US Patent 9580729 Method for producing ethanol

A method for producing ethanol from lignocellulosic biomass using yeast at low cost is provided. The method of the present invention for producing ethanol from lignocellulosic biomass includes steps of (1) pretreating lignocellulosic biomass, (2) treating a cellulose fraction obtained in Step (1) with a cellulose hydrolase, (3) mixing saccharified biomass obtained in Step (2) with yeasts to perform ethanol fermentation, and (4) subjecting a fermentation product obtained in Step (3) to a solid-liquid separation, wherein a cycle consisting of Steps (1), (2), (3) and (4) is repeated twice or more, and yeasts obtained in Step (4) are used as all or a portion of yeasts in Step (3) of the subsequent cycle.