P1aL14 Power Stations

Key Words

Fossil Fuels - Fuels that captured their energy from the Sun millions of years ago.

Generator - machine that turns kinetic energy into electrical energy.

National Grid - a network of high voltage cables that connect the countries power stations with electricity consumers

Non-renewable - resources that will run out and cannot be replaced.

Power station - huge industrial plant where electricity is generated in vast quantities.

Nuclear power station - power station where the boiler gains its heat from splitting of atoms instead of a fossil fuel

Step-up transformer - electro-magnetic machine that turns a low voltage into a high voltage

Turbine - a steam engine that works by steam driving several discs of vanes (instead of a piston moving forwards and backwards).  It drives a generator.

Voltage - electrical "pressure", or how much energy the electrons carry.

Wasted energy - energy that is lost and heats up the surroundings.

Grade E

Electricity is made in huge quantities in power stations.  They burn fossil fuels.  The stages are:

• Fuel is burned to boil water in a boiler;
• The boiler turns water into steam;
• The steam drives a turbine;
• Steam condenses back into water in the condenser and is returned to the boiler;
• The turbine turns the generator;
• The generator generates electricity;
• The step-up transformer raises the voltage to the high voltages for the National Grid.

Grade C

At every stage in the power station energy is lost as waste heat.  For example, the generator gets hot when it transfers kinetic energy into electrical energy.  The waste heat ends up warming up the environment.

A normal coal fired power station is about 35 % efficient.  The more modern combined cycle power station is about 50 % efficient.  In this type of station, gas is fed to a gas turbine that drives a generator.  The hot gases are then taken to a boiler, where they boil water to drive a steam turbine.

Barford Power Station is an example of a combined cycle power station.

In some power stations waste heat is used to heat greenhouses and local homes.  The efficiency is up to 70 %.

In nuclear power stations, the turbines and generators are exactly the same as in a normal power station.  The water is heated by a nuclear boiler called a reactor.  They are about 30 % efficient, like a coal fired station.  About 11 % of the UK's energy requirements come from nuclear power.  In France, it's 80 %.

Nuclear power stations give off NO greenhouse gases.  However their waste is some of the nastiest muck known to man.

Grade A

Fossil fuel power stations generate huge amounts of greenhouse gases like carbon dioxide.  They also produce sulphur dioxide, which is responsible for acid rain.

While most coal can be mined, there are some reserves that cannot be got at by mining.  Some engineers have suggested setting fire to these seams and using the gases to heat water.  However such fires could be impossible to put out, and could end up pushing so much CO₂ out into the atmosphere that we would get a run-away greenhouse effect.

In Germany, they are trying out carbon capture techniques so that waste CO₂ is stored underground.