Story 3
Big picture thinking
How to make wind float

On opposite sides of the Atlantic Ocean, DCNS is combining its below-the-surface expertise with its manufacturing and integration capabilities to help make deep water offshore wind power a reality.

While wind farms have become a common feature of the landscape in many countries, the their offshore siblings, and in particular floating wind turbines, are just beginning to reach commercial maturity. Because winds tend to be stronger along the coast and there are many available areas, it makes sense to install wind turbines offshore. But so far, installation has been limited to relatively shallow waters because their foundations need to be installed directly on the seabed.

What if wind farms could be built in harbors and installed with a standard tug boat in deep water, where winds are strongest, without requiring underwater foundations or heavy offshore construction techniques?

This is the promise of floating offshore wind turbines.

In France

Instead of using towers embedded in the sea floor, an international consortium led by EOFLI and CGN Europe Energy are developing floating offshore wind power for operation in waters up to 200 meters (650 feet) deep. EOFLI is the French leader in floating wind power and CGN Europe Energy is a subsidiary of China General Nuclear (CGN) Power Corporation. This design was recently chosen by the French government for the Ile-de- Groix wind turbine pilot project in the Bay of Biscay. DCNS and French construction firm Vinci will provide the submersible floating platform and General Electric will provide the turbines.

The turbine will be mounted on a semi-submersible platform that combines steel columns connected to a central concrete base. This so-called “hybrid” floater design is the fruit of DCNS’s expertise in naval architecture and industrial production. Not only can it withstand offshore conditions and be moored to a wide range of sea beds with minimal disruption to the habitat, it can be manufactured at most ports using local steel and concrete manufacturing facilities. The floater will be between 40 and 60 meters wide. Thanks also to the floating design, the structures can be assembled in port rather than in open sea and brought back to port for heavy maintenance. This reduces the time and cost associated with assembly and maintenance by removing the need for lengthy offshore campaigns.

In the United States

In May 2016, the US Department of Energy (DOE) announced funding for New England Aqua Ventus, a 12-MW floating offshore wind pilot project initiated by the University of Maine. DCNS is part of the winning consortium, along with the University of Maine, Emera and Cianbro.

The floating wind turbine hull design of the Aqua Ventus project was tested for nearly 19 months in Castine, Maine, using a 1:8-scale prototype. It was the first grid-connected offshore wind turbine in the Americas to send electricity into the power grid. It was also the first in the world to use a concrete hull.

DCNS will use its expertise in naval architecture, mooring systems and marine operations to participate in developing, constructing and operating the floating wind turbines capable of resisting the harsh North Atlantic conditions. It will be built using the same concrete technology used in bridges and dams and can be built locally, thanks to Maine’s existing concrete manufacturing infrastructure. This helps to reduce construction costs while contributing to the local economic development.

DCNS is playing an active role in helping develop the floating wind industry in both the US and France. With the projects in Ile-de-Groix and Maine, DCNS is involved in the installation of two floating offshore farms comprising six turbines and 36 MW of power generation capacity. By 2020, when the first farms will be installed, other international projects will be in the works, and DCNS aims at playing a major role in them.

A partnership between two international industrial compagnies GE's Haliade 150-6 MW offshore wind turbine and DCNS floating system