AQA Physics Unit P1a

1. Generating and Transmitting Electricity S Thompson Mr S Thompson

2. A renewable energy source is one that will not run out . A non-renewable energy source is one that when it has been used it is gone forever .

3. Non-renewable energy sources Advantages Disadvantages Cheap fuel costs Short start-up time for gas and oil Good for “basic demand” Fuel will run out Costs a lot of money to decommission a nuclear plant Pollution – CO 2 leads to global warming and SO 2 leads to acid rain Reliable Nuclear produces little pollution Coal, Oil, Gas and Nuclear

4. Fuels A “ fuel ” is something that can be burned to release heat and light energy. The main examples are: Coal, oil and gas are called “fossil fuels”. In other words, they were made from fossils.

5. Using non-renewable fuels in power stations 1) A fossil fuel is burned in the boiler 2) Water turns to steam and the steam drives a turbine 3) The turbine turns a generator 4) The generator produces electricity 5) The steam is cooled down in a cooling tower and reused

6. Start up times Different power stations have different start up times: Gas Oil Coal Nuclear Quick Slow

7. Pollution When a fuel is burned the two main waste products are carbon dioxide and sulphur dioxide . Carbon dioxide is a greenhouse gas and helps cause global warming . This is produced when any fossil fuels are burned .

8. Pollution Sulphur dioxide , when dissolved in rainwater , causes acid rain . This is mainly a problem for coal power stations. Nuclear power stations do not produce these pollutants because they don’t burn fossil fuels.

9. Other ways of generating electricity Can we drive the turbine directly without burning any fossil fuels?

10. Renewable energy sources summary Advantages Disadvantages Zero fuel costs Hydroelectric is good for a “sudden” demand Don’t produce pollution Tidal barrages destroy the habitats of wading birds and hydroelectric schemes involve flooding farmland Unreliable (except for hydroelectric) Expensive to build Solar is good for remote locations (e.g. satellites) Wind,Wave,Tidal, Solar,Hydroelectric, Geothermal and Biomass

11. The National Grid Electricity reaches our homes from power stations through the National Grid : If electricity companies transmitted electricity at 230 Volts through overhead power lines there would be too much power loss by the time electricity reaches our homes. This is because the current is high . Power station Step up transformer Step down transformer Homes

12. The National Grid To overcome this they use devices called transformers to “ step up ” the voltage onto the power lines. They then “ step-down ” the voltage at the end of the power lines before it reaches our homes. This way the voltage is high and the current and power loss are both low. Power station Step up transformer Step down transformer Homes

13. The Cost of Electricity Electricity is measured in units called “ kilowatt hours ” ( kWh ). kWh = No. of kW (Power) X No. of hours (Time) Remember 1kW=1000W

14. The Cost of Electricity Examples: A 3kW fire left on for 1 hour uses 3kWh of energy A 1kW toaster left on for 2 hours uses 2kWh A 0.5kW hoover left on for 4 hours uses 2kWh A 200W TV left on for 5 hours uses 1kWh A 2kW kettle left on for 15 minutes uses 0.5kWh