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A parametric study of the gasification of four feedstocks (corn stover, switchgrass, wheat straw, and wood) has been performed on an experimental, pilot-scale (0.5 ton/day) gasification facility. A comparison was made of the performance of the gasifier as a function of feedstock, in terms of the syngas production and composition. In these experiments, pelletized feedstock was used, so that the shapes and sizes of the materials did not influence the results. A total of 22 statistically designed experimental conditions were examined for each feedstock, including the effects of varying the temperature of the fluidized bed, the temperature of the secondary thermal cracker, and the steam-to-biomass ratio. For each experimental condition, the permanent-gas composition was measured continuously by gas chromatography (GC). Tars were measured continuously using a molecular-beam mass spectrometer (MBMS). Sulfur analysis by GC was also conducted for three of the feedstocks studied. The results from this study show that there were significant differences between the feedstocks studied in terms of light gases formed, but less apparent variation in tar formation. In general, the variations in products were smaller at higher temperatures. A preliminary analysis of gasifier efficiency was performed using an Aspen Plus process model for selected gasification conditions. Finally, a comparison was made between the results of this work and other similar biomass gasification studies.

Mitigation of tars produced during biomass gasification continues to be a technical barrier to developing systems. This effort combined the measurement of tar-reforming catalyst deactivation kinetics and the production of syngas in a pilot-scale biomass gasification system at a single steady-state condition with mixed woods, producing a gas with an H 2 -to-CO ratio of 2 and 13% methane. A slipstream from this process was introduced into a bench-scale 5.25 cm diameter fluidized-bed catalyst reactor charged with an alkali-promoted Ni-based/Al 2 O 3 catalyst. Catalyst conversion tests were performed at a constant space time and five temperatures from 775 to 875 °C. The initial catalyst-reforming activity for all measured components (benzene, toluene, naphthalene, and total tars) except light hydrocarbons was 100%. The residual steady-state conversion of tar ranged from 96.6% at 875 °C to 70.5% at 775 °C. Residual steady-state conversions at 875 °C for benzene and methane were 81% and 32%, respectively. Catalytic deactivation models with residual activity were developed and evaluated based on experimentally measured changes in conversion efficiencies as a function of time on stream for the catalytic reforming of tars, benzene, methane, and ethane. Both first-and second-order models were evaluated for the reforming reaction and for catalyst deactivation. Comparison of experimental and modeling results showed that the reforming reactions were adequately modeled by either first-order or second-order global kinetic expressions. However, second-order kinetics resulted in negative activation energies for deactivation. Activation energies were determined for firstorder reforming reactions and catalyst deactivation. For reforming, the representative activation energies were 32 kJ/g‚mol for ethane, 19 kJ/g‚mol for tars, 45 kJ/g‚mol for tars plus benzene, and 8-9 kJ/g‚mol for benzene and toluene. For catalyst deactivation, representative activation energies were 146 kJ/g‚mol for ethane, 121 kJ/g‚mol for tars plus benzene, 74 kJ/g‚mol for benzene, and 19 kJ/g‚mol for total tars. Methane was also modeled by a second-order reaction, with an activation energy of 18.6 kJ/g‚mol and a catalyst deactivation energy of 5.8 kJ/g‚mol.

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This techno-economic study investigates the production of mixed alcohols from lignocellulosic biomass using an entrained flow slagging gasifier. Similar analyses for 2000 dry tonne per day plants have been performed at the National Renewable Energy Laboratory using indirect, and direct dry ash gasifiers. The use of a high-temperature entrained flow gasifier differs from the previous studies because it eliminates equipment for tar and methane reformation. The conversion targets for tar reforming in the previous studies, and for alcohol synthesis in all of the studies, are based on DOE's research goals for 2012. The conversion cost increased compared to both of the previous studies, assuming the achievement of the 2012 research targets. Feed handling, high oxygen demand, and a high gasifier capital cost are primarily responsible for the high cost projected by this study. It is understood that the achievement of research targets, maturity, reliability, relative complexities, and redundancy requirements will be the other keys to commercialization. The effect of key assumptions and uncertainties were evaluated using sensitivity analysis.

A joint EERE-PI project was completed to estimate the worldwide potential to produce and transport ethanol and other biofuels, with an emphasis on the 5 year and 10 year potential for biofuels supply to the United States. The project included four specific tasks: 1) identify the range of countries to be included in the study, 2) assess the resource potential for production of ethanol from sugar and starch-based feedstocks, and biodiesel, 3) assess the resource potential for production of other biofuels, including lignocellulosic ethanol, pyrolysis oil, and renewable diesel, and 4) integrate results into the MARKAL energy policy model. The project team included DOE (Policy and International and the Office of the Biomass Program), Oak Ridge National Laboratory (feedstock supply curves), the National Renewable Energy Laboratory (conversion technology characterizations), and Brookhaven National Laboratory (MARKAL analysis).The NREL portion of this study was primarily concerned with estimating the plant gate price (PGP) of liquid biofuels (corn and wheat dry mill ethanol, cellulosic ethanol, biodiesel, renewable diesel, and pyrolytic fuel oil) from selected biomass feedstocks for countries included in the study using representative existing and developing technologies. A methodology for comparing costs between countries was developed. Plant sizes studies ranged from 25 MM GPY to 100 MM GPY. Technology Characterizations-Executive SummaryThe overall objective of the joint EERE-PI project is to estimate the worldwide potential to produce and transport ethanol and other biofuels, with an emphasis on the 5 year and 10 year potential for biofuels supply to the United States. The project identifies four specific tasks:• Task 1: Identify the range of countries to be included in the study • Task 2: Assess the resource potential for production of ethanol from sugar and starchbased feedstocks, and biodiesel.• Task 3: Assess the resource potential for production of other biofuels, including lignocellulosic ethanol, pyrolysis oil, and renewable diesel. The NREL portion of this study is primarily concerned with estimating the plant gate price (PGP) of liquid biofuels from selected biomass feedstocks for countries included in the study using representative existing and developing technologies. The results of the technology characterizations are presented in 2005 U.S. dollars and include estimates of comparative capital and operating costs in each country.

National Renewable Energy Laboratory 1617 C o l e Boulevard Golden, CO 80401-3393 An addendum to this report will be issued by the end o f t h e first quarter o f 1992, in which the results o f IGT gasifier operation at 1800 O F , and BCL g a s i f i e r operation with hot gas conditioning are shown. Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to