The resource

A predictable and unexploited energy source

The resource utilised mainly comes from tidal currents. In certain regions of the world, these currents present sufficient flow speeds at the seabed to be exploited (1.5 to 2 m/s).

The movements of water masses generated by the tide are regulated by astronomical phenomena. These phenomena are cyclic. They fluctuate on a daily basis throughout the year, but their range and times are totally predictable (ephemerides, tidal coefficients).

The Channel and the North European coast, the North Pacific shoreline, the Philippes, Indonesia, north Brazil and Patagonia are areas with a large tidal range and therefore have a high “hydrokinetic” potential. This energy is not diffuse but rather very localised on a few sites, very near the coast.

France boasts major emblematic tidal sites on the Atlantic coast and along the Channel. In Europe, the United Kingdom has the greatest potential with over 10 GW of power to exploit, while France comes second with 3 to 5 GW.

The exploitable tidal power potential worldwide is estimated by some experts at around 100 GW of electric power.

 

 

 

 

The cyclic nature of tides affects turbine exploitation during slack water (lack of current). The tidal range is defined by a tidal coefficient which varies between 20 and 120. The speed of tidal streams on a given site is directly proportional to the tidal coefficient. We can observe empirically that only coefficients from 50 to 120 can be utilised.