A distributed cellulosic biorefinery system in the US Midwest based on corn stover

摘要

Corn stover supply chains in a distributed biorefinery system are explored. The distributed cellulosic biorefinery uses pre-processed and densified cellulosic feedstock from a geographically separated facility (a depot) as raw material. A network of small-scale depot facilities supplies pre-processed feedstock to a distributed biorefinery. Depot facilities are assumed to be located at existing grain elevators, while distributed biorefineries are located adjacent to coal-fired power plants in areas with high gasoline consumption (urban areas) in the Midwest. The county level corn stover projections in 2022 by the US Billion-Ton Update report (2011) are used to estimate ethanol selling price and greenhouse gas (GHG) emissions of the ethanol fuel. The supply chain for each distributed biorefinery is determined by minimizing the ethanol selling price. Approximately ten distributed biorefineries based on corn stover could be established in the Midwest. Over 700 individual depot facilities participate in supplying the distributed biorefinery systems which collectively can produce greater than 12 hm(3) of ethanol (3.3 billion gallons) per year. Ethanol selling price in the distributed system ranges from US$0.66 to US$1.03 per liter. Some distributed biorefineries are economically competitive with a centralized biorefinery. However, not every region can support a distributed biorefinery system due to inadequate corn stover availability. Cradle-to-gate GHG emissions of ethanol in the distributed systems are 22.1-46.6 g CO2 per MJ. The external energy consumption in the depot facilities is the major GHG source. Optimizing process energy use in the depot facility is required to reduce both operation costs and GHG emissions. (c) 2016 Society of Chemical Industry and John Wiley & Sons, Ltd