Credit: Steve Hebert/Polaris

The irrational exuberance over ethanol that swept through the American corn belt over the last few years has given way to a dreary hangover, especially among those who invested heavily in the sprawling production facilities now dotting the rural landscape. It's the Midwest's version of the tech bubble, and in some ways, it is remarkably familiar: overeager investors enamored of a technology's seemingly unlimited potential ignore what, at least in retrospect, are obvious economic realities.

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