P3 Module Introduction

Transcription

1 OCR 21st Century Science: P3 Sustainable energy P3 Module Introduction Pages in the Student Book provide an introduction to this module. When and how to use these pages These pages summarise what students should already know from KS3 or previous GCSE units and provide an overview of the content that they will learn in this module. o Use these pages as a revision lesson before you start the first new topic. o Brainstorm everything that students remember about the different topics using the headings as a starting point. Compare your list with the points on page 266. o Use the questions on page 266 as a starting point for class discussions. o Ask students if they can tell you anything about the topics on the right-hand page. o Make a note of any unfamiliar / difficult terms and return to these in the relevant lessons. Suitable answers to the questions on page 266: o Likely to be loss of communication systems; food shortages; transport problems; shutdown of non-essential businesses and shops; problems with proper care in hospitals including cancellation of operations; increased crime. o Non-renewable: fossil fuels (coal, oil, gas), wood, biofuels, nuclear fuels (uranium, plutonium). Renewable: wind, waves, hydroelectricity, solar. o All equipment with motors (e.g. electric drill, food processor, CD player), electric bells, electromagnets, anything using a loudspeaker or microphone You could revisit these pages at the following points: o before lesson p3_06 on generators, Student Book pages o before lesson p3_11 on choosing the best energy source, Student Book pages Overview of module This module covers the topics of efficiency and power, and interpretation of data about energy usage. Students will learn how to calculate the cost of electricity. They will learn how power stations are used to generate electricity and the different energy sources used, along with their advantages and disadvantages including waste disposal. Students will find out how electricity is distributed using the National Grid and how to decide which is the most suitable energy source in different situations, including the impact of future energy demand on our choices. Obstacles to learning There is a lot of specialist vocabulary for students to learn in this module. In particular, students may need extra guidance with the following terms and concepts. Primary energy sources Students do not readily grasp the processes linking primary energy sources with power stations. Power Students may confuse the terms power and energy. They may find it hard to convert between watts and kilowatts, and to distinguish between kilowatts and kilowatt-hours. Electricity usage Some students find it hard to see a direct link between their electricity usage and the electricity bill. Sankey diagrams Students find Sankey diagrams hard to interpret at first they often do not see the link between the width of the arrow and the proportion of energy transferred in different ways. They may also find it hard to identify the full energy transfers taking place. Efficiency Students find it difficult to visualise and quantify wasted energy, and therefore find it hard to compare the total energy input and useful energy output.

2 P3 Module Introduction continued Power stations Students may find it difficult to relate large-scale generation in power stations with mains electricity. Power stations are very complex, so it is vital to simplify diagrams and information so students can spot similarities between the ways different power stations generate electricity. Hazards of radioactive waste Students are not likely to be familiar with radioactivity, or other aspects of nuclear physics, and so are likely to overestimate the risks. Renewable energy sources People are exposed to many simplistic and confused ideas related to green living, so students tend to confuse renewable energy with other green issues and with unrelated environmental issues. Transmission of electricity Many students find it hard to relate the different parts of the National Grid with their function because they do not see the actual connections and the National Grid is on such a large scale. Practicals in this module In this module students will do the following practical work: o Examining electrical devices to ascertain power rating and identify energy transfers o Setting up simple electrical circuits, measuring voltage and current for different components and calculating the power o Investigating the action of a dynamo o Demonstration of steam engine connected to generator and bulb o Investigating the power available from solar panels o Demonstration of energy loss in transmission lines Key vocabulary covered in this module primary energy source secondary energy source fossil fuel nuclear fuel biofuel greenhouse gas global warming power watt kilowatt kilowatt-hour (kwh) voltage current ampere rate rating component Unit of electricity Sankey diagram energy input energy output efficiency magnetic field generator electromagnet turbine turbine reactor radioactive ionising radiation irradiated contaminated hydroelectric wind turbine wave technology National Grid power output

3 OCR 21st Century Science: P3 Sustainable energy P3 Module Checklist Pages in the Student Book provide a student-friendly checklist for revision. When and how to use these pages This checklist is presented in three columns showing progression, based on the grading criteria. Bold italic means Higher tier only. Remind students that they need to be able to use these ideas in various ways, such as: o interpreting pictures, diagrams and graphs o applying ideas to new situations o explaining ethical implications o suggesting some benefits and risks to society o drawing conclusions from evidence they have been given. These pages can be used for individual or class revision using any combination of the suggestions below. o Ask students to construct a mind map linking the points on this checklist. o Work through the checklist as a class and note the points that need further class discussion. o Ask students to tick the boxes on the checklist worksheet (on the Teacher Pack CD) if they feel confident that they are well prepared for the topics. Students should refer back to the relevant Student Book pages to revise the points that they feel less confident about. o Ask students to use the search terms at the foot of the relevant Student Book pages to do further research on the different points in the checklist. o Students could work in pairs, and ask each other what points they think they can do, and why they think that they can do those, and not others.

