Tidal power plant
A tidal power plant is a plant that produces electricity using a source of renewable energy: tides.
The ebb and flow of water under the influence of the tides, and therefore gravity, can be used indefinitely to turn the wheels of tide mills or, in the case of tidal power plants, hydroelectric turbines.
The Rance plant in France is one such power plant that uses the ebb and flow of tides to produce electricity.
Tidal power plant: two methods for converting energy
There are two techniques for converting tidal energy into electricity: using the potential energy of water, thanks to the variations of thewater level between high tide and low tide;nbsp;using the kinetic energy of water masses put into motion by the ebb and flow (tide currents).
- The first method is the one used by tidal mills and power plants, such as the Rance tidal power plant. Tidal mills and power plants generally require significant infrastructure in locations where the tidal range is very wide. This is the case, for example, of the Bay of Mont-Saint-Michel (Rance estuary) or Fundy Bay, where tidal power plants use the tidal range of about 10 metres. The size of these installations and their location in ecologically important areas generate high environmental and economic costs that significantly limit the development of this technique.
- On the other hand, the second method is much more promising, both in terms of the number of exploitable sites as well as the environmental impact. Current tidal power plant projects therefore consist in installing marine power parks (ocean turbines) where tidal currents are favourable.
Advantages oftidal power plants
The main advantage of tidal power plants (which are a type of hydroelectric power plants), in addition to producing renewable energy, is that they can ensure predictable, regular output, as opposed to wind energy or photovoltaic plants.
Cross-section of the Rance tidal power plant dam. The turbine that converts the potential energy of water accumulated during high tide into electricity is shown in red. © Clipper, Wikimédia CC by-sa 3.0
Tidal power plant - 1 Photo