SCIENCE. Generating Electricity. Renewable Energy Sources

Transcription

1 StudyPacks STUDY. KS4 SCIENCE Generating Electricity Renewable Energy Sources This Study Pack aims to cover: 1. Generating Electricity using renewable energy sources 2. Comparison of Energy Resources 3. Energy sources and the Environment SP8 Study Packs are prepared by Qualified Teachers and Specialists and are a complete range of comprehensive compiled resources based on the UK National Curriculum covering the Primary and Secondary Frameworks including SATs and GCSE examinations. Student Name

2 Contents Renewable energy Sources Notes 2-9 Practice questions Exam questions Mark scheme

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10 Pros /cons of renewable energy sources 9

11 Renewable Energy Sources Worksheet 1 Complete the table below using the notes provided. Energy Resource Advantages Disadvantages Solar power Wind turbines Hydroele ctricity dam Tidal Barrages 10

12 Energy Resource Advantages Disadvantages Biomass Fuel Wave Energy Geotherm al Energy 11

13 Pumped storage worksheet Aim To learn more about renewable energy and pumped storage. In a pumped storage scheme, surplus electricity is used to pump water up to a large reservoir. When the demand for electricity is greater than the supply from other power stations, the flow of water is reversed so electricity is generated. Electricity is used to pump water uphill and then the flow is reversed. Complete the energy flow diagram, using the list below, to show the energy changes that happen. A Electri cal Kinetic energy of B D C F E Electrical energy Gravitational potential energy of water (use once) Kinetic energy of water (use once) Thermal energy of pump/generator (use twice) Thermal energy of water (use twice) a) When a certain pumped storage station pumps a certain amount of water to the upper reservoir, it uses 3000 MJ of electrical energy to supply 1500 MJ of gravitational potential energy to the water. Calculate: The waste energy The efficiency of the station when it transforms electrical energy into gravitational potential energy

14 ... b) When the same station is used to generate electricity, it produces 100 MW of electrical power when water drops through a height of 300 m and flows through it at a rate of kg/s. Change of gravitational potential energy (in joules) = mass (in kg) 10 N/kg change of height (in metres) i) Calculate the gravitational potential energy released by the water in 1 second Calculate the efficiency of the station when it produces electricity c) Discuss the overall efficiency of the station Energy resources quiz Aim To learn about fuels and renewable energy. a) A fossil fuel with three letters.... b) A solid fossil fuel.... c) A fossil fuel that reaches our homes through underground pipes.... d) A fuel that must be stored after it has been used.... e) A renewable energy resource that is dry and available only in day time.... f) A renewable energy resource that comes up through the ground in some countries

15 g) A renewable energy resource that can stop.... h) Canute couldn t stop this renewable resource.... i) A scheme for storing energy on a large scale when it is not wanted.... j) A gas that can be used as fuel for motor vehicles.... An energy conundrum where is it? Clues 1 A very popular tourist site where electricity is produced. 2 It never stops. 3 It was there long before electricity was discovered. 4 It will probably be there thousands of years from now. 5 It is near the border with another country. 6 You wouldn t want to go near it in a boat. 7 The first recorded powered flight took place in this country. Answer: Word puzzle! Use the clues to fill in the grey squares of the grid below Down 1 A liquid fossil fuel. 2 Surfers ride on the crest of this type of energy. 4 This fossil fuel is pumped through underground pipes. 5 It is from under the ground and it turns to ash as it burns. 14

16 Across 2 Too much of this form of energy can damage buildings. 3 A form of renewable energy that comes in and out regularly. 4 This form of renewable energy is deep underground. 6 This form of renewable energy is best in summer. Summary questions Complete the sentences below. a) Electricity in power stations are driven by turbines. b) Much energy is released per kilogram from uranium than from fossil fuel. c) Examples of fossil fuels include, and. a) i) Weather-dependent renewable energy resources that can produce electricity at night include, and. ii) power stations convert the gravitational potential energy of the Earth and the Moon into electricity. iii) is the thermal energy of hot rocks heated by radioactive substances deep inside the Earth. b) Solar energy devices include: i) that convert solar energy into thermal energy. ii) that convert solar energy into electricity. c) Pumped storage power stations transform: i) into when electricity demand is low. ii) into when electricity demand is high. a) produces more greenhouse gas than which produces more than. b) Nuclear fuels produce but no, 15

