Generating Electricity

• Renewable energy


  A source of energy which is not going to run out
• Efficiency


  Calculated using the equation: % efficiency = energy usefully transferred x 100% / total energy supplied
• You do not need to remember the efficiency equation, it will be on the equation sheet, but it is important to choose the correct values for the equation
• Useful energy


  The energy you want to use from the power station
• Energy supplied

  The energy put into the power station
• Non-renewable energy


  A source of energy which is going to run out
• Thermal power station


  1. Heat is created in the furnace by burning a fuel, or a nuclear reaction in nuclear power

  2. This heat turns water to steam which moves through the pipes to the turbine

  3. This turns the turbine which in turn turns the generator

  4. This generates electricity which is supplied to the National Grid

  5. The steam is cooled and sent back to the furnace to be heated again
• Advantages of renewable energy sources

  • Renewable
  • No waste or pollution
• Disadvantages of renewable energy sources

  • Low power output
  • Unreliable - dependent on the weather
  • Considered unsightly
• Advantages of non-renewable energy sources

  • Reliable
  • Large power output
• Disadvantages of non-renewable energy sources

  • Non-renewable
  • Produce greenhouse gases
  • Cause acid rain (mainly with coal)
• Advantages of nuclear power

  • Reliable
  • Large power output
  • No greenhouse gases
• Disadvantages of nuclear power

  • Non-renewable
  • Long start up time
  • Produces radioactive waste which must be stored for a long time
  • Expensive to commission and decommission
• Advantages of hydroelectric power

  • Renewable
  • Reliable
  • Short start up time
  • No waste or pollution
• Disadvantages of hydroelectric power

  • Not many suitable places for this power station
  • Must flood a large area which affects wildlife
• Advantages of tidal power

  • Renewable
  • No waste or pollution
• Disadvantages of tidal power

  • Must flood a large area which affects wildlife
• Advantages of biomass


  • Renewable
  • Reliable
  • Carbon neutral
• Disadvantages of biomass


  • Uses a lot of crops which require a lot of land to grow
• National Grid

  A network of cables which connects every power station to every home, shop, factory, school, hospital and every other consumer
• Demand for power changes

  Due to the seasons, weather and time of day
• At the end of a popular TV programme

  There is a sudden demand for electricity as people put their kettles on at the same time
• To meet this demand

  The National Grid switches on extra hydroelectric power stations or buys extra electricity from abroad
• Step up transformer


  Increases the voltage, which reduces the current and lowers heat losses in the cables. This increases the grid's efficiency.
• Step down transformer

  Lowers voltage to a safer level