An Overview of ethanol-fromcellulose Phillip C. Badger General Bioenergy, Inc. Appalachian Woody Biomass to Ethanol Conference Shepherdstown, WV September 5-6, 2007
Presentation Overview Cellulose vs starch and sugar feedstocks Cellulosic Processes in general Examples of commercialization activities
Basic Types of Feedstocks Sugar Starch Cellulosic (lignocellulosic)
Fermentation Microbes Yeast Fungi Bacteria All require carefully controlled living conditions All require single sugar molecules
Sugar Feedstocks Sugar feedstocks Already in bite-size form as single sugar molecules
Glucose Fermentation Glucose microbes Ethanol + CO 2 1 lb 0.5 lb 0.5 lb + HEAT
Sugar Feedstock Examples Sugarcane, sugar beets, sweet sorghum, fruit, melons, candies and other food wastes, beverage wastes
Starch Feedstocks Sugar feedstocks Starch feedstocks Starch molecules need to be broken up into single sugar molecules
Starch-to-Sugar Conversion Starch Heat Enzymes Glucose
Starch Feedstock Examples Cereal grains, Irish (white) potatoes, sweet potatoes, cassava, Kudzu tubers
Cellulose Feedstock Examples Trees, grasses, aquatic vegetation, cardboard, paper, animal manures, urban wood wastes
Why Ethanol-from-Cellulose? Cellulose most plentiful biomass resource in world From perennial plants Not in human food chain Relatively inexpensive
Feedstock Cost Comparisons Ethanol Production Corn Grain @ $2.50 bu = $105/dry ton $2.50/bu -------------- = $0.86/gal 2.9 gal/bu Wood at $35/dry ton = $17.50/green ton $35.00/dry ton ------------------- = $0.39/gal 90 gal/dry ton
Cellulose Biomass Composition Cellulose (Chains of glucose molecules) 45% 25% Other 5% 25% Hemicellulose (Chains of various sugar molecules) Lignin (Young clean coal)
Lignocellulosic vs. Starch Feedstocks Contain a variety of sugars Very long chain molecules Different chemical bonding Encased in lignin
Feedstocks Sugar feedstocks Starch feedstocks Cellulose feedstocks X X X X Cellulose molecules need to be broken up into single sugar molecules
Ethanol from Cellulose Technologies Biological via Hydrolysis & Fermentation Dilute acid Concentrated acid Enzymatic with pretreatment Thermochemical via gasification (FT) With catalytic conversion of gas to ethanol Thermochemical & Biological With fermentation of gas to ethanol
Cellulosic Ethanol Production Using Biological Pathways Cooking Acid + heat time = Sugars + residual solids (lignin) Ethanol fermentation and recovery Lignin utilization (boiler fuel)
Sugar from Cellulose Straight chain (polymer) of glucose molecules (C 6 sugars) Molecular weight cellulose estimated at 200,000 to 2,000,000
Sugars in Hemicellulose Relatively easily hydrolyzed Pentoses (C 5 ) Mostly xylose Some arabinose Hexoses (C 6 ), mainly: Mannose Glactose Glucose
Microbe Problems Microbes typically are sugar specific or prefer certain sugars over others The result: Multiple microbes have to be used to ferment mixtures of sugars Sequential fermentation Need GMOs that can use mixed sugars
Microbe Poisoning From plant components From leached metals from containers From alcohol concentrations From byproducts From high sugar concentrations Lower sugar concentrations leads to increased distillation expense
Distillation Energy (Btu/gal) x 10 4 Distillation Curve Vol% Etoh in Beer MJ/L
Feedstock Alkali Stillage 1 st Stage Hydrolysis Neutralization C5 Fermentation Acid Solids Gypsum Yeast Distillation 2 nd Stage Hydrolysis Neutralization C6 Fermentation Lignin Alkali Etoh Dilute Acid Hydrolysis
Dilute Acid Hydrolysis Oldest process, originally trickling bed Typically H 2 SO 4 used because of cost Pros: Process reaction in seconds or minutes Smallest hydrolysis process footprint requirements Small amounts of acid used (e.g. ~1%) Neutralization relatively easy
Cons: Dilute Acid Hydrolysis Requires processing under pressure Combo of acid, pressure, and high temps (160-210 C) requires exotic metals Limited to yields around 50 gal/dry ton Byproduct furfural poisonous to microbes
Dilute Acid Process Commercializing Companies Pure Energy Corporation Celunol (formerly BC International Corporation) Brelsford Engineering, Inc. Elsam A/S
Pure Energy Corporation Feedstock Etoh Glucose Fermentation Coproducts Dilute Acid Hydrolysis Organic Acids (and solvents) Lignin Xylose Thermal Chemical Processing Furfural Co-Generation Electricity Process Steam Process Power MTHF 2 nd Order Chemicals Other Aliphatic Chemicals
Celunol Corporation Uses GMO that can ferment both C5 and C6 sugars Developer Dr. Lonnie Graham, U of FL US Patent 5,000,000
Concentrated Acid Fermentation Etoh Process Sugar Lime Neutralization/ Filtration Solids (Gypsum) Acid Sugar/ Acid Solution Biomass Wet 1 st Stage Hydrolysis Solids Dewater/dry Dry Solids Pre-Hydrolysis Sugar/ Acid Solution liquid Filter Solids (Lignin) Slurry 2 nd Stage Hydrolysis Water Dry Solids Dewater/ dry Slurry
Concentrated Acid Process Pros: High sugar yields 90% Cellulose 80% Hemicellulose Operation at atmospheric pressure Can use fiberglass vessels
Concentrated Acid Process Cons: Biggest con need cost effective acid recovery method Hydrolysis process takes 2-3 hours Requires acid concentrations of 72% Lignin left in non-reactive form
