P3 - Energy resources

• Energy demands


  How most of your energy demands are met today
• Energy resources used


  • Nuclear
  • Hydroelectricity
  • Other renewables

  
• Nuclear fuels


  Used in power stations

  
• Fuels used to generate electricity

  • Fossil fuels
  • Nuclear fuels
  • Biofuels
• Most of the energy you use comes from burning fossil fuels, mostly gas or oil or coal
• The energy in homes, offices, and factories is mostly supplied by gas or by electricity generated in coal or gas-fired power stations
• Oil is needed to keep road vehicles, ships, and aeroplanes moving
• Burning one kilogram of fossil fuel releases about 30 million joules of energy
• You use about 5000 joules of energy each second, which is about 150 thousand million joules each year
• Because of the inefficiencies in how energy is distributed and used, a staggering 10000 kg of fuel is used each year to supply the energy needed just for you
• Sources of energy in 2013

  • Fossil fuels
  • Nuclear
  • Hydroelectricity
  • Other renewables

  
• Fossil fuels and nuclear fuel are non-renewable because they can not be replaced
• The use of fossil fuels and nuclear fuel is causing major environmental problems and increasing the levels of greenhouse gases, such as carbon dioxide, in the atmosphere
• Some of the electricity you use is from renewable energy resources such as wind energy, hydroelectricity and solar energy

  
• How electricity is generated in coal- or oil-fired power stations, and in most gas-fired power stations

  1. Burning fuel heats water in a boiler

  2. Steam drives a turbine that turns an electricity generator
• Fossil fuels


  Fuels that come from long-dead animals and plants
• Biofuel


  Any fuel taken from living or recently living organisms
• Biofuel


  • Renewable because its biological source either regrows (vegetation) or is continually produced (sewage and rubbish)
  • Carbon-neutral because the carbon taken in from the atmosphere as carbon dioxide can balance the amount released when the biofuel is burnt
• Nuclear fuel


  Uranium (or plutonium) in sealed cans in the core of the reactor
• How nuclear power stations generate electricity

  1. Uranium fuel is unstable and can split, releasing energy

  2. Energy from the core is transferred by a coolant fluid

  3. Coolant heats water to steam which drives turbines that turn electricity generators

  
• Ethanol


  A biofuel
• Carbon-neutral fuel


  The carbon taken in from the atmosphere as carbon dioxide can balance the amount released when the fuel is burnt
• Strong winds can cause lots of damage on a very stormy day
• Even when the wind is much weaker, it can still turn a wind turbine
• Renewable energy


  Energy from natural sources such as wind, waves and tides that can never be used up because they are always being replenished by natural processes

  
• No fuel is needed to produce electricity from renewable energy sources, so they are carbon-free to run
• Wind turbine


  An electricity generator at the top of a narrow tower, driven by the force of the wind
• The power generated by a wind turbine increases as the wind speed increases
• Wind turbines are unreliable because when there is little or no wind they do not generate any electricity
• Wave generator


  Uses the waves to make a floating generator move up and down, turning a generator to generate electricity
• Wave generators need to withstand storms, and they don't produce a constant supply of electricity
• Lots of cables (and buildings) are needed along the coast to connect the wave generators to the electricity grid, which can spoil areas of coastline
• Tidal flow patterns might also change, affecting the habitats of marine life and birds
• Hydroelectricity


  Generated when rainwater collected in a reservoir (or water in a pumped storage scheme) flows downhill, driving turbines that turn electricity generators
• Tidal power station


  Traps water from each high tide behind a barrage, then releases it through turbines to drive generators
• The Severn estuary is a promising site for a tidal power station in Britain because it rapidly becomes narrower as you move up-river away from the open sea, funnelling the incoming tide and making it higher
• In some coastal areas, electricity is generated by the tidal flow passing through undersea turbines on the sea bed, with underwater cables connecting them to the national grid

  
• Pumped storage scheme


  Where water is pumped uphill to a reservoir when electricity demand is low, then released downhill through turbines to generate electricity when demand is high
• The main benefit to electricity users of a pumped storage scheme is that it can provide electricity quickly when demand is high
• Solar cells


  Convert solar energy into electrical energy