Ethanol
Many manufacturers are now building “Flex Fuel” vehicles. “Flex Fuel” means the engine can use pure gasoline, or E-85 (ethanol with 15% gasoline), or any mix between these two. The premise is that, since E-85 is derived from a crop – corn in North America, or sugar cane in Brazil and other tropical countries, and sugar beet in Europe – it is a renewable fuel
Politically, ethanol is “in” right now, wrapped in this “green” or “renewable” mantle. Car manufacturers, particularly General motors, have leapt onto the bandwagon claiming “Energy Independence? The answer may be growing in our own back yard.” Politicians have been photographed in corn fields or “helping” unload corn from a truck into an ethanol plant.
It is true that ethanol can be derived from plants by fermenting their starch and sugar. This should make the ethanol renewable. However, using corn as the source and growing it with highly mechanised, input-intensive North American agriculture negates the “green” credentials it might have. With the technology in use in 2007, some experts reckon that ethanol requires ~20% more fossil energy to produce than it yields; others claim it requires ~20% less. Whatever the correct figure, the “renewability” of fuel ethanol derived from corn is a convenient illusion. The energy used to cultivate, fertilise, irrigate and harvest the crop, and ship it is all fossil. The fertiliser (ammonia or urea) requires huge amounts of (fossil) methane energy to make. Finally, distilling the ethanol from the fermenting medium (separating alcohol from the watery medium where fermentation takes place) is highly energy intensive.