Belgium's pioneering offshore energy island has reached a significant construction milestone, with the installation of the 23rd and final foundation caisson in the North Sea marking the completion of the structure's protective outer shell.

The work was carried out by TM EDISON, a joint venture comprising Jan De Nul and DEME, on behalf of grid operator Elia Transmission Belgium, with the completion enabling Elia to qualify for a USD 115.8 million European subsidy allocated to this phase of the project.

A Protective Shell Built at Sea

The Princess Elisabeth Island sits 45 kilometres off the Belgian coastline and will serve as a critical hub connecting Belgium's second offshore wind zone to the mainland, while also creating the potential for a future energy link with the United Kingdom.

The 23 foundation elements collectively form the island's outer protective structure, enclosing the area within which the island will now be built up using reclaimed sand.

Construction of the caissons began in 2024 with what Jan De Nul described as a technically challenging first installation. Each of the 23 caissons weighs approximately 22,000 tonnes and measures 58 metres in length, 28 metres in width, and between 23 and 32 metres in height.

The units were manufactured at Vlissingen, with around 300 workers engaged in their construction on any given day. Producing a single caisson took approximately three months, after which each element was transported to the installation site at sea, an operation described as highly dependent on weather conditions.

European Funding and Strategic Importance

The timely completion of the foundation works carries direct financial consequences. By finishing within the planned timeframe, Elia Transmission Belgium has been positioned to qualify for the USD 115.8 million European subsidy tied specifically to this construction phase.

Jan De Nul described the European financial support for what it termed a world first project as reflective of the broader importance placed on energy independence and cross-border energy exchange across the continent.

Frédéric Dunon, CEO of Elia Transmission Belgium, stated that completing the foundation works marks a major step in developing Belgium's offshore energy infrastructure, which he described as playing a crucial role in the energy transition and in strengthening the country's energy independence.

The island is being presented as an essential component of Belgium's efforts to generate more low-carbon electricity, reduce reliance on external energy sources, and maintain economic competitiveness.

A Long Road to Full Commissioning

With the foundation phase now concluded, the project moves into a sequence of subsequent construction stages stretching across the remainder of the decade. In the coming months, work will continue on reclaiming the island itself by filling the caisson structure with sand.

The installation of cable connections linking the island to the mainland is scheduled for 2027 and 2028. The island's electrical infrastructure is then set to be installed beginning in 2029, with the overall project expected to reach final completion in 2031, a timeline that was recently confirmed by law, according to Jan De Nul. At that point, the energy island will be capable of bringing its first electricity ashore.

Nature-Inclusive Design and Oyster Reef Restoration

Alongside the engineering and energy objectives, the project incorporates an environmental dimension developed in collaboration with marine experts. The foundation elements were designed with biodiversity in mind, aiming to support and enhance marine life on and around the island.

A central feature of this approach involves the creation of new oyster reefs. As part of the Reefcovery project, young oysters were grown on rocks which were then installed around the island at the end of July.

According to Bart Callens, Project Director for the Princess Elisabeth Island at Jan De Nul, the rocks serve a dual function: protecting the island against erosion while simultaneously providing the substrate for a new oyster reef to establish itself.

Callens described the outcome as a win-win and said the installation builds on Jan De Nul's existing expertise in restoring oyster reefs in the North Sea. He added that the work reinforces the company's ambition to embed nature-positive design across its core activities.

Demonstrating Belgian Offshore Capability

The completion of all 23 caisson installations has been characterised by those involved as a demonstration of the engineering capability available within Belgium for large-scale, complex offshore infrastructure projects.

The scale of the individual components, each one weighing tens of thousands of tonnes and standing as tall as 32 metres, combined with the weather-sensitive nature of offshore installation operations, meant the construction programme presented sustained logistical and technical demands throughout its duration.

The Princess Elisabeth Island represents the first such energy island of its kind, a distinction that has drawn European institutional attention and funding. Once operational, it is expected to function as the backbone of Belgium's expanded offshore wind infrastructure while opening the possibility of cross-border electricity exchange with the United Kingdom through a future interconnector link.

Belgium's Power Infrastructure Pipeline Is Moving Fast. Are You Keeping Up?

Every week, power infrastructure opportunities across Belgium emerge, shift, and close, often before unprepared teams even know they exist. The firms winning contracts and entering markets ahead of their competitors are not simply better resourced; they are better informed, tracking the right signals at the right time.

The Global Project Tracking (GPT) platform by Blackridge Research gives power infrastructure professionals a structured, continuously updated view of project activity across Belgium, from early planning stages through to completion. Whether you are monitoring a specific country, assessing regional demand, or benchmarking against awarded contracts, the platform brings critical intelligence into a single, accessible workspace.

Staying competitive in Belgium's power infrastructure sector means more than reading industry news. It means having a reliable system that surfaces actionable data before decisions are made elsewhere.

• Upcoming Projects

• Tender Notices

• Contract Awards

• Projects Under Construction

• Completed Projects
  

See how the Global Project Tracking (GPT) platform by Blackridge Research can sharpen your power infrastructure strategy across Belgium. Book a Free Demo with our team today.