You can't eat your cake and burn it too.
What seemed like an excellent alternative energy strategy just a couple years ago has become the latest victim to the great commodities squeeze of high prices and tight supplies.
As farmers divert crops to the production of ethanol and biodiesel, food prices rise.
Take corn, for example. In 2006, one-fifth of U.S. corn production was used for ethanol. That compares with 12 percent two years earlier. Meanwhile, prices have surged. Corn hit a record high of $6.47 a bushel on futures markets this year, having traded at about $2.20 two years ago.