TenneT has signed multi-year framework agreements with Heerema Marine Contractors and Allseas for transportation and installation of at least fourteen 2 gigawatt (2GW) offshore platforms. The fourteen converter stations will be installed in the Dutch and German parts of the North Sea.

The framework agreement covers at least 28 lots until 2031; fourteen lots (eight Dutch and six German) for transportation and installation of a jacket and fourteen lots for transportation and installation of a topside.

Heerema has been awarded approximately sixty per cent of the available lots and additional work can be added to the awarded contracts. The awarded lots 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 can install both jackets and topsides.

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Heerema will deploy the Semi-Submersible Crane Vessel (SSCV) Sleipnir, as well as an owned floatover barge for the installation of the jackets and topsides. These assets are suited to installing the heavy offshore wind infrastructure associated with the 2 GW programme.

Sleipnir has previously installed the Hollandse Kust Alpha and Beta jackets for TenneT in the Dutch North Sea.

Heerema's Sleipnir (picture by Heerema).
Heerema’s Sleipnir (picture by Heerema).

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Pioneering Spirit

At the same time, Allseas’ single-lift technology has been selected to install supersized offshore wind converter stations. The agreement continues the strong collaboration between TenneT and Allseas, following earlier offshore wind installation awards for transformer stations (700 MW) in the Dutch North Sea.

Allseas has been awarded fifteen “slots” for T&I of a supporting jacket or high voltage direct current (HVDC) converter topsides for the transmission of wind-generated power to shore. Allseas will deploy its revolutionary single-lift vessel Pioneering Spirit for the works.

Pieter Heerema, Allseas’ President: ‘Pioneering Spirit’s unique transport and installation capability has been used to great effect to deliver critical assets for offshore energy and wind developments across Europe. The next generation converter stations are substantial structures, similar in size to a football pitch and weighing up to 30,000 tonnes, housing complex and delicate HVDC technology that makes them a good match for our industry-leading installation capabilities.’

Also read: Pioneering Spirit installs DolWin kappa offshore converter station

European market players

‘With this agreement we secure global marine transportation and the heaviest offshore installation capacity in the market for our HVDC partners while expanding transportation capacity in the market,’ concludes Tim Meyerjürgens, COO at TenneT. ‘We are proud to have signed this framework agreement with Dutch and Swiss/Dutch suppliers. These European partners once again prove that they are global market leaders in offshore transportation and installation. They have the equipment to carry out projects of such magnitude safely and successfully.’

Picture (top): Pioneering Spirit installing the DolWin kappa offshore converter station (by Allseas).

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