Quote from piezoe:
The economics of ethanol from corn to use as a motor fuel are unfavorable as is the energy balance. This is a well established fact. Ethanol from sugar cane, however, can make economic sense and has been very successful in Brazil. I haven't seen any studies for ethanol from beets, but i'm sure they are out there. Cuba produces prodigious crops of sugar cane and the US is a producer of both sugar cane and sugar beets. Why is the US making ethanol from corn and burning it in cars? This makes no sense whatsoever.
The US sugar industrie is one of the most protected/subsidized ag industries in the world. US sugar prices are protected at levels well above world market. The US sugar industry is lorded over by the very rich, powerful and politically influential Fanjul Family. Even the US government is hesitant to mess with this family.