The Different Kinds of Power Stations and How They Work

There are different types of power station: hydro-electric, coal fired, oil fired, nuclear and more, but they all work in a similar way to produce electricity.

A power station is designed to transform kinetic energy into electrical energy by using turbines to drive generators. Where they differ is how they obtain the kinetic energy that drives the turbine.

Nuclear power station.

[photo: Avda]

Hydro-Electric Power Stations

Water is stored in a reservoir, usually situated in a valley in hilly or mountainous regions. Large pipes run downhill from this reservoir to a lower reservoir. Just before the water reaches the lower reservoir, the water has its maximum amount of kinetic energy. Here, the water passes through turbines where its kinetic energy turns the blades at high speed. The blades are connected to drive shafts which also rotate at high speed. The spinning shafts are used to turn the generators and produce electrical energy.

Thermal Power Stations

As the name suggests, these rely on heat to generate the electricity.

1. Fossil Fuel Power Stations

These are either coal fired, oil fired or gas fired. The fossil fuel is burned and the heat released is used to boil water. Since steam has about 800 times the volume that it had as water, it is at high pressure. The high pressure forces it out of the boiler at high speed, through pipes and into the turbines. The kinetic energy of the moving steam turns the turbine, which turns the generator to produce the electricity.

2. Biomass Power Station

The fuel for this type of power station is the methane gas from rotting material, for example animal dung or waste vegetation. The rest of the system works as if it was a fossil-fuel power station.

3. Nuclear Power Stations

Schematic animation of a nuclear power station.

[image: US NRC]

In nuclear power stations, heat is also used to generate steam, which drives the turbines and the generators. The heat comes from a controlled nuclear fission reaction that takes place in the fuel rods (usually uranium-235) in the core. The rate of the reaction is controlled by the use of a substance called a moderator plus control rods. A coolant passes through the reactor and collects the heat. The hot coolant is then passed through a heat exchanger. Here the heat from the coolant is transferred to water, which boils to form the high pressure steam.

The Final Step: The National Grid

National GridWhen the electricity is generated, it has to be sent around the country to reach homes, hospitals, factories, etc. This is done via the National Grid, which is a network that uses high voltages to efficiently transfer the electricity around the UK.

Each power station is linked to the grid and feeds electricity into it all the time. To get the electricity from the generator to the grid, a step-up transformer is used to increase the voltage to the high levels needed. At the other end, step-down transformers reduce the voltage to appropriate levels for consumers.

Taught science for 16 years at a secondary school in the East Midlands.