4 P3 Module Checklist continued Module summary In the introduction to this module, students were presented with a number of new ideas. Work through the list below as part of their revision. Ask students to write their own summaries and mind maps, using this list as a starting point. Energy transfer o energy transfers can be represented in Sankey diagrams o the rate of transfer of energy by an electrical device is its power, measured in watts o the efficiency of an energy transfer is (useful energy output energy supplied) 100% Generation of electricity o a generator produces electricity by spinning a magnet near a coil of wire o in power stations a primary energy source is used to spin turbines; these are connected to generators o electricity is a convenient secondary energy source, transmitted around the country at 230 volts o we pay for our electricity according to how many Units of electrical energy, or kilowatt-hours, that we use Sustainability of energy production o different types of power stations have different advantages and disadvantages in terms of cost, efficiency and impact on the environment o any waste produced, particularly the radioactive waste from nuclear power stations, needs to be considered o we all need to try to reduce our demand for energy because of rising population, problems with availability of energy resources and the effect of electricity production on the environment

5 OCR 21st Century Science: P3 Sustainable energy P3 Applying your knowledge Pages in the Student Book prepare students for assessment. When and how to use these pages This activity provides and opportunity for students to apply their science knowledge in a different context. Ask students to: o read through the context and tasks, listing any terms that they do not understand o as a whole class or in small groups, discuss the tasks to ensure that all students understand the terminology used and to clarify what is required o work in small groups or individually to answer the questions for each task. If time allows, students can mark one another s work using the mark scheme provided. Notes This situation presented is one that students are unlikely to have come across, at least not from the perspective of energy transfer, but they should be able to make sense of it and respond to it. They should see that the concepts of energy efficiency and the use of Sankey diagrams can be used as effectively here as in more contemporary situations. The questions are designed to prompt ideas and to require the development of responses; students are likely to gain more from these if they approach them collaboratively. Answers Task 1 The engines were huge and had large moving parts; they could be seen and heard from some way away; they were hot and noisy, and smelt of steam, coal dust and oil. The kinds of work they did in a mine were of two main types they were used to pump water (such engines running continuously) and to raise and lower workers and materials. Most of the energy was wasted, mainly as heat to the surroundings from the boiler; the machines were noisy so some energy would be transferred as sound; there would have been friction in the large moving parts, also lost as heat and sound. Task 2 Coal was easily and cheaply available in many parts of the country; it was easy to transport, store and handle. Transferred energy stored chemically in the coal to hot gases, which made the water get hotter and boil; the energy transferred to the water turned it into steam. Task 3 It happens mostly because the boiler and the engine are both much hotter than the surroundings and so transfer heat to it; the exhaust gases from the boiler are also hot; as is any steam that escapes.

6 P3 Applying your knowledge continued Task 4 Energy is transferred from the coal to hot gases in the fire, which then heat up water to produce steam; the steam expands and moves the pistons along the cylinders, making the engine turn; this is then transferred to the mine cage, lifting it up and giving it gravitational energy. They were much more efficient than previous engines. If coal has to be transported into an area it increases the cost of the fuel; so having a more efficient engine becomes more important. Mark scheme For grade E, students should show that they can: o describe advantages and disadvantages of different energy sources o comment on the significance of data relating to energy use and waste o draw and interpret simple Sankey diagrams o discuss methods used to reduce energy use. For grades D, C, in addition students should show that they can: o interpret and process data on energy sources, use and waste o draw and interpret more complex Sankey diagrams o discuss qualitatively and quantitatively the effectiveness of methods used to reduce energy use in the work place For grades B, A, in addition students should show that they can: o draw and interpret Sankey diagrams including an analysis of the efficiency of energy transfers o discuss qualitatively and quantitatively the effectiveness of methods used to reduce energy use nationally

