1. 2.11 Producing electrical energies: non-renewable sources 15 February, 2016

4. 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

6. 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

7. 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

8. 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

10. 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

13. 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

14. 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!

17. 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