2.11 Producing electrical energies: non-renewable sources

May 4, 2023

Key terms

• Non-renewable energy sources: energy sources that cannot be replaced easily, for example fossil fuels

• Main electricity: electricity that comes into our homes and places of work. The voltage is normally 230 V and the frequency is 50 Hz

Power stations

• Most power station produce electricity by heating water to create steam. This steam is used to turn turbines which rotate a generator to produce electricity

• This electricity is then sent to our homes through the national grid

• The water is often heated by non-renewable energy sources

Fossil fuels

• The efficiency of most power stations is 30% although with newer technologies we can reach 50%.

• When they burn carbon dioxide is produced

Nuclear power

• In a nuclear power station, energy given out during nuclear reactions is used to heat water to steam.

• No burning of fuel occurs so no carbon dioxide is produced

• It does produce radioactive waste which lasts for thousands of years

Producing electricity – ac generators

• Electrical generators use induction to supply electricity. The turbine that is turned by the steam created in the power station boilers rotates a generator which is a large coil of wire between magnets.

• The magnetic field induces a current in the coil

Science focus

• The current produced by an ac generator can be increased by:– Using stronger magnets– Rotating the coil faster– Increasing the number of turns of wire in the

coil– Making the coil thicker

Mains electricity

• The electricity supply in our homes is an alternating current with a frequency of 50 Hz

• This means the current changes direction 50X every second, this is faster than we can see

• Everything is turning on and off 50X a second but we never notice!

To do

• Mary is a trainee engineer working for an electricity company. Part of her job involves inveigating ways to make the electricity generators more efficient.

• Make a list of all the areas in a power station where energy may be wasted and the ways that these losses may be reduced