Generation of electricity

We are virtually completely dependent on electricity for our lifestyles. Fortunately, it is easy to generate an electric current! If a magnet is moved in the vicinity of a wire, a current will be generated in that wire. This involves an energy chain again:

Kinetic energy
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Electrical energy

The kinetic energy can come from the energy released from food in the body of a person moving the magnet. However this will not produce enough electrical energy to be useful and there are a variety of more sensible ways of producing this motion. The motion is most often produced by steam moving over a turbine which then rotates magnets near wire in which current is produced. The steam is generated by burning a fossil fuel or by harnessing a nuclear reaction. It is also possible to move the turbines directly with falling water in a hydroelectric power station. There are various ways of generating electricity with different energy sources.

The following are some of the fuels or energy sources that can be used to generate electricity:

These can be divided into renewable and non-renewable sources:

Renewable
solar
wind
tidal
hydroelectric

Non-renewable
gas
coal
oil

Non-renewable sources of energy will one day run out.

Renewable sources of energy are sources which are continually replenished naturally, such as the wind or the tide or the energy from the Sun. These sources will continue to provide energy as long as the Earth exists.

Unfortunately, the generation of electricity in a thermal power station is a very inefficient process and large amounts of energy are inevitably wasted in the form of heat energy. Modern coal fired and nuclear power stations are never more than 37 to 38% efficient. This means that about 62% of the energy released by the burning of the coal or the nuclear reaction is wasted.

More efficient gas fired power stations have been developed which are about 50% efficient. Hence if electricity is generated at a power station that uses natural gas as its fuel, only 50% of the energy released by the burning of the gas is transferred to electrical energy. If a saucepan of water is then filled from an electric kettle which has just boiled, 50% of the energy of the gas has been wasted. If the saucepan of water is boiled directly over a gas flame, nearer 100% of the energy released by the burning of the gas has been used to heat the water!

Contents

Energy chains
The Law of Conservation of Energy, Fuels, Fossil fuels
Examples of renewable resources
Energy and force
Energy reference material, Self assessment questions