(9c) Evaluation of the Environmental Impacts of Ethanol Production from Eastern Red Cedar

Based on the global interest in renewable fuel options, there has been significant research directed towards investigating lignocellulosic feedstocks that are suitable for ethanol production. These include: corn stover, wheat straw, eucalyptus, and switchgrass. This study evaluates the environmental impacts of an ethanol production system using eastern red cedar trees as the biomass feedstock using life cycle assessment (LCA) methodology. A process simulation was developed using Aspen Plus® to model the acid bisulfite pretreatment, enzymatic hydrolysis, fermentation, and distillation steps. A cradle to gate LCA will be presented that evaluates the environmental impacts from the cutting down of the trees to the production of anhydrous ethanol. The functional unit for this cradle to gate analysis is 1 MJ of equivalent energy and the relative mass, energy and economic (RMEE) system boundary selection method is used. The environmental impacts of this process are compared to that of the production of ethanol from corn. Inventory data for the system are collected and used to calculate a life cycle impact assessment (LCIA) using the IMPACT 2002+ framework in simapro 8. Three impact categories will be evaluated: water use, greenhouse gas (GHG) emissions, and non-renewable energy use. Preliminary results indicate that a significant percentage of environmental impacts are from the pretreatment step.