Allseas Signs Contract for Îles d’Yeu et de Noirmoutier Offshore Substation Installation

DEME and Allseas have signed a contract for the installation of the offshore substation for the Îles d’Yeu et de Noirmoutier offshore wind farm in France.

Illustration; Pioneering Spirit installing HKZ Alpha substation in the Netherlands

The 496 MW offshore wind farm has just moved into the construction stage after the consortium behind the project reached the final investment decision.

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DEME has been contracted for the transport and installation of the wind farm’s foundations and the substation.

For the substation, the Belgian company will install the pin piles for the jacket foundation and transport the jacket and the topside to the project site. Once at the offshore site, the jacket and the topside will be transferred to Allseas’ vessel Pioneering Spirit for installation with its 5000-tonne crane.

The offshore substation is scheduled to be installed in the first half of 2024.

The “lift and set down” operation is very similar to that carried out by Pioneering Spirit at the Saint-Nazaire offshore wind farm in 2021, which Allseas also performed under a contract with DEME and marked its first assignment in the offshore wind industry.

Since then, the crane vessel has also installed two offshore substations at the Dutch Hollandse Kust Zuid offshore wind farm area.

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“This latest award builds on our earlier successful collaboration with DEME on the Saint-Nazaire project and illustrates the important role Allseas can play, both in terms of transport and installation, in this fast-growing, sustainable offshore industry”, said Matthijs Groenewegen, Vice President Projects at Allseas.

“Weather and tidal conditions at the installation location can be challenging, which we’re able to mitigate thanks to the unprecedented size and stability of our installation vessel. We look forward to working closely with DEME to realise this important offshore wind development that will deliver clean energy to thousands of French households”.

The Îles d’Yeu and Noirmoutier offshore substation will be built by Chantiers de l’Atlantique in Saint-Nazaire. Spain’s Navantia will manufacture the substation’s jacket foundation and the associated piles.

The offshore wind project is owned by Éoliennes en Mer des Îles d’Yeu et de Noirmoutier (EMYN), a consortium including Ocean Winds (an ENGIE and EDPR joint venture), Sumitomo Corporation, La Banque des Territoires and Vendée Energie.

The 496 MW Îles d’Yeu and Noirmoutier offshore wind farm will comprise 62 Siemens Gamesa 8 MW wind turbines and is scheduled to be commissioned in 2025. Once in full operation, the wind farm will produce enough electricity to power up to 800,000 households.


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