Tidal energy is used to supply power plants with electricity. Tidal energy harnesses the power of water and the ocean in various ways. Very few commercial plants exist as tidal energy is still not widely in use.
Tidal energy has been used for centuries to turn waterwheels that give mechanical power to grain mills but the first large-scale, commercial tidal power plant was not built until 1966 in La Rance, France. The largest tidal power station is in South Korea.
There are three methods by which to acquire tidal energy: tidal streams, lagoons and barrages. For the first, a turbine is placed into a fast-flowing body of water created by the tide known as a tidal stream. The second, lagoons, requires the construction of a tidal lagoon. Built along the natural coastline, these can be man-made or natural structures of partially enclosed ocean water. This particular model has no functional examples yet but would have the least impact on the environment out of the three.
Barrages are essentially large dams built across tidal rivers, bays and estuaries. This works in much the same way as a river dam by opening gates as the tide rises and then shutting them as the tide goes out. This creates a pool of water that is then released through the turbines creating energy.
The power derived from tidal energy is reliable since the tides are predictable and uniform in nature. The electricity produced is cheap, sustainable and does not pollute nature in any way.
Tidal energy has been used for hundreds of years in many forms of machinery, such as grain mails that mechanically crush grains. The energy produced by the movement of ocean waters due to the gravitational attraction of the moon and Earth is a form of renewable energy, similar to geothermal, wind and solar.