Tidal power is the generation of electricity by harnessing the power of tides and is a form of renewable energy. Tidal power is, by its very nature, plentiful and reliable but there are a number of issues to take into consideration and there are only a relatively small number of suitable sites worldwide.
There are effectively two alternative tidal power systems. The barrage option involves a large dam being built across the mouth of an estuary. The tidal waters flow through tunnels in the barrage and turn turbines thus producing electricity. This method of producing tidal power, however, can have a major environmental impact on the local ecosystems. As less water is released as the tide goes out, there is the potential for sewage and other waste not to flow as readily out to sea. The fact that water remains would also diminish any mud flats thus affecting the local wildlife.
An alternative tidal power system is known as a tidal stream. This involves the construction of turbines under the water close to the coastline; almost like an underwater wind farm! This technology is still in its infancy but is thought to have a lower environmental risk as well as eliminating the visual impact of a barrage scheme.
Currently there is only one tidal power site in Europe located at La Rance on the northern coast of France. This is a 240 megawatt power station (a large coal or nuclear power station produces approximately 1000 megawatts of power) and it is estimated that a similar scheme across the Severn could produce as much as 10% of the UK’s electricity.
For more information on tidal power, visit www.environment-agency.gov.uk
