The effect of biomass moisture content on ethanol yields from steam pretreated lignocellulosics Renata Bura and Shannon Ewanick

Transcription

1 The effect of biomass moisture content on ethanol yields from steam pretreated lignocellulosics Renata Bura and Shannon Ewanick October 11 th, 2012 Pacific Rim Summit on Industrial Biotechnology and Bioenergy

2 2 The divide between biomass assembly and conversion Biomass production Harvest & collection Storage Transportation Biomass assembly Handling Feedstock conversion interface Pretreatment Hydrolysis Fermentation Distillation Biomass conversion 2

3 Feedstock factors affecting bioconversion 3 Biomass production Species Harvest & collection Bark content Storage Low moisture Transportation Low moisture Handling Low moisture 3

4 Objectives 4 How Objectives can we improve the production of fuels and chemicals from biomass? Understanding the effect of biomass assembly on subsequent processing Analyze the effect of the initial moisture content of biomass on the overall ethanol yield

5 Affect of preconditioning 5 Biomass preconditioning Biomass treatment $ Pretreatment $$ Product recovery and characteristics Pretreatment Enzyme $$$ Cellulose conversion to glucose Hydrolysis Ethanol yield Fermentation and SSF Microorganism $$$ Ethanol

6 6 Switchgrass and sugarcane bagasse preparation Air-dry (10 % moisture) No SO 2 added Steam explosion C min Switchgrass Sugarcane bagasse (Hawaii) Soak to 80% moisture Add 3% SO 2 SO 2 Starting material Moisture adjustment SO 2 addition Pretreatment (Ewanick & Bura 2011)

7 Pretreatment 7 Biomass preconditioning Products characteristics Pretreatment steam explosion Cellulose conversion to glucose Hydrolysis 5% (w/w) 10 FPU/g Ethanol yield Fermentation SSF Ethanol

8 8 Pretreated switchgrass solid fraction composition (% xylan, glucan, lignin) 60% 50% 40% 30% 20% Series1 Xyl LM Series2 Xyl HM Series3 Glu LM Series4 Glu HM Series5 Lig LM Series6 Lig HM 10% 0% Switchgrass Switchgrass+SO 2

9 Enzymatic hydrolysis 9 Biomass preconditioning Products characteristics Pretreatment steam explosion Cellulose conversion to glucose Hydrolysis 5% (w/w) 10 FPU/g Ethanol yield Fermentation SSF Ethanol

10 Cellulose to glucose conversion (%) Cellulose to glucose conversion (%) 10 Enzymatic hydrolysis 5% (w/w) 10 FPU/g cellulose Switchgrass Sugarcane bagasse % 10% Time (hours) SG HM+SO 2 SG LM+SO 2 SG HM SG LM Time (hours) SCB HM+SO 2 SCB LM+SO 2 SCB HM SCB LM (Ewanick and Bura, 2011; Bioresource Technology 102)

11 Fermentation 11 Biomass preconditioning Product recovery and quality Pretreatment steam explosion Cellulose conversion to glucose Hydrolysis 5% (w/w) 10 FPU/g Ethanol yield Fermentation SSF Ethanol

12 Ethanol % of theoretical Ethanol % of theoretical 12 SSF 5% (w/w), 10 FPU/g cellulose, 5 g/l of S. cerevisiae Switchgrass Sugarcane bagasse % 60 20% SG HM+SO 2 SCB HM+SO Time (hours) SG LM+SO 2 SG HM SG LM Time (hours) SCB LM+SO 2 SCB HM SCB LM (Ewanick and Bura, 2011; Bioresource Technology 102)

13 Glucan conversion / Ethanol yield (%) Xylan removal Hydrolysis (10 h glucan conversion) R 2 =0.781 SSF (24 h ethanol yield) R 2 = Xylan (%) (Ewanick and Bura, 2011; Bioresource Technology 102)

14 14 Final results theoretical ethanol yield from raw biomass Switchgrass - uncat Switchgrass Soaked Unsoaked Bagasse Bagasse - uncat Switchgrass - SO2 Switchgrass+SO 2 28% Bagasse+SO 2 Bagasse - SO2 28% 0% 0 20% 40% 60% 80% Theoretical ethanol yield from raw biomass (%) % of theoretical yield from raw biomass (Ewanick and Bura, 2011; Bioresource Technology 102)

15 Conclusions (1) 15 Biomass preconditioning Products characteristics Pretreatment steam explosion Cellulose conversion to glucose Hydrolysis 5% (w/w) 10 FPU/g Ethanol yield Fermentation SSF Ethanol

16 Conclusions (2) 16 Ethanol yields are over 25% higher for high MC, SO 2 -catalyzed samples Ethanol yields do not change for low MC, uncatalyzed samples Increased moisture improves SO 2 penetration, resulting in higher xylan removal and increasing cellulose accessibility Lower xylan content in high MC, SO 2 - catalyzed samples improves solids digestibility leading to high ethanol yield

17 Conclusions (3) 17 Biomass production Harvest & collection Storage Transportation Biomass assembly Handling Feedstock conversion interface Pretreatment Hydrolysis Fermentation Distillation Biomass conversion 17

18 Acknowledgements 18 Novozymes Inc. Weyerhaeuser Inc. Denman Professor in Bioresource Science Engineering Biofuels and Bioproducts Laboratory Research Group (