Uncertainties in corn stover feedstock supply logistics cost and life-cycle greenhouse gas emissions for butanol production

The success and sustainable operation of a commercial cellulosic biorefinery are highly dependent on price, quality, and availability of feedstocks. Currently, corn stover is a primary feedstock choice for cellulosic ethanol production and the same feedstock can be used for butanol production, which is a potential alternative biofuel. However, butanol production requires different levels of feedstock and logistical resources when compared to ethanol due to about 20% lower theoretical yield. A thorough analysis of cost, life-cycle energy use and life-cycle greenhouse gas emissions associated with a feedstock supply logistics system for butanol production is yet to be done. Additionally, quality standards for corn stover feedstock are yet to be determined, which could determine cost of the feedstock for commercial applications. Thus, this study aimed to fulfill these research gaps using techno-economic analysis and life-cycle assessment methodologies. Variability in logistical resources and other input parameters gathered from recent literature were used for analyses in this study. Average corn stover supply logistics cost ($/metric ton(t), dry), life-cycle energy use (MJ/t, dry) and life-cycle greenhouse gas emissions (kg CO2e/t, dry) were 86.9, 1073.7 and 83.8, which could increase at 95% certainty to 159–504, 1672–3817 and 138–271, respectively, depending on the types of probability distributions of the input parameters. However, the mode value of logistics cost ($/t, dry), life-cycle energy use (MJ/t, dry) and life-cycle greenhouse gas emissions (kg CO2e/t, dry) of 80–120, 913–1231 and 79–120, respectively, closely represents the results of the static model. The average estimated feedstock cost for butanol production was about 1.3 times and the minimum 95% certainty value is about 2 times more than the targeted feedstock cost ($/metric ton, dry) of 66.4, excluding preprocessing. Overall, the location of the biorefinery, quality of corn stover, sustainable agricultural practices, and optimum utilization of transportation resources were key factors that enable a sustainable feedstock supply logistics system.