If these reader’s numbers are right, it’s pretty devastating:

If you take the facts from the various corn producing states and do the math, you get the following:
300 gallons of ethanol per acre of corn
80 million acres of land in the US is used for corn production.
That means 24 Billion gallons of ethanol is theoretically possible, before we have to cust back on other crops or tear down cities.
The last numbers from the Feds say we use 142 Billion gallons of gasoline per year.
If we take all land that is suitable for growing crops and used it for corn (139 million acres) we still come up with only 105 billion gallons of fuel.
Throw in the fact that it currently requires more than one gallon of petroleum to produce one gallon of ethanol and it is eay to see how silly it all is.