Physics 1.4

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Fossil Fuels

  • Formed from the remains of living organisms
  • Main fossil fuels: gas, oil and coal
  • Non-renewable
  • Generating Electricity
    • There is chemical energy in fossil fuels which are burnt
    • The chemical energy transfers to heat energy which is used to boil water
    • This produces steam which contains kinetic energy which is used to turn a turbine  
    • The turbine is connected to a generator which transfers kinetic energy into electrical energy
  • Start-up time
    • How long it takes for a power station to produce electricity
    • Gas has the shortest start-up time, followed by oil and coal
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Advantages and Disadvantages of Fossil Fuels

  • Advantages
    • Relatively cheap
    • Produce a lot of electricity
    • Reliable energy
  • Disadvantages
    • Non-renewable
    • Releases carbon dioxide which contributes to climate change
    • Coal can release sulphur dioxide which leads to acid rain
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Carbon Capture

  • New technology and is advancing rapidly
  • Carbon dioxide is capured before being released into the air
  • It is pumped underground and stored
  • Old oil and gas fields could be used to trap carbon dioxide
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Biofuels

  • Comes from plants, which we can get energy out of, eg wood
  • Generating Electricity
    • Trees convert light energy into chemical energy during photosynthesis
    • When the wood is burnt, the chemical energy transfers into heat energy
    • The heat energy is used to boil water, which produces steam
    • The kinetic energy in high pressure steam is used to turn a turbine
    • The turnine is conntected to a generator which transfers kinetic energy into electrical energy
  • Advantages
    • Renewable
    • Carbon neutral
    • Reliable
  • Disadvantages
    • Destructive to habitats
    • Land could be used to grow crops
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Hydroelectric Power

  • Uses moving water - usually the flooding of a valley by building a big dam
  • Generating Electricity
    • Gravitational potential energy of water behind the dam transfers into kinetic energy and it flows out of the dam
    • The moving water passes through a turbine so there is then kinetic energy 
    • The turbine is connected to an electrical generator so there is electrical energy
  • Advantages
    • Renewable
    • Short start-up time
    • No carbon dioxide produced
    • Reliable
  • Disadvantages
    • Expesive to build dams
    • Destructive to wildlife habitats
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Wave Power

  • Generating Electricity
    • Kinetic energy of waves forces air up and down the column
    • This drives the turbine connected to the generator, electrical energy is produced
  • Advantages
    • Renewable
    • Doesn't produce carbon dioxide
  • Disadvantages
    • Not reliable
    • Noisy - affects wildlife
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Tidal Power

  • Creating a tidal barrage across an estuary
  • During high tide the barrage is open, allowing water to fill the estuary
  • At low tide, the water is allowed to flow through the turbines, generating electricity
  • Advantages
    • Renewable
    • Reliable - two high tides a day
    • No carbon dioxide produced
    • Could be used as a bridge
  • Disadvantages
    • Expensive
    • Destructive to wildlife habitats
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Wind Power

  • Generating Electricity
    • Blades are made to turn by the wind
    • Kinetic energy of wind is transfered to the kinetic energy of the blade
    • Blades are connected to a turbine which is connected to a generator which generates electricity
  • Advantages
    • Renewable
    • No carbon dioxide produced
    • Could generate a lot of electricity in the UK
  • Disadvantages
    • Unreliable - backup power stations needed
    • Noisy
    • Unsightly
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Solar Power

  • Generating Electricity
    • Solar cells convert light energy into electrical energy
  • Advantages
    • Renewable
    • No carbon dioxide produced
  • Disadvantages
    • Unreliable - if conditions are cloudly or at night
    • Backup power stations needed
    • Expensive
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Geothermal Power

  • Useful in volcanic areas eg Iceland
  • Generating Electricity
    • Steam and hot water rise to the surface and are used to drive a turbine connected to a generator and generate electricity
    • Kinetic energy of steam is transfered into kinetic energy of the turbine then  electrical energy in the generator
  • Advantages
    • Renewable
    • No carbon dioxide produced
    • Remaining hot water can provide heat for homes
  • Disadvantages
    • Can only be used in certain places
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Nuclear Power

  • Generating Electricity
    • Nuclear reactors contain fuel rods of uranium or plutonium
    • The uranium/plutonium undergo nuclear fission releasing heat energy
    • The heat energy is used to convert water into steam
    • The kinetic energy of the steam is used to drive a turbine which is connected to a generator and generates electricity
  • Advantages
    • No carbon dioxide produced
    • Reliable
  • Disadvantages
    • Not renewable
    • Very dangerous radioactive waste
    • Expensive to build and decomission a nuclear power station
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Matching Electricity Supply

  • When a powerstation is switches on, it takes time before any electricity is generated - startup time
  • Pumped-Stroage
    • During periods of low-demand (night), spare electricity is used to pump water into the top reservoir
    • During periods of high-demand, the water flows downhill through turbines connected to generators
    • We have to put in more electricity at night than we get out during the day
    • It is a way to store energy
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The National Grid

  • The National Grid consists of a system of transformers and high-voltage cables
  • Energy is always lost in the power cables. The bigger the distance between the power station and the homes the greater the energy loss
  • Energy loss can be reduced by buidng power stations near to homes
  • Transformers
    •  Electricity passes through a step-up transformer, which increases the voltage to several hundred thousand volts
    • Less energy is lost in the power cables at high voltages than at low voltages
    • The electricity passes through step-down transformers which reduce the voltage to several hundred volts
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Overhead Transmission Cables

  • Overhead Powerlines
    • Advantages
      • Cheap to install and repair
      • Easy to access for maintainance
      • Do not need to be electrically insulated
      • Heat produced is releases into air
  • Disadvantages
    • Visual pollution
    • Can be damaged by poor weather
    • Dangerous to low-flying aircraft/helicopters
    • Higher risk of electrical shock
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Underground Transmission Cables

  • Underground Power Lines
  • Advantages
    • No visual pollution
    • Not a danger to aircraft
    • Less affected by poor weather
  • Disadvantages
    • Expensive to install
    • Difficult and expensive to access and repair
    • Heat cannot escape so needs to be cooled
    • Land cannot be used along the pathway of the cable
    • Cable needs electrical insulation
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