Preliminary techno-economic evaluation of 2G ethanol production with co-products from rice straw

Abstract

A preliminary techno-economic analysis of 100 KLPD capacity of the second-generation (2G) ethanol with co-products from rice straw through conceptual process design is studied. Various pathways are investigated in this work. They are as follows: scenario 1 (baseline): separate enzymatic hydrolysis and hemicellulose (C5) and cellulose (C6) fermentation; scenario 2: separate hydrolysis and fermentation of C6 sugars and C5 sugar-to-furfural; scenario 3: separate hydrolysis and C5 and C6 sugar co-fermentation; scenario 4: C6 and C5 fermentation separately and hydrothermal liquefaction of lignin to produce biochemical; scenario 5: C6 fermentation, C5 to furfural and lignin to biochemical. The material and energy balances of all the pathways are performed using a steady-state simulation. Based on the results of mass and energy flows of the process, the economic analysis is performed using a discounted cash flow method. It is found that the minimum selling price of ethanol for the baseline scenario is 0.627$/litre whereas other scenarios (2–5) show 0.5, 0.563, 0.35 and 0.25 US$/litre, respectively. The lowest minimum selling price of bioethanol for the last scenario is due to the production of furfural from xylose and various bio-chemicals from lignin along with bioethanol production. Finally, a sensitivity analysis is performed to identify key parameters that influence the economics of the process.