So how does an electricity generator work?
An electricity generator is a simple device that moves a huge magnet near a wire to create a steady flow of electrons, otherwise known as an electric current.
In large power generators, the coils remain stationary, and the magnetic field rotates. This produces the same effect. The magnet rotates with the turbine, to which it is attached.
Fossil fuels provide energy that can be changed into electricity.
The diagram above shows an electricity generating plant.
Electricity can be generated from the heat produced when fossil fuels are burnt.
In the boiler or steam generating plant, heat from the burning fossil fuel turns water into steam. The steam, moving under high pressure, makes the turbine blades and shaft spin. The turbine is connected to the alternator, which produces electricity. Learn more about how to make electricity.
The steam used to drive the turbine is cooled into water in a condenser and reused.
The condenser uses water to cool the steam. As the steam cools, the water used by the condenser becomes hot. It must also be cooled down before it is used again.
To do this the water is pumped to the top of a cooling tower and broken into tiny droplets, which then fall through the tower to a reservoir.
As the droplets fall, some cool and some evaporate. Up to two per cent of the cooling water is lost through evaporation and must be replaced from outside the system. Often electricity powerplants are built close to rivers or lakes where there is a great supply of water that can replace these losses.
The electricity generated is then sent to the electricity grid for transmission to where it is needed.
The turbine in an electricity generator needs energy to work. This energy may come from moving water, wind, steam created by heat from the sun (solar energy) or by burning coal, oil or gas.
Some of these forms of energy will never run out. They are known as renewable energy sources. Other forms of energy are in limited supply, they are known as non-renewable energy sources.