Chapter 23 - Technoeconomic evaluation of 2G ethanol production with coproducts from rice straw

Abstract

Development and commercialization of the second-generation (2G) ethanol process are moving at a slower pace, mainly due to inherent process difficulties, challenges in establishing a supply chain for the collection of various types of biomass, its storage and delivery to the processing sites, and higher operating expenditure (OPEX) and capital expenditure (CAPEX). Thus a need for multidisciplinary scientific and engineering advances in all areas of the conversion process to make 2G ethanol production economically. In this context, a feasibility study of technoeconomic evaluation of producing 2G ethanol from cellulosic biomass is to be studied through process design. In this study, a process with a capacity of 100kL per day of 2G ethanol is to be designed from rice straw. In this process, separate enzymatic hydrolysis and xylose and glucose fermentation are considered as the base-case scenario. Also, various alternative cases such as separate hydrolysis and fermentation of glucose and conversion of xylose to furfural; separate hydrolysis and cofermentation of glucose and xylose; separate fermentation of glucose and xylose and production of biochemical from the hydrothermal liquefaction of lignin are studied. The designed process of the various cases is simulated for obtaining material and energy balances using Aspen Plus software. Furthermore, a discounted cash flow approach is adopted for performing economic investigation using the mass and energy flow data of each stream in the processes. The minimum selling price of the 2G ethanol from rice straw is found in the range of $0.25/L–$0.627/L. A similar range of values is also reported in the literature.