"Hydroelectricity is the term referring to electricity generated by hydropower; the production of electrical power through the use of the gravitational force of falling or flowing water. It is the most widely used form of renewable energy, accounting for 16 percent of global electricity generation – 3,427 terawatt-hours of electricity production in 2010, and is expected to increase about 3.1% each year for the next 25 years."
Hydroelectric power accounts for about 20% of the electricity in the world, and 6% of total commercial energy. Countries, however, use hydroelectric power in varying degrees. For instance, Norway's electricity is 99% hydroelectric, but only 13% of electricity in the US is hydroelectric. Read on from ww.lenntech.com/water-energy-faq.htm.