Rhamnolipid biosurfactant was added to rice straw hydrolysis system to enhance the production of reducing sugars. Differing from the traditional method, on-site production of rhamnolipid made the rice straw decomposing fungus Trichoderma reesei ZM4-F3 and rhamnolipid producing bacteria Pseudomonas aeruginosa BSZ-07 work together. As the growth periods of these two strains are 96 h and 48 h, respectively, a new two-stage co-hydrolysis bioprocess was achieved. T. reesei ZM4-F3 was cultivated for rice straw hydrolysis in the first 48 h at suitable conditions. For the next 48 h, the results showed that the temperature of 34 °C and pH value of 5.5 were the optimum conditions, and the optimum adding inoculation concentration ratio of P. aeruginosa BSZ-07 to T. reesei ZM4-F3 was 4%. Under these conditions, the co-hydrolysis sample could improve the production of reducing sugars to 2.57 g l−1, 15.20% higher than that of the control. The increased enzyme stability was indicated to be one of the mechanisms of the stimulatory effect of rhamnolipid on rice straw hydrolysis system. Compared with Tween-80 and sodium dodecylsulphate, rhamnolipid biosurfactant exhibited a better stimulatory effect on rice straw hydrolysis. Since the two-stage co-hydrolysis system could leave out the rhamnolipid purification process, thus reducing the biosurfactant production cost effectively, it seems to be a new prospective bioprocess for rice straw hydrolysis.
Raw glycerol, byproduct from bio-diesel production process, is used as carbon substrate in several biotechnological applications. Using Clostridium butyricum F2b, 47.1 g L−1 of 1,3-propanediol was produced in batch anaerobic cultures while substrate uptake rate (rS, expressed in g L−1 h−1) increased with increase in glycerol concentration in the medium. In continuous cultures, microbial behaviour was studied in transitory states after addition of 1,3-propanediol in the chemostat vessel. Microbial growth was not affected by the high 1,3-propanediol (which was added in the chemostat vessel) concentration, while butyric and acetic acids concentrations were increased. In a two-stage continuous culture, 43.5 g L−1 of 1,3-propanediol was produced with a total volumetric productivity of 1.33 g L−1 h−1.Yarrowia lipolytica ACA-DC 50109 was grown in nitrogen-limited aerobic cultures on raw glycerol and it exhibited remarkable biomass production even at high glycerol concentration media, while rS decreased with increase in glycerol concentration. Citric acid was produced after nitrogen depletion in the medium, with the highest quantity of 62.5 g L−1, and yield on glycerol consumed was 0.56 g g−1. Fatty acid analysis of total cellular lipids showed that glycerol concentration increase in the growth medium somehow increased the cellular unsaturated fatty acids content of lipids.Mortierella isabellina ATHUM 2935 exhibited satisfactory growth in nitrogen-limited aerobic cultures with raw glycerol used as sole substrate. When high initial glycerol quantities were employed (e.g. 100 g L−1), 4.4 g L−1 of lipid were accumulated corresponding to around 51% (wt/wt) of lipid in dry weight. rS constantly decreased with increase in glycerol concentration in the medium, and in all cases notable glycerol quantities remained unconsumed in the medium.
Biomass production and plant quality vary between plant species and morphological components of a plant. The purpose of this two-part experiment was (1) to study the influence of energycane [Saccharum sp. (L.) ‘US 72-1153’] harvest treatments (6) on dry biomass yield and (2) monitor changes in quantity and quality of plant components with increased plant height. Treatments for Part 1 determined the influence of plant height when harvested at 1.2, 2.5, and 3.7 m, mature stage in October (4.9 m, in flower), mature stage in December (4.9 m, in flower), and additional treatment harvested in October, which received half the total N (168 kg ha−1) on dry biomass yield from 1986 to 1989. Part 2 treatments were to monitor changes in quantity and quality (crude protein and in vitro organic matter digestion) of plant components (green leaf, dead leaf, and stem) at 0.6 m plant height increments to a final height of 4.3 m during 1986 and 1987. Treatments from both parts of the study received 25 kg P ha−1 and 93 kg K ha−1 in one application and 336 kg N ha−1 yr−1 in single or split applications applied prior to growth of each harvest. Plants repeatedly harvested at the 1.2 m height (Part 1) and mature stage produced a 4-year average yield of 10 and 48 Mg ha−1 yr−1 dry biomass, respectively and decreased in dry biomass yield 89% (1.2 m harvest) and 53% (mature harvest) between years 1 and 4. The stem (1986 and 1987) and dead leaf (1986) plant components increased quadratically as plant height increased, and green leaf decreased from 70% (0.6 m) to 17% (4.3 m height). The crude protein concentration decreased 51% (green leaf) and 81% (stem) and in-vitro organic matter digestion decreased 54, 32, and 34% for dead leaf, green leaf, and stem, respectively as plant height increased from 0.6 to 4.3 m. These data indicate that harvest management is an important factor for energycane biomass yield, ratoon-crop success and plant quality if biomass is used as a methane source.
Miscanthus is a perennial rhizomatous warm-season grass with C4-photosynthesis. It shows considerable production potentials (10– dry matter ha−1) under NW European growth conditions and plantations of Miscanthus are established to provide biomass for energy. The plant senesces in the autumn in response to adverse climatic conditions, but harvest is normally postponed until spring when the biomass is more suitable for combustion. Total pre-harvest and harvest losses may account for as much as two-thirds of autumn standing biomass and these losses provide a significant carbon input to the soil. In this study, we examine soil organic carbon (SOC) storage and turnovers beneath 9 and 16 year old Miscanthus plantations established at Hornum, Denmark (56°50′N, 09°26′E). The soil is a loamy sand (Typic Haplumbrept, coarse loamy, mixed, mesic) with a C3 vegetation history. Soil was sampled at 0–20, 20–50 and 50– depth in the Miscanthus plantations and in two reference sites under C3-plants. The 0– samples were divided into fine soil , particulate organic matter (POM; 250–), rhizomes/stubbles and coarse roots. All samples were analysed for carbon content and / ratio. Rhizomes/stubbles accounted for 10.9– and coarse roots for 3.2– at 0– depth. No rhizomes and coarse roots were observed in the deeper soil layers. Concentrations of SOC were higher at all soil depths under the 16 year old Miscanthus whereas 9 years of Miscanthus and reference sites showed similar SOC concentrations. in 0– reference soil averaged −27.6‰ while soil beneath 9 and 16 year Miscanthus showed −25.6‰ and −22.8‰, respectively. Difference in between reference and Miscanthus soils was smaller at greater soil depths. SOC inventories at 0– ranged from 91– in reference and 9 year Miscanthus to under 16 years of Miscanthus growing. The main part of the SOC was at 0–20 and 20– soil with 30– in each layer. Although changes in the overall SOC storage were less significant, 13% and 31% of the SOC present in 0– soil was derived from Miscanthus beneath 9 and 16 year plantations, respectively. The organic matter recovered in POM contained 48–65% of Miscanthus derived C. At 20–50 and 50– depth, the fractions of SOC from Miscanthus were 6–9% and 1.3–6%, respectively. It was estimated that 26–29% of the cumulated C input from Miscanthus had been retained in the soil.
