Ethanol from Indian agro-industrial lignocellulosic biomass: an emergy evaluation

Abstract

This study assesses the environmental performance of biomass feedstocks, rice husk, wheat stalk, cotton stalk, sorghum stalk, and sugarcane bagasse, for ethanol production in India. The analysis calculates emergy indicators and demonstrates the dilemma in selection of biomass feedstocks for meeting the ethanol blending target decided by the biofuel policy of the Government of India. It considers spatial variability, and computes the production potential of each lignocellulosic feedstock considered in the study. Achieving high return on energy invested, high renewability, and large production rates simultaneously seems difficult for the considered feedstocks. Among these cellulosic feedstocks, rice husk shows highest renewability and ethanol production potential. Although sorghum stalk has a high return on investment, it has lowest renewability among the feedstocks considered in the study. Rice husk and cotton stalk should be targeted first to fulfil the blending demand of gasoline as they show highest renewability and quality corrected emergy return on investment, along with a high production potential. Emergy analysis of cellulosic biofuels can provide a holistic platform for decision makers for designing the biofuel policy and selection of feedstock in the Indian context.