Unit 1.2

• 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

  2. Heat turns water to steam

  3. Steam moves through pipes to turbine

  4. Turbine turns generator

  5. Electricity generated and supplied to National Grid

  6. Steam cooled and sent back to furnace
• Advantages of renewable energy sources

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

  • Low power output
  • Unreliable - dependent on 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
  • 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
• To meet sudden 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, increasing the grid's efficiency
• Step down transformer


  Lowers voltage to a safer level
• Non-renewable energy resources

  1. Oil
  2. Gas
  3. Nuclear
  4. Coal
• Renewable energy resources

  1. Solar
  2. Wind
  3. Hydro
  4. Tidal
  5. Waves
  6. Biomass
  7. Geothermal
• Energy transferred by heating

  • Conduction
  • Convection
  • Radiation