7 OCR 21st Century Science: P3 Sustainable energy Checklist P3 Aiming for A Use these checklists to see what you can do now. Refer back to the relevant topic in your Student Book if you are not sure. Look across the rows to see how you could progress bold italic means Higher Tier only. Remember that you will need to be able to use these ideas in various ways, such as: interpreting pictures, diagrams and graphs applying ideas to new situations explaining ethical implications suggesting some benefits and risks to society drawing conclusions from evidence that you are given. Working towards an A grade Aiming for Grade C Aiming for Grade A understand that power stations that burn fossil fuels produce carbon dioxide; understand that increasing demand for energy raises issues about the availability of energy sources and their environmental effects understand that an electric current passing through a component transfers energy to the component and/or to the environment recall that the power in watts is the energy transferred each second; use power = voltage current to calculate how quickly an electrical device transfers energy use energy transferred = power time to calculate the electrical energy transferred in joules or kilowatt-hours recall that power is the rate of energy transfer; use and rearrange power = voltage current in calculations involving rate of electrical energy transfer use and rearrange energy transferred = power time in calculations involving electrical energy transfer calculate the cost of energy supplied by electricity use efficiency = (energy usefully transferred total energy supplied) 100% to calculate the efficiency of an electrical device or power station use and rearrange efficiency = (energy usefully transferred total energy supplied) 100% in calculations interpret and construct Sankey diagrams for various contexts including electricity generation and distribution, and use them to calculate efficiency of transfer explain how the voltage produced, and current supplied, by a generator can be increased; understand that a generator uses more primary fuel per second when it supplies a bigger current

8 OCR 21st Century Science: P3 Checklist Aiming for Grade C Aiming for Grade A understand that electricity is convenient because it is easily transmitted over long distances and has many uses understand that in many power stations a primary energy source heats water, producing steam which drives a turbine coupled to an electrical generator; label a block diagram of the basic components of hydroelectric, thermal and nuclear power stations; understand that some renewable energy sources drive the turbine directly understand that radioactive waste emits ionising radiation; and explain the difference between contamination and irradiation explain why contamination by a radioactive material is more dangerous than a short period of irradiation explain how the distribution of electricity through the National Grid at high voltages reduces energy losses discuss qualitatively and quantitatively the effectiveness of methods of reducing energy demand in a national context understand how different factors affect the choice of energy source for a given situation interpret and evaluate information about different energy sources for generating electricity, considering efficiency, economic costs and environmental impact understand that to ensure a security of electricity supply nationally, we need a mix of energy sources interpret and evaluate information about different energy sources for generating electricity, also considering power output and lifetime

9 OCR 21st Century Science: P3 Sustainable energy Checklist P3 Aiming for C o achieve your forecast grade in the exam you will need Use these checklists to see what you can do. Refer back to the relevant topic in your Student Book if you are not sure. Remember that you will need to be able to use these ideas in various ways, such as: interpreting pictures, diagrams and graphs applying ideas to new situations explaining ethical implications suggesting some benefits and risks to society drawing conclusions from evidence that you are given. Working towards a C grade Aiming for Grade E Aiming for Grade C understand that power stations that burn fossil fuels produce carbon dioxide; understand that increasing demand for energy raises issues about the availability of energy sources and their environmental effects understand that an electric current passing through a component transfers energy to the component and/or to the environment recall that the power in watts is the energy transferred each second; and use power = voltage current to calculate how quickly an electrical device transfers energy use energy transferred = power time to calculate the electrical energy transferred in joules or kilowatt-hours understand that a domestic electricity meter measures energy use in kilowatt-hours interpret information about energy use; and understand that a more efficient appliance transfers more of the energy supplied to a useful outcome interpret and construct simple Sankey diagrams showing energy transfer calculate the cost of energy supplied by electricity use efficiency = (energy usefully transferred total energy supplied) 100% to calculate the efficiency of an electrical device or power station interpret and construct Sankey diagrams for various contexts including electricity generation and distribution, and use them to calculate efficiency of transfer

10 OCR 21st Century Science: P3 Checklist Aiming for Grade E Aiming for Grade C recall that mains electricity is produced by generators; and that a generator produces a voltage across a coil of wire by spinning a magnet near it explain how the voltage produced, and current supplied, by a generator can be increased; understand that a generator uses more primary fuel per second when it supplies a bigger current understand that electricity is convenient because it is easily transmitted over long distances and has many uses understand that in many power stations a primary energy source heats water, producing steam which drives a turbine coupled to an electrical generator; label a block diagram of the basic components of hydroelectric, thermal and nuclear power stations; understand that some renewable energy sources drive the turbine directly recall that nuclear power stations produce radioactive waste and that this emits ionising radiation; and describe some of the hazards of ionising radiation recall that electricity is distributed through the National Grid and that the mains supply voltage to our homes is 230 volts discuss methods of reducing energy use at home and at work describe advantages and disadvantages of different energy sources interpret information about energy sources for generating electricity and apply it to different situations understand that radioactive waste emits ionising radiation; and explain the difference between contamination and irradiation explain how the distribution of electricity through the National Grid at high voltages reduces energy losses discuss qualitatively and quantitatively the effectiveness of methods of reducing energy demand in a national context understand how different factors affect the choice of energy source for a given situation interpret and evaluate information about different energy sources for generating electricity, considering efficiency, economic costs and environmental impact

