Hydroelectric power is generated by transforming the energy from moving water into electricity. Large dams and steep rivers facilitate the generation of hydroelectric power. Sometimes other sources of electricity are used to pump water back up into dams which store this energy, acting as batteries
The most hydroelectric power is generated in Canada, China, Brazil and the United States. Together these territories generate 44% of all hydroelectric power.
Fifteen territories do not use hydrolelectric power. These territories are generally either relatively small islands or Middle Eastern oil producers with low rainfall.