Fourteen clones of willow (Salix spp.) were characterised in terms of growth, nitrogen and water-use efficiency under different irrigation and fertilisation treatments. Cuttings of willow clones, some commercially introduced and others new material, were pot-grown outdoors in Central Sweden under four experimental treatments in a full-factorial design. The experiment covered the period from bud-break until leaf abscission and the experimental conditions included two irrigation and two fertilisation regimes. The growth of the clones was evaluated in terms of relative growth rate and total biomass production of whole plants and shoots. Nitrogen (N) economy was studied by means of N productivity, N accumulation and N losses by leaf abscission. Water economy was analysed with respect to intrinsic water-use efficiency (foliar carbon isotope ratio; δ13C) and the capacity of leaves to retain water (relative water content). Significant differences between clones were found in nearly all parameters measured and the clones varied in the responses to the experimental treatments (clone × factor interaction effects). Thus, clone ranking often changed depending on the experimental treatment. The results are discussed with respect to clone selection for different willow applications such as biomass production and phytoremediation, and willow growth performance under different water and nutrient availabilities. The growth-physiological characterisation of young willows in the short term (several months) is regarded as a suitable approach for pre-selection of promising clones prior to extensive field evaluation.
In 1995 ELSAM/MIDTKRAFT equipped the 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.
In a field experiment 60 kg N ha−1 of 15N-labelled fertilizer was applied to Miscanthus×giganteus planted 1, 2 or 3 years previously. Plots were destructively sampled at senescence 1, 2 or 3 years after labelled N was applied with aerial biomass harvested in intervening years. The objective was to quantify N uptake and distribution within the plant, labelled N remaining in the soil (0–50 cm) and overall losses. We report results for the 2nd and 3rd years and compare them to 1st year data previously published. Total biomass more than doubled over 2 years of growth but N concentration did not change. More labelled N was recovered by 3-year-old plants (65%) than by 2-year-old plants (55%) or 1-year-old plants (38%). Between 19% and 26% was found in the soil (0–50 cm) and more than 85% of this N was in topsoil (0–23 cm). Total recovery in plant and soil was 60–71% for 1-year-old plants, 76–81% for 2-year-old plants and 84% for 3-year-old plants. Overall losses (18–24%) from 2- and 3-year-old plants are similar to those from arable and permanent grass crops on the same soil type given similar amounts of N. Labelled (and unlabelled) N stored in rhizomes will take several years to decline because of transfers between rhizomes and shoots. Similarly, labelled N remaining in soil will decline slowly over many years; any N mineralized in subsequent years will be subject to plant uptake and/or loss.
A strain of Saccharomyces cerevisiae, which showed marked fermentation activity, ethanol and temperature tolerance and good flocculation ability, was selected for ethanol production. A stuck fermentation occurred at sucrose concentration of 25%. Increasing the yeast inoculum volume from 3% to 6% showed positive effects on fermentation from 25% sucrose. The ratio of added nitrogen to sucrose, which gave the best results (for the selected yeast strain), was determined. It was concluded that this ratio (nitrogen as ammonium sulphate at a rate of 5 mg g−1 of consumed sucrose) is constant at various sugar concentrations. Addition of nitrogen at this ratio produced 11.55% ethanol with complete consumption of 25% sucrose after 48 h of fermentation. However fermentation of 30% sucrose at the above optimum conditions was not complete. Addition of yeast extract at a level of 6 g l−1 together with thiamine at a level of 0.2 g l−1 led to complete utilization of 30% sucrose with resultant 14% ethanol production. However the selected yeast strain was not able to ferment 35% sucrose at the same optimum conditions. Addition of air at a rate of 150 dm3 min−1 m3 of reactor volume during the first 12 h of fermentation led to complete consumption of 35% sucrose and 16% ethanol was produced. This was approximately the theoretical maximum for ethanol production.
This paper discusses the contribution of biomass in the future global energy supply. The discussion is based on a review of 17 earlier studies on the subject. These studies have arrived at widely different conclusions about the possible contribution of biomass in the future global energy supply (e.g., from below 100 EJ yr−1 to above 400 EJ yr−1 in 2050). The major reason for the differences is that the two most crucial parameters—land availability and yield levels in energy crop production—are very uncertain, and subject to widely different opinions (e.g., the assessed 2050 plantation supply ranges from below 50 EJ yr−1 to almost 240 EJ yr−1). However, also the expectations about future availability of forest wood and of residues from agriculture and forestry vary substantially among the studies.The question how an expanding bioenergy sector would interact with other land uses, such as food production, biodiversity, soil and nature conservation, and carbon sequestration has been insufficiently analyzed in the studies. It is therefore difficult to establish to what extent bioenergy is an attractive option for climate change mitigation in the energy sector. A refined modeling of interactions between different uses and bioenergy, food and materials production—i.e., of competition for resources, and of synergies between different uses—would facilitate an improved understanding of the prospects for large-scale bioenergy and of future land-use and biomass management in general
A wave of Salix (willow) planting rolled over Sweden in the early 1990s, driven by subsidies and optimistic market expectations. The expected economic life span of such investments is 20 years or more. But in fact, many plantations were terminated or reduced much sooner. This article explores the reasons for this retreat. In a survey to Salix farmers, 41 per cent either have retreated or regretted starting at all. The reasons given are mostly agronomic, rather than economic. In particular, many farmers had planted on low-quality lands, ignoring best-practice advice. Policies in support of energy crops have been volatile and badly designed, in the sense of giving incentives to such reckless plantings, rather than promoting good farm management. Prices for wood chips have also been disappointing, but few farmers cite this as a key reason for termination or regrets.
