Methodology for estimating the French tidal current energy resource

This paper presents a method to compute the total tidal energy resource available in French Atlantic and Channel waters. An analysis of outputs from MARS2D hydrodynamic model allowed us to identify 20 potential sites for extraction of tidal energy. These sites are presented in the form of an atlas. Four promising sites with annual average currents exceeding 2 m/s, were identified in the English Channel (Raz Blanchard, Raz Barfleur, Paimpol-Bréhat) and at the westernmost part of Brittany (Fromveur Passage).

By defining characteristics of a turbine array (spacing and power coefficient), we compute the total extractable power for three cases: high, medium and low theoretical performance. Considering the sites with average currents exceeding 1.5 m/s, the total extractable power ranges from 1.46 to 9.71 GW for the low and high performance cases. For all 20 sites, where average currents exceed 0.5 m/s, the total extractable power ranges from 2.49 to 16.58 GW for the low and high performance cases.

Finally, we focus on the most promising site: the Raz Blanchard (Alderney Race) located in the Manche department (English Channel). The variability of the current intensities and directions are presented. Within this high tidal potential site, we define a zone (12 km²) wherein the current speeds are consistently high (exceeds 2.5 m/s for at least 40% of the year studied) and most often following the NNE/SSW axis.