Tidal turbine connected with electricity grid of island

Louise Smyth

Complete MacArtney connectivity solution helps French marine renewable energy pioneer Sabella pass with flying colours in cable operation connecting a tidal turbine to an onshore grid.

The successful operation was carried out in the Fromveur Passage, off the island of Ushant, France, and the future outcome of connecting the two halves is a coverage of 15 to 20% of the Ushant island’s electricity consumption needs. The Sabella D10 tidal stream turbine project includes two drymate GreenLink connectors, one linked with the turbine, the other one connected to the export cable. They are eventually lifted out of the water and connected to one another.

Over the past few years, Sabella has developed an original concept for a screen of tidal turbines being positioned on the seafloor. In accordance with a permit issued by the French government, Sabella therefore plans to keep the D10 tidal turbine submerged for one year to conduct various trials.

Following the gradual increase in the speed of the Fromveur Passage currents, Sabella’s D10 tidal energy turbine has produced 10 MW/h of electricity under real operating conditions. Having been deployed last June, the turbine started delivering limited quantities of power to Ushant island in November 2015.

For successfully transmitting the harnessed tidal power to the onshore grid, the Sabella D10 relies on a purpose-built subsea connectivity solution from MacArtney. Based on MacArtney’s GreenLink Inline Termination technology the power is transmitted back to the onshore grid via the dynamic subsea export cable. The solution also comprises a couple of hang-off stress terminations, a customised flange including various medium- and low-voltage fibre-optic connectors for the turbine nacelle, a junction box jumper cable, and various test cables.

Pre-orientated in the direction of natural tidal currents and empowered by symmetrical rotor blades, the turbines effectively capture the energy generated by the shift between ebb and flow. The rotor is activated even by modest current motion and powers a generator, which exports the electricity produced to the onshore grid via a submarine cable anchored and embedded at its landfall.