Cost reduction and feedstock diversity for sulfuric acid-free ethanol cooking of lignocellulosic biomass as a pretreatment to enzymatic saccharification.

We have previously demonstrated that a sulfuric acid-free ethanol (EtOH) cooking treatment enhances the enzymatic digestibility of eucalyptus wood and bagasse flour. In the present study, a reconfigured process that achieves similar performance was developed by identifying possible cost-competitive pretreatments that provide high cellulose-to-glucose conversion during subsequent enzymatic hydrolysis. The series of reconfigurations reduced EtOH usage in the pretreatment by more than 80% in comparison with our previous research. Higher initial pressures and intensive size reduction of the starting material are not required. The reconfigured process was applied to rice straw and Douglas fir, in order to confirm the feasibility of feedstock diversity.