Cellulose from wood, agricultural residue, and wastes from pulp and paper mills must first be converted to sugar before it can be fermented. Enormous amounts of carbohydrate-containing cellulosic waste are generated every year throughout the world. Cellulosic ethanol is claimed to reduce green­house gas emissions by more than 90% over conventional petroleum-based fuels [32]. In addition, cellulosic ethanol is free from the criticism of "food versus fuel" because it is not derived from food crops. Based on these rea­sons, lignocellulosic ethanol is classified as a second-generation biofuel. New ways of reducing the cost of cellulosic ethanol production include the devel­opment of effective pretreatment methods, replacement of acidic hydrolysis with efficient enzymatic hydrolysis, commercialization of robust enzymes,

and fine-tuning of enzymatic hydrolysis and fermentation times, in addition to the fermentation selectivity and effectiveness for both C6 and C5 sugars.