Renewable Energy Physics What is Energy Energy is
Renewable Energy Physics
What is Energy? Energy is needed to make things happen Energy can be useful in 5 different forms: heat, light, sound, movement and electrical energy. Energy can be stored in various ways: Type of energy store examples
What is Energy? Energy is needed to make things happen Energy can be useful in 5 different forms: heat, light, sound, movement and electrical energy. Energy can be stored in various ways: Type of energy store examples Chemical energy Gravitational potential energy Mechanical potential energy Nuclear or atomic energy (the word “potential” means stored. )
What is Energy? Energy is needed to make things happen Energy can be useful in 5 different forms: heat, light, sound, movement and electrical energy. Energy can be stored in various ways: Type of energy store examples Chemical energy Food, fuels, batteries Gravitational potential energy Water up high Mechanical potential energy Wind up toy, stretched string Nuclear or atomic energy Inside the nucleus of atoms (the word “potential” means stored. )
Conservation of Energy “ Energy is never created or destroyed, it is only changed from one form into another ” This is called the Law of Conservation of Energy. (Conservation means “kept the same”)
Energy Units Energy is measured in joules: 1000 J = 1 kilojoule = 1 k. J 1, 000 J = 1 megajoule = 1 MJ 1, 000, 000 J = 1 gigajoule = 1 GJ
Energy to Power the Planet We use natural sources of energy to make everything on Planet Earth happen. These sources of energy can be split into 2 types: Non-renewable sources – These will run out Renewable sources of energy – These will not run out.
Non-renewable sources of Energy Fossil Fuels are our main sources of energy on the planet The 3 fossil fuels are coal, oil and natural gas They are the fossilised remains of living things that died millions of years ago Fossil fuel Formed from Found coal Trees Under the ground oil Shelled sea creatures Under land sea Natural gas Shelled sea creatures Under land sea Formation of fossil fuels video: watch
Fossil fuels – The Problem Fossil fuels are running out. Once they are used up there will be none left. But there is a bigger problem: Burning fossil fuels produces greenhouse gases like carbon dioxide. These gases are causing the planet to trap the suns heat. This can cause: the polar ice to melt The planets temperature to increase global warming
Thermal Power Stations
Thermal (Heat) Power Stations It’s only the source of the heat that is different - the Fuel! The fuel is either: Fossil fuels: coal , oil , gas burned in a furnace (or Nuclear fuel: Uranium in a nuclear reactor)
Energy Changes in a power station Furnace boiler Turbine generator Chemical to Heat to kinetic Kinetic to electrical
Renewable Energy Sources Source Type of renewable How energy is captured energy wind Wind Power Wind turbines sun Solar Power Solar Cells and Solar Panels waves Wave Power Wave generators water Hydroelectric Power Dams store rain water up high Earths core Geothermal Heat from the centre of the Earth plants Using plants /trees for fuels Biofuels BBC Bitesize activity
Renewable Energy video clips Windpower http: //www. youtube. com/watch? v=ts. ZITSe. QFR 0 Solarpower http: //www. youtube. com/watch? v=0 elh. Ic. PVt. KE Wavepower http: //www. youtube. com/watch? v=90 Acxxwo. Pu 0 Hydroelectric http: //www. youtube. com/watch? v=tpig. NNTQix 8 Biomass http: //www. youtube. com/watch? v=ck 3 FYVNl 6 s Geothermal http: //www. youtube. com/watch? v=C 18 Eg_IZWME
Hydroelectric Power
Potential to Kinetic energy Water up high has gravitational potential energy Ep =mgh m =mass in kilograms (kg) g = Earth gravity = 9. 8 Nkg-1 h = height in metres (m) As the water runs downhill it changes to kinetic energy. m =mass in kilograms (kg) v = speed or velocity (ms-1)
Ep to Ek example 20, 000 kg of water flows through a hydroelectric power station each minute. The water falls from a dam at a height of 45 m into a loch at the bottom (a) How much potential energy does the water have up in the dam? (b) How much kinetic energy will it have at the bottom of the pipe? (c) What speed will the water be travelling at at the bottom? (a) Ep =mgh = 20000 x 9. 8 x 45 = 8, 820, 000 J (b) 8, 820, 000 J (c) Ek =1/2 mv 2 8, 820, 000 = 10, 000 v 2 = 882 v = 29. 7 ms-1
Wind Power
Nuclear Power In a nuclear reactor atoms of uranium are split and large amounts of energy are released.
Nuclear bombs A nuclear or atomic bomb is a chain reaction that happens very quickly. Huge amounts of heat and light energy are released in a fraction of a second. Atomic bombs were dropped on Japan at the end of the second word war Video 1 video 2 video 3 Tsar Bomb
Nuclear Power how it works mousetraps
Nuclear Reactor – how it works The fuel rods contain the uranium fuel element The control rods move up and down to control the speed of the chain reaction. The moderator slows the neutrons down to increase the chance of splitting uranium atoms The whole reactor is protected by a concrete shield called a containment vessel. Cold fluid is pumped in at the bottom and hot fluid comes out at the top. This heat is used to make steam to turn a turbine.
Efficiency is a measure of how good a machine is at transferring energy from its input to its output. Input energy % Efficiency machine = energy out energy in Output energy x 100
Power P = power in watts (W) E = energy in joules (J) t = time in seconds (s)
Efficiency and power Efficiency is also a measure of how good a machine is at transferring power from its input to its output. Input power (in watts) % Efficiency machine = power out power in Output power (in watts) x 100
Efficiency example A model steam engine uses 2400 J of chemical energy from the solid fuel it uses. It produces 480 J of useful energy at its output. What is the efficiency of the steam engine. Efficiency = (energy out/ energy in) x 100 = (480/ 2400) x 100 = 20% (80% of the input energy is wasted or “lost” to the atmosphere)
Efficiency and power lines No machine or system is 100% efficient. Energy is always wasted or “lost” at each stage in a process (as heat to the atmosphere) Most energy losses in electrical systems occur in transporting energy across the country: “The National Grid” The National grid is the network of power lines that carry energy across the whole country
The Grid system Transformers are used at the power station end to “step up” the generated electricity to a voltage suitable for sending over large distances. This high voltage electricity has to be “stepped down” again when it reaches towns and cities. Eventually it is stepped down to the correct voltage at your house (230 V)
The Transformer A transformer is made of 2 coils of wire wound on either side of an iron core. It’s the number of turns on each coil that determines how the voltage is stepped up or stepped down.
Without transformers Electricity has to be sent at a high voltage, low current. This stops the long wires heating up and energy being wasted. Without transformers no energy would get to the other end.
Book questions Progressive Problems P. 114 -116 Q 1 -12 Progressive Problems P 117 Q 1 -7
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