The worst misconception is that fuel ethanol will reduce dependency on
oil. Some studies show ethanol production to be slightly energy positive, other studies show it to be negative. In other words, approximately just as much energy (from petroleum) is required to produce the ethanol as is derived from it. Even if the production is energy positive, vehicle fuel consumption is much worse so there is absolutely no reduction in
oil dependency.
As Ernie has said, large amounts of water are required to grow the crops whether it be sugar cane or corn, and water in the mid west US where most of the corn is grown, is becoming a real problem. Also greatly increased demand for corn is pushing the price of the corn up. One bad crop and the price will go through the roof.
I am all in favour of alternative fuels, energy conservation, etc. but ethanol from food type crops is not the answer. Once we learn how to economically make ethanol from cellulose waste, that will be a completely different matter.
Wayne