Energy assessment of second generation (2G) ethanol production from wheat straw in Indian scenario.

Abstract

Impact of second-generation ethanol (2G) use in transportation sector mainly depends upon energy efficiency of entire production process. The objective of present study was to determine energy efficiency of a potential lignocellulosic feedstock; wheat straw and its conversion into cellulosic ethanol in Indian scenario. Energy efficiency was determined by calculating Net energy ratio (NER), i.e. ratio of output energy obtained by ethanol and input energy used in ethanol production. Energy consumption and generation at each step is calculated briefly (11,837.35MJ/ha during Indian dwarf irrigated variety of wheat crop production and 7.1148MJ/kg straw during ethanol production stage). Total energy consumption is calculated as 8.2988MJ/kg straw whereas energy generation from ethanol is 15.082MJ/kg straw; resulting into NER >1. Major portion of agricultural energy input is contributed by diesel and fertilisers whereas refining process of wheat straw feedstock to ethanol and by-products require mainly in the form of steam and electricity. On an average, 1671.8kg water free ethanol, 930kg lignin rich biomass (for combustion), and 561kg C5-molasses (for fodder) per hectare are produced. Findings of this study, net energy ratio (1.81) and figure of merit (14.8028MJ/nilkg carbon) proves wheat straw as highest energy efficient lignocellulosic feedstock for the country.