05 September 2022

DolWin kappa installation: Allseas strengthens position in offshore wind

Allseas’ Pioneering Spirit  has successfully installed TenneT’s 900-megawatt DolWin kappa offshore converter station for the DolWin6 offshore grid connection system in the German North Sea.

DolWin kappa was constructed at the Dragados Offshore shipyard in Cadiz, Spain. Siemens Energy was commissioned by TenneT as general contractor to build the system.

Comprising an approximately 5,000-tonne foundation jacket and 11,000-tonne topsides housing high-voltage direct current (HVDC) technology, DolWin kappa is Allseas’ first complete platform installation for the offshore wind industry.

Completed on 4 September after a 12-day campaign, installation of DolWin kappa – including piling of jacket foundations – again demonstrates Allseas’ ability to execute technically challenging offshore projects.

Complete transport and installation solution

Designed and built by Dragados Offshore in Cádiz, Spain, DolWin kappa arrived in the Port of Rotterdam in mid-August on Allseas’ cargo barge Iron Lady. In a quick turnaround operation, all components – jacket, topsides, piles and connecting bridge – were transferred to the world’s largest construction vessel for transport to the installation site.

All components were installed directly from Pioneering Spirit, using both the topside and jacket lift systems. In another first for Allseas, the 5,000-tonne special purpose crane was deployed to drive the 10 foundation piles up to 68 metres deep into the seabed to secure the foundation jacket.

The project confirms Allseas can adapt Pioneering Spirit’s single-lift capability to provide fast and efficient transport and installation solutions for the fast-growing offshore wind market, strengthening our ambition to become a key contractor in the renewables space.

Sustainable solutions to facilitate energy transition

The installation of DolWin kappa is key to unlocking additional North Sea wind energy capacity, advancing offshore grid expansion in support of Europe’s energy security. TenneT’s DolWin6 connection will provide more than 1 million homes with renewable energy when it comes on line in 2023.

Allseas is committed to driving sustainability offshore by pioneering solutions onshore to facilitate the transition and safeguard energy affordability.

Pioneering Spirit’s size and versatility delivers high workability all year round, fast-tracking the development cycle and enabling our clients to realise their project ambitions sooner.

Creative concepts for new challenges

DolWin kappa follows substation installations end 2021 / start 2022 for the Hollandse Kust Zuid (HKZ) offshore project off the Dutch coast for German-Dutch green grid operator TenneT, and the Saint-Nazaire wind farm in France.

Allseas is also developing new concepts for the installation of next generation turbines and foundations required to meet growing demand for renewable offshore energy.

Read more about Allseas’ projects.