Reply #7: Ethanol and land use

[Ezlivin]

Already, 14.3 percent of corn grown in the United States is converted to ethanol, replacing just 1.72 percent of gasoline usage. Even if all the remaining corn were converted to ethanol, the total ethanol would only offset 12 percent of gasoline. The entire soybean crop would replace a much smaller proportion of transportation fuels--only 6 percent of current diesel usage, which itself amounts to a tiny fraction of gasoline usage. (Source)

David Pimental, a leading Cornell University agricultural expert, has calculated that powering the average U.S. automobile for one year on ethanol (blended with gasoline) derived from corn would require 11 acres of farmland, the same space needed to grow a year's supply of food for seven people. Adding up the energy costs of corn production and its conversion into ethanol, 131,000 BTUs are needed to make one gallon of ethanol. One gallon of ethanol has an energy value of only 77,000 BTUS. Thus, 70 percent more energy is required to produce ethanol than the energy that actually is in it. Every time you make one gallon of ethanol, there is a net energy loss of 54,000 BTUs. (Source)

What do the numbers show?

Last year the U.S. produced just under 4 billion gallons of ethanol, serving just 1 percent of U.S. fuel needs. Academics say production can’t go much higher.

“If we used all the corn produced in the United States to produce ethanol, it would provide only 7 percent of our total vehicle fuel use,” said Cornell agriculture professor David Pimental.

Here’s another sober way of looking at it: if every car in America was fully powered by ethanol, it would take 97 percent of U.S. soil to grow enough corn to support it.

And that's not all. It turns out that it takes more energy to make ethanol than it could ever generate.

“About 30 percent more fossil energy is required to produce a gallon of ethanol than you actually get out in ethanol,” said Pimental.

“All in all, it’s in fact a very inefficient system of converting one kind of fossil energy into another kind of fossil energy,” said Patzek.(Source)