Process Design and Economics for Biochemical Conversion of ...

1 nrel is a national laboratory of the Department of Energy, Office of Energy Efficiency & Renewable Energy, operated by the Alliance for Sustainable Energy, LLC. Contract No. DE-AC36-08GO28308 Process Design and Economics for Biochemical Conversion of Lignocellulosic biomass to Ethanol Dilute-Acid Pretreatment and Enzymatic Hydrolysis of Corn Stover D. Humbird, R. Davis, L. Tao, C. Kinchin, D. Hsu, and A. Aden National Renewable Energy Laboratory Golden, Colorado P. Schoen, J. Lukas, B. Olthof, M.

2 Worley, D. Sexton, and D. Dudgeon Harris Group Inc. Seattle, Washington and Atlanta, Georgia Technical Report nrel /TP-5100-47764 May 2011 nrel is a national laboratory of the Department of Energy, Office of Energy Efficiency & Renewable Energy, operated by the Alliance for Sustainable Energy, LLC. National Renewable Energy Laboratory 1617 Cole Boulevard Golden, Colorado 80401 303-275-3000 Contract No. DE-AC36-08GO28308 Process Design and Economics for Biochemical Conversion of Lignocellulosic biomass to Ethanol Dilute-Acid Pretreatment and Enzymatic Hydrolysis of Corn Stover D.

3 Humbird, R. Davis, L. Tao, C. Kinchin, D. Hsu, and A. Aden National Renewable Energy Laboratory Golden, Colorado P. Schoen, J. Lukas, B. Olthof, M. Worley, D. Sexton, and D. Dudgeon Harris Group Inc. Seattle, Washington and Atlanta, Georgia Prepared under Task No. Technical Report nrel /TP-5100-47764 May 2011 NOTICE This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or Process disclosed, or represents that its use would not infringe privately owned rights.

4 Reference herein to any specific commercial product, Process , or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or any agency thereof. Available electronically at Available for a processing fee to Department of Energy and its contractors, in paper, from: Department of Energy Office of Scientific and Technical Information Box 62 Oak Ridge, TN 37831-0062 phone: fax: email: Available for sale to the public, in paper, from: Department of Commerce National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 phone: fax: email: online ordering: Cover Photos.

5 (left to right) PIX 16416, PIX 17423, PIX 16560, PIX 17613, PIX 17436, PIX 17721 Printed on paper containing at least 50% wastepaper, including 10% post consumer waste. iii Executive Summary The Department of Energy (DOE) promotes the production of ethanol and other liquid fuels from lignocellulosic biomass feedstocks by funding fundamental and applied research that advances the state of technology in biomass collection, Conversion , and sustainability. As part of its involvement in the program, the National Renewable Energy Laboratory ( nrel ) investigates the production Economics of these fuels.

6 This report describes in detail one potential Biochemical ethanol Conversion Process , conceptually based upon core Conversion and Process integration research at nrel . The overarching Process Design converts corn stover to ethanol by dilute-acid pretreatment, enzymatic saccharification, and co-fermentation. Ancillary areas feed handling, product recovery, wastewater treatment, lignin combustion, and utilities are also included in the Design . Detailed material and energy balances and capital and operating costs were developed for the entire Process , and they are documented in this report and accompanying Process simulation files, which are available to the public.

7 As a benchmark case study, this so-called technoeconomic model provides an absolute production cost for ethanol that can be used to assess its competitiveness and market potential. It can also be used to quantify the economic impact of individual Conversion performance targets and prioritize these in terms of their potential to reduce cost. Furthermore, by using the benchmark as a comparison, DOE can make more informed decisions about research proposals claiming to lower ethanol production costs. Building on Design reports published in 2002 and 1999, nrel , together with the subcontractor Harris Group Inc.

8 , performed a complete review of the Process Design and economic model for the biomass -to-ethanol Process . This update reflects nrel s current vision of the Biochemical ethanol Process and incorporates recent progress in the Conversion areas (pretreatment, conditioning, saccharification, and fermentation), optimizations in product recovery, and an improved understanding of the ethanol plant s back end (wastewater and utilities). The major Process updates in this Design report are the following: Feedstock composition is updated to a carbohydrate profile closer to the expected mean.

9 Pretreatment reactor configuration is revised with significant new detail. Whole-slurry pH adjustment of the pretreated biomass with ammonia replaced the previous conditioning practice of overliming, eliminating a solid-liquid separation step. Enzymatic hydrolysis and fermentation are modeled as a batch Process with a continuous high-solids hydrolysis reactor upstream of the batch reactors. On-site enzyme production is included to increase transparency on the cost of enzymes. Wastewater treatment section is redesigned to handle inorganics in the ethanol stillage.

10 The conceptual Design presented here reports ethanol production Economics as determined by 2012 Conversion targets and nth-plant project costs and financing. For the biorefinery described here, processing 2,205 dry ton/day at 76% theoretical ethanol yield (79 gal/dry ton), the ethanol selling price is $ in 2007$. iv Figure ES-1. Economic summary for ethanol production Minimum Ethanol Selling Price (MESP):$ MESP:$ gasoline equivalentContributions:Feedstock$ $ Conversion $ (Ethanol at 68 F)Ethanol / dry ton feedstockFeedstock + Handling Cost$ tonInternal Rate of Return (After-Tax)10%Equity Percent of Total Investment40%Capital CostsManufacturing Costs (cents/gal ethanol)Pretreatment$29,900,000 Feedstock + $3,000,000 Sulfuric & Fermentation$31,200, Enzyme production $18,300,000 Glucose (enzyme production )