Ethanol is colorless, flammable pure alcohol made by fermenting and distilling starch crops such as corn, sugar cane and others. The fuel is often mixed with gasoline in varying proportions and is heralded as a cheaper fuel that helps reduce our dependence on foreign oil. However, the energy return on energy invested (EROI) withethanol fuel production is very low and American use of corn for ethanol production has increased prices of meat and other foods closely tied with the commodity.
(CC Image of oil well in corn field juxtaposing the current corn ethanol biofuel production with traditional petroleum based fossil fuel production. Image by Dwight Burdette (Own work) [CC-BY-3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons)
Closely related to biodiesel in the sense that crops (such as soybeans and corn) can compete for biofuels, feedstock, and commodity market space. That is, the demand for these crops is increasing while available land mass is not. This predicament is evident in the perverse subsidies given by the government to the various food systems we have in order to maintain a living wage for farmers, and the illusion of cheap goods to consumers who are interwoven in this process.
(CC Image courtesy of Thomas via Flickr)