11 OCR 21st Century Science: P3 Sustainable energy P3 Exam-style questions Pages in the Student Book are exam-style questions. When and how to use these pages These questions are based on the whole of module P3 and cover a range of different types of questions that students will meet in their written exams. o The questions could be used as a revision test once you ve completed the module. o Work through the questions as a class as part of a revision lesson. o Ask students to mark each other s work, using the mark scheme provided. o As a class, make a list of the questions that most students did not get right. Work through these as a class. Notes on the worked example The worked example takes students through uses of electromagnetic radiation and the potential risks of X-rays. It also covers how people s perception of risk may differ from the actual risk, and whether or not the benefits of taking the risk outweigh the disadvantages. Assessment Objectives These exam-style questions cover the Assessment Objectives as described below. AO1 AO2 AO3 Assessment Objectives Recall, select and communicate their knowledge and understanding of science Apply skills, knowledge and understanding of science in practical and other contexts Analyse and evaluate evidence, make reasoned judgements and draw conclusions based on evidence Questions 1, 2, 3, 4, 5 worked example a 1, 2, 6, 7 worked example b, c 4, 6, 7 Answers These answers are also supplied on the Teacher Pack CD, so students can mark their own, or their peer s work. Question number Answer Additional notes Mark 1a Power = energy transferred time = J 60 s = 300 W b Power = voltage current The computer is less powerful than the microwave oven; the voltage is same (230 V) for both; so the computer does not use a larger current but a smaller current than the microwave oven. 1 mark for using correct values 1 mark for numerical answer, 1 mark for correct unit Equation given in data sheet a Energy = = 4.5 kwh b Cost = 16p 4.5 = 72p c The energy transfers to the surroundings

12 P3 Exam-style questions continued 3 2 = C; 3 = A; 4 = D; 5 = B 2 marks for 2 correctly numbered, 1 mark for 1 3 4a Efficiency is the proportion of energy converted to useful energy. b It will mean lower electricity bills. 1 c B; D 1 mark each A: radioactive; B: contaminated; C: is not; D: contamination 1 mark each 4 6 Wind farm: for it is a renewable, non polluting resource; each turbine is relatively cheap to produce; against it is unreliable/weather dependent; it takes up a lot of space and does not produce large amounts of electricity. Coal fired: for it is a reliable and relatively cheap source of energy; one power station can provide large amounts of energy; against coal-fired power stations emit greenhouse gases, contributing to global warming; resources are limited and large amounts of fuel need to be transported. Nuclear power: for it does not emit greenhouse gases; small amounts of fuel provide large amounts of energy reliably. against the problem of disposing of radioactive waste; safety precautions needed to reduce consequences of a nuclear accident are expensive. For 5 6 marks: Answer correctly describes arguments for and against each type of power station and comes to a consistent decision. All information in answer is relevant, clear, organised and presented in a structured and coherent format. Specialist terms are used appropriately. Few, if any, errors in grammar, punctuation and spelling. For 3 4 marks: Answer describes advantages and disadvantages of different power stations, and suggests one type with reasoning. For the most part the information is relevant and presented in a structured and coherent format. Specialist terms are used for the most part appropriately. There may be occasional errors in grammar, punctuation and spelling. For 1 2 marks: Answer makes limited statements for or against certain power stations; the reasoning may not be sound and the decision may not be the most appropriate choice. Answer may be simplistic. There may be limited use of specialist terms. Errors of grammar, punctuation and spelling may be intrusive. For 0 marks: Insufficient or irrelevant science. Answer not worthy of credit. 6 7a Bar chart correctly drawn. 2 marks for points correctly plotted 1 mark for correct labelling of axes. 1 mark lost per 2 points incorrectly plotted. b c Lights and any electrical heating not needed for such long periods during the summer months. The neighbour does not use as many electrical appliances as Matt s family. The neighbour uses more energyefficient equipment than Matt s family. The neighbour does not leave appliances on standby. The neighbour uses a different electricity supplier. Any 3 for 1 mark each 3 3 1

