AQA GCSE Physics Unit 1 Chapter 4 Generating Electricity
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- Created by: Annie
- Created on: 22-10-10 10:47
Fuels for Electricity
In most power stations, water is heated to produce steam. The steam drives a turbine, which is coupled to an electrical generator that produces electricity.
The heat can come from burning a fuel such as coal, oil or gas, these are fossil fuels; or hot gases may drive the turbine directly.
In a nuclear power station, the fuel that is used is called uranium (or sometimes plutonium). The nucleus of an unranium atom can under go a process called fission that releases energy. There are loads of uranium nuclei, so loads of fission reactions take place, producing loads of heat energy.
More energy is released from each kilogram of uranium under going fission reactions than from each kilogram of fossil fuels we burn.
Energy from Wind and Water
We can use energy from wind and water to drive turbines directly.
- In a wind turbine the wind passing over the blades makes them rotate and drive the generator at the top of a narrow tower.
Electricity can be produced from energy obtained from failing water, waves or tides.
- At a hydroelectric power station, water which has been collected in a reservoir is allowed to flow downhill and turns turbines at the bottom of the hill.
- In a pumped storage system, surplus electricity is used at times of low demand to pump the water back up the hill to a reservoir.
- This mean that energy is stored and then at time of high demand the water can be released to fall through the turbines and convert the stored energy to electrical energy.
Energy from Wind and Water Continued
- We can use movement of waves on the sea to geneate electricty with drivces that float on water and the movement drives the turbines and turns a geneator. Then the electricity is connected to the National Grid by cables on shore.
- The level of sea around the coast line rises and falls twice a day. These changes in sea level are called tides. If a barrage built across a river esturay, the water at each high tide can be trapped behind it. When the water is released to fall down to lower sea level it drives the turbine.
Power from the Sun and Earth
Energy from the Sun travels through space to Earth as electromagnetic radiation. A solar cell can convert this energy into electrical energy. Each cell only produces a small amount of electricity, so they are useful to power small devices such as watches and calcutalors. We can also join together large numbers of cells to form a solar panel. Water flowing through a olar heating panel is heated directly by energy from the sun.
Heat energy is produced inside the Earth by radioactive processes and this heats the surronding rock. In the few parts of the world, hot water comes up to the surface naturally and can be used to heat buildings near by.
In other places, very deep holes are drilled and cold water is pumped dowm to the hot rocks where it is heated and comes back to the surface as steam, this steam is used to drive turbines that turn generators and also produce electricity. This is called Geothermal energy.
Energy and the Enviorment
Coals advantages:
- Bigger reserves than other fossil fuels.
- Reliable.
Coals disadvantages:
- Non-renewable.
- Produces carbon dioxide, a green house gas.
- Produces sulfur dioxide, causing acid rain.
Oils advantages:
- Reliable.
Oils disadvantages:
- Non-renewable.
- Produces carbon dioxide, a green house gas.
- Produces sulfur dioxide, causing acid rain.
Energy and the Enviorment.
Advantages of Gas:
- Reliable.
- Gas power stations can be started up quickly to deal with high demand.
Disadvantages of Gas:
- Non-renewable.
- Produces carbon dioxide, a green house gas.
Advantages of Nuclear:
- No production of polluting gases.
- Reliable.
Disadvantages of Nulcear:
- Non renewable
- Produces nuclear waste, which is difficult to dipose of safely.
- Risk of a big accident, such as Chernobyl.
Energy and the Enviroment
Advantages of Wind:
- Renwable.
- Free.
- No production of polluting gases.
Disadvantages of Wind:
- Requires large turbines.
- Not pretty and noisy.
- Not reliable, the wind doesn't always blow.
Advantages of Falling Water:
- Renewable.
- Free.
- No production of polluting gases.
- Reliable in wet areas.
- Pumped storage system allows storage of energy.
- Can be started up quickly to deal with sudden demand.
Energy and the Enviroment
Disadvantages of Falling Water:
- Only works in wet and hilly areas.
- Flooding of areas will affect the ecology of the area.
Advantages of Waves:
- Free.
- Re-newable.
- No production of polluting gases.
Disadvantages of Waves:
- Can be hazards to boats.
- Not reliable.
Energy and the Enviroment
Advantages of Tides:
- Free.
- Re-newable.
- No production of polluting gases.
- Reliable, always tides twice a day.
Disadvantages of Tides:
- Only a few river estuaries are sutiable.
- Building a barriage affects the local ecology.
Advantages of Solar:
- Free.
- Re-newable.
- No production of polluting gases.
- Reliable in hot countries, in the daytime.
Energy and the Enviroment
Disadvantages of Solar:
- Only sitiable for small amounts of energy, or requires large cell numbers.
- Unreliable in less sunny countries.
Advantages of Geothermal:
- Renewable.
- Free.
- No production of polluting gases.
Disadvantages of Geothermal:
- Only economically viable in very few places.
- Drilling through the large depth of a rock is difficult and expensive.
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