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Ethanol Production from Lignocellulosics: Sheldon Duff

EtOH. Ethanol Production from Lignocellulosics: Sheldon Duff. Outline. Biorefinery/Biofuels Progress Feedstocks Pretreatment Fermentation of hydrolysates Process engineering Uncertainties/Current Status. nzymes (Cellulase & b-Glucosidase). Pretreatment (chemical or physical).

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Ethanol Production from Lignocellulosics: Sheldon Duff

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  1. EtOH Ethanol Production from Lignocellulosics: Sheldon Duff

  2. Outline • Biorefinery/Biofuels • Progress • Feedstocks • Pretreatment • Fermentation of hydrolysates • Process engineering • Uncertainties/Current Status

  3. nzymes (Cellulase & b-Glucosidase) Pretreatment (chemical or physical) Fermentation Plant Biomass ETHANOL Hydrolysis Bioconversion

  4. Feedstocks

  5. Paper Feedstocks • Partially pretreated • Clarifier sludges • SSL (knots/PCS) • Recycled fibre • Urban cellulosic wastes • Agricultural residues

  6. Pretreatment

  7. Pretreatment • Focus on oxygen delignification • Clean • Proven

  8. Mill Oxygen Delignification

  9. Can be used across range of substrates Conditions can be extended Application of OD to Recovered Fibre

  10. As with all most pulping / bleaching, limit is yield Application of OD to Recovered Fibre

  11. Can express sugar yield as a function of initial S, K and E Underpredicts high substrate case due to mixing limitations Modelling OD Effects

  12. Achievements • Dramatic improvements in yield, using known, proven technology • Allows reduction in enzyme loading

  13. Fermentation

  14. Fermentation-Challenges • Inhibitors • Pentose fermentation

  15. Inhibitors

  16. O O CH3C H+ + O- CH3C OH ATP ADP Fermentation Inhibitors • Acetic acid • Dissolved solids • Furfural pH 6 pH 4 H+ H+ H+

  17. Acetic acid

  18. Optimization of Prehydrolysate Fermentation Yeast extract Corn steep liquor Fermaid - K

  19. Achievements • Mechanistic understanding of inhibitors • Modelled using maintenance energy model • Improved fermentation (including growth on hardwood)

  20. Xylose Fermentation

  21. Xylose fermentation • S. cerevisiae 259ST (Dr. N Ho, Purdue U) NWY Ho, Z Chen, and AP Brainard, 1998 • Xylose  Xylulose • xylose reductase • xylitol dehydrogenase • xylulokinase • Xylulose fermented via pentose phosphate pathway & glycolysis

  22. Xylose fermentation

  23. Effect of Inhibitors • Maintenance energy has little impact on hexose metabolism • For xylose, metabolic rate is too slow to meet maintenance demand

  24. Hemicellulose Hydrolysate Fermentation • High [yeast] & high pH • Rapid hexose fermentation • Xylose fermentation

  25. Achievements • Xylose fermentation in SSL • Yield on xylose increased from 0 to 80% yield • Increased overall ethanol yield by 20 - 30%

  26. Process Engineering

  27. Modelling and Simulation • Kinetics and yields from pretreatment, hydrolysis and fermentation used • Output • M&E balances • Equipment sizing • Capital/operating costs • Sensitivity analysis

  28. Summary • No full-scale cellulose-to-ethanol plants • Any of several pretreatment technologies effective • Enzyme costs high/uncertain ($2.40-$70/MFPU)

  29. Summary • C5 fermentation possible but has problems: • Slow • Metabolically challenged • Moving toward simulation as a plant design tool

  30. Acknowledgements • NSERC, NRCan, P&P Companies • Steve Helle (UNBC), David Cameron, Bob Benson • Students: Janet Lam, Allison Murray, Kris Draude, Tony Lin, Rob Petretta, John Ruffell, John Moritz

  31. Thank you

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