Water / hydroelectricity

• Like wind power we have been harnessing the power of moving water for many years. Hydroelectrical schemes use a dam to block a river

  
• Once sufficient water has built up behind the dam, it's stored in a reservoir and it can be channelled through turbines that are used to turn generators for producing electricity

  
• The main cost is the building of the dam, but it has the advantage that as the water is held, electricity can be produced very quickly by opening valves that control the flow to the turbines

  
• The environmental effects are from the flooding of a valley and reducing the water flow below the dam that can affect the growing of crops and river ecosystems