Variations of this quote can be seen everywhere.
Filling the 25-gallon tank of an SUV with pure ethanol requires over 450 pounds of corn -- which contains enough calories to feed one person for a year. - Full Article
It is an emotional plea that is meant to suggest that ethanol is taking food out of peoples mouths. But there is more to story than what the quote suggests.
The conversion of corn to ethanol creates co-products, in the case of dry mill ethanol plants the co-product is dry distillers grains (DDG), which like corn is used as feed.
From about 10 kg of corn feedstock, about 3.3 kg of DDG can be harvested that has 27% protein (Stanton, 1999).
So the amount of distillers grains that would be left after ethanol production from the 450 pounds of corn would be 150 pounds. At 27% protein content that would mean that the remaining distillers grains would contain 40.5 pounds of protein.
40.5 pounds of protein converts into 18,370 grams of protein. Since the average daily requirement for protein is .8 grams per kilogram of bodyweight, this is enough protein to satisfy the daily requirements of a 138 pound person for a year.
As you can see the situation isn't the either/or scenario that it is made out to be. Producing ethanol doesn't destroy the feed value of corn, instead it allows us to make fuel and a co-product with it's own feed value. In other words, it allows us to produce food and fuel.