The widely recognised importance of biomass utilisation in controlling carbon build-up in the biosphere and the potential benefits of creating new industries and job opportunities, particularly in the rural areas, have added impetus to the development and commercialisation of advanced biomass energy conversion methods in some Western countries. The world-wide recoverable residues is estimated to be 31 exajoules per year, or 10% of global commercial use. The present biomass combustion power plants have efficiencies in the 15% to 20% range, with electricity costs in the range of US $0.065 to $0.08/kWh. In contrast, the advanced power-generating cycles utilising gasification have the potential for higher generation efficiencies, 35% to 40%, and lower costs of electricity, $0.045 to $0.055/kWh. The IEA Biomass Thermal Gasification Activity continued to promote information exchange among the nine participating countries, to ultimately commercialise biomass gasification. The Activity continued to monitor the latest developments in handling herbaceous feedstocks, pilot plant performance of advanced gasification processes, including hot-gas cleanup for demonstration and commercial design, and the testing of a close-coupled prototype gas turbine and a molten carbonate fuel cell. In addition, the participants conducted task studies on Biomass resources for gasification, Biomass feedstock preparation for gasification, Evaluation of biomass feeders, Strategies for sampling analysis of raw gas streams from gasifiers, Altholz gasification, MSW gasification, Hot-gas cleanup, and Combustion characteristics of LCV fuel gases.
The achievements of Task VIII (Efficient and Environmentally-Sound Production Systems) of the IEA Bioenergy Agreement are reviewed. Some of the achievements of the Task's Activities are highlighted, such as the development of a computerised handbook on short rotation forestry, DNA fingerprinting, disease surveys, waste disposal and environmental guidelines.
The program to be carried out within the framework of the IEA Bioenergy Agreement consists of cooperative research, development, demonstrations and exchange of information regarding bioenergy. Within Task X Biomass Utilisation, thirteen participating countries have focused research efforts on thermal processing of biomass, biological conversion of feedstocks, processing of specialised biomass, and cross-cutting topics of interest across several technical areas. This paper addresses the various work programs and summarises the progress of Task X Biomass Utilisation during the period 1992 through 1994.
Production of sugar cane in Brazil in the 1996/97 season was 273 million t (harvested wet wt)/year, leading to 13.7 million m3 ethanol and 13.5 million t of sugar. Emissions of greenhouse gases were evaluated for the agronomic/industrial production processes and product utilization including N2O and methane. Up-dating the energy balance from 1985 to 1995 indicated the effect of the main technological trends; apparently, fossil fuel consumption due to the increasing agricultural mechanization is largely off-set by technological advances in transportation and overall conversion efficiencies (agricultural and industrial). Output/input energy ratio in ethanol grew to 9.2 (average) and 11.2 (best values). Net savings in CO2 (equivalent) emissions, due to ethanol and bagasse substitution for fossil fuels, correspond to 46.7×106 t CO2 (equivalent)/year, nearly 20% of all CO2 emissions from fuels in Brazil. Ethanol alone is responsible for 64% of the net avoided emissions.
A quantitative analysis is given of the consequences of the recent EU White Paper on a strategy for renewable energy sources, by matching the woody biomass demand and supply by the forest industries and the energy sector in Europe in 2010, following the 5th European Timber Trends Study approach. An annual shortage of 229 million m3 of roundwood equivalents has been identified, which can be supplemented by the establishment of 11.5 million hectares of short rotation forestry systems. However, if 50% of available agricultural residues in Europe (such as straw) were used for bio-energy purposes, then the additional biomass needs are reduced to 101 million m3 of roundwood equivalents per annum, requiring the establishment of 5.1 million ha of dedicated energy crops.
An energy analysis in orchards is useful to deciding best management strategies. The objective of this study was to evaluate, by selecting organic and conventional sweet cherry orchards located in/or close to Natura 2000 sites (a) the energy flow between the two farming systems and (b) the effect of farming system to gas emissions (CO2, CH4 and N2O). Twenty farms [(2-conventional and 2-organic) × 5-locations] were selected during 2003–2004. Means averaged over all locations for insecticides and fungicides application, fuel, insecticides, fungicides, non-renewable energy inputs, energy shoot outputs, energy fruit outputs, energy shoot + fruit outputs, fruit production, shoot efficiency, fruit efficiency, shoot + fruit efficiency, non-renewable energy efficiency, gas emissions were higher in conventional than in organic orchards, while fertilizer application, harvesting, fertilizers, labor, total energy inputs, renewable energy inputs, intensity and non-renewable energy consumption were higher in organic orchards. Means averaged over two farming systems for fertilizer, insecticide and fungicide application were higher in GRL2 and GRL5. The means averaged over two systems for transportation had the highest value in GRL4 and the lowest in GRL5. Finally, means averaged over two farming systems for labor had the highest value in GRL2. Non-renewable energy inputs as percent of total inputs were 82.63 and 52.42% in conventional and organic sweet cherry orchards respectively. The results show that organic farming systems could reduce non-renewable energy inputs and gas emissions in an efficient way in areas related to Natura 2000 sites.
Large-scale implementation of wood pellets as a solid biomass fuel represents a change in the energy system that will have both economic and environmental consequences. This article represents a summary of a state of the art conference, which was organised in Sweden in September 2002. The aim was to bring together people to create a network where industry, research, other expertise and decision makers meet to build a strong pellet industry for the future. The sum of the economic, technological and environmental evidence presented at this conference weighs very heavily in favour of the pellet option.
This work presents the evaluation of energy balance and GHG emissions in the production and use of fuel ethanol from cane in Brazil for 2005/2006 (for a sample of mills processing up to 100 million tons of sugarcane per year), and for a conservative scenario proposed for 2020. Fossil energy ratio was 9.3 for 2005/2006 and may reach 11.6 in 2020 with technologies already commercial. For anhydrous ethanol production the total GHG emission was 436 kg CO2 eq m−3 ethanol for 2005/2006, decreasing to 345 kg CO2 eq m−3 in the 2020 scenario. Avoided emissions depend on the final use: for E100 use in Brazil they were (in 2005/2006) 2181 kg CO2 eq m−3 ethanol, and for E25 they were 2323 kg CO2 eq m−3 ethanol (anhydrous). Both values would increase about 26% for the conditions assumed for 2020 mostly due to the large increase in sales of electricity surpluses.A sensitivity analysis has been performed (with 2005/2006 values) to investigate the impacts of the huge variation of some important parameters throughout Brazilian mills on the energy and emissions balance. The results have shown the high impact of cane productivity and ethanol yield variation on these balances (and the impacts of average cane transportation distances, level of soil cultivation, and some others) and of bagasse and electricity surpluses on GHG emissions avoidance.