Concentrated Acid Process Researchers USDA Peoria Lab Purdue University Tennessee Valley Authority
Concentrated Acid Process Commercializing Companies: Arkenol (California) MASDA OXYNOL (Alabama)
Acid Recovery Chromatographic-based system - pseudo moving bed column Special resins (cationic or anionic) preferentially retard the flow of one components to be separated Arkenol has worked with Dow, Mitusbishi, Finex, Rohm & Hass
Arkenol Concentrated Acid Process
MASADA Oxynol
Feedstock Ethanol Acid Pretreatment C5 sugars Fermentation Yeast Distillation Cellulase Enzyme Enzymatic Hydrolysis C6 sugars Fermentation Lignin Stillage Enzymatic Hydrolysis Process
Enzymatic Pre-processing Physical methods High temperatures High pressures Freezing Milling Radiation Steam or ammonia explosion Chemical methods Solvents Acids
Enzymatic Process Pros: Relatively clean products High sugar yields 90% cellulose 95% hemicellulose
Enzymatic Process Cons: Biggest con--cost of enzymes Large amounts of enzymes needed Relatively slow (may take days) = larger plant footprints Still requires pretreatment
Enzymatic Processes Commercializing companies IOGEN Abengoa Bioenergy Pure Vision Elsam A/S MBI Lignol Innovations Corporation Bio-Process Innovation/Universal Entech
IOGEN Company is enzyme producer Investors Govt of Canada Shell Oil Petro-Canada Steam explosion pretreatment 1 million gal/yr pilot plant in Ottawa
Iogen 1 million gallon per year Cellulose-to-Ethanol Pilot Plant, Ottawa, Canada
IOGEN Enzymatic Process Requirements 3,000 dry tons biomass per day minimum Would require 30 square miles (200,000 acres @ 30% land use) yielding 5 dry tons/acre within 60 miles of plant Prefers hardwoods, ag residues, and grasses due to chemical content Assumed yield 90 gal/dry ton by 2012 Based on straw and corn stover
Abengoa Bioenergy in Galicia, Spain Process: Enzymatic Scheduled Startup: end of 2006 Resource: Barley husks and straw Capacity: 53 million gallons/year
Pure Vision Technology Colorado Pretreatment: Patented reactive fractionation Piloting with wheat straw/corn stover
MBI International Michigan AFEX Pretreatment Ammonia freeze explosion Tested at pilot scale Treatment of AFEX corn stover with xylanase and cellulase Tested at bench scale
MBI-AFEX
Lignol Innovations Company Canada Pretreatment ethanol based organosolv step to separate lignin, hemicellulose, and hydrophobic extractives from cellulose Organosolv liquor is processed to recover lignin, furfural, xylose, acetic acid, and extractives Cellulose very usable for enzymatic hydrolysis for ethanol production Organosolv process operated at 60 t/day for 6 years
DOE NREL Enzymatic Research Feedstock evaluations Pretreatment Enzymatic hydrolysis Cellulase enzymes Genencor/Novozymes GMO for fermenting mixed sugars Simultaneous Saccarification & Fermentation (SSF)
NREL SSF Process Syrup SSF = Simultaneous Scarification and Fermentation
Thermochemical Gasification & Fischer Tropsch Ethanol Gasification + Catalyst Byproducts
Ethanol from Biomass Gasification & FT Synthesis Off Gas Etoh Particle reduction and drying Gasification Gas Clean up FT Synthesis Reactor (catalyst) Biomass
Gasification/Fisher Tropsch Developed by Germans in 1920 s Commercial plants operating in South Africa on coal (Sasol) More feasible today because of more efficient catalysts and lower cost of catalysts
FT Process Conditions FT Reactor Temperature 400-600 F Pressure 15-40 bars Catalyst: Iron and Cobalt Exothermic reaction 80% of H2 and CO converted to gasoline and/or diesel
Pros Ethanol from Biomass Gasification & FT Synthesis Relatively simple process Good feedstock flexibility Relatively fast process (seconds or minutes) Relatively small plant footprint Smaller scale plants economically feasible Higher yields possible
Ethanol from Biomass Gasification & FT Synthesis Cons Catalyst problems Cost Short life Conversion of active sites to inactive oxide sites Sintering Loss of active area by coke deposition Chemical poisoning by sulfur, halides, and nitrogen compounds
Gasification/FT Vendors Power Energy Fuels (CO) Range Fuels (CO) Pearson Technologies (MS) Choren Industries (Germany)
Klepper Biomass Conversion Process Klepper Pyrolytic Steam Reforming Gasifier (PSRG) with a Staged Temperature Reaction Process (STRP)
Pearson Technologies FT Ethanol Production Process Proprietary catalyst with recycle to produce Etoh at over 98% efficiency. Projected Etoh cost $0.50 to $0.75/gal
Thermochemical Gasification & Fermentation Ethanol Gasification + Fermentation Byproducts
Thermochemical Gasificationbiological processes CO2 Ethanol Gasification Syn-gas Fermentation Ethanol recovery Biomass
Thermochemical Gasification- Biological Processes Pros Great feedstock flexibility Cons Loss of desirable traits of microbes after a few generations
Thermochemical Gasification- Biological Processes Commercialization Bioengineering Resources, Inc. (Arkansas)
Summary Biomass is a resource whose diversity and local availability helps increase national security There is potential to offset up to 30% of US petroleum imports by 2030 There are many different processes in various stages of development to convert biomass into liquid fuels