DF 7 & DF 8 Changing the fuel

Current problems  Aromatic hydrocarbons up to 40% of petrol  Give higher CO, CxHy & NO emissions  Some may cause cancer, e.g. benzene  Volatile components evaporate, causing ozone formation & photochemical smog

Other considerations  Butane and aromatic hydrocarbons have high octane numbers – so must be replaced by other high octane components  Oxygenates offer high octane and less pollution

Which oxygenates?  MTBE  Methanol  Methanol  Ethanol

MTBE  May be carcinogenic  Banned in parts of USA

Methanol  Burns cleanly  Octane number 114  Cheap BUT - BUT -  Does not mix readily with petrol  Very hygroscopic – absorbs water vapour, leading to corrosion of engine parts  Toxic

Ethanol  Burns cleanly  Octane number 111  Readily produced by fermentation

The future?  Hydrogen?  Can be produced by electrolysis of water  This needs energy, but solar energy or wind power could be used, thus replacing fossil fuel use with use of renewable energy sources

Renewable Energy: Is enough being done?Renewable Energy: Is enough being done? The government has released its Energy White Paper. The paper announced plans to radically cut the pollution linked to global warming.The government has released its Energy White Paper. The paper announced plans to radically cut the pollution linked to global warming. The paper suggests that It also announced the running down of nuclear power stations, which currently supply about 25% of all UK electricity.The paper suggests that It also announced the running down of nuclear power stations, which currently supply about 25% of all UK electricity. 10% of electricity should come from renewable power such as wind and wave energy by % of electricity should come from renewable power such as wind and wave energy by 2010.

November 2003 The first British off-shore wind farm opens off the Welsh coast 16 more are planned

How would hydrogen be used?  Hydrogen can be stored  It can be used in the internal combustion engine  A fuel cell in the car would use hydrogen to generate electricity

 The Fuel Cell is a device which converts hydrogen and oxygen into electricity. It achieves this using a process which is the reverse of electrolysis of water  As a result of hydrogen and oxygen combining to make water, electricity flows.

Problems with hydrogen  A gas with a small relative formula mass  A large volume is needed to power a vehicle  If hydrogen is compressed, a very strong fuel tank is needed (this would be heavy).

Assignment 12 Have a go!