Energy policy measures aim to increase energy production from forest chips in Finland to 10 TWh by year 2010. However, on the regional level production differences are large, and the regional estimates of the potential base of raw materials for the production of forest chips are heterogeneous. In order to analyse the validity of the above target, two methods are proposed to derive forecasts for region-level energy production from forest chips in Finland in the years 2008–2014. The plant-level data from 2003–2007 gives a starting point for a detailed statistical analysis of present and future region-level forest chip production. Observed 2008 regional levels are above the estimated prediction 95% confidence intervals based on aggregation of plant-level time averages. A simple time trend model with fixed-region effects provides accurate forecasts for the years 2008–2014. Forest chip production forecast confidence intervals cover almost all regions for the 2008 levels and the estimates of potential production levels for 2014. The forecast confidence intervals are also derived with re-sampling methods, i.e. with bootstrap methods, to obtain more reliable results. Results confirm that a general materials shortfall is not expected in the near future for forest chip energy production in Finland.
This paper presents a synthesis of assessment of the energy potential of non-plantation biomass resources in five Asian countries—China, India, Philippines, Sri Lanka and Thailand, and is based on the detailed national-level studies carried out in these countries under the Asian Regional Research Programme in Energy, Environment and Climate (ARRPEEC). The national level studies were undertaken to estimate the energy potential of: (i) primary residues, (ii) secondary and processing residues (iii) animal manure, (iv) municipal solid wastes (MSW), (v) fuelwood released through efficiency improvement and substitution by other fuels. The sustainable potential of non-plantation biomass resources in 2010 in China, India, Philippines, Sri Lanka and Thailand is estimated to be about 8.90, 8.77, 0.97, 0.14 and 0.82 EJ, respectively; the potential is estimated to be about 17, 45, 34, 33, and 14% of the projected total energy consumption in 2010, respectively, in the countries.
The feasibility of the utilization of woody biomass as energy resources in Japan is discussed based on its amount, availability, and energy-conversion technologies. The amount is currently estimated to be 31.7 Tg y−1 on a dry-weight basis, corresponding to 2.8% of the national primary energy supply. An analysis of the current systems for the harvest and transport of logging residues showed that improvements are needed for them to be sustainable/economic. The prospects for woody bioenergy utilization around the year 2010 and 2050 are also discussed based on the present state-of-the-art energy-conversion technologies. Around the year 2010, both the “on-site” utilization and the “regional” utilization are expected to be feasible as a small-scale and decentralized system. On the other hand, the co-firing of woody biomass with coal at an existing coal-fired power plant is expected as a large-scale and centralized system. Around the year 2050, the “regional” utilization is expected to be the main energy utilization for a small-scale and decentralized system. Biomass plantations in foreign countries will be needed for a large-scale and centralized system in Japan.
Carbon cycling and the global warming potential (GWP) of bioenergy cropping systems with complete biomass removal are of agronomic and environmental concern. Corn growers who plan to remove corn stover as a feedstock for the emerging cellulosic ethanol industry will benefit from carbon amendments such as manure and compost, to replace carbon removed with the corn stover. The objective of this research was to determine the effect of beef cattle feedlot manure and composted dairy manure on short-term carbon sequestration rates and net global warming potential (GWP) in a corn–soybean rotation with complete corn-stover removal. Field experiments consisting of a corn–soybean rotation with whole-plant corn harvest, were conducted near East Lansing, MI over a three-year period beginning in 2002. Compost and manure amendments raised soil carbon (C) at a level sufficient to overcome the C debt associated with manure production, manure collection and storage, land application, and post-application field emissions. The net GWP in carbon dioxide equivalents for the manure and compost amended cropping systems was −934 and −784 g m−2 y−1, respectively, compared to 52 g m−2 y−1 for the non-manure amended synthetic fertilizer check. This work further substantiates the environmental benefits associated with renewable fuels and demonstrates that with proper management, the integration of livestock manures in biofuel cropping systems can enhance greenhouse gas (GHG) remediation.
This paper provides a preliminary examination of present and projected land use in Africa to estimate the potential availability of land in 2025 for use in producing biomass energy. Fifty countries are included in the analysis. Future cropland requirements are projected on the basis of average African cereal crop yield improvements since 1972, and minimum nutritional requirements are assumed to be met in 2025 without increasing imports above present absolute levels. Cropland, natural forests and other wilderness areas are excluded from consideration for biomass energy use. Woody biomass energy yields are estimated on the basis of nationally averaged precipitation, using a yield-precipitation correlation for commercial eucalyptus plantations in Brazil. The total African bioenergy production potential in 2025 is estimated to be about 18 EJ per year for a set of baseline assumptions that includes planting only 10% of the available non-crop, non-forest, non-wilderness area with biomass energy crops. A preliminary cost assessment suggests that much of this biomass could be produced for $1–2 GJ−1. A number of uncertainties in the modelling assumptions are examined through a sensitivity analysis. Despite limitations in the model used here, one robust conclusion is that Africa as a whole has a significant biophysical potential for producing biomass energy. This result suggests that more detailed country and sub-country level assessments would be worthwhile to understand better the practical prospects for future biomass energy production in Africa.
Brazil is fortunate in having large areas of land that are not currently forested but that are suitable for silvicultural plantations. Changes in the area and regional distribution of the country’s silvicultural plantations imply a wide variety of environmental and social impacts. Projections of future development of plantation silviculture are needed for analyzing these impacts, as well as to serve as a reference scenario for evaluating the potential effects of climatic change on Brazil’s plantations, and for the related task of evaluating the implications of proposals to combat global warming by increasing the area of silvicultural plantations in Brazil beyond the extent to which they would otherwise expand. Such a reference scenario provides the control, or “business as usual” standard, against which one can compare the situation as affected by climatic change and/or by additional silvicultural or other activities carried out to help mitigate climatic change. Assuming constancy of climate, technology, per-capita consumption of wood products, and Brazil’s share of international trade, the area of plantations in 2050 would be 3.2 times larger than the area in 1991.
Estimates of world regional potentials of the sustainable use of biomass for energy uses through the year 2050 are presented. The estimated potentials are consistent with scenarios of agricultural production and land use developed at the International Institute for Applied Systems Analysis, Austria. They thus avoid inconsistent land use, in particular conflicts between the agricultural and bioenergy land use. As an illustration of the circumstances under which a large part of this potential could be used in practice, a global energy scenario with high economic growth and low greenhouse gas emissions, developed by IIASA and the World Energy Council is summarised. In that scenario, bioenergy supplies 15% of global primary energy by 2050. Our estimation method is transparent and reproducible. A computer program to repeat the calculation of the estimates with possibly changed assumptions is available on request.
