Belgium sank 23 concrete blocks weighing 22,000 tonnes each in the North Sea to build the world’s first artificial energy island in a €7 billion project.

Forty-five kilometers off the Belgian coast, in the North Sea, man is creating something that does not exist naturally in water. It is the world’s first artificial energy island, the size of eight football fields, and is built with 23 giant concrete caissons, each weighing approximately 22,000 tons.

While one might assume that the island would house humans or create a wildlife sanctuary, its purpose is neither of these. It is being built to collect all the electricity generated by future Belgian offshore wind farms and send it to the continent via undersea cables.The project known as Princess Elizabeth Island is being promoted by the Belgian electricity system operator Elia. It is being built by the TM Edison consortium, formed by the Belgian engineering companies DEME and Jan De Nul.

At the end of January 2026, those responsible announced a key milestone: the last caisson had been manufactured and was afloat. And that’s when the decisive phase begins.

A source of energy

" msid="133955066" imgsize="900131" resizemode="4" width="" title="In total, the operation spans two years, with breaks during the winter storm season. " placeholdersrc="https://static.toiimg.com/photo/83033472.cms" offsetvertical="0" placeholdermsid="47529300" type="thumb" fifu-data-src="https://i1.wp.com/static.toiimg.com/photo/imgsize-900131,msid-133955066/each-box-measures-approximately-58-metres-longbr.jpg?ssl=1" data-api-prerender="true">In total, the operation spans two years, with breaks during the winter storm season.

Each box measures approximately 58 meters long, 28 meters wide and between 23 and 32 meters high, depending on the configuration of the storm walls. They were manufactured in the port of Vlissingen (Netherlands), on a production line with five stations that allowed working on several units simultaneously. The entire process for a single block takes around 85 days.DEME confirmed in January 2026 that the final caisson was completed and launched, marking the end of the manufacturing phase. Now, the pieces are transferred to the Scaldia terminal for final finishing before final installation at sea.The blocks will not simply be thrown into the water and sink. They will be towed partially submerged to the site, where dredgers and ships have previously prepared a rock base.

Once in position, they will be filled with sand so that they can sink and rest on that base. The first immersion campaign began in April 2025 with two caissons. It ended in October and will resume this spring of 2026, weather permitting. In total, the operation spans two years, with breaks during the winter storm season.

The entire installation cycle, from departure from port to placement and fixing at the final destination, takes approximately 24 hours.The island is vital for the European electricity system. It is not an end in itself but a distribution center. Its infrastructure will combine high-voltage alternating current (HVAC) and high-voltage direct current (HVDC), a combination very rare at sea and critical to the project’s classification as the world’s first “energy island.”In practice, it will consolidate the submarine cables of the new wind farms that will occupy the so-called Princess Isabel Zone, a strip of land of 285 square kilometers destined to produce up to 3.5 GW of offshore wind energy.

This electricity will then be transmitted to the ground through high capacity cables.In addition, the connection with future international interconnectors is planned (Nautilus with the United Kingdom and TritonLink with Denmark), which will allow the exchange of electricity between national networks based on demand and the renewable production available at all times.

Inclusive nature

The design is not limited to being concrete in the middle of the sea.

Elia and her partners worked with marine conservation experts under an approach called “nature-inclusive design,” something like design integrated with nature. The outer walls incorporate ledges for the resting and breeding of the gull, a species classified as threatened in the North Sea. There are also submerged structures for marine organisms and specific solutions for the European flat oyster.

The NID4BirdLIFE programme, co-financed by the European Union’s LIFE programme, will follow the development of nests for six and a half years using cameras installed on the walls themselves.The economic figures reflect the magnitude of the effort. In October 2024, the European Investment Bank approved financing of €650 million for Elia Transmission Belgium for the first phase of the project, with a total estimated cost of €1,105 million.

But the project has been affected by a spectacular increase in costs, which have gone from an original estimate of 650 million euros to 7 billion euros. This increase is primarily due to increases in the cost of electrical equipment and has raised concerns about the viability of the project.According to available data, most of the civil engineering works should be completed by mid-2026. The electrical infrastructure itself will be installed between 2026 and 2030. The island should come into operation around 2030, in parallel with the new wind farms and the Ventilus and Boucle du Hainaut onshore projects, responsible for delivering electricity to the end consumer.