hydroelectricity and tidal barrage

• Hydroelectric dams


  Systems that generate electrical power by using the difference in water levels caused by a dam
• Tidal barrages


  Systems that generate electrical power by using the difference in water levels caused by tides
• Hydroelectric dams and tidal barrages


  Work in basically the same way
• How hydroelectric dams work

  1. Trap water that has come from upstream

  2. Prevent water from continuing its journey to the ocean

  3. Accumulate a huge amount of water in a reservoir
• How tidal barrages work

  1. Make use of tides, the cyclic rise and fall of sea levels due to the moon's gravity

  2. Trap water as the tide comes in

  3. Have a much higher water level on one side of the dam than the other when the tide goes back out
• Gravitational potential energy


  The difference in water levels is used to generate electricity
• How electricity is generated

  1. The force of the water released from the reservoirs spins the blades of turbines

  2. The turbines are connected to generators that generate electricity as they spin

  3. The water flows back into the river on the other side of the dam
• Pros of hydroelectric dams and tidal barrages

  • Generate large amounts of energy with no pollution
  • Reliable sources of electricity
  • Hydroelectric dams can provide an immediate response to increased demand
  • Running costs are fairly low
  • Can work on both large and small scales
• Cons of hydroelectric dams and tidal barrages

  • Big impact on the surrounding environment
  • Hydroelectric dams often flood huge areas, submerging important habitats and sometimes whole villages
  • Can stop boats and fish from traveling up or down the river, negatively affecting fish migrations
  • Initial setup is often expensive