The nature of deposit formation on the fireside surfaces of the boiler tubes in the various parts (water walls, platen superheater, final superheater, economizer, electrostatic precipitator etc.) of a commercial 20 MW stoker-fired boiler being fired with a mixture of 80% bagasse and 20% groundnut shell has been analyzed. The deposits in the various portions of the boiler were characterized by particle size analysis, chemical analysis, X-ray diffraction and scanning electron microscopy. The deposits were found to be mainly quartz, alkali and alkaline earth silicates and sulfates. From the phase constitution and other microscopic characteristics of the deposit, it can be inferred that the silicates in the deposit formed through inertial impaction and the sulfates formed by vapor phase deposition.
This paper presents the results of a postal questionnaire survey of local public opinion on a proposal to build a 21.5 MW(e) integrated combined cycle biomass gasifier on an old Royal Air Force airfield on the outskirts of the rural village of Winkleigh, Devon, England. To all households in Winkleigh Parish 1200 questionnaires were distributed in June 2004 and were returned by 573 people, representing 40% of all adults in the parish. Opinion was found to be overwhelmingly against the gasifier. The concerns of local people were varied, but the highest levels of shared concern were truck movements and associated pollution and nuisance, doubts about the developer's credibility, and gaseous emissions from the plant, including odour. In general, local people felt that they were being asked to accept an industrial scale development that would lead to deterioration in their quality of life. The grey and academic literatures on analogous cases anticipate some of the specific findings.
The availability of the resources is an important factor for high shares of biomass to penetrate the electricity, heat or liquid fuel markets. We have analysed the geographical and technical potential of energy crops for the years 2050–2100 for three land-use categories: abandoned agricultural land, low-productivity land and ‘rest land’, i.e. remaining no-productive land. We envisaged development paths using four scenarios resulting from different future land-use patterns that were developed by the Intergovernmental Panel on Climate Change in its Special Report on Emission Scenarios: A1, A2, B1 and B2. The geographical potential is defined as the product of the available area for energy crops and the corresponding productivity level for energy crops. The geographical potential of abandoned agricultural land is the largest contributor. For the year 2050 the geographical potential of abandoned land ranges from about 130 to 410 EJ yr−1. For the year 2100 it ranges from 240 to 850 EJ yr−1. The potential of low-productive land is negligible compared to the other categories. The rest land area is assumed to be partly available, resulting in ranges of the geographical potential from about 35 to 245 EJ yr−1 for the year 2050 and from about 35 to 265 EJ yr−1 in 2100. At a regional level, significant potentials are found in the Former USSR, East Asia and South America. The geographical potential can be converted to transportation fuels or electricity resulting in ranges of the technical potential for fuels in the year 2050 and 2100 equal to several times the present oil consumption.
Surface energy balance and 24-h evapotranspiration were mapped on an agricultural landscape with SRF willows using a remote sensing-based model to provide information on the water use by different land cover types. The results demonstrate the influence of land cover and vegetation type on surface energy balance and water losses. The evapotranspiration from forests was much higher than for other land cover types, corresponding to the significant cooling of the land surface. The SRF willow plantings were on average 3.6 °C cooler than the surrounding grassy areas; the 24-hour evapotranspiration from willows was 1.6 times higher than the evapotranspiration from surrounding grass, but lower than evapotranspiration from the forests. The possibility of changes in evapotranspiration patterns, local climate, and regional water balance with increasing acreage in SRF crop are discussed.
Energy balances are analysed from a life-cycle perspective for biogas systems based on 8 different raw materials. The analysis is based on published data and relates to Swedish conditions. The results show that the energy input into biogas systems (i.e. large-scale biogas plants) overall corresponds to 20–40% (on average approximately 30%) of the energy content in the biogas produced. The net energy output turns negative when transport distances exceed approximately 200 km (manure), or up to 700 km (slaughterhouse waste). Large variations exist in energy efficiency among the biogas systems studied. These variations depend both on the properties of the raw materials studied and on the system design and allocation methods chosen. The net energy output from biogas systems based on raw materials that have high water content and low biogas yield (e.g. manure) is relatively low. When energy-demanding handling of the raw materials is required, the energy input increases significantly. For instance, in a ley crop-based biogas system, the ley cropping alone corresponds to approximately 40% of the energy input. Overall, operation of the biogas plant is the most energy-demanding process, corresponding to 40–80% of the energy input into the systems. Thus, the results are substantially affected by the assumptions made about the allocation of a plant's entire energy demand among raw materials, e.g. regarding biogas yield or need of additional water for dilution.
Growth data were collected from 38 stands of European aspen (Populus tremula L.) growing on forest land in Sweden. The stands ranged in latitude from 56 to 65°N. The mean age of European aspen was 46 years (range 26–91), the mean stand density (range 245–3866), and the mean diameter at breast height (over bark) (range 11–).Soil types in the aspen stands were divided into five groups: sandy–silty till (14 stands), light clay till (6), fine sand (5), light clay (4) and sandy till (3). Soil types represented by only one or two stands were not included in the analysis. No statistically significant differences in site index were found between the five soil-type groups in aspen stands.The mean total standing dry weight above stump level () for aspens was with a range of 28–. In addition to estimating conventional dry weights of trees and tree components, specific leaf area, total surface area and LAI, among other measures, were estimated.A practical implication for management of aspen stands for biofuel production is to cut the aspen after 10–20 year-rotation. Otherwise the stand could be thinned for pulpwood and timber production and the removal is used for biofuel.
The use of forest fuels has more than doubled in Sweden over the last 25–30 years. Almost a fifth of the utilized energy is now based on forest biomass. Concurrently, real prices of bioenergy have decreased to less than a third of what they were 25 years ago. Some principal driving forces behind this development are identified and discussed in this paper.The origin of this development was equally the result of a foreseen shortage of fibre and a reaction to this vulnerable position, made obvious through the ‘oil crises’. Although Sweden has a long tradition of large-scale use of forest energy, 35 years ago she was almost totally dependent on imported oil. Forest mechanisation provided rational solutions to handling small diameter wood and stumps in conventional industrial processes, but also enabled the economical use of such wood for energy.During 3 decades of development, drivers and obstacles have shifted. What started to reduce dependence on fossil fuels was later driven by increased general environmental awareness. An emerging ‘green’ lobby blocked the development of nuclear power and expanded harnessing of hydropower which were alternative means of self-sufficiency.In the last 10–15 years, focus has changed again. Global concern for climatic change due to emissions of greenhouse gases is a powerful driver, endorsing increased use of CO2-neutral energy sources. Sustainability, resource cycling and the welfare of future generations are seen as goals for continued development.Ideals and policies do not, however, automatically induce change in regular operations. A set of drivers is identified, that has played the decisive role in practice. These include the direct technical–operational drivers, as well as indirect drivers through market development, taxation and other legislation.
