Biochemical Conversion Process of Producing Bioethanol from Lignocellulosic Biomass
Pages : 28-32
The use of bioethanol can reduce our dependence on fossil fuels, while at the same time decreasing net emissions of carbon dioxide, the main greenhouse gas. However, large-scale production of bioethanol is being increasingly criticized for its use of food sources as raw material. Bioethanol from cellulosic biomass materials (such as agricultural residues, trees, and grasses) is made by first using pretreatment and hydrolysis processes to extract sugars, followed by fermentation of the sugars. Brazil’s bioethanol production consumes large quantities of sugar cane, while in the USA, corn is used. Other starch-rich grains, such as wheat and barley, are mostly used in Europe. The use of such sugar-rich biomass causes the escalation of food prices, owing to competition on the market. Therefore, future expansion of biofuel production must be increasingly based on bioethanol from lignocellulosic materials, such as agricultural byproducts, forest residues, industrial waste streams or energy crops. These feedstock’s, which are being used in second-generation (2G) bioethanol production, are abundant, and their cost is lower than that of food crops. In Europe, wheat straw has the greatest potential of all agricultural residues because of its wide availability and low cost. Proper pretreatment methods can increase concentrations of fermentable sugars after enzymatic saccharification, thereby improving the efficiency of the whole process. Conversion of glucose as well as xylose to ethanol needs some new fermentation technologies, to make the whole process cost effective. Researchers are working to improve the efficiency and economics of the cellulosic bioethanol production process. In this review, available technologies for bioethanol production from agricultural wastes are discusses.
Keywords: Ethanol, Lignocellulosic Biomass, Cellulase, Pretreatment Technologies, Biofuels, Fermentation