Mussels growing on a floating wind turbine off France dropped enough shells to alter the sandy seabed beneath it

Offshore floating wind generation is key to France’s renewable energy transition, but long-term impacts remain mainly unknown.

These floating installations overcome significant terrestrial and nearshore bottlenecks, but also introduce new challenges.

They often overlap with vital marine ecosystems and create artificial submerged habitats.

To ensure deployment is sustainable, Fondation OPEN-C evaluates the real-world environmental footprint of this floating offshore technology.

Recent French research has focused on the effects of these turbines on the underlying benthic environment.

Can developers manage these unexpected ecological consequences as national projects expand?

How terrestrial green capacity growth faced bottlenecks

In recent years, France has faced major terrestrial and nearshore bottlenecks during renewable energy capacity expansions.

Onshore wind deployment has specifically been challenging.

These projects often face complex administrative hurdles, land-use limitations, and severe public opposition.

In France, proposed land-based projects’ approval is often delayed by more than seven years.

While offshore generation overcomes these barriers, nearshore shallow-water deployment presents similar challenges.

Foundation-based wind turbines deployed nearshore usually compete with heavy commercial shipping and local fishing.

These turbines have also raised visual pollution concerns.

Despite these distinct hurdles, wind generation remains crucial to France’s green energy transition.

The nation is targeting 40 GW of offshore wind capacity by 2050, requiring major growth beyond current output.

Beyond meeting decarbonization goals, it is also vital for meeting steadily rising electricity demand.

To bypass spatial limitations and still harness strong offshore wind resources, developers turned to deep-sea deployment.

This led to the rise of innovative floating technology.

Harnessing the deep sea’s stronger resources

Floating wind turbines are reshaping where the world can harvest high-capacity clean power.

They operate on buoyant concrete or steel platforms, which are anchored to the ocean floor with mooring lines.

Unlike standard turbines restricted to depths under 164 feet, floating structures work at depths of hundreds to thousands of feet.

For France, this technology is uniquely beneficial.

It enables tapping into the Atlantic and Mediterranean coasts’ strong, more consistent winds.

Floating wind power has even formed part of France’s broader offshore energy roadmap.

By 2040, the goal is to achieve at least 6 GW of installed capacity.

In mid-2025, the nation reached an important milestone after inaugurating its first floating offshore project.

However, while this deep-sea generation offers clear operational benefits, its long-term ecological consequences remain largely unknown.

Massive artificial structures are suddenly transforming previously untouched marine environments.

To ensure deployment is sustainable, Fondation OPEN-C evaluates the real-world environmental footprint of this floating offshore technology.

Analyzing deep-water ecological impacts of Floatgen floating wind turbine

France’s pioneering Floatgen turbine at the SEM-REV offshore test site became the focus of real-world environmental shift measurement.

The site is located off Le Croisic, and the turbine serves as an ideal long-term testing platform.

The study was conducted under the collaborative Velella R&D project.

The team also consisted of Centrale Nantes, BW Ideol, IFREMER, ENSTA, and IVM Technologies.

Evaluating different factors over multi-year operations

Dynamic mooring lines, subsea structural integrity, and biofouling colonization were evaluated.

As time passed, thick colonies of blue mussels settled on the turbine’s submerged hull and mooring lines.

The research discovered heavy, continuous shell shedding down to the ocean floor occurred.

This was caused by physical competition, strong wave action, and natural mortality.

The persistent shedding altered the underlying seabed, transforming it into a structured substrate.

A localized artificial reef effect was triggered, attracting other marine species.

Local benthic food chains and sediment chemistry also changed beneath the structure.

The Velella project is still underway, as the four-year initiative continues to evaluate evolving subsea dynamics.

The biofouling results provide vital baseline empirical data for eco-design strategies.

It will also be invaluable to commercial permitting frameworks and environmental impact assessments.

Ultimately, these ecological lessons will help offshore floating wind projects meet decarbonization goals while protecting ecosystem health.