The Sustainability of Ethanol Fuel in the United States

Ethanol has long been considered the “Fuel of the Future, ” but concerns about the sustainable production of gasoline in the next century suggest perhaps the future is now. US ethanol production exceeds 3 billion gallons per year and capacity is rising more than 10 % per year. Air pollution regulations and the banning of MTBE in several states have opened a market for fuel ethanol. Domestic production of ethanol may reduce dependence on imported oil and lower greenhouse gas emissions. Studies from the USDA and Cornell University, ignoring their differing system expansions, suggest ~5 % more energy is extracted from ethanol than is used to produce it. About 52 % of the energy input is from domestically produced coal. The impact of ethanol is limited by the size of the resource. Grain ethanol production consumes 10 % of US grown corn, but it replaces only 2.6 % of US gasoline consumption. The maximum sustainable stover ethanol production of the US is estimated at 4 billion gallons per year. The use of many other lignocellulosic biomass fuel sources would be necessary to impact the US gasoline demand of over 134 billion gallon per year