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Cellulosic Ethanol 101

Cellulosic Ethanol 101. Tom Richard Department of Agricultural and Biological Engineering Penn State University www.bioenergy.psu.edu. Biomass Energy Alternatives. Sugar, starch now; Lignocellulose? Coming soon…. Mature. Semi-mature. US Biomass inventory = 1.3 billion tons.

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Cellulosic Ethanol 101

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  1. Cellulosic Ethanol 101 Tom Richard Department of Agricultural and Biological Engineering Penn State University www.bioenergy.psu.edu

  2. Biomass Energy Alternatives Sugar, starch now; Lignocellulose? Coming soon… Mature Semi-mature

  3. US Biomass inventory = 1.3 billion tons Wheat straw Corn stover 6.1% Soy 19.9% 6.2% Crop residues 7.6% Grains 5.2% Manure 4.1% Urban waste 2.9% Perennial crops 35.2% Forest 12.8% From: Billion ton Vision, DOE & USDA 2005 (projections to 2030)

  4. Ethanol Production Today BRAZIL sugarcane (sucrose) Sugars ethanol extract ferment USA (starch) Sugars ethanol Hydrolyze(enzymes) ferment Brazil and the US are the leaders in ethanol fuel production They use the “easy way” to make ethanol. Cosgrove, 2006

  5. Chemical structure of starch STARCH http://www.ucmp.berkeley.edu/monocots/corngrainls.jpg http://www.scientificpsychic.com/fitness/carbohydrates1.html

  6. The rest of the plant is mostly sugar too! Section of a pine board 3 nm Somerville, 2006 Polymerized glucose

  7. Slow & expensive step enzyme digestion sugars Fermentation ethanol Plant cell wall Cell walls fuel Cellulose,Hemicellulose, + lignin “recalcitrance” Cellulose microfibril chemical pretreatments Parallel strands of glucose polymers Cosgrove, 2006

  8. Components of plant cell walls Cellulose Cellulose (6 carbon sugars) Lignin Lignin (phenols) Extractives Extractives Hemicellulose (both 5 and 6 carbon sugars) (need modified microbe to convert to ethanol) Ash Ash Chapple, 2006; Ladisch, 1979, 2006

  9. Ethanol from glucose or xylose Jeffries & Shi Adv. Bioch Eng 65,118

  10. Conversion of sugar to alkanes Huber et al., (2005) Science 308,1446

  11. Protein Convert Carbohydrate LDV Fuels Organic Chemicals Power LDV & HDV Fuels Integration of bioconversion and thermochemical platforms Lignin-Rich Residue (More energy dense than original feedstock) Bioconversion Platform Biomass Feedstock Feedstock Handling Pretreatment Biological Conversion Product Recovery Power/TCF Production Waste Treatment Lee Lynd, 2006

  12. Evolution of Biomass Processing Featuring Enzymatic Hydrolysis Biologically-Mediated Event Processing Strategy (each box represents a bioreactor - not to scale) SHF SSF SSCF CBP O2 O2 O2 Cellulase production Cellulose hydrolysis Hexose fermentation Pentose fermentation SHF: Separate hydrolysis & fermentation CBP: Consolidated bioprocessing SSF:Simultaneous saccharification & fermentation SSCF: Simultaneous saccharification & co-fermentation _____________ Lee Lynd, 2006

  13. Biorefinery By-Product Utilization • Lignin • Burn to power the plant & export electricity • Platform for specialty chemicals? • Wastewater • Conventional treatment? Energy recovery? • Still Bottoms • Value as animal feed? • Fire boiler to supplement heating demand • Must be dried, co-fired with coal or equivalent • 5000-8000 BTU/lb

  14. Ethanol dry-mill with process heat produced by Anaerobic Digestion of manure and thin stillage. No drying of WDG or evaporation of thin stillage. Net Energy = 16 MJ/L Ethanol dry-mill with process heat produced by firing stover in a solid-fuel boiler. Net Energy = 12.2 MJ/L Rob Anex, Iowa State Univ.

  15. Relative cost factors of cellulosic ethanol Capital Recovery Charge* Raw Materials Process Electricity Grid Electricity Total Plant Electricity Fixed Costs 33% Biomass Feedstock 5% Feed Handling 18% Pretreatment / Conditioning Saccharification and fermentation 12% 9% Cellulase Distillation and Solids 10% Recovery 4% Wastewater Treatment 4% Boiler/Turbogenerator Utilities 4% Storage 1% (0.30) (0.20) (0.10) - 0.10 0.20 0.30 0.40 NREL Analysis

  16. Enzyme Operating (non-enzyme) Capital (non-enzyme) Current Feedstock $0.194 $0.168 Mature $0.083 $0.079 With Coproducts With Coproducts Cellulosic Biomass For current technology, the lower purchase price of cellulosic biomass is entirely cancelled by the cost of hydrolysis Economic Drivers: Biological Processing of Lignocellulose $0.30 $0.25 $0.20 $0.152 Fermentable Carbohydrate Cost ($/kg) $0.148 $0.15 $0.10 $0.05 $0.00 With Coproducts Laser and Lynd, 2007 Corn (dry mill)

  17. Simultaneous C5 & C6 Use 6% Improved sugars product Increased fermentation yield 2% Increased ethanol titer 11% 0% 10% 20% 30% 40% 50% Increased ethanol titer following CBP 6% Economic Impact of Various R&D-Driven Improvements Increase hydrolysis yield 3% Improved feedstock sugars 13% Halve cellulase loading Eliminate pretreatment 22% Consolidated bioprocessing (CBP) 41% Error bars denote two different base cases Processing Cost Reduction

  18. www.bioenergy.psu.edu Acknowledgements Lee Lynd and Mark Laser, Dartmouth Rob Anex, Iowa State University Alex Farrell, UC Berkeley USDA-ARS DOE-NREL

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