Disadvantages of Ethanol-

1. Engines run on ethanol may give starting problems when the air is cool.

2. Ethanol is highly hydrophilic. As a result, it can absorb moisture from atmosphere, etc.

3. It reacts with metals used in the alloys of carburettors etc. It can be remedied by using nickel in the engine alloys.

4. The downstream processing for ethanol recovery is costly as it requires lots of energy.

5. Ethanol run engines use about 10% more fuel than petrol, which means a proportionately larger tank.