Popular Mechanics – The idea is so appealing: We can reduce our dependence on oil-stop sending U.S. dollars to corrupt petro-dictators, stop spewing megatons of carbon into the atmosphere—by replacing it with clean, home-grown, all-American corn. It sounds too good to be true.

Sadly, it is.

Of course we need alternatives to oil. The world uses a cubic mile of petroleum each year, and demand keeps rising as the global economy booms. At first glance, corn seems like a heaven-sent substitute. American corn farmers are the most productive in the world, growing far more of the grain than we can possibly eat, and exporting mountains of the stuff to other countries. And the corn kernel is a marvel of energy storage. Converting that compact bundle of starches into alcohol is a relatively simple trick known to generations of moonshiners. So why not build corn liquor stills on an industrial scale and use the output to power our cars and trucks?

That’s exactly what this country has been doing for the past several years. Some 134 ethanol plants are now in operation, consuming close to 1.6 billion bushels of grain, about 15 percent of our total corn production. To feed the ethanol machine, farmers planted almost 93 million acres of corn in 2007, a 19 percent increase over the previous year, and the highest figure since 1944 (when yields per acre were far lower).

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