17 c) Renewable energy resources affect plant and animal life. Such resources need to cover areas to generate the same amount of electricity as a fossil-fuel or nuclear power station. Generating electricity A hydroelectric power station uses two lakes. coupled to a generator that produces electricity. What is the energy transformation that takes place as the water flows? 1 As water flows from the top to the bottom lake it turns a turbine A B C Electrical energy to kinetic energy. Gravitational potential energy to kinetic energy. Kinetic energy to gravitational potential energy. D Kinetic energy to heat energy. (1) 2 Where does geothermal energy come from? A B C Radioactive processes in nuclear power stations. Radioactive processes within the Earth. The decay of organic material. D The movement of the tides. (1) 3 Renewable energy sources can be used to generate electricity. However these sources are not always available. Match words from the list with the numbers 1 to 4 in the table. A B C D hydroelectric scheme. solar cells. tidal barrage. wind farm. Renewable energy source Source is available to generate electricity 1 only during the daylight 2 only when the weather is suitable 3 only during certain periods of the day and night 4 usually whenever it is needed 16

18 4 Wind energy, waves, tides, falling water and solar energy can all be used as energy sources to generate electricity. (a) What do all these energy sources have in common? A B C They are available at any time of the day or night. They are renewable energy sources. They do not affect wildlife. D They do not cause any sort of pollution. (1) (b) Which of these energy sources is most appropriate to generate electricity to run a well in a remote African village? A falling water B solar energy C tides D waves (1) (c) Which of these energy sources is most likely to produce noise pollution when used to generate electricity? A solar energy B tides C waves D wind energy (1) (d) Which of these energy sources is least likely to be associated with damaging wildlife or the habitat of wildlife when used to generate electricity? A falling water B tides C waves D wind energy (1) 5 In coal, gas and oil-fired power stations fuels are burnt to produce heat. (a) How is heat produced in a nuclear power station? (1) (b) How is the heat used to produce electricity? (4) (c) Apart from the cost of the electricity, what are the advantages and disadvantages of using a nuclear power station to produce electricity? (5)

19 6 In the UK there are three different fossil fuels burnt in power stations. (a) Name the three fossil fuels (3) (b) During burning, all fossil fuels release carbon dioxide into the atmosphere. Some also release sulfur dioxide. (i) Why does the release of carbon dioxide into the atmosphere produce a problem for the environment? (3) (ii) Why is the release of sulfur dioxide a problem for the environment? (2) 18

20 Exam question Q1. (a) Coal, gas, oil and wood are all examples of fuels. (i) What are fuels?... (1) (ii) Write the names of these fuels in the table below to show which are renewable and which are non-renewable. (2) (b) The list below shows energy resources which are not fuels. geothermal nuclear solar tides wind Write the names of the energy resources in the table below to show which are renewable and which are non-renewable. (2) 19

21 (c) Why is it better to use more renewable energy resources rather than non-renewable resources? (2) (Total 7 marks) Q2. The bar chart shows how the UK s electricity demands in 2007 were met. (a) What proportion of electricity was generated using renewable energy sources? Show clearly how you work out your answer. (b) By 2020, most of the UK s nuclear reactors and one-third of coal-fired power stations are due to close, yet the demand for electricity is expected to increase. Four students, A, B, C and D, were asked how a demand of 380 billion kilowatt-hours could be met. They made the suggestions given in the table. (2) Student Fossil fuels Nuclear Renewable Bought from other countries A B C D

22 (i) Which student has made the suggestion most likely to result in the lowest carbon dioxide emissions?... Give a reason for your answer (2) (ii) Suggest one realistic way in which a householder could help to reduce the annual electricity demand (1) (c) To increase the amount of electricity generated using renewable energy resources would probably involve erecting many new wind turbines. The graph shows the power curve of a wind turbine. (i) Describe, in detail, how the power output of the turbine varies with the wind speed (3) 21

