Tidal Power Introduction
The diversity of marine environments from which we may begin to tap tidal energy has ensured that no single technical development is likely to emerge that can solve all our tidal energy extraction problems. No one system is likely to be suited for every location. At present, the industry is following up a range of experimental devices. No system has demonstrated itself the clear technological leader. Shallow tidal estuaries can play host to extreme tidal ranges. It is the high tidal range that barrages and their concept offspring such as artificial lagoons and impoundment basins use. All other tidal devices fall into the category of harnessing kinetic energy from tidal currents, or what is being talked of as “tidal stream”.

Tidal Stream Devices
A portfolio of tidal energy conversion devices must be developed. To date, most of the grid-tied designs under trial are based on marinised horizontal axis wind turbines. Work has also focused on extracting energy via hydraulic hydrofoils. Given the vast global tidal stream resources, it is to be hoped that new breakthrough technology will be seen in this sector.

Tidal Barrage Technology
A number of tidal barrage generators have been installed across the world since the 1960's. The installation of the early estuarine tidal barrages, most notably France’s 240MW La Rance barrage, has demonstrated the ecological problems associated with large scale estuarine constriction. Despite the absence of a pre-project EIA preventing a true catalogue of environmental impacts to be prepared, the clear impact on the local marine ecosystems helped subdue the much larger barrage projects such as the UK’s Severn Estuary.

Artificial Tidal Lagoons
The exploration of the tidal barrage concept has encouraged the concept of impounding water for both electricity generation and energy storage to move beyond the strict geological walls of tidal estuaries. Artificial Tidal lagoons are now being seriously considered as a cheaper a more environmentally sound method of developing temporary potential energy from tidal estuary.