13 OCR 21st Century Science: P3 Sustainable energy p3_01 Energy sources 1 Primary and secondary energy sources Primary energy comes from natural resources. These are not processed, but are used in the form they are found in. Primary energy sources are used to produce secondary energy sources. These are often more convenient and portable. 1 Put the following sources of energy into the table. battery coal mains electricity ethanol (a processed biofuel) solar energy steam power uranium (a nuclear fuel) waves wind power wood Primary energy source Secondary energy source 2 Explain why you put these energy sources in these groups. 2 How we use energy sources Over the last century, there have been many changes in the way energy is used. Discuss your ideas about these changes in a group. 1 Make notes in the table on the next sheet to compare the energy use for a typical lifestyle now with a typical lifestyle about 120 years ago. Think in particular of changes relating to the use of electricity, transportation and manufacturing.

14 p3_01 Energy sources continued Use of energy 1890 Now Travel e.g. how people travel, how far they travel in their normal routine and for holidays Heating and cooking e.g. how we heat and cook in our homes Products e.g. where the goods and items we use are made, how far they travel, how often we replace items Leisure activities and communication 2 Use your table to write an explanation of why more energy and more types of energy are used now compared with the late 19th century. 3 Using fossil fuels Fossil fuels are an important energy source but they have disadvantages. Use your Student Book and other resources to write a report on: the advantages of using fossil fuels the disadvantages of using fossil fuels some ways to reduce the environmental impact of using fossil fuels

15 p3_02 Power OCR 21st Century Science: P3 Sustainable energy 1 What s the power? Look at the equipment your teacher has displayed. Write down the power of each piece of equipment in the table, in order of increasing power. Include the unit: W (for watts) or kw (for kilowatts) Write down the amount of energy transferred per second: 1 W = 1 J/s (joule per second) 1 kilowatt = 1000 J/s Equipment Power Energy transferred per second 2 Investigating power Set up the circuit shown here. Connect a bulb, a motor, a buzzer, or other equipment provided, where the diagram says equipment. Measure the current and voltage through each piece of equipment. Calculate the power. Equipment Voltage (V) Current (A) Power (W) 1 If the voltage remained the same, how did the current change as the power changed?

16 p3_02 Power continued 3 Calculating rate of energy transfer In each of these questions, select the correct equation to use. Always use the right units. power (W) = voltage (V) current (A) energy transferred (J) = power (W) time (S) energy transferred (kwh) = power (kw) time (h) 1 a) How much energy does a 100 W bulb transfer in 1 hour? b) Mains voltage is supplied at 230 V. What current flows through the 100 W bulb? c) How does the rate of energy transfer compare with that by a 20 W low-energy bulb? 2 a) How much energy does a 1.2 kw kettle transfer in 15 minutes? b) The voltage supplied to the kettle is 230 V. What current flows through it? c) How long would it take for a 1.8 kw kettle to heat the same mass of water by the same amount? 3 a) The energy used by a washing machine is 0.95 kwh per wash. Each cycle lasts 2 hours. What is the average power of the washing machine? b) Explain whether more energy is transferred by a 200 W fridge in a week, or by the washing machine used three times in that week.

17 OCR 21st Century Science: P3 Sustainable energy p3_03 Buying electricity 1 Transferring energy Look at the electrical equipment your teacher has displayed. They all transfer electrical energy to other forms of energy. Fill in the table to show: the useful energy transfer that takes place (state the type(s) of energy the equipment is designed to produce) the non-useful energy transfer that takes place (state the type(s) of energy produced that were not intended). An example has been done for you. Equipment Useful energy transfer From electrical energy to Non-useful energy transfer From electrical energy to Kettle the water as heat the surroundings as heat Think of three other pieces of equipment that use electricity and add them to the table. What do you notice about many of the transfers that are not useful?

18 p3_03 Buying electricity continued 2 Working out the energy used Write down the electrical equipment that is being used in the room during the lesson. Your teacher can tell you the power of the different pieces of equipment. Calculate the energy used by each piece of equipment in kwh. Equipment Time used (hours) Power (kw) Energy transferred (kwh) 3 Buying electricity Prepare an information leaflet for customers explaining: how to read their electricity meter how the readings are used to calculate the energy used how the bill is calculated Include diagrams showing the electricity meter and a typical bill.

