Switchgrass (Panicum virgatum) is a native, perennial prairie grass that is being developed as a bioenergy feedstock that can be converted to ethanol for use as a transportation fuel.
A Life Cycle Assessment (LCA) of ethanol from switchgrass is a cradle to grave evaluation of energy and environmental issues associated with producing, harvesting, and transporting switchgrass, converting switchgrass into ethanol, and distributing and using the ethanol in cars and trucks. Switchgrass ethanol LCAs frequently include an assessment of gasoline, the petroleum derived product that ethanol will displace, as a means to compare the two products.
The production of ethanol from switchgrass also produces electricity and steam (from the lignin) which can be used by the conversion facility or sold to the electrical grid, and displaces electricity and steam generated from fossil fuels.
Switchgrass production practices and production location are important considerations as environmental impacts associated with changes in soil characteristics vary with soil type and physical characteristics, climate, and tillage and other management practices.
Recent LCAs estimate that the use of ethanol produced from switchgrass could decrease nonrenewable energy consumption, crude oil consumption, and greenhouse gas emissions compared with using gasoline. The use of fertilizers (nitrogen and phosphorus) to produce switchgrass can potentially increase acid rain, dead zones in aquatic systems (i.e., eutrophication), and smog relative to gasoline, depending on the assumed fertilizer application rates.