studies have shown that ethanol has a higher energy content than the fossil energy used in its productionWhat that means, apparently, is that the amount of energy in hydrocarbon fuel needed to plough, plant, fertilize, harvest, etc, is less than the yield.
http://www.freerepublic.com/focus/news/1473964/posts?page=169#169
http://www.freerepublic.com/focus/news/1514702/posts?page=249#249