AQA GCSE 1a-4Generating Electricity AQA GCSE Physics pages 62 to 73 AQA GCSE Science pages 266 to 277 April 10th 2010
AQA GCSE Specification ENERGY RESOURCES & THE GENERATION OF ELECTRICITY 11.4 How should we generate the electricity we need? Using skills, knowledge and understanding of how science works: • to compare and contrast the particular advantages and disadvantages of using different energy sources to generate electricity. Skills, knowledge and understanding of how science works set in the context of: • In most power stations an energy source is used to heat water. The steam produced drives a turbine which is coupled to an electrical generator. • Common energy sources include coal, oil and gas, which are burned to produce heat and uranium/plutonium, in which nuclear fission produces heat. • Energy from renewable energy sources can be used to drive turbines directly. • Renewable energy sources used in this way include wind, the rise and fall of water due to waves and tides, and the falling of water in hydroelectric schemes. • Electricity can be produced directly from the Sun’s radiation using solar cells. • In some volcanic areas hot water and steam rise to the surface. The steam can be tapped and used to drive turbines. This is known as geothermal energy. • Using different energy resources has different effects on the environment. These effects include the release of substances into the atmosphere, noise and visual pollution, and the destruction of wildlife habitats. • The advantages and disadvantages of using fossil fuels, nuclear fuels and renewable energy sources to generate electricity. These include the cost of building power stations, the start-up time of power stations, the reliability of the energy source, the relative cost of energy generated and the location in which the energy is needed.
Thermal power stations A thermal power station generates electricity by using the heat produced by the burning a fossil fuel such as coal, gas, oil or by the fission of uranium. Over 90% of our electricity is produced by these type of power stations.
BOILER TURBINES GENERATOR Thermal power station block diagram BOILER Fuel is burnt to turn water into high pressure steam. TURBINE High pressure steam turns a turbine (like a windmill) GENERATOR The turbine rotates the coils of a generator to produce electricity.
Comparison of uranium and fossil fuels Energy released per kg of fuel 1 000 000 kWh 100 kWh radioactive waste that needs to be stored for many years non-radioactive waste Waste Greenhouse gases Yes, mostly carbon dioxide None
Choose appropriate words to fill in the gaps below: Most of our electricity is produced by __________ power stations. These use the _______ produced by burning _____ or the fission of __________ to generate electricity. The heat produced is used to change ________ into high pressure steam. This steam is used to turn a _________ which in turn _________ an electrical generator. Over _______ of our electricity is generated by using thermal power stations. thermal fuels heat uranium water turbine rotates 90% WORD SELECTION: rotates fuels heat 90% uranium turbine water thermal
Power Station Animation - eChalk Generator- Fendt Nuclear Fission - Powerpoint presentation by Richard Miller of 5SJW (2005) Nuclear Fission - Powerpoint presentation that includes a link to the 'mousetrap' demonstration Nuclear Physics - PhET - Start a chain reaction, or introduce non-radioactive isotopes to prevent one. Watch alpha particles escape from a Polonium nucleus, causing radioactive alpha decay. Control energy production in a nuclear reactor! Chain reaction demonstration using mousetraps - University of Michigan BBC Bitesize Revision: Introduction Page on AQA Generating Electricity Test Bite on Generating Electricity BBC Bitesize Revision: Fossil Fuels Nuclear Fuels Comparing Sources - includes short and long term costs Test Bite on Generating Electricity Simulations
Fuel for electricityNotes questions from pages 62/266 & 63/267 • Copy figure 1 on page 62/266. • Explain the differences between coal and gas fired power stations. • Copy and answer questions (a) and (b) on page 62/266. • Copy figure 4 on page 63/267. • What is ‘nuclear fission’? • Explain how a nuclear power station produces electricity. • Copy the table on page 63/267. • Copy the Key Points on page 63/267. • Answer the summary questions on page 63/267.
