An endless amount of research has been put into harvesting the energy in the oceans of the world. Tidal wave energy is one of many strategies.

Tidal Wave Energy

Tidal energy exploits the natural rise and fall of coastal tidal waters caused principally by the interaction of the gravitational fields of the Sun and the Moon. Some coastlines, particularly estuaries, accentuate this effect creating tidal ranges of up to 30 feet.

Tidal wave energy has been around for thousands of years. Historically known as tide mills, the ancient process consisted of a pond filled through a sluice during the flood tide and emptied on the ebb tide via an undershot waterwheel Tide mills were in use on the coasts of Spain, France and the UK before 1100AD. They remained in common use for many centuries, but were gradually replaced by cheaper and more convenient methods of power generation.

The modern version of a tide mill is a semi-permeable barrage built across an estuary, allowing flood waters to fill an impounded basin via a series of sluices. At high water the sluice gates are closed, creating a head of water on the ebb tide. Electricity is generated by releasing the water through a series of conventional bulb turbines. In future schemes the energy yield would be enhanced by pumping water into the estuary on the flood tide ('flood pumping'), thereby increasing the volume of water released through the turbines on the ebb tide.

A variant is tidal stream (or marine current) technology, which aims to exploit the strong tidal currents which are found in shallow seas, particularly where natural constrictions exist, such as around headlands or between islands. Tidal stream technology is in its infancy. Devices similar to submerged wind turbines would be used to exploit the kinetic energy in tidal currents. Only one of these devices exists - a 5kW machine that has been operated in Japan since 1990. In 1993, the UK had a go at a major project, but ultimately determined it was not cost effective.


Tidal energy potential has been investigated by a number of countries, notably France where a 240 MW demonstration plant was built on the Rance estuary during the 1960's and has now completed 30 years of successful operation. The Russians have built a small 400kW device near Murmansk which was later followed by a 17.4MW experimental device. A series of small plants have also been installed in China. None of these countries have progressed to further development.

At the moment, tidal wave energy seems to have stagnated as a potential energy source. Don’t you find it ironic that tidal wave energy worked a thousand years ago, but doesn’t now? That’s progress for you.