|Figure 2. Materials made from fossil fuels are all around us.|| |
|Why are oil and gas so useful?|
- Oil is a liquid - though sometimes a very thick one. This means that oil may be transported and delivered through pipes. Crude oil contains many substances which are useful to us. These substances are separated by fractional distillation.
Compare oil with coal. Coal is a solid, which comes in lumps. To remove coal from the ground, miners have to work underground in dangerous conditions. Crude oil and natural gas, on the other hand, can be removed from beneath the surface, piped to storage tanks and processed into things we use.
- Hydrocarbons with small molecules make good fuels. Methane (CH4) has the smallest molecules, and is a gas, used for cooking and heating and generating electricity. Gasoline, diesel, aviation fuel (for aeroplanes) and fuel oil (for ships) are all liquid fuels. In 1996 oil and gas provided the UK with about 70% of our primary energy needs.
- Hydrocarbon molecules can be spllit up into smaller ones, built up into bigger ones, altered in shape or modified by adding other atoms. This is why they are a very useful starting point (called a chemical feedstock) for making other materials. Figure 2 shows a variety of things made from petrochemicals.
- Even the thick black tarry residue left after distillation is useful. It is called bitumen, and is used in tarmac for road surfacing, and for roofing.