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TenneT awards transport and installation slots for 2GW offshore platforms to Allseas and Heerema

TenneT has signed multi-year framework agreements with Allseas and Heerema Marine Contractors for transport and installation of at least fourteen 2 gigawatt (2GW) offshore platforms. The fourteen 2GW converter stations will be installed in the Dutch and German parts of the North Sea. The framework agreement covers at least twenty-eight slots until 2031; fourteen slots for transport and installation of a jacket and fourteen slots for transport and installation of a topside.

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  • TenneT signs framework agreements for transport and installation of fourteen 2GW offshore converter stations with Allseas and Heerema Marine Contractors
  • Agreement reserves early transport and installation of jackets and topsides for at least eight Dutch and six German 2GW projects and future projects
  • All major framework agreements of the 2GW Program have thus been awarded: for civil works, fabrication of offshore and onshore converter stations, production and installation of HVDC cables, and transport and installation of offshore converter stations.


Well-known, experienced installation vessels

Semi-Submersible Crane Vessel (SSCV) Sleipnir and single-lift installation vessel Pioneering Spirit

Heerema will deploy the Semi-Submersible Crane Vessel (SSCV) Sleipnir as well as an owned floatover barge, Allseas will use its single-lift installation vessel Pioneering Spirit for the installation of the jackets and topsides. Both vessels have been used several times in recent years to install jackets and topsides for TenneT in the Dutch and German North Sea. Heerema has been awarded about 60% of the available slots, while Allseas has been awarded approximately 40% of the slots. Additional work can be added to the awarded contracts. The awarded slots are not linked to specific 2 GW projects. The HVDC suppliers building the jackets and topsides for TenneT (Hitachi Energy/Petrofac, GE/Sembcorp, GE/McDermott and Siemens/Dragados) can choose from the suppliers whereby Heerema and Allseas can install both jackets and topsides. 

Boskalis will act as a subcontractor to Allseas, building one or two new transport vessels specifically for the 2GW Program that will meet the most stringent future legislation standards on sustainability and emissions.

  • Offshore Sleipnir HKZ beta installation

    Semi-Submersible Crane Vessel (SSCV) Sleipnir working on the Hollandse Kust (zuid) Beta installation

  • Pioneering Spirit DolWin kappa offshore platform installation

    Single-lift installation vessel Pioneering Spirit at the DolWin Kappa offshore platform installation.

European market players

Tim Meyerjürgens, COO at TenneT says

"With this agreement we secure global marine transport and the heaviest offshore installation capacity in the market for our HVDC partners while expanding transport capacity in the market. We are proud to have signed this framework agreement with these Dutch and Swiss-Dutch suppliers. These European partners once again prove that they are global market leaders in offshore transport and installation. They have the equipment to carry out projects of such magnitude safely and successfully."

Willingness to invest

Recently, TenneT awarded framework agreements for the civil works for the land stations in the Netherlands, offshore and onshore converter stations and the cable connections of the fourteen 2 GW projects in the Netherlands and Germany. The new tendering approach accelerated the process, with agreements being reached with all suppliers in a short period of time. Marco Kuijpers, Director Large Projects Offshore at TenneT:

"With the partnership values in these long-term agreements, we offer a strong basis for the successful implementation of the projects. These contracts give planning certainty and predictability to our suppliers, which they need to invest."


Pieter Heerema, Allseas’ President, said: “We are delighted that Allseas’ superior single-lift technology has been selected to help TenneT realise its ambitious 2GW Program, and play a key role in Europe’s energy transition. When my father, Edward Heerema, devised the single-lift concept in 1987, no one could have envisioned it would be deployed for a landmark offshore energy project of such strategic importance four decades later. Pioneering Spirit’s unique transport and installation capability has been used to great effect to deliver critical assets for offshore wind developments across Europe. The ship’s large lift capacity and high workability ensure that the installations can be safely performed all year round, creating maximum flexibility in the vast and complex building schedules. We look forward to strengthening our relationship with TenneT and getting started on this prestigious project.”

Jeroen van Oosten, Heerema’s Chief Commercial Officer said: ‘We are proud to be selected to work alongside TenneT to deliver clean energy for the Netherlands and Germany. The award of this framework agreement is an important showcase of the benefits of forming trust-based partnerships between clients and contractors. To ensure clean energy demands are met, there should be a continued focus on collaborative, forward-looking agreements that recognize the need to secure transport and installation capacity.’


Ostend Declaration

Belgium, Denmark, Germany, the Netherlands, France, Ireland, Luxembourg, Norway and the United Kingdom signed the Ostend Declaration at the North Sea Energy Summit in April 2023. In this declaration, the countries agreed to jointly install at least 120 gigawatts (GW) of offshore wind power capacity by 2030. TenneT, Europe's leading offshore transmission system operator, will account for about one-third of this volume, or 40 GW of grid connections. To this end, TenneT is building offshore grid connection systems in Germany and the Netherlands with a total capacity of 20 GW each.

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