Robert Rapier has all your (grain) ethanol-bashing needs covered with this latest salvo:

My opposition to ethanol is primarily due to the inefficiency of the process. My opening commentary here is primarily aimed at grain ethanol. … To make ethanol, we use petroleum-fueled tractors to plow the fields. We apply petroleum-based herbicides to kill the weeds. We apply petroleum-based pesticides to kill the bugs. We apply petroleum-based fertilizers to feed the plants. We harvest the corn with petroleum-fueled tractors, and ship the corn to the ethanol plants in petroleum-fueled trucks. The ethanol plants are natural gas hogs, consuming enormous quantities to ferment and purify an ethanol solution that is primarily water. We then ship the ethanol, often halfway across the country, in petroleum-fueled trucks. The customer on the receiving end usually pays less than market price for the ethanol, due to the subsidies, which are paid by taxpayers. Then, they suffer a decrease in gas mileage, meaning they have to fuel up more often.

Some of the proponents think adoption of ethanol is a way to "stick it to Big Oil". What they overlook is that Big Oil benefits greatly at all steps of the ethanol process. They make the fossil fuels that drive the tractors. They supply the petrochemicals that make the fertilizers, pesticides, and herbicides. And who do you think is the largest natural gas producer in the U.S.? I will give you a hint: One of the members of "Big Oil".

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… So, in light of all this, I have to ask if it actually makes sense to support such a process. Wouldn’t we be far better off just using the natural gas to directly fuel our vehicles? Every step in the process of making ethanol has efficiency losses. The more steps in the process, the higher the efficiency losses. Every BTU of heat that ends up radiating into the environment during the process is a BTU that did no useful work. By directly using the natural gas to fuel the vehicles, the cost would be far lower to the consumer and the taxpayer, and the efficiency much greater. Billions of dollars of subsidies would be eliminated in the process. Why, oh why do we continue down this insane path?

Why indeed? Read the whole thing.