Hydropower has been used since ancient times to grind flour, pump water and irrigate fields and perform other tasks. With the discovery of electricity and electrical generators, by the late 19th century, hydraulics began to be utilized to produce electrical power which in turn started accomplishing even greater range of tasks. The world’s first hydroelectric power scheme was developed in 1878 at Cragside in Northumberland, England by William George Armstrong. It was used to power a single arc lamp in his art gallery. Soon after, the first power station came up in the Niagara Falls producing electricity in 1881.

Today, hydropower is the most widely used form of renewable energy, but still accounts for only 16 percent of global electricity generation. Lack of accessible water sources is one of the main reasons why hydropower is lagging behind alternatives such as fossil fuels and nuclear power. But this is expected to change in the next few decades as several major hydroelectric projects are underway mostly in the Asia-Pacific region, that already generates 32 percent of global hydropower. China is the largest hydroelectricity producer, with 721 terawatt-hours of production in 2010, representing around 17 percent of domestic electricity use. Paraguay produces 100% of its electricity from hydroelectric dams, and Norway 98–99%. Brazil, Canada, New Zealand, Austria, Switzerland, and Venezuela – all have a majority of the internal electric energy production from hydroelectric power.