Energy and environmental impact assessment of Indian rice straw for the production of second-generation bioethanol

Abstract

This study assessed the energy and environmental impacts in terms of second-generation (2G) bioethanol production, renewable electricity generation and greenhouse gas (GHG) emissions reduction potential of surplus rice straw (SRS) in India. National rice production database, and standard procedures for life cycle assessment of rice straw to 2G bioethanol production using two different pretreatment technologies namely, dilute acid (DA) and steam explosion (SE) pretreatments were explored for the analysis. Two scenarios (benchmark and resource-efficient) were constructed to evaluate the availability of SRS and to determine the potential from 2020 to 21 to 2030–31. Under benchmark for the year 2030–31, the potential from SRS using DA and SE pretreatment methods for the production of 2G bioethanol and the surplus renewable electricity generation were estimated to be 10,547 and 11,165 million L; and 5295 and 6928 GWh, respectively, and the corresponding GHG emissions reduction potential were assessed to be 11,954 and 14,375 kt CO2eq., respectively while generated renewable electricity replaces crude oil-driven grid electricity, and 11,498 and 14,498 kt CO2eq., respectively while generated renewable electricity replaces coal-driven grid electricity. The study revealed that both the availability of SRS and the choice of pretreatment method play decisive roles in the determination of its potential.