In this century, it is believed that crude oil and petroleum products will become very scarce and costly. Day-to-day, fuel economy of engines is getting improved and will continue to improve. However, enormous increase in number of vehicles has started dictating the demand for fuel. With increased use and depletion of fossil fuels, alternative fuel technology will become more common in the coming decades. Because of the high cost of petroleum products, emission problems some developing countries are trying to use alternate fuels for their vehicles.

Liquid Fuels

Liquid fuels are preferred for IC engines because they are easy to store and have reasonably good calorific value. The main alternative is the alcohol.

Alcohol

Alcohols are attractive alternate fuels because they can be obtained from both natural and manufactured sources. Methanol and ethanol are two kinds of alcohols that seem most promising.

Advantages

1. It is a high octane fuel with anti-knock index numbers of over 100.Engines using high octane fuel can run more efficiently by using higher compression ratios. Alcohols have higher flame speed.
2. It produces less overall emissions compared to gasoline.
3. When alcohols are burned, it forms more moles of exhaust gases, which gives higher pressure and more power in the expansion stroke.
4. It has high latent heat of vaporization which results in a cooler intake process. This raises the volumetric efficiency of the engine and reduces the required work input in the compression stroke.
5. Alcohols have low sulphur content in the fuel.6.Reduced petroleum imports and transportation.