French offshore renewable energy hybrid leaves sea after two-year trial

The WAVEGEM hybrid autonomous platform, which generates clean power by exploiting both solar and wave energy, has been retrieved ashore after two years of tests at the SEM-REV site offshore France.

The retrieval of the WAVEGEM platform marks the end of the first phase of sea trials as part of the Integrated Harvesting Energy System (IHES) project, led by Geps Techno, the company which designed the platform.

WAVEGEM spent two years at the SEM-REV site, operated by the Ecole Centrale de Nantes, before being towed back to the Port of Saint-Nazaire with the help of Alka Marine’s Alma Kappa vessel earlier in November.

The platform, deemed as medium-power device, is an autonomous hybrid energy producing platform featuring six turbines, and 68 square metres of solar panels, which jointly bring the prototype’s capacity to 150kW.

According to Geps Techno, a number of lessons have been learned during the two-year deployment period, most notably those related to the ability of the anchor to withstand marine conditions and the aging of the platform.

“The platform has aged well knowing that it is a prototype designed to have a limited life”, Geps Techno said.

During trials, the company managed to produce, convert and store energy – though not quite reaching the specified energy production objectives.

“That’s one of the issues we’ll be working on in the new phase with the improvement of the energy extraction system”, Geps Techno confirmed.

The new phase will see the platform redeployed to the same test site at the end of summer 2022 for a new period of testing, expected to last for one year.

Beforehand, Geps Techno plans to implement modifications to the platform, which will include the installation of new power take-off (PTO) systems for wave energy extraction, in addition to a new conversion system.

Furthermore, Geps Techno confirmed it will add two wind turbines – developed by HydroQuest – to have an additional renewable source of energy production at the platform.

In addition to all of the planned modifications, Geps Techno will also work with Fench renewable hydrogen project developer Lhyfe on its offshore hydrogen production project.

According to the company, the new platform will host ‘the first prototype for hydrogen production on-board’. Offshore energy reported earlier that an electrolyser will be installed at Geps Techno’s floating platform at the SEM-REV site and then be connected to various marine renewable energy sources, including floating offshore wind turbine Floatgen.

“For this test, Lhyfe will not store hydrogen, as it is aimed to demonstrate the possibility of producing gas at sea. The storage and transport or use of hydrogen will come later”, Geps Techno explained.

One other difference to the first phase of testing is that an umbilical will be used to connect the platform, which was not linked to SEM-REV earlier, to ensure sufficient power supply to the prototype.