Construction has begun on the Princess Elisabeth Island, the world’s first energy island, in the Belgian North Sea, with the first two of 23 caissons already submerged at their final location.
The work is being carried out on behalf of grid operator Elia Transmission Belgium by TM Edison , a joint venture between DEME and Jan De Nul.
The transport and installation of the caissons began on 21 April 2025. Each caisson weighs approximately 22,000 tonnes and measures 58 metres in length, 28 metres in width, and between 23 metres and 32 metres in height, depending on the presence of a storm wall.
For the transport from the Vlissingen Port, the Netherlands, four tugboats are used to tow each caisson via the Western Scheldt and the North Sea to the island site, covering a distance of approximately 53 nautical miles (about 98 kilometres).
The complete installation cycle takes about 24 hours, said Elia.
Once at its destination, some 45 kilometres from the coast, the caisson is connected to pre-installed anchors and positioned above the foundation zone. The unit, built in Vlissingen, is then filled with water, allowing it to descend to the seabed in a controlled and stable manner, according to Elia.
The next construction phase includes placing rock armour around the submerged caisson to protect it against potential summer storms, filling the unit with sand, and preparing for the installation of the next caisson.
Finally, the opening between the caissons is sealed to prevent sand from escaping later when the interior surface is filled.
The construction of the Princess Elisabeth Island and the implementation of the already signed high-voltage alternating current (HVAC) contracts are continuing without interruption, said Elia.
Due to the price increase for high-voltage direct current (HVDC) infrastructure, the decision on the final contracts for the island has been delayed.
Princess Elisabeth Island 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.