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Argument: Corn ethanol cannot scale

Issue Report: Corn ethanol

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Corn grain, the current source of ethanol in the United States, requires large amounts of land and energy to produce. This, along with the demand for corn as food, limits the total amount of ethanol that can be produced from corn to about 15 billion gallons a year–about three times what is currently produced. If the fuel is to supplant a sizable fraction of the 140 billion gallons of gasoline consumed each year in the United States, ethanol producers will need to turn to biomass such as wood chips and switchgrass. These resources are cheaper and potentially much more abundant, and they can be converted to ethanol much more efficiently than corn can because they require less energy to grow (see “Redesigning Life to Make Ethanol”).
Since ethanol has less energy per gallon than gasoline that potential 15 billion gallons of ethanol amounts to only 10 billion gallons of gasoline or one fourteenth of current US gasoline consumption. Since demand is rising it represents an even smaller fraction of future demand and does not address demand for diesel, aircraft fuel, and other uses of fossil fuels.
Biomass from wood and other sources might be able to replace all gasoline in the United States.
Indeed, ethanol from such sources could replace “a very large fraction” of the gasoline currently used for vehicles, says Gregory Stephanopoulos, professor of chemical engineering at MIT. He says some experts estimate that with gains in efficiency and high yields of ethanol, all the gasoline for transportation could be replaced; the most conservative estimates say that about 20 percent could be replaced.”