Generating Electricity

FUEL FOR ELECTRICITY

In most power stations, water is heated to produce steam.  The steam drives a turbine which is coupled to an electric generator that produces the electricity.

The energy to turn the water into steam can come from burning a fossil fuel such as coal, oil or gas.  Fossil fuels are obtained from long-dead biological material.  In some gas-fired power stations, hot gases may drive the turbine directly.  This means that a gas-fired turbine can be switched on very quickly.

A biofuel is a fuel obtained from living or recently living organisms.  Some biofuels are used in small-scale, gas-fired power stations.  Biofuels are renewable sources of energy.

In a nuclear power station, the fuel used is often uranium, or sometimes plutonium.  The nucleus of a uranium atom can undergo a process called nuclear fission, which releases a lot of energy.  There are lots of uranium nuclei, so lots of fission take place, releasing lots of energy.  The energy is used to heat water, turning it into steam.  Much more energy is released per kilogram of uranium than each kilogram of fossil fuel.  Also, nuclear power stations do not release greenhouse gases, unlike fossil fuel power stations.  However, nuclear power stations produce radioactive waste that must be safely stored away for a long period of time.

ENERGY FROM WIND AND WATER

Energy from wind and water is renewable energy.  These sources of energy can never be used up, unlike our sources of fossil or nuclear fuels.

We can use energy from the wind to drive turbines directly.  In a wind turbine, wind passing over the blades makes them rotate and drive a generator at the top of the tower.

Electricity can be produced from falling water, waves or tides.  

• In a hydroelectric power station, water is collected in a reservoir.  The water is allowed to flow downhill and turn turbines at the bottom of the hill.  This is called hydroelectric power, or HEP.  A pumped storage system uses surplus electricity (often during times of low demand) to pump the water back up the hill to the reservoir.  At times of high demand the water can be released to fall through the turbines and transfer the stored energy to electrical energy.  
• We can use the movement of the waves on the sea to generate electricity.  The movement drives a floating…