Hydropower uses the energy of flowing water. They do this by having reservoirs filled with water, when they want to access the water it is released downwards into tubes that lead to a turbin. The movement energy from the turbine, and some added pressure around it, drives the turbine around. The turbine is further connected to a generator that creates electric energy from the mechanic energy created by the turbine. The generator is connected to power lines that lead the electricity onwards. The leftover water is then released into a river.

• Hydropower is a renewable and clean energy source
• It's reliable and flexible because the water can be stored in the reservoirs
• It's low-cost electricity that can be produced fairly locally
• The potential for hydropower is greatest where energy is most needed (South America, Asia and Africa)
• Cheapest way to generate electricity (2009)

• The building of hydropower plants are invasive to nature since they need to be places where there are some altitude differences and a sufficient amount of water, which is often in the middle of nature
• The construction hurts the biodiversity, especially the fish since it often disturbs their mating paten
• Fairly expensive to build
• Location dependent