Ocean power cable protection put to test in France

The casting subsidiary of Farinia Group – FMGC – has installed the cast iron shells (IBOCS) used to ballast subsea power cables employed in marine renewable energy projects for trials at the SEM-REV site in western France.

FMGC cast iron shells (Photo: Centrale Nantes)

Installed at a depth of 30 meters back in August 2018, the FMGC shells will be challenged to demonstrate the stability of the cables ballasted with these cast iron shells, including under heavy swell conditions, according to Centrale Nantes.

The FMGC shells, used to protect, stabilize and restrict the bend of subsea electrical cables, will remain on site for several months and will be subjected to extreme winter conditions.

These tests will also provide comparative data, since three sections of test cables – two equipped with shells of different linear density and the third completely bare – were installed alongside each other.

The condition of cast iron shells will be assessed through regular on-site measurements, current measurements and cable movements.

During trials, the FMGC and SEM-REV teams will observe how the shells bear up to factors such as resistance, and corrosion, in order to gain feedback from real-sea environment.

Deployment of IBOCS (Photos: Centrale Nantes)

Innosea, a Centrale Nantes spin-off, worked with FMGC on shell design methods to calculate the optimal mass required to ensure cable stability on the sea floor, Centrale Nantes said.

The tests are part of the FORESEA project, supported by Interreg Europe funding, which aims to help bring marine renewable energy technologies to market by providing access to the North-European network of offshore test sites, which includes SEM-REV, European Marine Energy Centre (EMEC), SmartBay, and Dutch Marine Energy Centre (DMEC).

The FMGC is the third company to make use of the Centrale Nantes offshore test site, following on from NEREIS Environnement’s acoustic sensor and the Floatgen floating wind turbine – a European research project involving Idéol, Bouygues TP and Centrale Nantes.

The technology solutions from FMGC are mainly employed in tidal, floating and fixed offshore wind power and submarine cable protection.

To remind, FMGC’s cast iron protection was used to stabilize and safeguard subsea cable as part of first deployment of French developer Sabella’s D10 tidal turbine, near Ushant island in France.