First- and Second-Generation Ethanol in India: A Comprehensive Overview on Feedstock Availability, Composition, and Potential Conversion Yields

Abstract

With imports of crude oil touching 80% of the total requirement, India is a nation heavily dependent on foreign oil. There are serious efforts to replace part of the transportation fuels with renewable alternatives—notably biofuels. Bioethanol from biomass is probably the near-term solution, since the country is dependent on imports for edible oils, which in turn makes the possibility of near-term implementation of biodiesel as a renewable transportation fuel remote. Being an agrarian economy, the country has abundant feedstock for bioethanol production in the form of agricultural residues. The country generates a total of nearly 650 million metric tons (MMT) of lignocellulosic agro-residues annually, and though a major part of it is used for other purposes, there are still huge quantities of the feedstock available as surplus. Major technical bottlenecks in the conversion of lignocellulose to ethanol have been addressed worldwide, and companies claim to have started operation in the production of second-generation ethanol. While these international technologies can be implemented here directly or with modifications, the major challenge in India’s context would be to ensure availability of quality raw material at the sites of production. Sustainability of such industries would depend on the availability of feedstock at affordable prices which inherently involve logistic issues. Understanding the type and amount of biomass available in the country and its geographical location is important in establishing bioethanol industries, as well as the potential of converting these feedstocks to ethanol. The chapter introduces the background of India’s need for bioethanol and why first-generation bioethanol cannot fully cater to the gasoline blending demands of the nation and proceeds to describe the availability of agro-residues as potential feedstock for bioethanol in the country. Data on the generation of agro-residues which form major agricultural crops in the country is provided along with estimates for the consumption of these feedstocks for competing applications. It gives a fair estimate of the surplus biomass availability in the country and gives the possible realistic amounts of ethanol that can be generated from these biomass residues based on primary and secondary data about the compositions and conversion efficiencies. The study shows that there is a potential of producing ~30 billion liters of ethanol annually from surplus agro-residues in the country (estimated at ~175 MMT) even at very conservative calculations. The importance of logistics and collection models suited for the country is also highlighted