Since 2025, Belgium installed 23 concrete blocks weighing 22,000 tonnes each in the North Sea; together, they now form the walls of a new artificial energy island

Belgium’s Offshore Energy Island Takes Shape: Forty-five kilometers off the coast, workers recently lowered the final concrete caisson to complete the outer walls of Princess Elisabeth Island. These 23 massive blocks, each weighing 22,000 tonnes, enclose an offshore area roughly the size of eight football fields. Crews are now filling the interior with sand to create a stable ground for the central electrical hub. By collecting power from upcoming 3.5-gigawatt wind farms, the island will streamline power transmission while eliminating the need for numerous individual cables running ashore.

Building this infrastructure brought both ecological design and steep budget challenges. Project costs expanded toward seven billion euros, prompting engineers to adjust the electrical architecture. Alongside its energy role, the island features artificial ledges along the concrete walls to harbor threatened seabirds, while underwater oyster beds protect the foundation against seabed erosion.

Why does Belgium need an energy island in the North Sea?

Belgium is looking to offshore wind as an important source of low-carbon electricity. The country’s second offshore wind zone is expected to add significant generation capacity, but producing electricity far out at sea is only part of the challenge. That power must be collected, managed and transported to the mainland through an increasingly complex electricity network.


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The Princess Elisabeth Island is being developed by Elia Transmission Belgium to serve that role. Rather than relying only on individual offshore connections, the island is designed as a central point for electricity infrastructure. It will connect the second Belgian offshore wind zone and create the possibility of linking Belgium’s power system with the United Kingdom.

That cross-border element gives the project significance beyond Belgium’s own electricity supply. Electricity demand and generation do not always peak at the same time in different countries. Interconnections can allow power to move between markets when supply conditions change, potentially making the wider European electricity system more flexible.

How were the island’s foundations built?

The foundation is not a conventional island built by simply piling material into the sea. Its outer structure consists of 23 large caissons, which are engineered hollow structures installed in the seabed to create a contained perimeter. Once the shell is in place, sand can be placed inside it to create the reclaimed land on which the island’s infrastructure will eventually stand.

The foundation works were carried out by TM EDISON, together with DEME, on behalf of Elia Transmission Belgium. The installation of the first caisson in 2024 marked the beginning of a particularly challenging offshore construction phase. Completing the final element means the complete perimeter needed for the next stage is now in place.

The location itself adds to the difficulty. Construction is taking place 45 kilometres offshore in the North Sea, where marine conditions, weather and the logistics of transporting and positioning massive structures all have to be carefully managed. Finishing the foundation works within the planned timeframe was therefore important not only for construction progress but also for the project's wider funding and schedule.

What happens to the island after the foundations are finished?

The completed caisson structure is only the beginning of the island’s development. The next major task is to reclaim the area inside the protective shell by filling it with sand. This will gradually turn the enclosed offshore structure into the physical platform required for the island’s future electrical facilities.

The project then moves into a series of longer-term construction stages. Cable connections to the mainland are scheduled for installation in 2027 and 2028. Electrical infrastructure is expected to begin going into the island in 2029, bringing the project closer to its intended role as an offshore electricity hub.

The final completion date is planned for 2031, a timeline recently confirmed by law. If that schedule is maintained, the island will be ready to bring its first electricity ashore by then, linking the offshore generation network with Belgium’s mainland electricity system.

Why is the project important beyond Belgium?

The island reflects a broader change in how European countries are planning offshore wind infrastructure. As more wind farms move farther into the sea, electricity networks need to evolve alongside generation. A large offshore hub can provide a way to concentrate connections and potentially link several electricity systems rather than treating each wind farm as an isolated project.

The proposed connection with the United Kingdom adds another layer to that strategy. Cross-border electricity links can help countries exchange power and make better use of available generation. In a system increasingly dependent on variable renewable sources such as wind, the ability to move electricity between markets can become particularly valuable when production and demand differ from one region to another.

There is also a financial dimension to the construction milestone. The project team said completing the foundation works within the planned timeframe allowed Elia to qualify for a €99 million European subsidy allocated to this phase. That support reflects the project’s wider European relevance, particularly its focus on energy independence and cross-border electricity exchange.

Belgium is not alone: Europe is turning the North Sea into a new energy network

Belgium’s Princess Elisabeth Island is part of a much bigger change taking shape across Europe. Denmark has its own plan for an artificial energy island in the North Sea. The idea is simple, but the engineering is not. Instead of bringing power from each offshore wind farm straight to shore, a central hub could collect electricity from several projects and send it where it is needed. Denmark’s planned island could eventually support several gigawatts of offshore wind power and connect energy networks across national borders.

Another project shows how the same idea can work without creating new land. Denmark’s Bornholm Energy Island will use the existing island of Bornholm as a power hub for offshore wind in the Baltic Sea. Electricity generated at sea can be brought together and then transmitted toward Denmark and Germany. It is a different design, but the thinking is similar. Offshore wind is no longer being treated as a collection of isolated projects. Countries are beginning to plan shared infrastructure around it.

There is also the proposed North Sea Wind Power Hub, which goes even further. The long-term concept involves artificial islands or offshore hubs around the shallow Dogger Bank area. They could gather electricity from surrounding wind farms and connect several European grids.

These projects are still at different stages, and some remain plans rather than construction sites. But together, they point to a significant shift. Europe is not simply building more wind turbines. It is beginning to build an energy system around them, much of it far out at sea.

What will the Princess Elisabeth Island ultimately change?

The immediate achievement is a completed foundation shell in the North Sea. The larger objective is to create infrastructure capable of connecting offshore wind generation with Belgium’s electricity network while opening the door to international power exchanges.

Frédéric Dunon, CEO of Elia Transmission Belgium, described completion of the foundation works as a major step in developing Belgium’s offshore energy infrastructure. The significance of the milestone lies less in the visible structure itself than in what it is designed to carry: the electrical systems and connections that will determine how effectively offshore power can reach consumers.

The island is still years from its planned completion, and several technically demanding stages remain. But the transition from an offshore construction site to a reclaimed energy platform has now begun. With all 23 foundation elements in place, Belgium has completed the physical shell of a project intended to connect its next generation of offshore wind power with both its own grid and a wider European electricity network.