23 (ii) Give one disadvantage of using wind turbines to generate a high proportion of the electricity required in the UK (1) (Total 9 marks) Q3. On a very windy hilltop there are two wind generators side by side. The bar charts show the lengths of the turbine blades and the electrical outputs of the two wind generators. Complete the following table. LENGTH OF TURBINE BLADE (m) ELECTRICAL OUTPUT (MW) Large wind generator 60 Small wind generator Q4. (a) Solar energy is a renewable energy source that can be used to generate electricity. (Total 3 marks) (i) What is meant by an energy source being renewable?... (1) 22

24 (ii) Name two further renewable energy sources used to generate electricity (1) (b) A householder uses a bank of solar cells to generate electricity for his home. The solar cells are tilted to receive the maximum energy input from the Sun. The data in the table gives the average energy input each second (in J/s), to a 1 m 2 area of solar cells for different angles of tilt and different months of the year. Month Angle of tilt February April June August October December (i) Use the data in the table to describe how the average energy input to the solar cells depends on the angle of tilt (ii) The bank of solar cells used by the householder has an area of 8 m 2. (2) The efficiency of the solar cells is 0.15 Use the equation in the box to calculate the average maximum electrical energy available from 23

25 the bank of solar cells each second in June. efficiency = Show clearly how you work out your answer Maximum energy =... joules/second (3) (c) The graph shows how the householder s electrical energy needs change over one year. Why would it be advisable for the householder to remain connected to the National Grid? (1) (Total 8 marks) Q5. Wind and tides are renewable energy sources that are used to generate electricity. (a) Complete each sentence by putting a tick ( ) in the box next to the correct answer. (i) The wind is: 24

26 a predictable energy source. a constant energy source. an unreliable energy source. (1) (ii) The tides are: a predictable energy source. a constant energy source. an unreliable energy source. (1) (b) If wood is to be used as a renewable energy source, what must be done each time a tree is chopped down? (1) (c) In the UK, electricity is generated using renewable and non-renewable energy sources. The graph shows the percentage of electricity generated using renewable energy sources between 1990 and Complete the following sentence by drawing a ring around the correct line in the box. In 2015, the percentage of electricity generated using renewable energy sources is most likely to be greater than 4% equal to 4% less than 4%. (Total 4 marks) 25

27 Q6. Use of renewable sources of energy is expected to increase. The table shows the comparative costs of producing I kwh of electricity from different energy sources. Types of energy sources used in the UK Cost of producing 1 kwh of electrical energy Fossil fuels (non-renewable) Coal 1.0 p Gas 1.4 p Oil 1.5 p Nuclear fuels (non-renewable) Nuclear 0.9 p Renewable Hydroelectric 0.2 p Wind Installation and decommissioning costs are not included At present about 2% of electricity generated in the UK uses renewable energy sources. Consider the three types of energy sources in the table and give one advantage and one disadvantage for each (other than installation and decommissioning costs). 0.9 p Advantage Using fossil fuels Using nuclear fuels Using renewable sources Disadvantage Using fossil fuels Using nuclear fuels Using renewable sources (Total 6 marks) 26

28 Q7. (a) The pie-chart shows how energy is used in a home. Complete the table using the information on the pie-chart. (2) (b) We get some of the energy we need in our homes from electricity. The graphs show how the amounts of coal and gas used to generate electricity changed between 1960 and Describe these changes. Coal... Gas... (4) (c) Read the information below. More carbon dioxide in the air may change the weather. Farmers may then not be able to produce the food we need. Burning coal produces sulphur dioxide. Burning gas does not do this. It is cheaper to generate electricity from gas than from coal. 27

29 Sulphur dioxide causes acid rain which can kill fish and damage buildings. Two power stations generate the same amount of electricity. The one which burns gas produces less carbon dioxide than the other which burns coal. Many people say that the change from coal to gas is better for the environment. Why do you think they say this? (3) (Total 9 marks) Q8. (a) The bar chart shows the start-up time for different types of fuel-burning power stations. Which type of power station would be the quickest to start producing electricity? (1) (b) A fuel-burning power station is more reliable than a wind generator at producing electricity. Explain why. (2) (c) Fuel-burning power stations may produce air pollution. Why does a wind generator not produce any air pollution? (1) (Total 4 marks) 28

