Hydroelectricity is an energy that uses hydraulic energy to produce electricity using hydroelectric turbines. Hydroelectric turbines convert the mechanical energy of moving water (waterfall, watercourse, current)t into electricity .
Hydroelectricity therefore produces electricity in a renewable manner while emitting very little greenhouse gas. Hydroelectricity is not, however, completely sustainable energy because it often requires the creation of a dam, therefore an obstacle to the circulation of species, sediment and boats.
A hydroelectric plant on the Niagara River in the United States. © bgilliard CC by-sa 2.0