Abstract Process Economics Program Report 270 THERMOCHEMICAL CELLULOSIC ETHANOL (December 2009)

Transcription

1 Abstract Process Economics Program Report 270 THERMOCHEMICAL CELLULOSIC ETHANOL (December 2009) World ethanol production has experienced spectacular growth. This growth has been based on starch and sugar feedstocks. Cellulosic biomass has the potential to become an alternative feedstock for ethanol production. Cellulosic biomass consists of forestry wastes, agricultural residues and municipal sold waste (MSW).There are numerous challenges, both technical and infrastructure related, associated with commercializing lignocellulosic biomass as feedstock for ethanol production. While large quantities of various crop wastes go unused throughout the world, these lignocellulosic materials are difficult to efficiently convert into chemical products due to their complex polymeric structures. Innovative new technologies that couple biotechnology and chemistry with process engineering are necessary in order to achieve efficient commercial processes. To support commercialization, the Department of Energy announced in 2007 that the government would invest up to $385 million in six commercial scale U.S. projects for lignocellulosic ethanol. Four of the six projects will utilize biochemical conversion technologies and the others will utilize thermochemical conversion technologies. In this report, PEP presents process designs and associated cost estimates for producing ethanol in the United States from syngas derived from cellulosic biomass. We examine the conversion of wood chips to syngas followed by its conversion to ethanol via chemical catalysis and also via fermentation. We also compare this economics to the production of ethanol via dry corn milling. This report supplements PEP Report 263 Biochemical Cellulosic Ethanol (2008).The general conclusions are summarized below: It is unlikely that thermochemical cellulosic ethanol will be competitive with corn dry milling in the near future. This is largely due to the high capital investment required for a new plant. However, recent legislation in the United States provides various incentives for commercialization of cellulosic ethanol. Large scale initiatives underway in the United States could change the competitive situation of cellulosic ethanol in the longer term. Some of these initiatives include development of feedstock infrastructure to lower the potential cost of cellulosic feedstock. Other initiatives are underway related to processing technologies for lowering fixed capital requirements. SRI Consulting PEP Report 270

2

3 SRIC agrees to assign professionally qualified personnel to the preparation of the Process Economics Program s reports and will perform the work in conformance with generally accepted professional standards. No other warranties expressed or implied are made. Because the reports are of an advisory nature, neither SRIC nor its employees will assume any liability for the special or consequential damages arising from the Client s use of the results contained in the reports. The Client agrees to indemnify, defend, and hold SRIC, its officers, and employees harmless from any liability to any third party resulting directly or indirectly from the Client s use of the reports or other deliverables produced by SRIC pursuant to this agreement For detailed marketing data and information, the reader is referred to one of the SRI Consulting programs specializing in marketing research. THE CHEMICAL ECONOMICS HANDBOOK Program covers most major chemicals and chemical products produced in the United States and the WORLD PETROCHEMICALS PROGRAM covers major hydrocarbons and their derivatives on a worldwide basis. In addition the SRIC DIRECTORY OF CHEMICAL PRODUCERS services provide detailed lists of chemical producers by company, product, and plant for the United States, Western Europe, Canada, and East Asia, South America and Mexico.

4 CONTENTS 1 INTRODUCTION SUMMARY INTRODUCTION INDUSTRY STATUS AGRICULTURAL RESOURCES TECHNICAL ASPECTS Ethanol via Chemical Catalysis of Syngas Ethanol via Fermentation of Syngas ECONOMIC ASPECTS CONCLUSIONS INDUSTRY STATUS STATUS IN BRAZIL U.S. STATUS ETHANOL PRODUCTION Cellulosic Ethanol ETHANOL MARKET AND U.S. BLEND WALL GLOBAL TARIFFS AND TRADE ETHANOL PRICES United States Brazil BIOMASS FEEDSTOCKS BIOMASS AVAILABILITY AGRICULTURAL RESOURCES Corn Corn Stover SRI Consulting iii PEP Report 270

