Economic and environmental performance of mixing hybrid poplar and wheat straw during bioconversion to ethanol production

Most previous research targeting the development of viable technologies for ethanol production has utilized a single biomass species. Ours study is the first to consider the impact of mixing different biomass species on the production cost of ethanol in a biorefinery. We have previously reported that mixed biomass including hybrid poplar (HP) and wheat straw (WS) showed on average 20% higher sugar yields than single HP and WS, after steam pretreatment and saccharification. In this work a techno-economic analysis was performed to evaluate the economic feasibility of mixing HP and WS during ethanol production. Based on different annual production plans, two scenarios were analyzed. The first scenario used mixed biomass (MB) (75% HP and 25% WS) which is processed simultaneously; the second scenario used single HP and WS biomass as feedstocks for a campaign production plan (CP). The MB production plan yielded 10 gallons more ethanol per ton of biomass than single HP and WS. The ethanol production costs of MB and CP were estimated to be $1.5 and $1.7 per gallon, respectively. MB generates almost twice as much income per year than using single biomass in CP processing, which is equivalent to extra 13.5 million per year in a 773,000 dry ton/year sized biorefinery. Consequently, it will take 4.7 more years to recover the investment by running the biorefinery with a campaign methodology in comparison by using MB. Additionally, we will present Life Cycle Assessment (LCA) of ethanol production under the different scenarios.