchgrass root characteristics was determined, which indicated that any increase in C sequestration by switchgrass roots will be due to increased root biomass rather than increased carbon concentration.
Abstract: One approach to reducing the concentration of atmospheric carbon dioxide, which is a dominant greenhouse gas, is to develop renewable energy sources from biofuel crops. Switchgrass, ( Panicum virgatum L.) as an energy crop, can partly mitigate potential global warming by supplementing fossil fuels and sequestering carbon (C). Although switchgrass grown for energy may impact C sequestration via the input of root biomass, information on the impact of soil management on switchgrass root growth is extremely limited. We determined the influence of row spacing, nitrogen (N) rate, switchgrass cultivar, and soil type on switchgrass root characteristics. Roots were mainly distributed in the surface soil (0–15 cm), and were 90.4 and 68.2% of the total in the intrarow and interrow profile, respectively. Nitrogen application altered root N but not C concentration, implying that any increase in C sequestration by switchgrass roots will be due to increased root biomass rather than increased C concentration. Root weight density generally decreased in the interrow with wider row width, and N application generally did not affect root weight density. Root weight density in the Pacolet soil was higher than in the other four soils, and root density was 4.1 times higher in the Pacolet soil than in the Norfolk soil. Root mass in the Pacolet soil (36,327 kg ha −1 ) was 2.7 times greater than that found in the Norfolk soil (13,204 kg ha −1 ) within 150 cm of the soil surface. Differences in root characteristics were found among cultivars: root weight density with ‘Cave-in-Rock’ switchgrass was 29.4 and 47.6% higher than ‘Alamo’ and ‘Kanlow’, respectively. Variations in switchgrass root biomass production owing to soil type and cultivar suggest that site and cultivar selection will be important determinants of C sequestration by switchgrass roots. A potential benefit of switchgrass is the reduced loss of nutrients associated with non-point pollution, owing to its deep root system that may extend 330 cm below the soil surface.
TL;DR: In this article, evolution profiles of the main tar constituents of the product gases from gasification of biomass are presented. But the authors do not consider the effect of the subsequent process stages on the resulting tar content.
Abstract: The tar content of the product gases from gasification of biomass is one of the major factors affecting the subsequent process stages. In this work, evolution profiles of the main tar constituents, ...
TL;DR: In this paper, nine pellet assortments, made on a large scale of fresh and stored sawdust, bark and logging residues (a mixture of Norway spruce and Scots pine) were tested for changes in moisture content, heating value and ash content.
Abstract: Storage of wood pellets is substantially different from the storage of unprocessed raw materials, one of the most obvious differences being the low moisture content of pellets. However, temperature development and fungal growth in the pellet piles have been observed at some plants. Documented knowledge of the storage of pellets is limited. In this pilot study, nine pellet assortments, made on a large scale of fresh and stored sawdust, bark and logging residues (a mixture of Norway spruce and Scots pine) were tested for changes in moisture content, heating value and ash content. Dimensions, bulk density, density of individual pellets and durability were also determined. The process variables were constant during pelleting. The five months storage has done in plastic bags (1.3 m 3 ) in an unheated barn. The storage led to negative effects on durability, especially on pellets made of fresh materials. Pellets made out of fresh logging residues were found to have lowest durability after storage. The average length was decreased due to breakage during storage. Microbial growth was noticed in some of the pellet assortments. Water absorption tests showed the largest hygroscopicity of the pellets from fresh materials. In general, the changes in pellet quality during storage in large bags were not large, but notable. The tendency to reach the equilibrium with the ambient moisture content should be taken into consideration during production if the pellets are to be stored.
TL;DR: The Policy Analysis System (POLYSYS) as mentioned in this paper is a simulation model of the US agriculture sector which can incorporate agricultural supply and demand and related modules to estimate agricultural production response, resource use, price, income, and environmental impacts of projected changes from an agricultural baseline.
