Hydroelectric power, or hydropower, is renewable electrical energy produced by converting hydro-power into electricity. The kinetic energy of the water flow, natural or generated by the difference in level, is converted into mechanical energy by a hydraulic turbine, then into electrical energy by a synchronous electric generator.
There are three main forms of hydropower generation:
- The so-called gravitation water vortex power plants, are so called because the inflow of water into their reservoir or intake is mainly from gravitational streams, such as run-of-river or lake hydroelectric power plants;
- The pumped energy transfer stations (S T E P) in which reversible turbines pump water from a lower basin to an upper basin. They also frequently include a gravity part.
- The tidal power plants, which use the energy of the movement of the sea, whether it is the alternating flow of tides (tidal in the strict sense), permanent marine currents (tidal turbines in the strict sense) or wave movement.