Initial Comparative Process Economics of Leading Pretreatment Technologies Richard T. Elander, National Renewable Energy Laboratory Charles E. Wyman, Dartmouth College Bruce E. Dale, Michigan State University Mark Holtzapple, Texas A&M University Michael R. Ladisch, Purdue University Y.Y. Lee, Auburn University Mohammed Moniruzzaman, Genencor International John N. Saddler, University of British Columbia Tim Eggeman, Neoterics International BIO 2006 Annual International Convention Recent Research Results of the Consortium for Applied Fundamentals and Innovation (CAFI) Session Chicago, IL April 12, 2006 Biomass Refining CAFI

Process Modeling in CAFI Projects Pretreatment Model Aspen Plus Bioethanol Plant Model 2001 NREL Design Case 2000 Metric Tons Stover (dry)/Day Stover Cost: $35/ton Enzyme Cost: ~$0.15/gal ethanol Thermodynamics Process Analogies Design Methods Chemistry CAFI Researcher Biomass Refining CAFI Updated Model Basis and Feedstock Basis in “CAFI 2” Project

General Process Flow Diagram Biomass Refining CAFI Boiler + Generator Hydrolysis + Fermentation Feed Handling Recovery Pretreatment Stover Syrup + Solids Chemicals Water Enzymes CO 2 Water EtOH Steam Power

Hydrolysis Stages Biomass Refining CAFI Stage 2 Enzymatic hydrolysis Dissolved sugars, oligomers Solids: cellulose, hemicellulose, lignin Chemicals Biomass Stage 1 Pretreatment Dissolved sugars, oligomers, lignin Residual solids: cellulose, hemicellulose, lignin Cellulase enzyme

Dilute acid Flowthrough Controlled pH Maximum possible ARP AFEX Lime Pretreatment Yields Comparisons at 15 FPU (~58 mg Protein)/g Glucan

Pretreatment Yield Comparisons at 15 FPU (~58 mg Protein)/g Glucan— Component Yield Basis Biomass Refining CAFI Pretreatment System Xylose Yields, % of Theoretical* Glucose Yields, % of Theoretical* After Pretreatment After Enzymatic Hydrolysis After Pretreatment After Enzymatic Hydrolysis Dilute Acid 90.2 / / / / 84.6 Controlled pH Hot Water 50.8 / / / / 88.0 AFEX0 / / / ARP47.2 / / Lime24.3 / / / / 91.3 No Pretreatment Ideal Pretreatment *Cumulative soluble sugars as (oligomers+monomers) / monomers. Single number = just monomers.

Capital Cost Estimates Biomass Refining CAFI Pretreatment System Pretreatment Direct Fixed Capital ($MM) Pretreatment Breakdown, (% Reactor/ % Other) Total Fixed Capital ($MM) Ethanol Production (MM gal/yr) Total Fixed Capital ($/gal Annual Capacity) Dilute Acid25.064/ Controlled pH Hot Water / AFEX25.726/ ARP28.325/ Lime22.319/ No Pretreatment Ideal Pretreatment Basis: 2000 metric tons (dry basis) feedstock/day, assumes only monomers fermented

Minimum Ethanol Selling Price (MESP) Biomass Refining CAFI Assumptions: 2.5 years construction, 0.5 years start up, 20 year plant life, zero net present value when cash flows are discounted at 10% real after tax rate

Effect of Oligomer Conversion Biomass Refining CAFI

Key Findings from CAFI 1 Project Initial set of comparative pretreatment data produced –1 st generation economic models developed Significant differences observed in pretreatment and enzymatic hydrolysis yields –Especially for xylan conversion Pretreatment capital costs more similar than anticipated –High costs for catalyst recovery or regeneration Findings published in a special issue of Bioresource Technology (96:18, p , December 2005) Significant data gaps remain (being addressed in CAFI 2) –Enzyme types –Hydrolyzate fermentability at relevant sugar concentrations –Rigor of economic models (esp. pretreatment area capital costs) Biomass Refining CAFI

Process Engineering Updates in CAFI 2 Project (1) Updating model basis to current NREL case Graphical User Interface (GUI) format Development of ASPEN model for SO 2 pretreatment (UBC) Designing wood chip feedstock handling system for poplar feedstock Modifying CAFI pretreatment models based upon improved vision of scaled-up process –More rigorous pretreatment reactor and pretreatment catalyst recycle system design and costing being developed by Harris Group Inc. Biomass Refining CAFI

Process Engineering Updates in CAFI 2 Project (2) Populate models with CAFI 2 project data –Stover and poplar –Match required enzyme types and loadings with pretreated substrate properties –Include hydrolyzate conditioning process and costs (as necessary) –Include actual fermentation performance of glucose and xylose on conditioned and/or un-conditioned hydrolyzate (as appropriate) Develop “current” and “target” cases for each pretreatment/feedstock combination –Gauge current stage of development vs. reasonable potential for each pretreatment/feedstock scenario Biomass Refining CAFI

Process Economic Implications of Early CAFI 2 Data Higher glucan:xylan ratio in poplar –Optimizing glucose yields becomes more important Lower sugar yields (from both pretreatment and enzymatic hydrolysis stages) will strongly affect predicted MESP More severe pretreatment conditions required to achieve good yields will have an economic impact –Hydrolyzate conditioning and fermentability impact –Can good yields be obtained at less severe conditions with proper enzyme activities and loadings? Higher acetyl content in poplar –Additional hydrolyzate conditioning requirements? Biomass Refining CAFI

Summary Initial process engineering analysis from CAFI 1 project on corn stover showed differences in sugar yields and resulting MESP estimates — Oligomer conversion at no additional enzyme cost diminishes most of the cost differentiation Work is underway to develop and update CAFI pretreatment process economic models — Milestone for initial model updates—June, 2006 Significant process performance differences observed on poplar as compared to corn stover — Required pretreatment conditions — Required enzyme activities and loadings — Hydrolyzate conditioning requirements — Fermentability of hydrolyzates Biomass Refining CAFI

Acknowledgements US Department of Agriculture Initiative for Future Agricultural and Food Systems Program, Contract US Department of Energy Office of the Biomass Program, Contract DE-FG36-04GO14017 Natural Resources Canada Genencor International Our team from Dartmouth College; Auburn, Michigan State, Purdue, and Texas A&M Universities; the University of British Columbia; and the National Renewable Energy Laboratory Biomass Refining CAFI