Mammoet has signed a support agreement with Heerema Marine Contractors to assist with the offshore installation of two massive topsides for TenneT’s 2GW Program, a major European grid expansion initiative.
Under this agreement, Mammoet will play a crucial role in preparing the topsides for floatover operations. The process begins with skidding the enormous structures from a Heavy Transport Vessel (HTV) onto the newly constructed Heerema H-731 barge using hydraulic skid shoes—a precision operation requiring careful coordination and powerful, high-capacity equipment.
Once the topsides are in position on the H-731, Mammoet’s proprietary Mega Jack System will be deployed to lift them to the designated floatover height. This system, designed for lifting extremely heavy modules with millimeter precision, allows Mammoet to safely raise the topsides without relying on cranes—an advantage in offshore environments where weather windows and space are tight.
Following the lift, a Deck Support Frame—also known as a floatover frame—will be slid underneath the topsides. This component ensures a seamless transition to final installation, enabling the topsides to be secured onto pre-installed jacket foundations on the seabed.
The two topsides are part of a much larger energy infrastructure project led by TenneT, the Dutch-German transmission system operator. The 2GW Program will see the installation of fourteen offshore high-voltage direct current (HVDC) grid connection systems in the North Sea by 2032—eight off the Dutch coast and six off Germany. Each of these systems will have a capacity of 2 gigawatts, providing a total of 28GW of offshore grid connectivity.
Designed to transmit electricity generated by offshore wind farms, these HVDC platforms convert alternating current (AC) to direct current (DC) offshore before transmitting it to land via fewer, higher-capacity cables. This technology reduces losses and infrastructure needs, enabling faster and more efficient integration of renewable energy into mainland grids.
Richard Verhoeff, Sales Director at Mammoet, emphasized the significance of the partnership:
“With this contract, Mammoet will be playing a key role in securing the future of energy in Northern Europe while showcasing our unique capabilities in both high-precision skidding and jacking operations. We are delighted to be working closely with Heerema and thank them for enabling us to play an even greater role in the wider energy transition.”
Martijn Wijdeveld, Director of Supply Chain Management and Procurement at Heerema, echoed this sentiment:
“Mammoet is a market leader in offshore wind heavy lift and transport, and has proven it has the knowledge, equipment and engineers to manage the world’s biggest projects. We look forward to collaborating with them, benefitting from their vast experience of carrying out heavy lifts and transports safely and efficiently.”
This installation campaign forms part of a broader drive to meet Europe’s energy transition goals, with the North Sea positioned as a critical hub for renewable power generation. Once operational, the 2GW systems will support the transmission of wind-generated electricity to millions of homes and businesses across the continent.
Mammoet’s participation in this project adds to its growing portfolio of offshore wind and energy infrastructure operations. Its use of crane-independent systems like the Mega Jack and hydraulic skid shoes reflects a shift in offshore construction strategies—reducing dependence on heavy-lift vessels and allowing for greater flexibility in complex offshore settings.
The two topsides to be installed with Heerema are among the first of the 14 planned units. With the 2GW Program progressing toward its 2032 target, further installation campaigns are expected to follow in a carefully phased rollout over the next seven years.
