A complaint I've heard is that America is wasting food to make fuel. That complaint isn't supported by the facts surrounding corn or ethanol production in America. The first point to understand is that the type of corn being discussed is not the sweet corn you'd buy in the grocery store. The overwhelming majority of corn grown in America is #2 yellow field corn, which is processed into food ingredients, industrial supplies, or animal food.
America produces vastly more of this kind of corn than the American economy has any use for, so we export a lot of it. When some (a small percentage of the total) is used to make ethanol, it isn't wasted as a food source. You get ethanol out of one end of the factory and cheap cattle feed out of the other. So the corn used to make ethanol never leaves the domestic food cycle. The rest of the corn that wasn't used in ethanol production (the vast majority of it) is still available for other uses such as exporting so that other nations can use it in their food cycle.
The total energy available from a gallon of corn ethanol versus the total energy spent to produce it is getting better. Lately I think that ratio has been something like 1.3 to 1. Which isn't great when compared to straight gasoline or even ethanol from sugar cane. But corn is readily available here, so that is what is being used. I imagine that the efficiency of production will continue to improve, but probably never to the point that corn ethanol can take care of all of our domestic gasoline needs.
What corn based ethanol can do is to buy America a little bit of time of slightly lower gasoline prices while we figure out how to sustain our energy needs in a better way. That's it folks. Current ethanol production isn't a cure-all for our energy problems. It is a stop-gap measure.
Cellulosic ethanol holds a lot of promise, but at this point we do not have a way to mass produce it efficiently. Hopefully that research will benefit from ongoing corn ethanol improvements and cellulosic ethanol will be ready in time to pick up the burden of our fuel needs when oil really gets terribly expensive. In the meantime, we can use corn ethanol to ease the transition and maybe prevent gasoline prices from suddenly jumping 100 or more percent.
You know what we REALLY need? Better batteries. We don't have a energy problem. We have an energy storage problem. Really that is all gasoline or ethanol is -- a medium for storing and transporting energy that can be utilized by an automobile. Energy is everywhere. Wind, light, tides, crops, hydrothermal, etc. We just don't have a means of storing much of that energy, which is why gasoline is so useful. But if we just had a way to store about 30 gallons of gasoline worth of energy in about the same mass and space as 30 gallons of gasoline... oh well... maybe someday.