After installing the wind turbine’s mooring system off the coast of Le Croisic last July, the foundation took to the water, marking a new key stage in the project implemented by Ideol, the Ecole Centrale de Nantes and Bouygues Travaux Publics. The concrete foundation was tugged into the Forme Joubert Lock, a dry dock at the entrance to the port of Saint-Nazaire to be floated, a tricky technical operation to float off the floater from the three barges on which it had been built.

“Everything was placed in dry dock on concrete and wooden blocks which support the keel of a ship during dry construction. The barges were then filled with water to be sunk. When the lock was filled with water, the floater disengaged from its support”, explains Perceval Modiano, project manager at Bouygues Travaux Publics.

Floatgen, a first in France

The imposing, 5,000-tonne concrete structure, 36 metres square by 9.5 metres high, will soon be accommodating a 2-MW wind turbine. The project’s next stage will be to mount the wind turbine’s tower, the turbine and its blades. The final unit will top out at over 80 metres.

By mid-October, it will be towed to the SEM-REV installation site, 22 km off the coast of Le Croisic for initial trials covering a period of 2 years.

Highlight of the worksite: “we have developed a lightweight, self-compacting type of concrete to minimise the weight of the structure and pour the concrete without vibrating it,” explains Régis Bigard, head of the Floatgen project with Bouygues Travaux Publics.

Floatgen ©Ideol[/caption]

Porté par un consortium européen de sept industriels et organismes de recherche, Floatgen fait figure de première à plusieurs titres. Première éolienne en mer qui entrera en service en France mi-2017, elle est également le premier démonstrateur grandeur nature de la fondation flottante développée et brevetée par Ideol.

« Ce projet est un bel exemple de coopération entre une start-up, un organisme de recherche (l’Ecole Centrale Nantes) et le grand groupe que nous sommes » confie Nicolas Jestin, responsable commercial pour Bouygues Travaux Publics.

Une innovation durable et créatrice d’emplois

Floatgen ©Ideol

L’objectif de ce projet est de démontrer à échelle un le bon fonctionnement de cette technologie. Le potentiel de l’éolien en mer flottant à échelle commerciale est immense ; il permet de produire l’électricité d’origine renouvelable loin des côtes, donc avec un impact paysager réduit et au meilleur coût grâce à la qualité du vent au large. À terme, cette technologie pourrait accélérer la part de l’éolien dans le mix énergétique français, comme mondial, et participer à répondre aux objectifs de la loi de transition énergétique qui fixe à 32 % la part d’énergies renouvelables dans le mix en 2030.

Il permet également de montrer le potentiel industriel de cette nouvelle filière, créatrice de retombées économiques au plus proche des sites d’installation. Le choix du béton pour la construction de la coque offre l’avantage de produire localement et générera de nombreux emplois avec près de 80 personnes mobilisées sur le port de Saint-Nazaire. Les sites industriels des principaux fournisseurs en bénéficieront également, comme en témoigne le contrat de fourniture du système d’ancrage signé avec la société Le Béon.

Floatgen ©Ideol

Les équipes de Bouygues Travaux Publics, qui s’appuient sur une expertise reconnue dans la fabrication de caissons en béton, construiront la coque flottante qui sera maintenue en place par 6 lignes d’ancrage reliées au fond marin. Une fois la coque achevée, l’éolienne sera installée, à quai, sur sa fondation. L’ensemble sera remorqué vers le site d’installation au large du Croisic, SEM-REV, premier site d’essais en mer au monde multi-technologies connecté au réseau électrique, propriété de Centrale Nantes et opéré conjointement avec le CNRS. L’éolienne sera ensuite raccordée au système d’ancrage et au câble d’export de l’électricité à l’été 2017.

Le projet Floatgen est soutenu par l’Union Européenne dans le cadre du programme FP7, et par l’ADEME dans le cadre du Programme des investissements d’avenir.

Saint-Nazaire port is playing host to a major innovative project in renewable energy. On 1 June, construction work began on the first offshore wind turbine in French waters, Floatgen. The go-ahead was officially given by the European partners behind this project which offers high industrial potential. The turbine will stand upon a floating foundation, designed by French wind energy specialist Ideol and built by Bouygues Travaux Publics. It will be installed off the coast of the town of Le Croisic, on the maritime test site SEM-REV belonging the Nantes engineering school ECN (Ecole Centrale de Nantes).

Made possible thanks to a European consortium of seven manufacturers and research bodies, Floatgen is, on several fronts, a first occurrence of its kind. Due to be commissioned in mid-2017, it is the first offshore wind turbine in French waters. Furthermore, it is the first life-size demonstration of the floating foundation developed and patented by Ideol.

“This project is a fine example of how a start-up, a research body (Ecole Centrale de Nantes) and a large corporate group like us can work together,” said Nicolas Jestin, Sales Manager at Bouygues Travaux Publics.

A sustainable, job-creating innovation

The project seeks to show how this this technology works well full-scale. From a business perspective, there is huge potential on offer from floating offshore wind turbines. Thanks to this technology, electricity can be generated from a renewable source far from our coastlines, thereby minimising the landscape impact while maximising cost-efficiency through the power of sea winds. This technology could eventually expand the share of wind power in France’s energy mix, or even in the world’s range of energy sources. It should also help meet the goals of France’s energy transition law, which seeks to bring up to 32% by 2030 the quota of renewable energy used in the country’s total assortment of energy sources.

Moreover, it will demonstrate this new sector’s industrial potential as it generates local economic benefits in the areas surrounding the facilities. The choice of concrete for building the shell brings the added advantage of producing locally and creating plenty of jobs, with around 80 people brought into play at Saint-Nazaire port. The main suppliers’ industrial sites will also benefit from the project, as attested by the contract signed with the company Le Béon for their provision of an anchoring system.

The Bouygues Travaux Publics teams, putting to good use their proven expertise in producing concrete caissons, will build the floating shell, which will be held in place by six anchor lines tied to the seabed. Once the shell is built, the wind turbine will be mounted on its foundation from the quayside. The whole assembly will be towed to the installation site off the coast of Le Croisic. This maritime zone known as SEM-REV is the world’s first multi-technological test site, connected to France’s electrical grid. It belongs to the Nantes engineering school ECN (Ecole Centrale de Nantes) and is used jointly by the CNRS (French national scientific research centre). In the summer of 2017, the wind turbine will then be connected to the anchoring system and the electricity export cable.

Floatgen is supported by the European Union as part of the FP7 programme, by the French Environment and Energy Management Agency as part of the national Investments for the Future Programme.