Integrated enzyme production lowers the cost of cellulosic ethanol

Previous studies of cellulosic-ethanol production have shown that the cost of producing cellulase is surprisingly significant, and that reducing this cost is key to making cellulosic-ethanol economically viable. This study confirms that finding, and compares the costs of the three approaches for producing cellulase: off-site, on-site, and integrated. It finds that the integrated method is the lowest cost, primarily because it substitutes an inexpensive feedstock, biomass, for a relatively expensive one, glucose. This substitution also makes the ethanol a 100% second-generation biofuel, i.e., it uses no food for fuel'. This study also compares the activity of cellulase produced by the integrated method versus that produced by the off-site method. Laboratory trials of the two show the integrated' cellulase to be better or equal to commercially available off-site' cellulase in converting cellulose to sugar. (c) 2016 The Authors. Biofuels, Bioproducts, Biorefining published by Society of Chemical Industry and John Wiley & Sons, Ltd.