World's first energy island: How Belgium built a switchboard in the North Sea

Forty-five kilometres off the Belgian coast, in open North Sea, a ring of concrete now sits where there was nothing.

The 23rd and final caisson of Princess Elisabeth Island was installed in August 2026, completing the foundation works of what its developers call the world's first artificial energy island, according to a Times of India report.

The European Investment Bank has now confirmed a €1 billion green credit facility to Elia Transmission Belgium to pay for the electrical infrastructure of the project's second phase. The loan was signed on July 17 and confirmed publicly in early September. It is the largest single loan the bank has made for energy infrastructure anywhere in the Benelux region.


The island is not a place for people to live or a wildlife reserve, though it will host both a small harbour for maintenance crews and a helideck. It is a switchboard. Its job is to gather the electricity produced by future offshore wind farms and push it to the mainland through submarine cables.

How it was built

The island is being delivered on behalf of grid operator Elia by TM Edison, a consortium of the Belgian engineering firms DEME and Jan De Nul.

As The Times of India reported, each of the 23 caissons measures about 58 metres long and 28 metres wide, stands between 23 and 32 metres high depending on whether it carries a storm wall, and weighs roughly 22,000 tonnes. All were cast at the port of Vlissingen in the Netherlands on a five-station production line that allowed several units to be worked on at once, with around 300 people on site each day. A single caisson took about three months to complete.

They were not simply dropped into the sea. Dredgers and ships first prepared a foundation bed on the seabed. Each caisson was then towed out partially submerged, positioned, and filled with sand so it would sink and settle onto that base. The full cycle from leaving port to final placement took roughly 24 hours.

Installation ran from April 2025, paused over the winter storm season, and resumed in spring 2026 across a second offshore campaign. Work now moves inside the ring, reclaiming land with sand and building out the interior.

Room for birds in the walls

Elia and its partners worked with marine conservation specialists on what the project calls nature-inclusive design. According to TOI, the outer walls carry protrusions built for the kittiwake, a seabird classified as threatened in the North Sea, to roost and breed on. Submerged structures were added for marine organisms, with specific provision for the European flat oyster.

A programme called NID4BirdLIFE, co-funded by the European Union's LIFE programme, will monitor nesting over six and a half years using cameras set into the walls themselves.

What it will carry, and what it will not

The island will collect cables from the wind farms planned for the Princess Elisabeth Zone, a 285-square-kilometre area designated for up to 3.5 GW of offshore wind capacity, and send that power ashore.

The original design paired high-voltage alternating current with high-voltage direct current, an unusual combination at sea. That is no longer the plan. In June 2025, after a restricted cabinet meeting, Belgian Energy Minister Mathieu Bihet announced the island would proceed with AC connections only. The HVDC component was suspended.

The decision followed months of review by the energy regulator Creg, the federal energy directorate and Elia, which concluded that alternatives were technically viable, economically better and legally sound. Industry analysis had also questioned whether HVDC was necessary over the relatively short distances involved.

The DC component was what would have enabled the planned international interconnectors, Nautilus to the United Kingdom and TritonLink to Denmark, allowing countries to trade power according to demand and available renewable output. The AC-only design still connects two of the three planned wind farms, of 700 MW and 1,400 MW, covering roughly 60% of the zone.

Why the plan changed

Elia said the budget for the wider Princess Elisabeth Zone project roughly doubled from about €3.6 billion to somewhere between €7 billion and €8 billion, driven overwhelmingly by the price of HVDC equipment amid inflation, material shortages and what Elia's tender process described as an overheated global supply chain for the technology.

In February 2025, Elia's board postponed signing the HVDC contracts rather than commit at those prices. The government decision to drop the component followed in June.

The financing has been split across phases. The EIB approved €650 million in October 2024 for phase one, which covers the island's construction and carried an estimated cost of around €1.105 billion. The new €1 billion facility covers phase two, estimated by the EIB at roughly €2.296 billion, funding a 220 kV offshore substation, 66 kV switchgear, transformers and six three-phase 220 kV cables running to an onshore substation. Total EIB exposure now stands at €1.65 billion. The project also qualified for a €99 million EU subsidy for one construction phase.

Elia has said the favourable financing terms should hold down overall borrowing costs and limit what gets passed to consumer bills, a live political question in Belgium where electricity affordability remains near the top of the federal agenda.

When it switches on

Around 165 kilometres of subsea and onshore cabling at 220 kV still has to be laid, alongside the island's interior works and electrical plant. Elia is working toward readiness in 2031, the year the first wind farm is expected to connect. Onshore, the Ventilus and Boucle du Hainaut projects will carry the power to end consumers.

One piece of the picture remains unsettled. In 2025 the Belgian Council of Ministers postponed the tender for the Princess Elisabeth Zone I site, saying procurement would open in 2026.

(With inputs from TOI)