Other locations where tidal energy could viably be harnessed include the Bay of Fundy in Canada, with a average tidal range of 10.8 metres, the largest in the world, and the Severn Estuary in Britain where the average range is 8.8 metres. Indeed, most of the potential for harnessing tidal energy in Europe lies on the British coast, where the exploitation of all practical sites could provide up to 20 per cent of the electricity needs of England and Wales. Despite the environmental advantages of tidally generated electricity, including the lack of pollutants generated and the protection barrages offer to coastlines against storm-surge tides, such schemes inevitably modify the hydrodynamics of their estuaries. Alterations to the tidal range, currents and the intertidal area behind the barrage would affect several other environmental parameters, including water quality and the movement of sediment, which would in turn have an impact on the food chain, ultimately affecting bird and fish populations. Whereas the energy of the tides is derived from forces acting between the Earth, the sun and the moon, wave energy ultimately stems from the sun.
Solar energy drives our planet's winds and it is the winds that generate waves.
The technology of wave energy collection is still at a fairly early stage, in contrast to the tried and tested technology used in a tidal energy plant. The number of methods available for the collection of energy from waves is diverse and although many devices have been invented, only a small proportion have been tested and evaluated. Furthermore, only a few have been tested at sea, in ocean waves, rather than in artificial waves generated in laboratory tanks. Some systems extract energy from surface waves while others harness energy from pressure fluctuations below the water surface or from the full wave. Some systems are fixed in position and let waves pass them by, while others follow the waves and move with them.