Life Cycle Assessments (LCA) of ethanol from corn grain is a cradle to grave evaluation of energy and environmental issues associated with the production and use of ethanol made from corn grain and examines the energy and environmental impacts of producing and transporting corn, converting the corn into ethanol, and distributing and using the ethanol in cars and trucks. Corn grain 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 corn production practices and location of production are important considerations in the LCA. Environmental impacts vary with soil type, physical characteristics (e.g., slope), climate, and tillage and other management practices (fertilizer and chemical inputs). Corn grain yields are also an important consideration.
A recent LCA of the corn dry grind ethanol production process found that use of E85 (85% ethanol, 15% gasoline used in flex-fueled vehicles) decreased the use of gasoline, the amount of petroleum used, the amount of other fossil fuels used, and the amount of greenhouse gas emissions compared to using gasoline. Compounds that can cause smog are also reduced. Compounds that can lead to acid rain (e.g, soil nitrogen compounds) and compounds that cause dead zones in aquatic systems (i.e., nitrogen and phosphorous fertilizers) increase somewhat with the use of E85 relative to gasoline.