19 OCR 21st Century Science: P3 Sustainable energy p3_04 Energy diagrams 1 Presenting data Here is some data about the energy used by a family in two different months. What the energy was used for Energy used in August Energy used in February Heating and cooking 450 kwh 700 kwh Lighting 120 kwh 150 kwh TV/computer/radio 50 kwh 100 kwh Washing and cleaning 180 kwh 250 kwh Total energy used 1 Work out the total energy used in each month. 2 Show the information on two different types of graph: a) a bar chart for each energy use show a bar for August and a bar for February b) a stacked bar chart for each month, draw one bar showing the total energy use, divided into sections for each type of use. 3 Explain which graph was better for comparing how energy the use differed in the two months Explain which graph was better for comparing the total energy use in August and in February....

20 p3_04 Energy diagrams continued 2 Interpreting Sankey diagrams Explain what energy transfers are taking place in each of these diagrams. Use a ruler to measure the thickness of each arrow, to work out the proportion (%) of input energy changed into the different output forms.

21 p3_04 Energy diagrams continued 3 Drawing Sankey diagrams Draw Sankey diagrams to represent these energy transfers. Make your input arrow 4 cm wide. 1 A fluorescent lamp changes 100 J of electrical energy into 25 J of light energy and 75 J of heat energy. 2 An electric drill changes 1000 J of electrical energy into 500 J of kinetic energy, 400 J of heat and 100 J of sound energy. 3 A battery-powered toy changes 40% of the input electrical energy into kinetic energy, 20% into sound energy and 40% into heat energy.

22 p3_05 Efficiency OCR 21st Century Science: P3 Sustainable energy 1 What is efficiency? efficiency = energy usefully transferred total energy supplied 1 Calculate the efficiency of each item in the table. Item Energy supplied / J Useful energy output / J Efficiency (as a decimal) Efficiency (as a percentage) Electric fan % Kettle % Washing machine % Diode lamp % Iron % Lamp % 2 Write the items in order most efficient first. 3 Explain why the useful energy output is always less than the energy supplied. 2 Reducing energy use at home Find out about Energy Performance Certificates, and prepare an information sheet for homeowners. This should explain: a) what an Energy Performance Certificate is and when it is needed b) what the Energy Performance Certificate shows c) how the information in the Energy Performance Certificate is obtained d) how a householder can use the Energy Performance Certificate to use energy more efficiently e) why Energy Performance Certificates are not always useful.

23 p3_05 Efficiency continued 3 Reducing our impact on the environment As the world s population increases, we must all use resources more carefully to reduce the impact on the environment. We have an impact when producing goods, transporting them, using them and disposing of them. Find out more about one area where scientists are reducing the impact of humans on the environment. This could be, for example: improvements in power stations the technical development in the use of renewable energy sources the design of more efficient engines in road vehicles and/or planes the design of more efficient electrical equipment. Produce a leaflet or poster. It should explain what environmental problem is being tackled and how scientists helped to develop a solution.

24 p3_06 Generators OCR 21st Century Science: P3 Sustainable energy 1 Investigating a generator Test the generator. Watch what happens to the bulb and to the current reading. 1 How did you make the bulb shine more brightly?. 2 How did you generate a larger current?. 3 Which part of the generator is moving?. 2 Generators in power stations Didcot has two power stations: Didcot A uses crushed coal, a small amount of biomass and natural gas to power its generators. Didcot B uses just natural gas. The maximum capacity from Didcot A and B together is 3360 MW of electrical power. Each generator produces between 225 MW and 500 MW of power. The generators at Didcot A are huge the rotors that spin weigh 74 tonnes (about the same as 74 small cars). The rotors at both Didcot A and B are strong electromagnets. These are surrounded by stators (which do not turn), in which the generated current flows. Each stator is a series of hollow insulated copper bars. The electricity produced in the stators is at a voltage of to V. 1 Which primary fuels are used to power Didcot power stations? 2 Describe the structure of the generators. 3 Explain how the amount of primary fuel used by Didcot power station varies as the voltage it produces varies. 3 Regulating electricity production The electricity industry is regulated very carefully. Regulations apply to all companies that generate, transmit and supply electricity. This provides advantages to different groups of people such as customers and business users, electricity workers and local residents. Some aspects that are regulated are: how electricity is produced and supplied the type and design of power stations health and safety the price of electricity. Find out some of the benefits of regulations in the electricity industry. Produce a brief information sheet explaining some of these benefits.