5 CONTENTS (Continued) Stover Collection Municipal Solid Waste (MSW) Energy Crops THERMOCHEMICAL ETHANOL PROCESS REVIEW BACKGROUND GASIFICATION NREL TARGETS GASIFICATION CHEMISTRY ALCOHOL SYNTHESIS CHEMISTRY VIA CHEMICAL CATALYST Water Gas Shift ALOCOHOL SYNTHESIS Dow Chemical Company Range Fuels ExxonMobil British Petroleum ETHANOL VIA FERMENTATION OF SYNGAS TECHNOLOGY OVERVIEW Syngas Fermentation Chemistry Ethanol Production Acetic Acid Production Fermentor Design GASIFICATION PROCESS DISCUSSION Feed Pretreatment TYPE OF GASIFIERS Fixed Bed Gasifiers Updraft Fixed Bed Gasifier Downdraft Fixed Bed Gasifiers SRI Consulting iv PEP Report 270

6 CONTENTS (Continued) Fluid Bed Gasifiers Circulating Fluid Bed Directly Heated or Indirectly Heated Entrained-Flow Gasifier PROPRIETARY GASIFIER TECHNOLOGIES Range Fuels CARBO-V GASIFICATION TECHNOLOGY Pearson Technologies AlterNRG InEntec GAS CLEANING TAR REMOVAL Primary Tar Removal Secondary Tar Removal Water Scrubbing Solvent Scrubbing Tar Cracking Catalytic Tar-Cracking Nonmetallic Oxides Commercial Reforming Catalysts Thermal Tar-Cracking PARTICULATES SLAGGING VS. NON-SLAGGING GASIFIERS ALKALI REMOVAL NITROGEN REMOVAL Catalytic Destruction of Nitrogen Compounds ACID GAS REMOVAL SRI Consulting v PEP Report 270

7 CONTENTS (Continued) H2S Removal HCL Removal SUMMARY THERMOCHEMICAL ETHANOL FROM CELLULOSIC BIOMASS INTRODUCTION CHEMISTRY ALCOHOL SYNTHSIS VIA CHEMICAL CATALYST PRODUCT CONVERSION AND SELECTIVITY Selectivity CO/Hydrogen Ratio Carbon Dioxide Levels PROCESS OVERVIEW PROCESS DESCRIPTION Section 100-Drying and Gasification Section 200-Gasification Char Destruction Reforming Catalyst Regeneration Water Scrubbing Section 300-Gas Conditioning Carbon Dioxide Removal Section 400-Alcohol Synthesis Section 500-Alcohol Purification Dehydration Distillation PROCESS DISCUSSION Feedstock SRI Consulting vi PEP Report 270

8 CONTENTS (Continued) Capacity Factors Product Yield and Carbon Efficiency Drier Selection Gasifier Design Indirect Versus Direct Heat Combustor Ash Agglomeration Gas Conditioning Scrubbing Syngas Compression Catalyst Selection Reactor Selection Syngas Purge and Recycle MATERIALS OF CONSTRUCTION WASTE STREAMS PROCESS ECONOMICS Capital Costs Production Costs DISCUSSION OF COSTS Raw Materials By-product Credits DISCUSSION OF PRODUCT VALUE CONCLUSIONS ETHANOL BY FERMENTATION OF SYNTHESIS GAS DERIVED FROM BIOMASS 7-1 TECHNOLOGY OVERVIEW Biomass Gasification SRI Consulting vii PEP Report 270

9 CONTENTS (Continued) Syngas Fermentation Chemistry Ethanol Production Acetic Acid Production Fermentor Design Fermentation Nutrient Requirements Ethanol Recovery (Distillation and Dehydration) PROCESS DESCRIPTION Section 100-Biomass Handling and Feed Preparation Drying Section 200-Biomass Gasification and Syngas Clean-up Gasification Char Destruction Gas Conditioning Section 300-Syngas Fermentation Section 400-Ethanol Distillation and Dehydration PROCESS DISCUSSION Feedstock Capacity Factors Drier Selection Gasifier Indirect Versus Direct Heat Combustor Gas Conditioning Scrubbing Syngas Fermentation Fermentor Flue Gas Oxidation MATERIALS OF CONSTRUCTION SRI Consulting viii PEP Report 270

