All biomass is local: economic and environmental performance of cellulosic biofuels depend strongly on logistics and local conditions

The cellulosic ethanol fuel production system is investigated to determine potential feedstock supply clusters and the maximum capacity of cellulosic biorefineries across the United States. A potential feedstock supply cluster is a group of counties that supply feedstock to a biorefinery in a given region. Supply clusters are determined by minimizing costs associated with cellulosic ethanol production, including feedstock price, logistics costs, operational costs, capital investment costs, labor, and so on. The analysis is based on county-level cellulosic feedstock production data with respect to different feedstock prices projected in the US Billion-Ton Update report.  Each cluster is unique in terms of geographical characteristics (e.g., geographical size, feedstock characteristics, etc.), biorefinery capacity, ethanol selling price, and global warming intensity. Very large-scale biorefineries (≥ 20,000 dry Mg day^-1) are feasible in some regions if local roads will support the truck traffic. Feedstock price greatly affects the feedstock supply chains that are likely to develop. Interestingly, increased feedstock price does not always raise the final ethanol selling price. Farmers will supply more cellulosic biomass at higher feedstock prices, leading to shorter transportation distances with reduced transportation costs and thereby larger biorefineries with improved economies of scale.  Cellulosic feedstocks from some counties do not participate in any feedstock supply clusters because including feedstock from those counties would raise the ethanol fuel production costs due to increased transport costs without compensating effects on economies of scale.