All biomass is local: The cost, volume produced, and global warming impact of cellulosic biofuels depend strongly on logistics and local conditions

Current models of cellulosic biofuel systems require that the delivered price of the cellulosic biomass feedstock be kept low. Thus the predicted biorefinery size is relatively small, limiting potential economies of scale. However, it is actually the ultimate selling price of the biofuel that largely determines market penetration. We relaxed the constraint of low delivered feedstock price and explored the resulting effects on biofuel price, biofuel volume produced, and global warming impact (GWI). Feedstock price greatly affects the feedstock supply chains that may develop. Increased feedstock price does not affect the final ethanol selling price very much, but higher feedstock prices greatly increase the amount of ethanol produced. Farmers will supply much more cellulosic biomass at higher feedstock prices, leading to shorter transportation distances with reduced transportation costs and enabling larger biorefineries with improved economies of scale, thereby reducing the ethanol selling price. The cellulosic feedstock supply chain systems were studied as a function of feedstock prices by determining potential feedstock supply clusters and the maximum capacity of cellulosic biorefineries across the United States. Supply clusters were determined by minimizing costs associated with ethanol production. The analysis is based on county-level cellulosic feedstock production data projected in the US Billion-Ton Update report. Each biomass supply cluster is unique in terms of local and regional characteristics (e.g. area, feedstock types), biorefinery capacity, ethanol selling price, and GWI. Very large-scale biorefineries (>= 20 000 dry Mg day(-1)) may be feasible in some regions. (C) 2015 Society of Chemical Industry and John Wiley & Sons, Ltd