10 CONTENTS (Continued) PROCESS ECONOMICS Capital Costs DISCUSSION OF PROCESS COSTS Raw Material Cost Capital Costs CORN MILLING WET MILLING PROCESS Wet Milling Advances DRY MILLING PROCESS Dry Milling Advances PROCESS DESCRIPTION Saccharification Anaerobic Fermentation Distillation and Dehydration DDGS Recovery PROCESS DISCUSSION Conventional Dry Mill Design Anaerobic Fermentation On-Stream Factor DDGS Quality Waste Treatment CAPITAL AND PRODUCTION COSTS DISCUSSION OF PRODUCT VALUE APPENDIX A: PATENT SUMMARY TABLES... A-1 APPENDIX B: DESIGN AND COST BASES... B-1 SRI Consulting ix PEP Report 270

11 CONTENTS (Concluded) APPENDIX C: CITED REFERENCES... C-1 APPENDIX D: PATENT REFERENCES BY COMPANY... D-1 APPENDIX E: PROCESS FLOW DIAGRAM... E-1 SRI Consulting x PEP Report 270

12 ILLUSTRATIONS 3.1 Fossil Fuel Price History World Ethanol Production in Corn Wet Milling and Dry Milling US Wholesale Ethanol and Gasoline Prices Fuel Price Composition in Brazil Producer Prices for Ethanol and Gasoline in Brazil Cumulative US Biomass Quantities by Price Total Arable Land in Crops World Crop Values U.S. Corn Prices Research and Technology Development Pathway Toward Achieving Feedstock Price Target ISBAL Model Corn Yield Improvement Declining Cost of Corn with Time Midwestern States Examined: Corn Density The Effect of Plant Size on Collection Distance Supply Curves for Round and Square Bales of Corn Stover Shipping Cost per Ton, 35 Miles Corn Stover Delivery Scenarios Feedstock from Corn Field to Refinery Municipal Solid Waste Composition ORNL-BFDP Switchgrass Research Sites Relationships Between Total Cost and Yield Ethanol Yields from Switchgrass, Corn and Stover Simplified Block Flow Diagram of Biosyngas to Ethanol Process Moving Bed Bioreactor (MMBR) Configuration Membrane Supported Bioreactor for Syngas Fermentation SRI Consulting xi PEP Report 270

13 ILLUSTRATIONS (Continued) 5.4 Fixed Bed Gasifier Circulating Bed Gasifier Up-Flow Fixed Bed Gasifier Down-Draft Fixed Bed Gasifier Bubbling Fluid Bed Gasifier Circulating Fluid Bed Indirectly Heated Gasifier Entrained-Flow Gasifier Range Fuels Gasifier Range Fuels Gasifier Carbo-V Gasifier Carbo-V Technology Gas Cleaning Technologies OLGA System Ethanol From Chemical Catalysis of Syngas Process Flow Diagram... E Range Fuels Process Block Flow Thermochemical Block Flow Diagram Exergy Steam Drier Indirectly Heated Gasifier Cumulative Biomass Supply Simplified Block Flow Diagram of Biosyngas to Ethanol Process Moving Bed Bioreactor (MMBR) Configuration Membrane Supported Bioreactor for Syngas Fermentation A Schematic Diagram Showing Transfer of Syngas Components to Biofilm Ethanol via Fermentation of Syngas Process Flow Diagram... E Amylose and Amylopectin SRI Consulting xii PEP Report 270

