Net energy, CO2 emission, and life-cycle cost assessment of cassava-based ethanol as an alternative automotive fuel in China

Assessment on net energy, external cost of carbon dioxide (CO2) emissions and cost of using cassava-based ethanol as an alternative automotive fuel has been conducted based on its holistic life-cycle, from feedstock production (source) to fuel combustion. And, a new indicator, figure of merit (FM), is proposed for grading conventional gasoline (CG) and cassava-based ethanol (CE): it links net energy yield, external cost of CO2 emissions, and production cost (the higher the FM reading, the better the total performance). On the life-cycle basis, the net energy yield of CE is found to be 0.37 MJ/MJ, i.e. about 49% that of CG. The external cost to society of CO2 emission of CE is about 83% of CGʹs, and the production cost of CE is 0.14 RMB/MJ, i.e. about 200% of CGʹs. The FM of CE is 0.37, i.e. 46% lower than that of CG. From the standpoint of these indicators, CE is currently not competitive with CG, but it has great potential to be improved in the future.