The present biofuel policies in the European Union primarily stimulate 1st generation biofuels that are produced based on conventional food crops. They may be a distraction from lignocellulose based 2nd generation biofuels – and also from biomass use for heat and electricity – by keeping farmers' attention and significant investments focusing on first generation biofuels and the cultivation of conventional food crops as feedstocks. This article presents two strategies that can contribute to the development of 2nd generation biofuels based on lignocellulosic feedstocks. The integration of gasification-based biofuel plants in district heating systems is one option for increasing the energy efficiency and improving the economic competitiveness of such biofuels. Another option, biomass co-firing with coal, generates high-efficiency biomass electricity and reduces CO2 emissions by replacing coal. It also offers a near-term market for lignocellulosic biomass, which can stimulate development of supply systems for biomass also suitable as feedstock for 2nd generation biofuels. Regardless of the long-term priorities of biomass use for energy, the stimulation of lignocellulosic biomass production by development of near term and cost-effective markets is judged to be a no-regrets strategy for Europe. Strategies that induce a relevant development and exploit existing energy infrastructures in order to reduce risk and reach lower costs, are proposed an attractive complement the present and prospective biofuel policies.
The use of congress grass (Parthenium sp.) and water hyacinth (Eichhornia crassipes) as low cost raw materials for xylanase production from mutant Penicillium oxalicum SAUE-3.510 in submerged fermentation was investigated. For development of mutant from wild type P. oxalicum SA-8 ITCC 6024, a strategy of mixed mutagenesis was followed using UV-irradiation and ethidium bromide, which had resulted into 1.87 fold increases in the activity of the enzyme. For enzyme production, the fungus was cultivated in mineral medium containing congress grass as carbon source. Considerably higher levels of production (475.2 ± 6.0 IU ml−1) were achieved in media containing congress grass, although it was slightly less than that was obtained (488.5 ± 6.5 IU ml−1) in presence of commercial oat spelt xylan. This fact confirms the feasibility of using this low cost non-food resource as an alternative carbon source to save costs of the enzyme production process. Maximum xylanase activity was reported at 55 °C with its stability at 80 °C for 2 h. The highest activity of xylanase at pH 9.0 and its stability at similar pH for 24 h denote the alkalitolerant nature of enzyme.
Populus species and hybrids have many practical applications, but there is a paucity of data regarding selections that perform well in the southeastern US. We compared pest susceptibility of 31 Populus clones over 3 years in South Carolina, USA. Cuttings were planted in spring 2001 on two study sites. Clones planted in the bottomland site received granular fertilizer yearly and irrigation the first two years only, while those on the sandy, upland site received irrigation and fertilization throughout each growing season. Foliar damage by the cottonwood leaf beetle (Chrysomela scripta), cottonwood leafcurl mite (Tetra lobulifera), and poplar leaf rust (Melampsora medusae) was visually monitored several times each growing season. Damage ratings differed significantly among clones, and clonal rankings changed from year to year. Irrigation increased C. scripta and M. medusae damage, but had no effect on T. lobulifera damage. Certain clones received greater pest damage at a particular study site. Temporal damage patterns were evident among individual clones and on each site. At the upland site, OP367 and 7300502 were highly resistant to all three pests; I45/51 was highly resistant to C. scripta and M. medusae; NM6 and 15–29 were highly resistant to M. medusae; and 7302801 was highly resistant to T. lobulifera and M. medusae. At the bottomland site, NM6, Eridano, I45/51, and 7302801 were highly resistant to all three pests; clone 7300502 was highly resistant to M. medusae only. Based on this preliminary 3-year study of pest damage levels, we would recommend clones NM6, Eridano, I45/51, OP367, 15–29, 7302801, 7300502, and Kentucky 8 for use in this region.
Since the year 2000 or so there has been a rapid growth on fuel ethanol production and consumption, particularly in US and Brazil. Ethanol trade represented about 10% of world consumption in 2005, Brazil being the main exporter. The most important consumer markets—US and European Union (EU)—have trade regimes that constrained the comparative advantages of the most efficient producers, such as Brazil. This paper evaluates the fuel ethanol market up to 2030 together with the potential for international biotrade. Based on forecasts of gasoline consumption and on targets and mandates of fuel ethanol use, it is estimated that demand could reach 272 Gl in 2030, displacing 10% of the estimated demand of gasoline (Scenario 1), or even 566 Gl in the same year, displacing about 20% of the gasoline demand (Scenario 2). The analysis considers fuel ethanol consumption and production in US, EU-25, Japan, China, Brazil and the rest of the world (ROW-BR). Without significant production of ethanol from cellulosic materials in this period, displacing 10% of the gasoline demand in 2030, at reasonable cost, can only be accomplished by fostering fuel ethanol production in developing countries and enhancing ethanol trade. If the US and EU-25 reach their full production potential (based on conventional routes), the minimum amount that could be traded in 2030 would be about 34 Gl. Displacing 20% of the gasoline demand by 2030 will require the combined development of second-generation technologies and large-scale international trade in ethanol fuel. Without second-generation technologies, Scenario 2 could become a reality only with large-scale production of ethanol from sugarcane in developing countries, e.g., Brazil and ROW-BR could be able to export at least 14.5 Gl in 2010, 73.9 Gl in 2020 and 71.8 Gl in 2030.
The successful experience in developing the advanced Foster Wheeler Energia Oy’s (former Ahlstrom Pyropower) Circulating Fluidized Bed combustion system subsequently led to the development of the CFB Gasification Technology in the early 80 s. The driving force for the developing work was the dramatically increase in oil price during the oil crises. The primary advantage of CFB gasification technology is that it enables the substitution of expensive fuels e.g. oil or gas with cheap solid fuels. These cheap fuels are typically different types of waste woods, bark or other biofuels. In the CFB gasifier these solid fuels are converted to gaseous fuel which can be used instead of other expensive fuels. In some cases this also solves a waste disposal problem, providing a secondary economic and environmental benefit. Foster Wheeler Energia Oy has supplied four commercial scale atmospheric CFB gasifiers in the mid 80 s to the pulp and paper industry with capacities from 17-35 MW based on fuel input. These applications utilize waste wood as feedstock and the units are still successfully operational today.