In text questions: It goes into the cooling tower, where it condenses into water. It is carried away by the hot water from the cooling tower escaping into the air. Summary questions: 1. (a) uranium (b) gas (c) oil, uranium 2. (a) (i) Advantage of oil-fired station: no radioactive waste; disadvantage: produces greenhouse gases. (ii) Advantage of gas-fired station: can be started quicker; disadvantage: gas supplies will run out before coal supplies. (b) 10 000 kg (c) Balanced arguments for and against required. Fuel for electricityANSWERS
Renewable energy sources A renewable energy resource is one that will not run out. Renewable energy sources do not produce radioactive waste, greenhouse gases or acid rain. Examples include wind, hydroelectric, wave, tidal, solar and geothermal. Fossil fuels such as coal. gas and oil as well as uranium are non-renewable energy sources.
A wind farm Wind power Wind is used to drive a turbine directly which rotates an electrical generator.
ADVANTAGES Renewable energy source No greenhouse gases No acid rain No radioactive waste Inexpensive to build Short start up time DISADVANTAGES Unreliable – needs wind! Best used in places where they will often be regarded as unsightly Many turbines are needed to produce the same energy of a small thermal power station Noise Danger to wildlife Wind power versus thermal power stations
Wave power Waves can be used to drive an electrical generator.
ADVANTAGES Renewable No greenhouse gases No acid rain No radioactive waste No land needed Short start up time DISADVANTAGES Unreliable Can only be used in areas with suitable waves Prone to storm damage Many needed to produce the same energy of a small thermal power station Danger to shipping Wave power versus thermal power stations
The Hoover Dam near Las Vegas Hydroelectric power Falling water is used to drive a turbine directly which rotates an electrical generator.
ADVANTAGES Renewable Can produce as much energy as a thermal power station No greenhouse gases No acid rain No radioactive waste Short start up time DISADVANTAGES Can only be used in mountainous areas A large amount of land needs to be flooded Expensive to build Hydroelectric power versus thermal power stations
Tidal power station at La Rance, Brittany Proposed Severn Estuary Tidal Power Scheme Tidal power Moving water caused by the tides is used to drive a turbine directly which rotates an electrical generator.
ADVANTAGES Renewable No greenhouse gases No acid rain No radioactive waste Short start up time DISADVANTAGES Very limited locations Wildlife affected Expensive to build Tidal power versus thermal power stations
Wind Energy Wave, Tidal & HEP Simulations
Energy from wind and waterNotes questions from pages 64/268 & 65/269 • Describe a wind turbine. • Copy and answer question (a) on page 64/268. • Copy figure 2 on page 64/268 and describe how waves can generate electricity. • Copy and answer question (b) on page 64/268. • What is (a) ‘hydroelectric power’ and (b) ‘tidal power’? • Copy and answer questions (c) and (d) on page 65/269. • Copy the Key Points on page 65/269. • Answer the summary questions on page 65/269.
In text questions: No electricity is generated Too much electricity would be needed to pump the water ‘uphill’. From the gravitational potential energy of water in the reservoirs. The tides are very predictable whereas the wind isn’t. Summary questions: (a) wind (b) tidal (c) hydroelectric (d) wave 2. (a) (i) 1000 (ii) 25 km (b) From top to bottom: hilly or coastal areas, estuaries, coastline, mountain areas. (c) Check reasons given. Energy from wind and water ANSWERS
Solar power (cells) Electricity can be produced directly from the Sun’s radiation using solar cells.
Solar power (panels) Solar panels are used to heat water saving electricity or gas use.
ADVANTAGES Renewable No greenhouse gases No acid rain No radioactive waste Short start up time DISADVANTAGES Unreliable in the UK! – sunshine is needed for solar cells Can only be used during the day Only 10% of solar energy is converted into electricity by solar cells Many cells needed to produce the same energy of a small thermal power station Solar power versus thermal power stations
Geothermal energy In some volcanic areas hot water and steam rise to the surface. The steam can be tapped and used to drive turbines. This is known as geothermal energy.
ADVANTAGES Renewable No greenhouse gases No acid rain No radioactive waste Short start up time DISADVANTAGES Very limited locations Expensive to build Geothermal versus thermal power stations
Power from the Sun and the EarthNotes questions from pages 66/270 & 67/271 • What is solar power? • Describe how (a) solar cells and (b) solar heating panels make use of solar power. • Copy and answer questions (a) and (b) on page 66/270. • What is ‘geothermal energy’? • Explain how geothermal energy can be used to generate electricity. • Copy and answer question (c) on page 67/271. • Copy the Key Points on page 67/271. • Answer the summary questions on page 67/271.
