Fossil fuels are non-renewable energy resources.
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Coal, oil and gas are known as fossil fuels. -They are the remains of plants and animals which lived millions of years ago. These supplies are limited. Oil is a fossil fuel which is used widely for petrol in cars to making plastic. But this non-renewable energy source is soon to run out in 40 years time.
Most of our power stations use coal as their source of energy. When coal is burnt, its stored chemical energy is released as heat energy. This heat energy boils water at high pressure to make superheated steam at temperatures of about 700°C. The kinetic energy in the superheated steam is used to drive turbines. These are connected to the electricity generator by large coils rotating inside a strong magnetic field.
Unlike ordinary cells, solar cells do not use chemical energy. Instead they change light energy into electricity. Solar cells are known as photovoltaic (high-voltage) cells. Small solar cells power some pocket calculators. In some places, such as Antarctica, where there is no mains electricity supply, big panel containing many solar cells are sometimes used instead. Most solar cells are devices called silicon diodes.
Coal is cheap and easy to buy from shops and is also good effective source. However coal is very limited as it is a fossil fuel and will run out in 300 years at the rate we are using it at the moment.
Uranium is a non-renewable energy source but will last another few thousand years. But uranium and nuclear power worries people because of its radio active waste produced.
Wind is a cheap energy source which is renewable as there is a constant source of wind. However wind turbines have to be built where there is enough wind and also they are sometimes an eye-saw which do not produce much energy in some places.
Waves are another renewable energy source, but not many locations can provide enough energy. Also they are not reliable as there are not always large waves. Although wave energy would be a cheap energy resource.
Geothermal energy is also a renewable energy source which is found inside the Earth. The Earth is hot due to radioactivity, hot water comes to the surface naturally in some parts of the world such as in New Zealand, but in other countries cold water is pumped down very deep holes and steam comes back to the surface. This energy process emits no greenhouse gases and is clean and efficient.
The world’s non-renewable energy resources such as fossil fuels are soon to run out in generations to come. We must find a way how to make more effective use of them. In power plants with coal there is only 25% efficient which means that 75% of the energy produced is wasted. The wasted energy could be used to heat nearby homes.
