Sustainability evaluation of lignocellulosic ethanol production in India: Life cycle assessment review

Abstract

To reduce reliance on conventional fossil fuels for transportation, ethanol is an environmentally friendly biofuel that can be blended with gasoline. The second-generation (2G) ethanol production process involves several steps, including pretreatment, enzymatic hydrolysis, fermentation, and distillation. During the process conversion, various chemical agents, such as acids, alkalis, and enzymes, along with process water and energy, are utilised. Thus, the environmental impacts of the 2G ethanol production process need to be investigated. This review provides a brief overview and analysis of the literature on the life cycle assessment (LCA) of 2G ethanol, specifically in the Indian context. Various LCA studies in India have revealed that 2G ethanol production has lower GHG emissions and a better net energy ratio. The central portion of the environmental impact lies in the production stage or cultivation stage of biomass, where water footprints are high due to improper water usage during cropping in India. Furthermore, the impact of electricity use can be reduced by substituting conventional coal-based electricity with bioelectricity generated from leftover lignin during the process. The 2G ethanol production in India can enhance the nation's sustainability goals, thereby reducing environmental loads by replacing the burning of lignocellulosic biomass in fields.