title: Accounting for all sugars produced during integrated production of ethanol from lignocellulosic biomass.
abstract: Accurate mass balance and conversion data from integrated operation is needed to fully elucidate the economics of biofuel production processes. This study explored integrated conversion of corn stover to ethanol and highlights techniques for accurate yield calculations. Acid pretreated corn stover (PCS) produced in a pilot-scale reactor was enzymatically hydrolyzed and the resulting sugars were fermented to ethanol by the glucose-xylose fermenting bacteria, Zymomonas mobilis 8b. The calculations presented here account for high solids operation and oligomeric sugars produced during pretreatment, enzymatic hydrolysis, and fermentation, which, if not accounted for, leads to overestimating ethanol yields. The calculations are illustrated for enzymatic hydrolysis and fermentation of PCS at 17.5% and 20.0% total solids achieving 80.1% and 77.9% conversion of cellulose and xylan to ethanol and ethanol titers of 63g/L and 69g/L, respectively. These procedures will be employed in the future and the resulting information used for techno-economic analysis.
authors.affiliation: National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401, USA. Electronic address: dan.schell@nrel.gov.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Schell
authors.affiliation: National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401, USA.
authors.forename: Nancy
authors.initials: N
authors.lastname: Dowe
authors.affiliation: P2 Science, 4 Research Drive, Woodbridge, CT 06525, USA.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Chapeaux
authors.affiliation: National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401, USA.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Nelson
authors.affiliation: National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401, USA.
authors.forename: Edward W
authors.initials: EW
authors.lastname: Jennings
mesh_terms: D056804:Biofuels; D018533:Biomass; D019149:Bioreactors; D001709:Biotechnology / Q000295:instrumentation / Q000379:methods*; D002482:Cellulose / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D006868:Hydrolysis; D008031:Lignin / Q000378:metabolism; D014990:Xylans / Q000378:metabolism; D014994:Xylose / Q000378:metabolism; D003313:Zea mays / Q000378:metabolism*; D017355:Zymomonas / Q000378:metabolism
chemical_list: D056804:Biofuels; D014990:Xylans; C036909:lignocellulose; D000431:Ethanol; D002482:Cellulose; D008031:Lignin; D014994:Xylose
keywords: Enzymatic hydrolysis; Ethanol; Fermentation; Pretreatment; Yields