30 Q9. (a) Water waves are a renewable energy source. The government wants more electricity to be generated from renewable energy sources. Some people do not think this is a good idea. What reasons could a government scientist give to show people that using more renewable energy sources is a good idea? (b) The diagram shows a wave-powered generator. The generator transforms kinetic energy from the waves to electrical energy. (2) AQA GCSE SCIENCE CORE FOUNDATION STUDENT S BOOK by Graham Hill, Nigel Heslop, Christine Woodward,Steve Witney and Toby Houghton. Published by Hodder and Stoughton 2006 Reproduced by permission of John Murray (Publishers) Ltd The following sentences describe how the wave generator works. The sentences are in the wrong order. R S T U V Waves push air up and down a chamber inside the building. The turbine turns the generator. The generator transforms kinetic energy to electrical energy. The air rushes through a turbine making it spin. Strong waves move towards the wave-powered generator. Arrange these sentences in the correct order. Start with letter V. V (3) (Total 5 marks) 29

31 Q10. The map below shows an industrial region (shaded). The prevailing wind is from the west. There is a nearby mountainous area, from which a river flows through the region. The major road and rail links are shown. A power station is to be built to supply electrical energy to the region. The energy will be for a range of domestic and industrial uses. The choice is between a coal fired power station, wind turbines and a hydroelectric scheme. Three local groups each support a different option. Choose which option you would support and justify your choice by making reference to the financial, social and environmental implications of your choice compared with those of the alternative systems. (Total 8 marks) Q11. (a) Different energy sources are used to generate electricity. Which two of the energy sources in the box are likely to be used up first? Draw a ring around each of your answers. gas oil Sun tides waves wind (2) (b) The diagram shows a geothermal power station. Hot rocks in the Earth s crust heat water to produce steam. The steam is used to drive turbines that turn electrical generators. How is the way in which a geothermal power station generates electricity the same as the way in which a coal burning power station generates electricity? 30

32 (1) (c) The graph shows how the temperature of the rocks in the Earth s crust depends on how far the rocks are below the Earth s surface. Estimate the temperature of the rocks 5 kilometres below the Earth s surface. Show clearly how you have used the graph to get your answer Temperature =... C (2) (d) Scientists have estimated that one quarter of the world s electricity could be generated using geothermal energy. Give one reason that scientists might use to persuade a government to spend large amounts of money building geothermal power stations (1) (Total 6 marks) 31

33 Q12. Antarctica is a huge land mass surrounding the Earth s south pole. It is covered in a very thick layer of ice and is the only remaining large area of the Earth s surface that has not been affected very much by humans. There are, however, teams of scientists from various countries studying Antarctica. These scientists need electricity for lighting, for their computers and other scientific instruments and to communicate, via satellite, with the rest of the world. The temperature in Antarctica is always subzero, so the scientists need some way of keeping their buildings warm. They also need fuel to be able to get around on their snowmobiles. Scientists cannot avoid affecting the environment. However, they want to affect it as little as possible. Atmospheric pollution produced in one country eventually affects the whole of the Earth s atmosphere. The hole that appears each year in the ozone layer above Antarctica, for example, is mainly caused by pollutants such as CFCs from countries in the northern half of the Earth. Discuss the advantages and disadvantages of using the following energy sources to meet the scientists needs: solar energy energy from the wind 32

34 natural gas (present in large quantities deep down in the Antarctic land mass) diesel oil (which would have to be imported) (Total 10 marks) 33

