Ethanol is described as a renewable biofuel because it is made from biomass. A clear, colorless alcohol made from a variety of biomass materials called feedstocks (the raw materials used to make a product), fuel ethanol feedstocks include grains and crops with high starch and sugar content such as corn, sorghum, barley, sugar cane, and sugar beets. Ethanol can also be made from grasses, trees, and agricultural and forestry residues such as corn cobs and stocks, rice straw, sawdust, and wood chips.
Corn is the main feedstock for fuel ethanol in the United States because of its abundance and low price. The starch in corn kernels is fermented into sugar, which is then fermented into alcohol. From the EIA
Even though ethanol advocates claim that it is a green fuel source, industrial-scale corn farming comes with a large environmental footprint. Corn requires an average of 138 pounds of fertilizer per acre. The overuse of nitrogen fertilizer is what emits nitrous oxide (N2O), a GHG 300 times more potent than CO2, and increases nutrient run-off. Thus, corn ethanol may be worse for the environment than fossil fuels when considering the impacts associated with its production – i.e., plowing, growing, harvesting, transporting, and processing.
In 2005, The Renewable Fuel Standard (RFS) was established by the Energy Policy Act and upgraded in 2007. In a nutshell, the RFS, which is administered by the Environmental Protection Agency (EPA), requires petroleum refiners to add increasing amounts of renewable alternatives into the nation’s transportation fuels. The motive behind the RFS was to reduce greenhouse gas (GHG) emissions, curb America’s addiction to foreign oil, and catalyze the development of new biofuels. Of the 36 billion gallons of biofuel which will be required in 2022, up to 15 billion gallons can be produced from corn. In doing so, the portion of the US corn crop devoted to fuel has quickly risen from 11 percent in 2004 to 40 percent in the present day.
By displacing about 10 percent of petroleum at the gas pump, the ethanol mandate has done little more than expand the supply of gasoline, thereby helping keep fossil fuel prices low. As a result, people can drive more while buying less efficient vehicles.