Alcohol and ethanol are formed by the fermentation of glucose by the enzyme in yeast, and although it contains very little nutritional value, it may represent a large part of the energy intake of individuals ingesting large amounts of alcohol.

Alcohol is one of the four energy sources of the human body along with carbohydrates, fat and protein. If you study how wine is metabolized, you learn that the liver converts the alcohol into acetate, which the body burns for fuel. The body creates 7 calories of energy per gram of alcohol.

Ethanol is made by fermenting and then distilling starch and sugar crops — maize, sorghum, potatoes, wheat, sugar-cane, even cornstalks, fruit and vegetable waste.

Ethanol does not require digestion and is directly absorbed through the gastrointestinal track. It is metabolized primarily in the liver by the enzyme alcohol dehydrogenase where ethanol is converted to acetaldehyde. The rate of metabolism of alcohol is increased by the simultaneous metabolism of carbohydrate pyruvate.

Ethanol (ethyl alcohol, grain alcohol), according to the US Department of Energy's National Renewable Energy Laboratory, is a "clear, colorless liquid with a characteristic, agreeable odour" — and taste, some would add. This is the drinkable alcohol, the active ingredient in beer, wine and spirits. Methanol (methyl alcohol, wood alcohol) is the poisonous one.

Ethanol is also a high-performance motor fuel that cuts poisonous exhaust emissions and is better for the environment. One ethanol plant owned by farmers in Minnesota processes 11,751 bushels of grain a day to produce 33,990 gallons of ethanol and 95 tons of high-protein livestock feed.

If you happen to have a spare acre in your back yard, you can raise enough maize to make enough ethanol to drive even a gas-guzzling Land Rover (17.5 miles per gallon) about 5,000 miles, along with enough animal feed to help keep you in eggs and chickens.

If the climate favours sugarcane, an acre's worth will take you nearly 15,000 miles. A few fruit trees would help a lot, too. You could put the by-product in a digester, along with other organic wastes, to produce methane gas for cooking — or as a heat source for the distillation process.