tidal-enery-dam-la-ranceTides are the most predictable renewable energy source. Contrary to wind and sun, tidal currents are 100% predictable a very reliable estimation of the total output from a tidal energy project can be easily made. The energy potential of tidal basins is large — the largest facility, the La Rance station in France, generates 240 megawatts of power. Currently, France has the largest tidal energy site. Other countries such as Russia, Canada and Norway are also active but at a much smaller scale. The total tidal power potential worldwide exceeds 450 TW.

It is possible to harness tidal energy using:

Dams and turbines

A tidal dams capture the water that moves in a bay or river due to tidal forces. The dam includes a sluice that is kepted open when the water rises to allow the tide to flow into the basin. Then , when the water in level start to do down again the sluice is closed. The water that is captured in the dam is later released through hydropower turbines to generate electricity from the elevated water in the basin.

 

Bottom-founded turbines

Bottom-founded turbines are simply attached to the sea floor without the need to construct a dam. Several firms are trying to make it so. Some, such as Andritz Hydro Hammerfest, in Norway, and Marine Current Turbines from Bristol, in Britain, take the relatively simple approach of sticking what are little more than strengthened wind turbines onto the seabed. Innovator in this field include:

 

Floating turbines

Flowting turbines are easier to install and more accessible maintenance than bottom-founded turbines. Several companies are competing for the development of a cheap and robust floating Tidal Energy Converter (TEC).The most promising concepts are:

Scotrenewables Tidal Turbine
The Scotrenewables Tidal Turbine is a tidal stream turbine designed for ease of installation, operations and maintenance, robustness and survivability in the harsh offshore environment. The device can be installed, transported or completely removed from the site requiring a small and readily available vessel.

BlueTEC
Bluewater’s Tidal Energy Converter (BlueTEC) is an open-architecture floating support platform suitable for tidal turbines. Unlike conventional bottom founded designs, BlueTEC offers significant advantages by accommodating most of the critical equipment above the waterline, where it is dry and protected, allowing for easy access for inspection and repair.

Evopod Concept
Ocean Flow energy in developing the Evopod which is a semi-submerged, floating, tethered tidal energy converter. It uses a simple mooring system that allows the free floating device to maintain optimum heading into the tidal stream.