Assessing Fertilization and Landscape Impacts on the Overall Life Cycle of Switchgrass Used to Produce Cellulosic Ethanol.

Switchgrass, a tall grass native to US is considered a suitable feedstock to produce non–corn (or cellulosic) biofuel mandated by US energy Act of 2007. However, the switchgrass production is impacted by environmental conditions and agricultural management, especially in the first few years of establishment. The environmental conditions and agricultural management can impact the yield, soil greenhouse gas emissions, and water pollution. There is important to understand these impacts on the overall life cycle of switchgrass. There are many previous life cycle analyses (LCA) for biofuel production from switchgrass, however, assessment of nitrogen fertilization rate and landscape position impacts on the whole life cycle of switchgrass has not been studies. In this study, the environmental impacts from ethanol produced from switchgrass were analyzed using a life cycle analysis. The ASPEN plus was used to analyze the ethanol generation pathway, and the Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) model used to analyze greenhouse house gas emissions, energy use and regulated emissions.  Other environmental impacts such as eutrophication due to nitrogen loss were evaluated using SimaPro software. The results showed difference in overall emissions and energy use if switchgrass is grown at the footslope of the hill compared to the shoulder slope position. This could be linked to higher biomass, soil CO₂ emissions, and carbon sequestration at the footslope compared to the shoulder position. Fertilization increased yield but also added to overall emission of N₂O.  This study concluded that consideration of various management and landscape influence on switchgrass production are needed to generate an accurate life cycle impacts of ethanol produced from switchgrass.