Doesn't it actually take oil based fertilizers to make the corn/etc grow enough to produce enough ethanol, so it's a lose/lose situation? Plus all those cornfields could be producing FOOD for people! We've got lots of water, wouldn't hydrogen be a better solution? (ya, i'm a geekess)
To a degree, yes, it is a lose / lose situation...but, the net output of corn = food, fuel and meat - all of which are far more valuable, economically, than the root product (the limited amount of oil, plastic equipment and other crude derived products that were used to create the corn).
However as we've seen with the massive increase in the Earth's population (7 billion globally, per one estimate) where it was only 6 billion ten years ago....food prices are skyrocketing.
As a result, the trade off the USA makes on fuel / vs food hurts developing countries a lot more than it does us....another reason we've become embroiled in more & more wars abroad.
The last article I read said that is not efficient but that faced with potential petroleum shortages it is more of a security blanket.
As for hydrogen it is tricky to handle and requires large amounts of electrical energy to produce from H2O.