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Belgium's Princess Elisabeth Island completes foundation ring in North Sea

Belgium's Princess Elisabeth Island completes foundation ring in North Sea

Built World

The $4.2B island will serve most of Belgium's new offshore wind zone, though cost overruns shelved its largest lot and a UK link.

October 27th, 2026: Utility Week reports island construction complete, flags open risks

Overview

Updated Oct 30

Workers have finished the outer shell of the world's first artificial energy island, 45 kilometers off Belgium's North Sea coast. Twenty-three concrete caissons, each weighing about 22,000 metric tons, form its perimeter, and sand fill is now underway.

In October, Elia said it would postpone signing its HVDC contracts because of higher equipment prices. Elia put the resulting slip at about three years, according to a report in Italian outlet Rinnovabili. Jan De Nul still cites a 2031 completion date set in law, and Utility Week reports the island's construction is complete, but the cable and power-equipment contracts that connect it to the grid remain unsigned.

Why it matters

If energy islands work, offshore wind can move far from shore and countries can share power across borders.

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Key Indicators

23
Concrete caissons forming the island's perimeter
Each caisson stands up to 105 feet tall and was built onshore in the Netherlands.
$4.2B
Reported project cost
Reported by Engineering News-Record in October 2026; Left in place, with a note that the €7 billion figure is unverified in this update.
3.5 GW
Planned offshore wind capacity
Design capacity for Belgium's second offshore wind zone; the initial alternating-current hookup serves about 60% of it.
22,000
Weight of each caisson (metric tons)
Each caisson is about 190 feet long and 92 feet wide.
6 ha
Island footprint
The artificial island covers about 15 acres.
€2.3B
European Investment Bank green financing
Elia closed the full funding package for the island's electrical infrastructure in 2026.

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People Involved

Gert De Smet
Gert De Smet
DEME project director for TM Edison consortium
Overseeing island construction
BC
Bart Callens
Jan De Nul project manager
Leading sand reclamation and island interior work
 Carolien Pouleyn
Carolien Pouleyn
Elia Transmission Belgium representative
Spokesperson for the project owner

Organizations Involved

ET
Elia Transmission Belgium
Grid operator
Project owner; postponed HVDC contract signing in October 2026

Elia operates Belgium's high-voltage grid and parts of Germany's, and owns Princess Elisabeth Island.
ED
TM Edison
Construction consortium
Building the island

TM Edison is the joint venture of Jan De Nul and DEME Group building Princess Elisabeth Island for Elia.
Jan De Nul Group
Jan De Nul Group
Marine contractor
TM Edison consortium member

Belgian marine contractor specializing in dredging and offshore construction.
DEME Group
DEME Group
Marine engineering contractor
TM Edison consortium member

Belgian marine contractor specializing in dredging and offshore energy.

Timeline

January 2024 October 2026

10 events Latest: October 27th, 2026 · 2 weeks ago
Tap a bar to jump to that date

  1. Utility Week reports island construction complete, flags open risks

    Latest Report

    Utility Week reports Elia has completed construction on the island. It names supply-chain limits and political approval for the UK connection as open challenges.

  2. Elia postpones signing of HVDC contracts

    Financial

    Elia temporarily postponed signing the island's HVDC contracts because of rising prices. Elia says the delay could push the whole project back about three years.

  3. Engineering News-Record reports the completed foundation ring

    Report

    ENR covers the milestone, detailing the caisson construction process and the island's role in expanding offshore wind.

  4. EIB finalizes €650 million green financing for the island

    Financing

    Elia and the European Investment Bank signed €650 million in green financing, completing the island's €2.3 billion funding package and unlocking procurement for transformer substations.

  5. 23rd and final caisson installed, completing the foundation ring

    Construction

    The last caisson is placed, finishing the island's perimeter and securing a €99 million European subsidy for Elia.

  6. Permits granted for Ventilus onshore grid link

    Regulatory

    Flemish minister Jo Brouns granted permits for the Ventilus grid reinforcement, the mainland link that will carry the island's power to demand centers.

  7. Belgium halts high-voltage direct-current contract for the island

    Regulatory

    The federal government told Elia not to sign a negotiated contract for the island's high-voltage direct-current equipment, citing cost overruns, and ordered it to work with regulator CREG on a cheaper concept.

  8. Elia pauses high-voltage direct-current equipment contracts

    Financial

    Elia suspended signing final contracts for the island's high-voltage direct-current equipment, citing extraordinary global price increases.

  9. First caisson installed at the island site

    Construction

    The first caisson is towed 45 kilometers offshore and sunk into place on a leveled rock foundation.

  10. Caisson production begins in the Netherlands

    Construction

    A 300-person crew starts building concrete caissons at a facility in Vlissingen, Netherlands, producing up to five at a time.

Scenarios

1

Princess Elisabeth Island delivers first power by 2031

Likely Resolves by End of 2031

Discussed by: Elia Transmission Belgium and project contractors

Jan De Nul says the 2031 completion date was recently set in law. Cable installation runs through 2027–2028 and electrical work through 2029. An October report, however, says the postponed HVDC contracts could delay the whole project by about three years, which would put first power well past 2031.

2

Belgium confirms a UK interconnector

Possible Resolves by End of 2027

Discussed by: Elia Transmission Belgium

Elia says it is in discussions to develop an interconnection to the UK. If those talks succeed, the island would link Belgium's grid to Britain's, adding cross-border trading to its role as a wind hub. The island is already designed to connect to Denmark.

3

Construction slips past 2031

Possible Resolves by End of 2031

Discussed by: Elia Transmission Belgium and the TM Edison consortium

The island's schedule is tight: cable installation runs through 2027-2028 and electrical work through 2029. Weather, supply delays, or technical problems could push completion past 2031. The Bornholm Energy Island in Denmark paused for seven months over financial concerns, a reminder of how schedules slip.

4

Third Wind Lot Waits on a Cheaper HVDC Design

Possible Resolves by End of 2027

Discussed by: Elia Transmission Belgium and Belgian energy regulator CREG

The zone's largest lot (1,400 MW) has no connection route until Elia and CREG settle and price a replacement for the canceled high-voltage direct-current concept. The relaunched 700 MW tender for the first two lots has no winning bid yet, and no wind farm in the zone has been awarded.

Historical Context

2 moments from history that rhyme with this story — and how they unfolded.

1995

Troll A platform (1995)

Norway installed Troll A, a concrete gravity platform in the North Sea standing about 369 meters tall. It was one of the largest concrete structures ever moved, towed into place in the Troll gas field.

Then

The platform began producing natural gas from the Troll field, one of Norway's largest.

Now

It proved that massive concrete structures could be built onshore, towed across open sea, and sunk into place — the same method Princess Elisabeth Island uses.

Why this matters now

Troll A showed the engineering path for building huge concrete structures in the North Sea and placing them on the seabed.

1991

Vindeby offshore wind farm (1991)

Denmark built the world's first offshore wind farm at Vindeby, 11 turbines about 2 kilometers from shore producing 5 megawatts.

Then

The farm proved offshore wind was technically feasible and ran for 25 years before being decommissioned in 2017.

Now

It launched an industry that now spans the North Sea, with turbines moving steadily further from shore.

Why this matters now

Vindeby started the move offshore; energy islands are the next step, letting wind farms sit so far out that a fixed platform is needed to gather their power.

Sources

(12)
+6
Engineering News-Record Jan De Nul Offshore Wind Dredging Today Voltformer Construction Review Online The Japan Times Flows Rinnovabili Utility Week Reuters Voltformer