That 40-45% is used for both ethanol and animal feed production and you could produce a similar amount of animal feed in about 1/3 of the land if you didn't extract ethanol first. So if you consider animal feed a productive and non-wasteful use of the land, we're only "wasting" 2/3 of 40-45% on ethanol production.
Ah, ok, I get what you're saying now. Thanks for the clarification and insight into this data. USDA site is confusing when it says "nearly 45 percent of total corn use".
Still, one wonders if we'd bother with so much of our fields going to grow corn if the main use was just DDGS. I wonder how the economics of everything else in the corn industry would change if we stopped requiring E10.
Corn would be grown for animal feed even if we weren't using it for ethanol. As an optimized C4 plant it's one of the most efficient plants in terms of converting sunlight to biomass; far more efficient than traditional animal foods like barley or oats. Sugarcane and algae are even more efficient but require growing conditions not available in the mid-west.
