Production of Fuel Ethanol from Woody Biomass

The most abundant bioenergy feedstock in the world is lignocellulosic material. This material can be categorized in three main parts; agricultural, forestry and recycled materials. The key steps in lignocellulosic bioethanol production are pretreatment, enzymatic hydrolysis, fermentation and recovery of non-fermentable fractions (e.g. lignin). Out of the many available lignocellulosic feedstocks some have been considered to be less tractable because the pretreatment required to make them usable includes acid hydrolysis or steam explosion with an acid catalyst. These pretreatments may lead to negative impacts on downstream processing and may lower ethanol yield or lower the value of the recoverable by-products. Also, the acidic reactants may cause corrosion and require expensive materials. Another technology for producing bioethanol from woody materials is the gasification of biomass, followed by fermentation to ethanol using anaerobic bacteria. This eliminates the need for hydrolysis to break up the cellulose and hemicellulose fractions of the biomass. In this process, the lignin fraction can also be converted into ethanol. The choice of conversion method is based on the properties of feedstock. This study will categorize and compare the lignocellulosic feedstock options for lignocellulosic bioethanol plant.