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Generating Electricity 5 Syllabus Specifications 3.2 d Sankey diagrams to show energy transfers; energy efficiency in terms of input energy in terms of input energy and energy usefully transferred in a range of contexts including electrical power generation and transmission. % 𝒆𝒇𝒇𝒊𝒄𝒊𝒆𝒏𝒄𝒚 = 𝒆𝒏𝒆𝒓𝒈𝒚 𝒑𝒐𝒘𝒆𝒓 ) 𝒖𝒔𝒆𝒇𝒖𝒍𝒍𝒚 𝒕𝒓𝒂𝒏𝒔𝒇𝒆𝒓𝒓𝒆𝒅 𝒕𝒐𝒕𝒂𝒍 𝒆𝒏𝒆𝒓𝒈𝒚 𝒑𝒐𝒘𝒆𝒓 𝒔𝒖𝒑𝒑𝒍𝒊𝒆𝒅 𝒙 𝟏𝟎𝟎 Calculating efficiency Example 25 J light 100 J electrical 75 J Heat Energy circus • Find the efficiencies of 5 common appliances • You have 1 minute at each station. Sankey diagrams can be drawn to scale e.g. An energy efficient light bulb produces 7J of light for every 10J input. 10 Joules electrical energy input 7 squares = 7 joules – light energy 3 squares = 3 joules – heat energy 1 square is 1 joule of energy Efficiency 1 5 Complete this Sankey diagram for a coal fired power station Energy In: 100 % Chemical Hair dryer 100 % electrical 50 % kinetic 40 % heat 10 % sound Draw Sankey diagram Energy Out: 40 % Electrical 50 % Heat 10 % Sound Answer 2 TV Energy transferred = power x time kilowatt hours kilowatts hours How efficiency is the hair dryer? Answer 6 Lamp Label the energy The TV is rated at 900 Watts How much will it cost to watch it for 2 hours? ( 1 kilowatt hour = 20p) 3 Toy Efficiency = Energy usefully transferred x 100 Total energy supplied How efficient is this toy? 4 Heater Elastic potential = 200 Joules Sound = 30 Joules Heat = 70 Joules Movement = 100 joules This heater is rated at 3 kilowatts It is turned on for 3 hours How much does it cost? Mains electricity is 230 V Calculate the current Power = voltage Watts Volts x current Amps Calculate the efficiency Answer Answer Percentage Decimal 7 Radio Answer Energy in: 200 Joules electrical Answer Energy out: 40 Joules - light 80 Joules - sound 80 Joules - heat Draw a Sankey diagram Energy splat! 1 Kinetic energy Heat energy Gravitational potential energy Electrical energy Chemical energy Light energy What is the useful energy ? Energy splat! 2 Kinetic energy Heat energy Gravitational potential energy Electrical energy Chemical energy Light energy What is the useful energy? Energy splat! 3 Kinetic energy Heat energy Gravitational potential energy Electrical energy Chemical energy Light energy What is the useful energy produced in the moving air? Energy splat! 4 Kinetic energy Heat energy Gravitational potential energy Electrical energy Chemical energy Light energy What type of energy is generated from a wind turbine? Energy splat! 7 Kinetic energy Heat energy Gravitational potential energy Electrical energy Chemical energy Light energy What type of energy is generated? Energy splat! 8 Kinetic energy Heat energy Gravitational potential energy Electrical energy Chemical energy Light energy What type of energy is used up by the kettle? Energy splat! 9 Kinetic energy Sound energy Gravitational potential energy Electrical energy Chemical energy Light energy What type of energy is generated? Energy splat! 11 Kinetic energy Heat energy Gravitational potential energy Electrical energy Chemical energy Light energy What type of energy is stored in the match? Energy splat! 12 Kinetic energy Heat energy Gravitational potential energy Electrical energy Chemical energy Light energy An object high above the Earth has lots of this type of energy! Energy splat! 13 Kinetic energy Heat energy Gravitational potential energy Electrical energy Chemical energy Light energy What type of energy does coal contain? Energy splat! 14 100 joules 75% 20% 50 joules 200 joules 1,000 joules 150 J light 200 J in What is the efficiency 50 J in Energy splat! 15 100 joules 25 joules 20% 50 joules 200 joules 1,000 joules 300j light 500j in How much waste energy? ?? j waste