Final caissons for world’s first artificial energy island readying for spring installation

January 29, 2026, by Adrijana Buljan

Jan De Nul has constructed and floated the remaining concrete structures for the Belgian Princess Elisabeth Energy Island at the Vlissingen site in the Netherlands. The concrete caissons are now at the Scaldia terminal, where they will undergo final works before being installed offshore this spring.

Princess Elisabeth Island caissons; Video screenshot; Source: Jan De Nul

The installation of the caissons started in April last year, when the first two of 23 concrete structures were submerged at the energy island’s site, 45 kilometers off the Belgian coast.

The offshore installation campaign for 2025 was completed in October last year and will resume this spring with the installation of the remaining structures, alongside continued works to prepare the island’s interior, according to Jan De Nul.

Each of the caissons, which form the outer walls of the future island, weighs approximately 22,000 tons and measures 58 meters in length, 28 meters in width, and between 23 meters and 32 meters in height, depending on the presence of a storm wall.

Developed by Belgium grid operator Elia Group, the project is being built by TM Edison, a consortium including DEME and Jan De Nul.

The Princess Elisabeth Island will serve as a key connection point for transporting at least 2.1 GW of offshore wind energy generated in the Princess Elisabeth Zone to the mainland.

This will be the first artificial energy island in the world to combine both direct current (HVDC) and alternating current (HVAC). The high-voltage infrastructure on the island will bundle together the electricity cables from the wind farms in the Princess Elisabeth Zone.