35 Mark scheme M1. (a) (i) sources of energy for 1 mark M2 continued output peaks at 21 / 22m/s (ii) wood coal oil gas output constant between 21 / 22 and 25 / 26 m/s all correct gains 2 marks 3 correct gains 1 mark 3 (b) geothermal nuclear tides wind solar all correct gains 2 marks 4 correct gains 1 mark 2 output falls (rapidly) after 25 / 26m/s accept for 1 mark goes up then comes down (ii) any one from: unreliable energy source 3 (c) non-renewable fuels cause pollution (or reverse) conserve/limit use of coal/gas/oil; so supplies last longer/renewable sources can be replaced any 2 from 4 for 1 mark each M2. (a) 1/25 or 1:25 or [7] dilute energy source take up too much land accept wind does not always blow accept need thousands / lots of turbines ignore reference to visual / noise pollution ignore reference to kill birds 1 accept 4 % or marks or 1 in 25 for both c) the solar cells will not meet demand at all times of the year / day accept to maintain a constant supply of electricity / energy allow 1 mark for total of 375 allow 1 mark for a clearly correct method using a clearly incorrect total do not accept 1:26 (b) (i) B do not credit reason if B is not chosen 1 or to make up the shortfall in energy required at certain times of the year or to be able to sell surplus electricity (to the National Grid) accept to provide energy at night do not accept because it s cloudy on it s own 1 [8] (only) burning fossil fuels produces carbon dioxide / carbon (emissions) or nuclear fuels don t produce carbon dioxide insufficient smallest amount of fossil fuels accept less carbon dioxide (ii) accept anything reasonable eg increased level of insulation 1 M each for 1 mark M4. (a) (i) replaced faster than it is used accept replaced as quick as it is used accept will never run out do not accept can be used again 1 [3] use energy efficient light bulbs do not leave appliances on standby (ii) any two from: two sources required for the mark switch thermostats down (1 C) wind generate own electricity waves(*) install solar panels accept insulate accept specific examples eg loft (c) (i) any three from: 1 tides(*) (*)do not accept water / oceans accept OTEC fall of water accept hydroelectric no power output until wind speed exceeds 4m/s biomass output rises rapidly after 4m/s output begins to level out / rises less rapidly at / after 13m/s geothermal accept a named biomass / biofuel eg wood (b) (i) any two from: 1 34

36 M4 continued increases from 20 to 30 reaches maximum value at 30 then decreases from 30 same pattern for each month accept peaks at 30 for both marks accept goes up then down for 1 mark ignore it s always the lowest at 50 (ii) 864 an answer of 108 gains 2 marks allow 1 mark for using 720 value only from table allow 2 marks for answers 852, 816, 768, 825 allow 1 mark for answers 106.5, 102, 96, 103 (.125) M5. (a) (i) an unreliable energy source (ii) (b) a predictable energy source plant / grow (at least) one new tree (c) greater than 4 % 1[4] M6. do not give any credit for renewable or non-renewable or installation or decommissioning costs M7 (a) cooking and heating water 30 heating rooms 50 each for 1 mark (b) coal idea that amount used fell/declined/line goes down gains 1 mark but idea that fall/decline is steady/gradually/approx halved gains 2 marks gas ideas that amount used rose/increased in/from 1980/more used before 1980/ref to 1980 as an important date/rapid increase in use (credit idea that gas>coal from c.1990 in either part with 1 mark (to maximum 4) each for 1 mark max 4 (c) less carbon dioxide produced less change to weather/food production/gained warming/water levels (no mark for greenhouse gas alone) no/less sulphur dioxide produced/coal produces sulphur dioxide less acid rain/damage to fish/buildings/trees/crops/animals/tumours etc (do not credit reference to cost unless : cheaper so can spend more on environment) ( It used in an answer will refer to gas ) any 3 for 1 mark each M8. (a) gas fossil fuel advantage a reliable source of energy fossil fuel disadvantage pollution by carbon dioxide / accept causes acid rain accept highest costs / more expensive than nuclear / more expensive than renewable 1 nuclear advantage do not produce gases that increase the greenhouse effect or cause acid rain accept nuclear is cheaper than fossil 1 nuclear disadvantage 1 (b) fuel burning stations produce electricity at any time / all the time accept fuel available all the time wind generator can only produce when the wind is strong enough accept it s not always windy (c) no fuel is burnt or no fuel is used or uses only energy from wind or does not emit harmful gases / soot / smoke do not accept wind is natural / environmentally friendly / renewable answer must be in terms of wind, not negative of fuel burning specific examples of gases CO 2, SO 2, acid rain and greenhouse gases can be accepted ozone negates credit accidents / waste can release very dangerous radioactive material radiation accept it produces waste that stays dangerously radioactive for thousands of years or radioactive waste has to be stored safely for thousands of years 1 renewable advantage there are no fuel costs almost pollution free (apart from noise and visual) accept cheaper than fossil 1 renewable disadvantage not a reliable source of energy except for hydroelectric accept (most) require large areas of land accept visual / noise pollution 1 [6] 35

