Hydropower generates over 15 percent of the world’s electricity and the consumption of energy generated by hydropower continues to increase. Predictably, hydroelectricity is most commonly used in countries with plenty of running water. In fact, hydropower is considered one of the cheapest sources of energy; after a facility’s construction and installation, harnessing the power of flowing water is essentially free. The speed of running water can also be controlled through turbines to produce electricity on demand.
Although hydropower is considered a renewable energy source, large hydropower dams can still be responsible for environmental problems such as disrupting and damaging aquatic ecosystems. Most new hydropower projects worldwide must undergo an Environmental and Social Impact Assessment. An alternative to large dam facilities is small hydropower technologies, which garnered about 3.4 billion U.S. dollars in funding in 2017. Many hydropower plants can also be used for other purposes, such as agricultural irrigation.