In text questions: Solar cell The motor stops The energy is from radioactive substances inside the Earth. Summary questions: (a) solar energy (b) radioactivity, geothermal energy (c) radiation 2. (a) 1500 (b) To supply electricity when the solar panels are in darkness Advantages of solar energy: widely available, simple set up – domestic use possible. Disadvantages: Not continuously available (eg not at night!), smaller scale electricity generation Power from the Sun and the Earth ANSWERS
Electricity generation pie-chart Most of our electricity is generated by burning fossil fuels (74% according to the pie chart opposite) Nearly 20% is nuclear Less than 5% is currently generated using renewable sources.
An effect of acid rain Problems with fossil fuels Burning coal, gas and oil produces carbon dioxide. This is a greenhouse gas which causes global warming. Fossil fuel burning can also produce sulfur dioxide gas. This can dissolve in water and produce acid rain which causes damage to forests and buildings. Modern power stations remove most sulfur dioxide producing compounds before burning. Fossil fuels are not renewable. They are running out. Estimates vary between 50 to 200 years to when we will need to find alternative sources of energy.
The destroyed Chernobyl nuclear reactor Problems with nuclear power stations Nuclear fuel (uranium) does not produce greenhouse gases and it generates 10000 times more energy per kilogram than fossil fuels. However: Nuclear waste is radioactive and may have to be stored safely for thousands of years. Although safe in normal operation, accidents can release radioactive material over a large area. The area around Chernobyl in Ukraine has been closed off since 1986.
Choose appropriate words to fill in the gaps below: Renewable energy sources will not _____ out and they do not cause __________ gases, acid rain or radioactive waste. However, most of our ___________ is produced using non-renewable sources such as ______ fuels (coal, gas and oil) and _________. These are highly concentrated and ________ energy sources. In the near future we hope to use more renewable sources such as wind, wave and _______ power. This will help us to conserve the remaining _______________ energy sources. run greenhouse electricity fossil uranium reliable tidal non-renewable WORD SELECTION: fossil non-renewable electricity uranium greenhouse tidal reliable run
Energy and the environmentNotes questions from pages 68/272 & 69/273 • Copy the pie chart on page 68/272. • What are the problems of using fossil fuels? • Copy and answer question (a) on page 68/272. • Why are fossil fuels used? • List the advantages and disadvantages of nuclear power compared with renewable sources. • Copy and answer question (b) on page 69/273. • List the advantages and disadvantages of using renewable energy sources. • Copy and answer question (c) on page 69/273. • Copy the Key Points on page 69/273. • Answer summary questions 1 and 2 on page 69/273.
In text questions: (i) carbon dioxide (ii) sulfur dioxide It turns into radioactive waste when it is used. They affect birds and can upset humans. Summary questions: (a) fossil fuels (b) acid rain, greenhouse gas. (c) radioactive waste, plant and animal life. (i) A (ii) D (iii) C (iv) B Energy and the environment ANSWERS
Big energy issuesNotes questions from pages 70/274 & 71/275 • Answer questions 1 and 2 on pages 70/274 and 71/275.
Big energy issuesANSWERS • (a) Not enough electricity would be generated at night if there were no wind or waves. (b) More pumped storage schemes would be needed to store electricity when it is not needed. 2. Fusion relies on fusing together ‘heavy hydrogen’ (deuterium) atoms. There is an almost unlimited supply of this in seawater and so we could produce electricity for thousands of years.
Tamara could have used a piece of card and placed it over different parts of the solar cell. All other variables would have been kept the same. Each time she would record the voltage. Each time the voltage would remain the same. Results show that covering more of the solar cell reduces the voltage. Tamara’s independent variable was an ordered variable and so was not as powerful as a continuous variable. To improve her independent variable, Tamara should have measured the area of the solar cell covered, this would have been a continuous variable. This would have allowed Tamara to produce a graph and her conclusion would have been more powerful. The readings were only to 0.1 volts and this did not produce a difference between some of the readings for different exposures. The voltmeter was not sensitive enough. Farzana probably suggested a digital voltmeter that read to 0.01 volts. Yes, even when the solar cell is completely covered there is a reading of 0.1 volts. She could start again! Realistically she should take 0.1 volts off each of the readings. How Science WorksANSWERS