Wood Waste as a Renewable Energy Source: Effect of Pretreatment Technology for Sustainable Bioethanol Production

Concerning the availability of further fossil fuel supply, greenhouse gas emissions, global warming, and rising fuel prices, it is necessary to identify renewable, ecologically friendly, and economically feasible new alternatives for raw materials for energy sources. Lignocellulosic biomass (LB) derived from wood waste has great potential as an alternative source to produce second-generation biofuels without affecting global food security. However, the major constraints of LB are the presence of physical and chemical barriers caused by the interconnection of the primary constituents of lignocellulosic biomass (cellulose, hemicellulose, and lignin), which makes this component resistant to hydrolysis into fermentable sugars. Thus, the conversion of LB to bioethanol requires extensive processing, especially at the pretreatment stage. In general, pretreatment procedures for turning wood waste into bioethanol are classified into chemical, physicochemical, and biological. The objective of pretreatment is to improve enzyme accessibility, thereby enhancing the digestibility of cellulose and other components that can increase the production yield. Current findings addressing the application, mechanism, and production yield of different pretreatment strategies, such as chemical, physiochemical, and biological procedures, to produce bioethanol from wood waste have been expansively presented.