Establishing short-rotation tree plantations for bioenergy and fiber production on agricultural land (abandoned farmland) would provide significant environmental and economic benefits for rural communities and society as a whole. Walker hybrid poplar (Populus deltoides x P. nigra) is one of the most commonly used varieties cultivated in Saskatchewan, Canada; however, there are no existing hybrid poplar growth models in the literature. The aim of this work was to parameterize and evaluate the 3PG model (Physiological Principles in Predicting Growth) to predict Walker tree growth in the climate and soils of Saskatchewan. We used annual data from Walker poplar trials (4- to 11-yr old stands) established at three spacing levels (2.4, 3.0, and 3.7 m) at three sites located in central Saskatchewan, Hnr, BH, and ML sites. The data were split into two sets – the modeling set from the Hnr site was used to parameterize 3PG, and the testing sets from the BH and ML sites were used to evaluate Walker growth predictions made by 3PG. The bias, sum(predicted minus observed) divided by number of observations, for tree height predictions ranged from −1.76 to 1.45 m, and bias for diameter at breast height (DBH) ranged from −2.61 to 0.66 cm. Regression R-square values of 3PG-predicted versus observed height and DBH ranged from 0.75 to 0.98. Our results indicated that, once parameterized, 3PG could predict Walker hybrid poplar growth with desirable accuracy by only utilizing commonly available soils and climate data for marginal or more productive agricultural land across Saskatchewan.
Several long-term experiments with fluctuating thermal outputs have been carried out in a newly developed biomass fuelled boiler suitable for small district heating networks. The experiments have been performed by either using the furnace only or the furnace together with a water heat store. Comparisons between these two operation strategies have been made concerning emissions and overall performance. Furthermore, the plant has been run to match a simulated heat demand during different seasons, in order to study the performance of the system during more realistic operation conditions.The results are very satisfactory concerning both performance and emissions, using any of the control strategies. Typical emissions of CO and NOx during the experiments are in the range of 10– (5–) and 130– (60–), respectively. However, during summer when the heat demand is low or zero, operational problems will occur if the heat store is excluded. Therefore, the main conclusion is that the most appropriate solution for a small district-heating system is to use a water heat store to match the heat load variations, while the furnace operates at as constant thermal output as possible.
A continuous stirred tank reactor (CSTR) (750 cm3 working volume) was operated with pig slurry under hyper-thermophilic (70 °C) temperature for hydrogen production. The hydraulic retention time (HRT) was 24 h and the organic loading rate was 24.9 g d−1 of volatile solid (VS). The inoculum used in the hyper-thermophilic reactor was sludge obtained from a mesophilic methanogenic reactor. The continuous feeding with active biomass (inoculum) from the mesophilic methanogenic reactor was necessary in order to achieve hydrogen production. The hyper-thermophilic reactor started to produce hydrogen after a short adapted period of 4 days. During the steady state period the mean hydrogen yield was 3.65 cm3 g−1 of volatile solid added. The high operation temperature of the reactor enhanced the hydrolytic activity in pig slurry and increased the volatile fatty acids (VFA) production. The short HRT (24 h) and the hyper-thermophilic temperature applied in the reactor were enough to prevent methanogenesis. No pre-treatment methods or other control methods for preventing methanogenesis were necessary. Hyper-thermophilic hydrogen production was demonstrated for the first time in a CSTR system, fed with pig slurry, using mixed culture. The results indicate that this system is a promising one for biohydrogen production from pig slurry.
Ligno-cellulosic biomass from different sources presents variable composition. The main aim of this work was to develop a method to predict the gas yields after flash pyrolysis (and tar cracking) at 950 °C in an Entrained Flow Reactor of any biomass from its composition in the three main components – cellulose, hemicellulose and lignin.For this approach to be successful, three conditions need to be met:(C1)Pyrolytic behaviour of celluloses from different biomasses is similar, as is hemicellulose and lignin behaviour.(C2)There is no interaction between the components.(C3)Extractives and ashes have no impact on the pyrolysis process.Two approaches were chosen to investigate the condition C1:(i)Celluloses, hemicelluloses and lignins of various sources were pyrolysed. Results show that hemicelluloses and lignins from different sources do not form the same quantities of gases.(ii)An attempt was made to identify the gas yields of “theoretical components” that are able to predict flash pyrolytic behaviour of any biomass. Results tend to show that this is not possible.The condition C2 is investigated by comparing the gas yields of the components taken separately and the gas yields of mixes of the components. Two types of mixing were carried out: simple mixing and intimate mixing. Results show that interactions occur between the components during flash pyrolysis.The condition C3 was not investigated here; it can nevertheless be concluded that the behaviour of a biomass during flash pyrolysis at high temperature cannot be predicted from its composition in cellulose, hemicellulose and lignin.
We explored the production cost of energy crops at abandoned agricultural land and at rest land at a regional and a global level to the year 2050 using four different land-use scenarios. The estimations were based on grid cell data on the productivity of short-rotation crops on the available land over time and assumptions regarding the capital and the labour input required to reach these productivity levels. It was concluded that large amounts of grown biomass at abandoned agricultural land and rest land, 130–270 EJ yr−1 (about 40–70% of the present energy consumption) may be produced at costs below $2 GJ−1 by 2050 (present lower limit of cost of coal). Interesting regions because of their low production cost and significant potentials are the Former USSR, Oceania, Eastern and Western Africa and East Asia. Such low costs presume significant land productivity improvements over time and cost reductions due to learning and capital-labour substitution. An assessment of biomass fuel cost, using the primary biomass energy costs, showed that the future costs of biomass liquid fuels may be in the same order of the present diesel production costs, although this may change in the long term. Biomass-derived electricity costs are at present slightly higher than electricity baseload costs and may directly compete with estimated future production costs of fossil fuel electricity with CO2 sequestration. The present world electricity consumption of around 20 PWh yr−1 may be generated in 2050 at costs below $45 MWh−1 in A1 and B1 and below $55 MWh−1 in A2 and B2. At costs of $60 MWh−1, about 18 (A2) to 53 (A1) PWh yr−1 can be produced.
