Water power: Falling water

Hydroelectricity is essentially using water falling downhill to turn turbine generators as it flows past. Building a dam is a great way to boost the water's generating power. A enormous wall of concrete, usually built across a river valley, traps the river water behind it, which builds up into a giant reservoir creating huge water pressure to spin the turbines.

What could seem less polluting and environmentally friendly than
water? Building a dam is such a huge engineering task that it can
have big consequences for everything and everyone living both
upstream and downstream of it.

• Dams and greenhouse gases
• Dams and risk
• Case study: The Three Gorges Dam, China
  

Dams and greenhouse gases