Construction has commenced on the Princess Elisabeth Island in the Belgian North Sea, a key infrastructure project aimed at strengthening Belgium’s future energy supply through offshore wind integration.
The artificial island, located approximately 45 kilometres off the Belgian coast, will serve as a central hub for high-voltage infrastructure connecting upcoming offshore wind farms. The development is being led by Elia Transmission Belgium (Elia), the national grid operator, with construction carried out by TM Edison—a consortium comprising Belgian marine contractors DEME and Jan De Nul.
The project reached a milestone with the successful placement of the first two caissons, massive concrete blocks that will form the perimeter of the island. A total of 23 caissons, each weighing about 22,000 tonnes and measuring up to 32 metres in height, will be installed over the coming months.
“The transport and installation of the caissons at sea is a technically complex operation,” Elia said. “It requires extremely precise planning and is carried out in close collaboration with maritime authorities.”
The operation began on April 21 and involves a fleet of around ten vessels and a workforce of approximately 150 people. Caissons are towed from the port of Vlissingen and submerged using controlled water-filling techniques, guided by advanced surveying and real-time monitoring systems. The successful placement depends heavily on favourable weather and sea conditions, with wind speeds restricted to below 5 Beaufort and waves no higher than 1.5 metres.
Once installed, each caisson is secured to anchors and surrounded by rock armour for protection. The interior will later be filled with sand to support the high-voltage infrastructure needed to connect offshore wind farms to the mainland grid.
The island is considered a cornerstone of Belgium’s energy transition strategy. It forms part of the Federal Development Plan for the high-voltage network and supports the integration of renewable energy into a future pan-European electricity system.
“This project will become a crucial link in connecting new offshore wind farms and offers long-term opportunities for cross-border electricity exchange,” Elia said.
While construction of the island and the associated alternating current (HVAC) systems is ongoing, the final contracts for the high-voltage direct current (HVDC) infrastructure are still under review due to rising costs. Elia noted that the delay, while consequential, allows for a reassessment of design options in light of evolving market conditions.
Discussions between Elia and federal authorities continue, with the goal of arriving at a balanced political decision that aligns with technical and economic realities.
