Is Corn Ethanol a Low-Carbon Fuel?

Reports of disappearing glaciers, shrinking arctic ice, rising sea levels, stronger hurricanes, and unprecedented European heat waves combined with an inexorable buildup in atmospheric carbon dioxide levels is increasing pressure on governments to respond with new greenhouse gas initiatives. California and other states are providing policy leadership in the United States. Of particular interest to the biofuels industry is Governor Arnold Schwarzenegger’s January 2007 executive order that requires a 10 percent reduction in the carbon content of California’s transportation fuels by 2020. In contrast to federal renewable fuel standards, which mandate levels of use of biofuels, California’s fuel standard does not tell fuel suppliers (oil companies) how they should meet the new requirements. Alternative fuels will have to compete in terms of cost and carbon content. Only those fuels that can reduce carbon content at reasonable cost will be included in California fuel blends. Given that ethanol from corn comprises more than 90 percent of U.S. alternative fuels, a key determinant of the feasibility of meeting California’s ambitious goals is the extent to which corn ethanol reduces greenhouse gas emissions. Accounting for Corn Ethanol’s Greenhouse Gas Emissions Whether corn ethanol reduces net greenhouse gas emissions has been studied by many, and many different answers have been found. Sometimes the difference in answers rests on assumptions. For example, Professor David Pimental from Cornell University attributes all greenhouse gas emissions from ethanol plants to ethanol rather than attributing a portion to distillers grains, which displace feed (more about this later). But sometimes the differences in answers are caused by researchers answering different questions. To illustrate the process that researchers follow to calculate greenhouse gas emissions we answer the following question: Does expansion of Iowa corn production to produce ethanol help reduce the buildup of greenhouse gases? If the answer is yes, then corn-based ethanol produced from Iowa corn may qualify as a low-carbon fuel. If not, then the future of the current ethanol industry may be threatened because it may not help California meet its fuel composition target. To answer this question requires careful accounting of the differences in production and consumption that lead to changes in greenhouse gas emissions. The method commonly used to estimate greenhouse gas emissions is to conduct a life cycle analysis of the feedstock used to make biofuels. We present results of a life cycle analysis for Iowa corn from planting to refi ning to burning as fuel. In addition, we also consider changes in emissions caused by land use changes that are attributable to expansion of corn production. These land use changes can occur both domestically and overseas.