37 M9. (a) any two from: M11. (a) gas 1 (burning) fossil fuels produces greenhouse gases / pollutant gases / acid rain / leads to global warming Oil 1 accept a named fossil fuel accept a named pollutant gas nuclear fuels produce dangerous waste accept radioactive for dangerous accept reference to dangers of nuclear fuels fossil fuels are non-renewable accept running out of fuels renewable energy resources produce no pollutant gases large amounts of energy are available accept renewable won t run out running costs are low accept any reasonable benefit of renewables accept any reasonable drawback of non-renewables do not accept better for the environment on its own 2 (b) (both) use steam to drive a turbine accept (both) use turbines to drive generators do not accept both have a turbine /generator / use steam must describe a step in the process accept heat / thermal energy transformed to kinetic / electrical energy (c) 140 ( C) correct answer only allow 1 mark for method clearly shown on graph accept a cross or other indication at correct position on the line accept correct description accept even if numerical answer is incorrect (d) any one from: do not accept answers purely in terms of disadvantages of other methods except for fossil fuels are running out 1 2 (b) R U S T all in correct order allow 2 marks for 2 correct allow 1 mark for one correct 3 [5] very large energy source / reserves no polluting / harmful gases produced accept named gas CO 2 SO 2 NO x accept reduces harmful carbon emissions M10. To gain marks the candidate must 1. Select one option Advantages ) Max 4 reduces carbon emissions accept does not contribute to global warming no fuel needed 2. State 8 valid advantages/disadvantages/relevant Disadvantages) Min 1 comparisons with either of the alternatives Comparisons ) If no A or D or C then Max 4 No option then Max 4 Look for As, Ds for chosen scheme. Then for Cs compared with A/D for chosen scheme. Below are listed some of the relevant mark scoring points. Advantages Disadvantages Wind Land available to North Initial cost No pollution Many windmills/much land Close/low transmission costs Calm day problem No fuel costs Few long term jobs Renewable energy resource energy is free can generate energy for a long time accept energy available for a long time renewable (energy source) fossil fuels are running out accept it saves fossil fuels / non-renewable accept reduces the amount of fossil fuels being burnt accept a named fossil fuel Better for the environment / environmentally friendly insufficient it is cheaper is insufficient 1 [6] Coal Waste land to North Pollution Prevailing wind to East Initial costs Good road/rail transport Fuel costs Close/low transmission costs Non-renewable energy Save coal industry Resource Overall labour intensive Hydroelectric No pollution Mountains/lake/river nearby No fuel costs Renewable energy source underground environment Possible drought Distant/transmission costs Few jobs created Possible expensive transmission cable Construction of dam affects 36

38 M12. ideas that direct solar radiation will provide enough energy to heat the (specially designed) buildings during the period Oct-Mar / summer solar cells will produce plenty of electricity in Oct-Mar / summer (when wind generators produce little) a couple of wind generators will produce all electricity needed (for all but heating) Apr-Oct / winter number required makes wind generators unsuitable for heating / buildings no solar energy in June and July / little in winter solar / wind have little effect on environment or cause no air pollution solar and wind complement each other or together provide energy all year fuel / gas / diesel can provide energy all the time / at any time fuel / gas / diesel needed for transport fuel / gas / diesel needed for heating in winter diesel has to be imported diesel likely to freeze gas wouldn t have to be imported drilling for gas difficult / harms environment but atmospheric pollution a global rather than local matter so any produced in Antarctic doesn t matter much (deduct 1 mark (to min m. zero) for incorrect claims about destroying ozone layer) gas produces less carbon dioxide (for the same energy released) than diesel* gas produces less sulphur dioxide (for the same energy released than diesel* (* these ideas met by candidates in Q.16 so must be allowed, though not required) any ten for 1 mark each [10] 2 37