In regions of extensive forest cover relative to agricultural open ground, as in northern Scandinavia, farmland abandonment greatly changes the landscape pattern. Cultivation of herbaceous energy crops would help to keep an open landscape as a positive side effect of bioenergy production and the lowland rental costs of abandoned farmland would positively improve the economy of energy grass cultivation.For this study, in the municipality of Bjurholm in the northeast of Sweden, a method was developed to separate abandoned fields into two classes, A and B, with low and high preparation costs, respectively, by using digital orthophoto interpretation. From field studies of a chosen sample, the mean preparation cost per hectare was determined to be 173 and 3990 SEK, respectively, for fields in class A and B. Peat and fine sediment soils had higher preparation costs than coarse sediment soils.
Biomass production was estimated in 10 stands each of pendula birch (Betula pendula Roth) and pubescent birch (Betula pubescens Ehrh.) growing on abandoned farmland. The pendula birch stands were located in Sweden at latitudes ranging from 66° to 58°N, and their total age varied from 8 to 32 years. Pubescent birch stands were located at latitudes ranging from 66° to 60°N, and their total age varied from 6 to 20 years. A modified “mean tree technique” was used to estimate biomass production; i.e. the tallest tree was chosen for sampling. The actual mean total dry weight above stump level was 71 tonnes ha−1 (range, 6 to 175 tonnes d.w. ha−1) for pendula birch stands and 27.3 tonnes ha−1 (range, 7 to 61 tonnes d.w. ha−1) for pubescent birch stands. In addition to estimating conventional dry weights of trees and tree components, specific leaf area, total surface area and LAI, among other measures, were estimated.
During the last decade, more than 400 000 ha of agricultural land was abandoned in Estonia. Such areas are often characterized by rapid natural afforestation with silver birch, which has led to an increase both in the woodland area and in the area of silver birch stands. However, many bioenergetic aspects related to birch stands growing on arable land are still poorly understood. The main aim of the present study was to investigate the above-ground biomass production, nutrient (NPK) accumulation, and foliar characteristics of young silver birch stands on abandoned agricultural land. Five 8-year-old stands of silver birch growing on different soil types were included in the study.
A study was conducted in order to construct functions for aboveground biomass of fractions of young European aspens (Populus tremula L.). The constructed functions were designed to be used for predicting the amount of biofuel produced from small areas. Biomass production was estimated in 11 stands of European aspen growing on abandoned farmland. The stands were located in Sweden at latitudes ranging from 65° to 60° N, and their total age varied from 5 to 24 years. A modified “mean tree technique” was used to estimate biomass production; i.e. depending on the plot area size, the number of sampled trees was chosen. The mean total dry weight above stump level for aspen stands was 78 tonnes ha−1 with a range of 14–162 d.w. ha−1. Mean annual increment for the stands was 5.56 tonnes ha−1 year−1 (2.86–9.15). Aspens growing on silt soils produced more than on fine sand soils. In addition to estimating conventional dry weights of trees and tree components, specific leaf area, total surface area and LAI, among other measures, were estimated. The mean LAI was 2.58 and the specific leaf area was 9.4 m2 kg−1. Some practical implications are given.
Product distributions from the pyrolysis of a common sample of pine-wood have been determined for two reactors with different configurations. The ablative pyrolysis reactor operates on the principle of “scraping” a continuous stream of biomass particles onto a heated surface under conditions of high relative motion and high applied pressure. In the wire-mesh reactor configuration, fine dispersion of a small quantity [4–6 mg] of sample and the rapid removal of volatiles from the reaction zone ensures that volatiles released during pyrolysis are captured under conditions minimising extra particle secondary reactions.Comparison of liquid yields determined for the two reactors has been undertaken in order to assess the effect of secondary reactions on yields during ablative pyrolysis. Structural characterisations and comparison of liquids produced in the two reactors have been carried out by size exclusion chromatography, UV-fluorescence spectroscopy and FTIR spectroscopy. Slight differences in structures were apparent either due to cracking of lignin-derived macromolecules on the heated reactor surface or low molecular weight components formed during slow pyrolysis reactions of a small proportion of the feed material. Comparison of the ablative liquids with those from other ablative pyrolysis reactors show similar trends in molecular mass distributions and structures suggesting that the ablative pyrolysis process inherently cracks some liquids during volatilisation. Dry organic liquid yields from the ablative pyrolysis reactor were between 2.5 and 5.3% lower than the wire-mesh reactor between 55° and 600°C. This is believed to be a result of non-optimised reactor operation of the ablative pyrolysis reactor.
Ablative pyrolysis is one of a range of fast or flash pyrolysis technologies for the production of liquids in high yields which offers the potential for high reactor specific throughputs with reduced equipment size, costs and improved controllability. The main objectives of the work are to design, construct and operate an ablative pyrolysis reactor and a pyrolysis liquids collection system which includes identification of key process parameters, exploration of relationships between parameters and product quality and the development of a new model to account for the ablative pyrolysis process. A reactor has been operated at temperatures from 450° to 600°C and at dry reacted wood feedrates up to 2.5 kg/h. Run times of 45 min have been achieved at steady state. Total liquid yields up to 81 wt% on dry ablatively pyrolysed wood basis have been achieved.
Above-ground biomass production was estimated for Gmelina arborea (Roxb) plantations (ages 5–21 years) in Oluwa Forest Reserve, Nigeria. A total of 120 trees were harvested and weighed to provide data for the estimation of biomass as well as for developing biomass equations. The results showed that Gmelina has high biomass yield, ranging from (5 years) to (21 years). Mean annual biomass increment varied from 16.2 to . Average biomass allocations to different components of the tree were as follows: Stem about 84%; branch 13% and foliage 3%. The high biomass values were attributed to fast growth, high stand density (range: 837–) and good site conditions in the study area. Biomass values of the various tree components (stem, branch and foliage) as well as total above-ground biomass (TAGB) were regressed with diameter at breast height (dbh) on the one hand (equation form 1), and with dbh and total height (in the form of D2H) on the other (equation form 2), with the aim of choosing the most suitable equation form. All equations generated had very high adjusted R2 and very low standard error of estimate. Residuals for both equation forms were normally and randomly distributed. Only little improvement in the ability of the equations to explain the variations in biomass was achieved by including the variable of total height. Considering the ease and accuracy in obtaining dbh data and the enormous time, errors and difficulty in obtaining height data, the equation form involving only dbh data as independent variable was recommended for use in estimating biomass for Gmelina in Oluwa forest reserve.