Ethanol

Ethanol is a type of alcohol produced through the fermentation of grain, corn or sugarcane. It is blended with petrol and used as a motor fuel in many countries.

In Australia, ethanol content is limited to 10 percent (E10) by law, although higher concentrations are used in some countries, with blends containing 85 percent ethanol (E85) being commonly available.

Most vehicles sold in Australia after 1986 can use E10. It is not recommended for use in pre-1986 vehicles or those fitted with a carburettor, due to potential material incompatibility and hot fuel handling problems. About 70 percent of Australia's current vehicle fleet will accept E10.

The following link will be useful in determining a vehicles suitability for E10.

The use of ethanol concentrations above about 10 percent necessitates the use of ethanol compatible materials in fuel systems and changes to engine management system calibration. Some manufacturers produce vehicles that will operate on higher and varying concentrations of ethanol. However, at present they are not common in Australia.

As ethanol has a slightly lower energy content than petrol, its use will increase fuel consumption. Compared to unleaded petrol, an E10 blend will increase fuel usage by approximately three percent while E85 consumption will increase by about 35%.

Ethanol has a scouring effect on fuel systems and its use in poorly maintained vehicles may result in filter blockages. Once clean, the system should remain clean with continued use of ethanol-blended fuel.

Ethanol will absorb small amounts of water, however water content above about 0.5 percent, will cause the ethanol, and the water mixed with it, to drop out of suspension and fall to the bottom of the tank. Generally engines do not run well, if at all, on ethanol/water mixtures. For this reason petrol containing ethanol is not recommended for marine applications.

Ethanol is a clean burning fuel that produces less greenhouse gases than unleaded petrol. However, when the growing of crops and the production and use of ethanol is compared with the production and use of petrol, the environmental gains may be small, depending on the crops used and the production methods. There are also concerns around the world that using land to grow crops for ethanol production is damaging the environment and worsening the international food shortage.