Power Alcohol:

When ethyl alcohol is used as a fuel in internal combustion engine, it is called as power alcohol.

Generally ethyl alcohol is used as it 5-25% mixture with petrol.

Use of ethyl alcohol in petrol reduces our dependence for petrol on foreign countries & even 5% ethyl alcohol blending in petrol saves our foreign reserves by about Rs. 5000 crores/ annum.

Further it gives boost to indigenous manufacturers of ethyl alcohol & farmers get better price of their grain produce.

Ethyl alcohol is mainly manufactured by fermentation of molasses, starch, carbohydrates on a large scale & cheaply. It can also be obtained from synthesis gas (CO, $H_2$)

The ethyl alcohol obtained contains 95.5% alcohol & 4.5% water.

This water is separated either by use of suitable dehydrating agent or by distilling it along with benzene.

ADVANTAGES OF POWER ALCOHOL:

1. Ethyl alcohol has good Ant knocking property and its octane number is 90.
2. It has property of absorbing any traces of water if present in petrol.
3. If a specially designed engine with higher compression ratio is used then the disadvantage and lower CV can be overcome.
4. It contains O atoms which help for complete combustion of power alcohol & the polluting emission of CO, hydrocarbon, particulates are reduced largely.
5. Use of ethyl alcohol in petrol reduces our dependence on foreign countries for petrol and saves foreign currency considerably.
6. Power alcohol is cheaper than petrol.