Bioethanol: Technologies, Trends, and Prospects

Abstract

India is the fourth largest ethanol-producing country in the world and produces first generation ethanol from molasses (C molasses and B heavy molasses), sugarcane juice or syrup, and different grains. Present mandate of Government of India is to achieve 10% blending of ethanol in petrol up to 2022 and 20% up to 2025. In the year 2022–2023, Oil Marketing Companies (OMCs) in India are expecting to achieve 10.0% blending for which they have offered attractive differential pricing for ethanol to be produced from sugarcane juice or syrup or sugar, B heavy molasses, C molasses, rice, and other grains. The Ministry of Food and Civil Supplies, Department of Food and Public Distribution (DFPD) has also offered financial support through interest subvention scheme for setting-up of new distilleries or for modernization/expansion of existing distilleries. In last three decades, technologies for fermentation of sugary raw materials have shifted from batch fermentation to continuous fermentation to fed-batch fermentation. For starchy raw materials, the fermentation is carried out typically in batch fermentation using high alcohol tolerant yeast strains. Distillation technology to produce alcohol has also shifted from atmospheric to multi-pressure distillation systems with inbuilt heat integration/recovery concepts. The removal of water from rectified spirit to produce absolute alcohol has shifted from Azeotropic distillation to more efficient Molecular Sieve-based Dehydration (MSDH) technique. Ethanol or distillery plants in India are required to achieve Zero Liquid Discharge (ZLD), which has resulted in development of different downstream effluent treatment technologies and combination of such technologies are to be used to achieve ZLD. Feedstock used in ethanol production is also an equally important point that affects ultimately the final cost of ethanol and therefore, considerable research is being carried-out to minimize the feedstock cost. In such circumstances, sugar beet can play a significant role in offering additional and cheaper feedstock for ethanol production and, at the same time, offers an opportunity to enhance the capacity utilization of sugar mills with attached distilleries. The above-mentioned aspects of bioethanol production in India are discussed in this chapter. It explains the technologies useful for ethanol production from sugar beet and how bioethanol from sugar beet can help Indian sugar industry to improve its techno-economic performance.