The limits of Ethanol
According to research published in the Proceedings of the National Academy of the Sciences, if all of last year's corn crop had been used to make ethanol, it would only have provided 12 percent of U.S. gasoline demand.
Ethanol contains about one third less energy than gasoline, limiting its benefit.
Some experts doubt the wisdom of giving ethanol the prominent role itwas given in the 2005 energy bill.
A naging doubt that has yet to be put to rest is whether ethanol delivers more energy than tha which is used to make it. Researchers in Minnesota recently concluded that corn based ehtanol provides 25% more energy than is required to produce it; but most of that gain came from a byproduct that is used for animal feed.
Contrast this with the 100 to 1 return on energy invested in the early days of the oil boom and you get some idea of the "limits of growth" we face in the future.