Renewable Energy — UPSC Mains Model Answer

2G biofuels utilise agricultural residues such as paddy straw, sugarcane bagasse, and woody biomass — materials that would otherwise be burned or discarded. This decouples fuel production from food crop cultivation, addressing the food-versus-fuel ethical concern that undermines first-generation ethanol and biodiesel. Dedicated energy crops on degraded land further expand feedstock options without displacing food agriculture.

Converting cellulose and hemicellulose into fermentable sugars requires pretreatment and enzymatic hydrolysis — processes that remain technically complex and commercially expensive at scale. Unlike first-generation sugar-to-ethanol conversion, no globally standardised, cost-competitive 2G pathway exists yet. High capital costs and enzyme inefficiencies continue to constrain commercial viability, making this a key area requiring R&D investment.

India's National Biofuel Policy provides a framework prioritising 2G ethanol from agricultural residues, with public sector oil companies establishing dedicated 2G ethanol plants. The SATAT scheme promotes Compressed Bio-Gas from organic waste and agricultural residues; however, CBG is technically classified under bio-gas rather than lignocellulosic 2G biofuels, reflecting a nuanced distinction in categorisation.

Effective biomass aggregation, supply-chain logistics, and farmer linkages remain weak. Decentralised collection of agricultural residues demands institutional coordination between state governments, local bodies, and private enterprises — an area where implementation has lagged behind policy ambition.