Tidal power, sometimes also called tidal energy, is a form of hydropower. These tide mills convert energy from the moving water into other forms of power, usually electricity. Tide mills work similarly to windmills except with water.

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Just as wind mills are placed in areas where the winds are strong and steady, tide mills have to be waterways with strong water flows. This is why tidal power plants are sometimes placed at the mouth of a lagoon or water basin; anywhere where water is being forced through a small opening can be an ideal place for a tidal power station. 



Tidal power plants typically erect a dam across the entrance to a tidal basin. When the tide starts to come in, as the sea level rises, the increase in tidal power is held behind the dam. As the water is released through the dam and into the basin it will power turbines that create electrical power through generators. These dams or barrages are the most effective way to the harness the power of the tides. The main factor that restricts the building of these power stations is that there must be at least 16 feet in difference between high tide and low tide. Without this variation in water level the station will not be able to generate enough power.



Tidal turbines can also be placed in waterways with strong currents. These turbines look a lot like windmills that are upside-down in the water. The passing currents rotate the blades and power the turbine.

 



While the technology may have change, water has been used for thousands of years as a source of energy. Watermills were used as far back as first century B.C. and have been used by a variety of cultures including the Romans and across Europe. It is estimated that there were more than 20,000 mills in Europe by the 19th century.  Although these watermills were traditionally used for corn, they could also be used to prepare animal feed, grind flint, power sawmills and 'blowing engines' to feed air to iron forges. These watermills provided a consistent and powerful form of energy that played a big role in human's history. 

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