14 ILLUSTRATIONS (Concluded) 8.2 Corn Wet Milling Process Overview Comparison of Conventional and Enzymatic Corn Wet Milling Starch Yield as Function of Enzyme Addition Corn Dry Milling Ethanol Production and Residual Starch Corn Dry Grind Process with Fiber Conversion to Ethanol Multiple Pressure Distillation + PSA Molecular Sieve Process Multiple Pressure Distillation + BNRI VP Membrane Process Corn Dry Mill Process Flow Diagram... E-21 SRI Consulting xiii PEP Report 270

15 TABLES 2.1 Capital Investment Comparison Ethanol Process Economics Ethanol Targets Around the World Comparisons of 2004 Gasoline and Ethanol Equivalents U.S. Fuel Ethanol Production Major U.S. Ethanol Producers as of December Major Brazilian Ethanol Producers Proposed Cellulose to Ethanol Plants in the United States Ethanol Import Tariffs Available Biomass in the United States Potential Bioethanol Production Major Energy Inputs for Selected Crops /08 Yields for Major U.S. Field Crops Corn and Stover Production in Corn and Stover Compositions Corn Stover Composition Range Theoretical Ethanol Yield from Corn Stover Fractions Estimated Costs for Corn Stover Harvest Cost Variation Under Low and High Resource Availability One Pass harvest and Rail System Economics Generation and Recovery of MSW Materials Lingnocellulosic Crops Chemical Composition of Switchgrass Switchgrass Yield Data Comparative Traits of Corn and Switchgrass Thermochemical Alcohol Technical Challenges Thermochemical Targets SRI Consulting xiv PEP Report 270

16 TABLES (Continued) 5.3 Chemical Composition of Different Gasification Feedstocks Dow Global Technologies Reaction Summary Biosyngas Compositions for Different Gasifier Types Typical Particulate and Tar Compositions for Different Gasifier Configurations Product Gas Compositions for Direct and Indirect Type Gasifiers Syngas Requirements Tar Removal Comparison Catalytic Tar Cracking Tar Content Versus Temperature Inorganic Content of Biomass Feedstocks Melting Temperatures of Potassium Compounds Ethanol from Syngas Thermochemical Ethanol Design Basis Ethanol via Catalytic Conversion of Syngas Stream Flows Ethanol from Biomass Syngas Major Equipment Ethanol from Biomass Syngas Utilities Summary Biosyngas Compositions for Different Gasifier Types Waste Summary Ethanol from Biomass Syngas Total Capital Investment Ethanol from Biomass Syngas Capital Investment by Section Ethanol from Biomass Syngas Production Costs Fermentation Medium Compositions Mineral Solution SRI Consulting xv PEP Report 270

17 TABLES (Continued) 7.3 Trace Metals Solution Vitamin Solution Reducing Agent Biomass Gasification Process (Front End) Design Basis Ethanol via Fermentation of Syngas Stream Flows Thermochemical Ethanol via Syngas Fermentation Major Equipment Thermochemical Ethanol via Syngas Fermentation Utilities Summary Biosyngas Composition for Different Gasifier Types Thermochemical Ethanol via Syngas Fermentation Total Capital Investment Thermochemical Ethanol via Syngas Fermentation Capital Investment by Section Thermochemical Ethanol via Syngas Fermentation Production Costs Thermochemical Ethanol via Syngas Fermentation Direct Costs by Section Corn Wet Milling Coproducts Yield Comparison Between Enzymatic and Conventional Corn Wet Milling Continuous Fermentation Productiveness Co-immobilized Enzyme-Microbe Fluidized Bed Yields Corn Dry Mill Design Bases Corn Dry Mill Stream Flows Corn Dry Mill Major Equipment Corn Dry Mill Utilities Summary SRI Consulting xvi PEP Report 270

18 TABLES (Concluded) 8.9 Corn Dry Mill Total Capital Investment Corn Dry Mill Capital Investment by Section Corn Dry Mill Production Costs SRI Consulting xvii PEP Report 270