25 OCR 21st Century Science: P3 Sustainable energy p3_07 How power stations work 1 How a generator is made to spin Cut out these sentences and stick them in the correct order to describe how a generator is made to spin. The turbine is connected to a generator. The water changes to steam. Primary fuels heat water in a power station. The generator spins to generate electricity. The steam is sent through pipes to spin a turbine.

26 p3_07 How power stations work continued 2 The structure of power stations 1 This represents a coal-fired power station. Label the parts of the diagram with the following labels, completing the job description of each part. Boiler This is where Generator Its job is Cooling tower Its job is Turbine Its job is Pipes Their job is Furnace This is where 2 This represents a hydroelectric power station. Label the parts of the diagram with the following labels, completing the job description of each part. Outflow Its job is Generator Its job is Dam Its job is Turbine Its job is Pipes Their job is Reservoir Its job is

27 p3_07 How power stations work continued 3 Which type of power station? 1 The diagram represents a nuclear power station. Label the parts with the following labels, and add a short job description of each part. reactor fuel rods control rods boiler turbine generator 2 a) Think about the different types of power station you have learned about: coal-fired, gas-fired, nuclear and hydroelectric. Describe the features that are identical. Describe the features that are similar. Describe the features that are different. b) Suggest a situation in which one of the types of power station could be considered advantageous, and explain why.

28 OCR 21st Century Science: P3 Sustainable energy p3_08 Waste from power stations 1 Dealing with radioactive waste Use your Student Book page 284 to decide whether these statements are true or false. Tick the correct column. Statement True False Most radioactive waste is thrown out with household rubbish. Over time, radioactive waste becomes less radioactive. It is safe to store radioactive waste in warehouses. Some radioactive waste is recycled and reused. Radioactive waste emits ionising radiation. All radioactive waste is highly dangerous. 2 Irradiation and contamination Contamination and irradiation occurs not only with radioactive waste but in some everyday situations. 1 State whether each of these situations is an example of contamination or irradiation. For each, suggest how to prevent or reduce the contamination or irradiation, or its effects, and why this will help. a) Putting diesel into a car that runs on petrol. b) Exposure to sunlight. c) Standing close to a bonfire. 2 Explain why contamination may be more dangerous than irradiation.

29 p3_08 Waste from power stations continued 3 Understanding risks People do not always estimate risks correctly. They are likely to overstate unfamiliar risks and understate familiar risks. Prepare a questionnaire to use with other people of your age to find out how they estimate risks. Ask them to: rank the causes of death listed below from most likely (1) to least likely (8) say how likely it is that this that people will die from this cause. One way to give an answer to how likely is 1 per 200 deaths, for example. This means that if you look at the causes of death for 200 people, 1 person will have died from this cause. A less likely cause of death could cause 1 death per , for example. Causes of death Accident at work Accident on road Influenza (flu) Release of radiation from nearby nuclear power station Playing football Smoking 10 cigarettes per day Accident at home hit by lightning Your teacher will tell you the actual risks of these things causing death. Explain why you think some people assessed some of these as more, or less, risky than they actually are.

30 OCR 21st Century Science: P3 Sustainable energy p3_09 Renewable energy sources 1 Investigating a solar panel Use the practical sheet to find out about the effect of radiation on solar panels. 2 Pros and cons of renewable energy sources Produce a report about the advantages and disadvantages of renewable energy sources. Include information about: solar energy hydroelectricity wind power wave energy tidal energy. For each of these state where it can be used, what the benefits are and what the problems and environmental impacts are. 3 Unintended consequences Sometimes new technologies have results that are unexpected these are called unintended consequences. The British Government is encouraging the construction of offshore wind farms to help to reduce the use of fossil fuels for electricity generation. There are advantages but also disadvantages, some of which are unexpected. Find out some of the unintended consequences of using offshore wind farms, and explain them. Try an internet search for offshore wind energy. You might want to find out about cost, engineering problems, reliability, maintenance, environmental impact. Here is some data you can use to start with. Investment costs per kw of electricity produced Cost of generating electricity per kwh Lifetime of structures Other factors Offshore Around 1200 depending on the site 4p 8p Depends on conditions offshore Expensive to connect to the National Grid As technology develops, more challenging sites can be used, increasing installation costs but increasing output Onshore p 7.5p Expected to be years Noise considerations can affect maximum usage Limited number and size of suitable sites on land

