Ethanol or Ethyl Alcohol can be made chemically from Petroleum or by the more traditional method of fermenting sugar derived from vegetable matter. In this case it is often known as “Bio-Ethanol”.
The main sources of sugar required to produce ethanol are fuel or energy crops, grown specifically for energy use and include cereals, sugar beet, sugar cane and maize. Obviously there is a possible conflict between the need to grown these crops for food and for fuels, and next generation processes to derive sugar by hydrolysis from waste straw, sawdust, grass and other cellulose sources are now being piloted. There is also ongoing research into the possible use of municipal solid wastes.
Ethanol is a high octane fuel and can be used as an octane enhancer in gasoline. Many gasoline engines can use gasoline with up to 10% ethanol. For higher concentrations, specially designed engines are necessary. These are usually “flexible fuel engines”, which are equipped to detect the level of ethanol concentration and adjust their tuning accordingly.
The main environmental benefit of bio-ethanol is that the CO2 generated when it is burned comes originally from the atmosphere. The plants used to make ethanol absorb CO2 as they grow, so the cycle of making and then burning bio-ethanol does not increase atmospheric CO2.