A techno-economic and environmental evaluation of the life cycle of bioethanol produced from rice straw by RT-CaCCO process

Japan has set an ambitious goal to produce bioethanol from abundant biomass in views to offset some of her greenhouse gas (GHG) emissions. This study attempts to evaluate the life cycle of bioethanol produced from the most common variety of rice straw in Japan (cv. Koshihikari) by enzymatic hydrolysis. Three scenarios are established in the evaluation process. The net energy consumption, CO2 emission and production costs are estimated to determine if environmentally friendly and economically viable bioethanol can be produced from rice straw in Japan. The net energy consumption, CO2 emission and production costs are estimated to be 10.43–11.56 GJ/m3, 1106.34–1144.94 kg/L and 88.54–137.55 k¥/m3 (1 US$≈100¥), respectively depending on the scenarios of this study. This study reveals that despite a bit of environmental benefits, the economic viability is doubtful unless innovative technologies along with the renewable energy policy and stakeholders participation are considered. A shift in scenarios not only reduces the production cost, but may also minimize the risk of soil degradation and productivity loss and encourage more stakeholder participation and investment in the bioethanol industry in Japan.