Economics and environmental impact of bioethanol production technologies: an appraisal

Abstract

Contemporary industrial developments and rapid pace of urbanization have called for an environ-mentally sustainable energy sources. Ethanol made from biomass provides unique environmental, economic strategic benefits and can be considered as a safe and cleanest liquid fuel alternative to fossil fuels. There is a copious amount of lignocellulosic biomass worldwide that can be exploited for fuel ethanol production. Significant advances have been made at bench scale towards the fuel ethanol generation from lignocellulosics. However there are still technical and economical hurdles, which make the bioethanol program unsuccessful at commercial scale. This review provides a broad overview on current status of bioethanol production technologies in terms of their economic and environmental viability. These technologies include pretreatment of biomass, the use of cellulolytic enzymes for depolymerisation of carbohydrate polymers into fermentable constituents and the use of robust fermentative microorganisms for ethanol production. Among all the available technologies, dilute acid hydrolysis followed by enzymatic hydrolysis by less expensive and more efficient cellulases has been found more promising towards the potential economics and environmental impact.