Abstract: The Policy Analysis System (POLYSYS) is a national simulation model of the US agriculture sector which can incorporate agricultural supply and demand and related modules to estimate agricultural production response, resource use, price, income, and environmental impacts of projected changes from an agricultural baseline. The framework recursively incorporates linear programming, econometric, and process models to estimate an impact path resulting from changes imposed on a baseline scenario and its underlying assumptions. POLYSYS estimates crop production and supply at a disaggregated regional level, whereby the 48 contiguous states are subdivided into 305 geographic regions with relatively homogeneous production characteristics. POLYSYS is capable of estimating a wide range of policy alternatives and economic and environmental conditions and simulations may be tailored to a variety of specific analytical needs. This paper presents a broad overview of the structure and approach of the POLYSYS model with emphasis on biomass and bioenergy related applications of the model.
TL;DR: In this article, the authors estimate the biomass and the carbon contained in biomass of Indian forests for the year 1993, using species-wise volume inventories for all forest strata in various states.
Abstract: Forest volume inventories are valuable source of data for estimating above-ground biomass density and the carbon stored in biomass of forests. In view of the importance of biomass estimates in the global carbon (C) cycle, the present study estimates the biomass and the C contained in biomass of Indian forests for the year 1993, using species-wise volume inventories for all forest strata in various states. The above-ground biomass densities ranged from 14 to 210 Mg ha −1 , with a mean of 67.4 Mg ha −1 , which equals around 34 Mg C ha −1 . As most of the biomass is concentrated in lower diameter classes of potentially large species, the low biomass estimates in Indian forests implies that there is a large potential to sequester carbon over several decades to continue if left undisturbed.
TL;DR: In this article, the authors present a tar sampling protocol for large scale gasification processes, which consists of a heated probe, a particulate filter and a series of impinger bottles.
Abstract: This paper presents tar sampling protocols for pressurised and atmospheric large scale gasification processes Methods for constructing sampling lines either to on-line analysers or into sampling systems are described The tar sampling system consists of a heated probe, a particulate filter and a series of impinger bottles Dichloromethane is used as the tar abosrbing solvent The solvent containing bottles are placed in a cold bath so that gradual cooling of the sampled gas from about 0°C to the final temperature −79°C takes place in them Recommendations for suitable sampling gas flow rates and gas temperatures are given Tar characterisation methods based on different garvimetric measurements and GC analysis are described
TL;DR: In this article, ELSAM/MIDTKRAFT equipped the 150 MW e pulverised coal-fired Studstrup power station, unit 1, for a technology demonstration cofiring of coal and straw.
Abstract: In 1995 ELSAM/MIDTKRAFT equipped the 150 MW e pulverised coal-fired Studstrup power station, unit 1, for a technology demonstration cofiring of coal and straw. The conversion consisted of establishing a straw pre-processing plant and modifying the burner system. After plant commissioning in January 1996, a 2-year demonstration program was initiated. The objective of the program was to evaluate the influence of cofiring on boiler plant performance, combustion chemistry, heat surface deposits and corrosion, residue quality, emissions, and selective catalytic reduction (SCR) systems. This paper presents the plant conversion and results from the demonstration period.
TL;DR: In this paper, the nitrogen content of switchgrass biomass from different genotypes and management systems was analyzed for five years and the differences in N removed between harvest systems reflected the low N concentration of the fall harvest of one-cut and the higher N concentration in the summer harvest of the two-cut system.
Abstract: Information is lacking on the nitrogen content of switchgrass ( Panicum virgatum L.) biomass from different genotypes and management systems. Nitrogen removed in the biomass would be important in determining fertilization practices and biological degradation. Six switchgrass entries were grown for biomass yield under two harvest systems, one-cut: cut once near the end of October, and two-cut: cut in early summer and near the end of October. Dry matter yield, N concentration, and N content of biomass were determined for five years. More N was usually removed in the two-cut system than in the one-cut system. Nitrogen removed in the biomass exceeded N applied under the two- cut system in all years except one year with a severe summer drought. In the one-cut system N removed was less than applied in all years except when no N was applied in the last year. Nitrogen concentration was higher in the summer harvest than the fall harvest of the two-cut system. Nitrogen concentration in the fall harvest was lower for the one-cut than the two-cut system. Differences in N removed between harvest systems reflected the low N concentration of the fall harvest of the one-cut system and the higher N concentration in the summer harvest of the two-cut system.