Elia is building an island with 23 megablocks of concrete

The high-voltage grid operator Elia is working on the first ‘stone’ for the construction of an island off the Belgian coast. The energy island, with high-voltage infrastructure for both new wind farms and connecting cables with neighboring countries, is a world first.

In a remote corner of the port of the Zeeland city of Vlissingen, the foundation for 13 hectares of additional Belgian territory is being laid. On a reinforced quay, TM Edison, the combination of the marine builders DEME and Jan De Nul, is making enormous concrete blocks for an artificial island that will be built gradually in the coming years. That island is necessary to import electricity from or export electricity to neighboring countries using Elia’s new high-voltage infrastructure for the connection of additional offshore wind farms and submarine cables.

The energy island will be one of the most remarkable achievements of the federal government in the energy transition. It was not included in the coalition agreement, but is moving rapidly from the drawing board to realization. Last year the model was presented for the first time at the North Sea Summit in Ostend. Today, the island’s building block yard is almost finished producing the first concrete block for the island.

Although concrete block is a somewhat derogatory word for the concrete structures, called caissons, that are cast at the shipyard in Vlissingen. Such a caisson looks like a windowless apartment building, measuring 57 by 28 meters and 22 meters high. “They weigh 22,000 tons,” explains Valérie Daloze, Elia project manager, during a site visit in the presence of Prime Minister Alexander De Croo (Open VLD), Energy Minister Tinne Van der Straeten (Green) and State Secretary for Relance Thomas Dermine (PS). .

At the yard, caissons in various stages of finishing are towed from one finishing station to another by a hundred lifting trucks. Farthest from the quay is a bottom plate where 100 men have to braid 350 tons of steel. Another caisson is as good as finished and after inspection it still needs a concrete top plate. When the caisson is ready, it is launched and temporarily stored in the port.

Meanwhile, in the Belgian North Sea, 45 kilometers off the coast, the seabed is being reinforced and prepared to install 23 caissons. During calm summer weather, the hollow blocks will first be sunk on site with water and then filled with sand.

If this is done perfectly, a rectangle will be created that will form the outer edge of the future Princess Elisabeth Island. The inside of that rectangle will be filled with sand, making the 500-meter artificial island ready for the construction of all kinds of high-voltage infrastructure in the summer of 2026.

“The energy island will give our country access to cheap and sustainable energy,” says De Croo. This will come from additional Belgian offshore wind farms, but also from other North Sea countries such as the United Kingdom or Denmark.

Minister Van der Straeten notes that our country is not only pioneering the concept of the energy island, but also the ‘nature-inclusive design’. In certain places, ledges and panels have been installed on which seabirds can build nests or where marine animals can take shelter.

It is not yet clear exactly how much the island costs. The construction of the island itself is a contract worth more than 600 million euros; the tender for the electrical infrastructure and cables is still ongoing. The island, which received European subsidies worth 100 million euros, was cheaper than building separate steel platforms in the North Sea.