http://www.forbes.com/sites/jamesconca/2014/04/20/its-final-corn-ethanol-is-of-no-use/The UN has now found that if you count the energy used in growing the corn and all related transportation, it is far worse for the planet than Oil... for which they counted extraction, refining, and transport from the start. I would have honestly trusted a grade schooler to work this out. Fuel source made over thousands upon thousands of years just sitting there all compressed and for free after extraction cost and some centuries developed refining, vs a fuel source from the same principle, un-compressed/concentrated, that requires continuous cultivation and refining and just as much transport as the other stuff.
Oh, and woops, increasing food prices also starves folks, and increasing fuel prices causes not just travel/transport opportunity costs, but folks freezing to death in winter. Oopsies.
I wish I could think it was rationality breaking in, but I really thing its just a prelude to the next great wonder of energy alternative with massive gov. intervention for the choosing of winners and losers.
Edit: Useful synopsis for side effects and fallouts that basically follow 20 seconds of thought. (From the same article, citing a gov report)
"In 2000, over 90% of the U.S. corn crop went to feed people and livestock, many in undeveloped countries, with less than 5% used to produce ethanol. In 2013, however, 40% went to produce ethanol, 45% was used to feed livestock, and only 15% was used for food and beverage (AgMRC)."