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Hydroelectricity is the production of electricity from mechanical energy stored in water. With more than 15% of the world’s electricity produced by hydroelectric generators, it is the most significant current source of renewable and sustainable energy. Most hydroelectricity is generated by harnessing the potential energy of dammed water. The high-pressure water near the foot of the dam drives turbines, which are connected to the generators that supply power to the grid.

The largest single producing nation of hydroelectricity is China, generating more than 1200 TWh annually, more than a quarter of world capacity. However, this represents only 18% of domestic power generation. In contrast, Norway produces nearly all (95%) of its 140 TWh by hydroelectric generation. Brazil, Canada, and the United States are also major producers of hydroelectricity, with nearly 1100 TWh combined. This represents roughly 60% of domestic production in Brazil and Canada, but only 7% in the United States.

One of the advantages of hydroelectric dams is that the vast amount of energy stored in their reservoirs enables them to respond quickly to short-term changes in demand by simply increasing or decreasing flow through the turbines. Seasonal variations in rainfall are accommodated by allowing the reservoir level to vary.

Tune in to our next post where we’ll explore some of the disadvantages with Hydroelectric Power.