First building blocks in place for Belgium’s North Sea energy island

Transmission company Elia Group has announced that construction has started on the Princess Elisabeth Island, an artificial energy island located 45km off the coast in the Belgian North Sea.

The company confirmed that the first two of 23 caissons have been submerged at their final location.

Caissons are concrete building blocks that will form the outline of the island. Each caisson weighs approximately 22,000 tonnes and measures 58 metres in length, 28 metres in width, and between 23 and 32 metres in height.

The blocks are built at the port of Vlissingen, Netherlands, and transported via four tugboats to the island site. This process takes about 24 hours.

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Elia Group explains that once at its destination, the caisson is connected to pre-installed anchors and positioned above the foundation zone. Continuous monitoring is required to ensure the structure is lowered at the right place, allowing it to descend in a controlled and stable manner.

The transport and placement of the caissons is dependent on tidal and weather conditions, with the operation only getting the green light if waves do not exceed 1.5 metres and wind speeds remain below 5 Beaufort.

The operation required 10 vessels, 150 people and collaboration with the Rescue and Coordination Centre (MRCC) in Ostend, the Joint Nautical Authority and North Sea Port.

Once a caisson is installed, rock armour is placed around it to protect it against storms and it’s filled with sand to accommodate the high-voltage infrastructure that will connect the offshore wind farms. Finally, the opening between the caissons is sealed to prevent sand from escaping later when the interior surface is filled.

The work is being carried out by TM Edison, a consortium of Belgian marine construction companies DEME and Jan De Nul.

Belgium’s Princess Elisabeth Island is considered an important link in connecting future offshore wind farms in the Belgian North Sea and will provide an efficient and economically viable way to expand Belgium’s offshore wind electricity production.

The project was approved in 2023. Earlier this year, Elia Group announced it is temporarily postponing the signing of the final contracts due to the price increase for high-voltage direct current (HVDC) infrastructure.

The company cited policy and regulatory uncertainties as the main reason for the decision, with the postponement providing time to weigh the changing market conditions and their associated impact on the project.

Originally published on powerengineeringint.com