IN Brief:
- DEME has secured foundation installation work for Zeevonk’s first 1GW phase.
- The contract covers transport and installation of 69 monopiles and associated secondary steel.
- A second phase is intended to combine another 1GW of wind with 500MW of system integration.
DEME has secured the foundation transport and installation contract for the first 1GW phase of the Zeevonk offshore wind project in the Dutch North Sea.
Subject to the project reaching final investment decision, DEME will transport and install 69 monopile foundations, manage the marshalling of primary and secondary steel, install secondary steel components, and prepare the filter layer used for scour protection around each foundation.
The company’s Orion vessel is expected to undertake monopile installation, supported by a jack-up vessel for secondary steel and a fallpipe vessel for the filter layer. Together, the three-vessel arrangement covers the principal marine operations required before turbine installation can begin.
Zeevonk is being developed by a joint venture between Vattenfall and Copenhagen Infrastructure Partners. The project area lies approximately 63km to 84km from the Dutch coast, near Bergen aan Zee, and was awarded through the IJmuiden Ver Beta offshore wind tender in 2024.
The development is divided into two 1GW phases. The first is intended to enter operation during 2029, while the second is planned for 2032 and is expected to combine a further 1GW of offshore wind with 500MW of system-integration capacity, including an electrolyser at the Port of Rotterdam.
A 250MW power-purchase agreement has already been signed with Google for output from the project. Long-term offtake provides a defined commercial route for part of the electricity, while foundations, turbines, array cables, substations, export infrastructure, and grid-connection works must still be aligned across the construction programme.
Marine works define the construction sequence
Monopile installation is one of the most schedule-sensitive stages in offshore wind construction. Each foundation must be transported, lifted, positioned, driven or drilled to the specified depth, surveyed, and prepared for the later installation of transition equipment and turbines.
Weather windows, vessel availability, seabed conditions, underwater-noise restrictions, and component delivery all influence progress, while the 69-unit programme also places substantial demands on fabrication and marshalling ports. Monopiles and secondary steel must arrive in the correct sequence, undergo inspection, and remain available without congesting the quayside or delaying vessel operations.
Scour protection forms part of the structural system rather than a finishing operation. Water movement around the monopile can remove sediment and alter seabed levels, affecting structural assumptions and cable approaches, while the filter layer provides a controlled base for further rock placement and helps maintain the intended seabed profile.
Although the foundation contract is primarily marine and structural, it fixes the physical geometry on which the electrical system depends. Turbine positions determine array-cable routes and lengths, while foundation interfaces must accommodate cable entry, internal electrical equipment, earthing, communications, corrosion protection, access systems, and monitoring equipment.
The phased structure of Zeevonk reflects a broader move towards offshore projects that combine generation with controllable demand and cross-system coordination. The planned electrolyser would allow some electricity to be converted into hydrogen when direct power export is constrained or when hydrogen production provides a stronger commercial route.
Such integration increases the number of interfaces requiring coordinated control. Wind output, grid availability, electricity prices, electrolyser loading, hydrogen storage, and port demand must be managed together, while the electrical connection still has to satisfy protection, reactive-power, fault ride-through, communications, and dispatch requirements over a long offshore export route.
North Sea transmission is developing along similar lines, with hybrid interconnector proposals linking offshore generation with more than one national market. That model moves beyond radial export cables and towards coordinated offshore energy infrastructure.
Zeevonk is not dependent on that specific connection concept, but both developments belong to the same transition from isolated offshore assets towards integrated generation, conversion, transmission, and flexible demand.
Final investment approval remains the next commercial threshold. Once granted, vessel scheduling, component supply, marine logistics, and electrical-interface management will need to remain aligned through a multi-year construction programme in which delays in one workstream can rapidly affect several others.