31 OCR 21st Century Science: P3 Sustainable energy p3_10 The National Grid 1 The National Grid On A4 paper draw a large, simple block diagram showing the parts of the National Grid. Label the parts: power station power cables substation 1 pylon substation 2 Cut out these boxes and stick them onto your diagram by the correct parts. Increases voltages to thousands of volts Supports power cables Generates electricity Carries electricity from power stations to homes Reduces voltages to safe levels 2 Voltages in the National Grid Complete these labels and add them to your diagram in appropriate places, to explain why the voltages are different in different parts of the National Grid. Making the voltage even higher, about V, reduces the current, so reducing the.. The voltage is reduced for use in homes to the very much lower level of. V Electricity is generated at about V

32 p3_10 The National Grid continued 3 Energy losses in the National Grid Use the Sankey diagram to answer these questions. 1 Explain in as much detail as possible what the Sankey diagram shows. 2 Calculate the efficiency of the power station when generating electricity. 3 Calculate the efficiency of the transmission lines. 4 Describe how the energy losses may be reduced.

33 OCR 21st Century Science: P3 Sustainable energy p3_11 Choosing the best energy source 1 Advantages and disadvantages of energy sources Use Student Book page 290 to decide on advantages and disadvantages of different energy sources. Tick the columns that the advantages/disadvantages apply to. Advantage Fossil fuels Nuclear fuels Wind power Energy from water Solar energy Large amounts of electricity are generated No greenhouse gases are released The energy source is free when used The energy source will not run out Disadvantage Fossil fuels Nuclear fuels Wind power Energy from water Solar energy The energy source is weatherdependent Extracting the fuels is dangerous Only some sites are suitable Using the fuel produces greenhouse gases Extracting and using the fuel causes pollution The waste is radioactive Causes large-scale flooding

34 p3_11 Choosing the best energy source continued 2 Choosing an energy source You need to choose the most suitable energy source for a particular situation. Discuss the important factors in your group, and carry out more research if necessary. Use the information to back up your argument. Factors to consider for each situation: possible energy sources the best energy source main reasons why this would be best the impact on different groups of people what information supports this. Situation 1 A small, hilly island about 30 miles north of mainland Scotland in the North Sea. The population of 1000 people mainly lives in one small town. Supplies come in by boat once a week. The coastline is rocky, and the weather is very stormy during winter months. Situation 2 A city in the Midlands, England, with residents. The area is well served by rail, road and river links. The surrounding countryside is flat there are no large hills or mountains in the region. 3 Comparing power stations Use the internet to find: the expected cost of building a new power station information about running costs of the power station what is included in the figures anything that makes the data difficult to interpret or to compare with other data There is information available for coal-fired, gas-fired and nuclear power stations. Hint for searching: Choose the Google option pages from the UK to get data for the UK. Present what you find out as an information sheet.

35 OCR 21st Century Science: P3 Sustainable energy p3_12 Dealing with future energy demand 1 Can we reduce energy demands? Several people have been asked if they can help to reduce the country s energy demands, and so its carbon dioxide emissions. Each person can help in some way, so prepare a reply for each one, suggesting one or two changes they can make. 1 I live alone and I don t use much electricity so I can t do anything that will help. 2 In my shop, we use lots of electricity on heating and lighting. We always try to keep the shop comfortable for customers. What we do won t make much difference. 3 I work in a factory manufacturing clothes. My manager s asked us for suggestions on how to save energy but can we really make a difference? 4 My job is designing cars. People want fast cars so I can t see how we can change anything to help

36 p3_12 Dealing with future energy demand continued 2 How should we reduce emissions? Decide whether you agree strongly, agree, disagree or disagree strongly with these statements. Be prepared to explain why you chose each response. 1 All countries should reduce their greenhouse gas emissions. Why? 2 Countries should all reduce their greenhouse gas emissions by the same percentage. Why? 3 It is acceptable if countries with growing populations produce increasing amounts of greenhouse gases. Why? 4 People in industrialised countries should be able to keep their standard of living high, even if this means increased greenhouse gas emissions. Why? 5 People in developing countries should be able to improve their lifestyle, even if this means increased greenhouse gas emissions. Why? Agree strongly Agree Disagree Disagree strongly 3 How can we achieve a secure energy supply? Look at your notes, the Student Book and carry out additional research if you need to. Design a combination of energy sources you think would give an ideal mix for the UK. Choose from the following: coal oil gas nuclear fuel wind hydroelectricity geothermal energy solar energy tidal energy Suggest a percentage for each of your chosen sources, as a proportion of the total energy supply. Explain your reasons.