title: Effect of reduction in yeast and enzyme concentrations in a simultaneous- saccharification-and-fermentation-based bioethanol process: technical and economic evaluation.
abstract: The ethanol production cost in a simultaneous saccharification and fermentation-based bioethanol process is influenced by the requirements for yeast production and for enzymes. The main objective of this study was to evaluate--technically and economically--the influence of these two factors on the production cost. A base case with 5 g/L of baker's yeast and an initial concentration of water-insoluble solids of 5% resulted in an experimental yield of 85%. When these data were implemented in Aspen Plus, yeast was assumed to be produced from sugars in the hydrolysate, reducing the overall ethanol yield to 69%. The ethanol production cost was 4.80 SEK/L (2.34 US$/gal). When adapted yeast was used at 2 g/L, an experimental yield of 74% was achieved and the estimated ethanol production cost was the same as in the base case. A 50% reduction in enzyme addition resulted in an increased production cost, to 5.06 SEK/L (2.47 US$/gal) owing to reduced ethanol yield.
authors.affiliation: Department of Chemical Engineering, Lund University, PO Box 124, SE-221 00 Lund, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Wingren
authors.forename: Mats
authors.initials: M
authors.lastname: Galbe
authors.forename: Christian
authors.initials: C
authors.lastname: Roslander
authors.forename: Andreas
authors.initials: A
authors.lastname: Rudolf
authors.forename: Guido
authors.initials: G
authors.lastname: Zacchi
mesh_terms: D019149:Bioreactors / Q000191:economics* / Q000382:microbiology; D018929:Cell Culture Techniques / Q000191:economics* / Q000379:methods; D002480:Cellulase / Q000737:chemistry / Q000191:economics* / Q000378:metabolism; D003198:Computer Simulation; D003362:Cost-Benefit Analysis; D000431:Ethanol / Q000737:chemistry / Q000191:economics* / Q000378:metabolism*; D008954:Models, Biological; D017059:Models, Econometric; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D013548:Sweden; D001617:beta-Glucosidase / Q000191:economics* / Q000378:metabolism
chemical_list: D000431:Ethanol; C427304:Novozym 188; D001617:beta-Glucosidase; D002480:Cellulase