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The efficient construction of Walney Extension offshore wind farm

  • 19 kilometres off Walney Island, Cumbria, United Kingdom
  • 87 foundations
  • 659 megawatts of renewable generating capacity
  • capable of supplying more than 500,000 UK homes with renewable electricity

Van Oord has completed the installation of scour protection and the transport and installation of the 87 foundations for the Walney Extension offshore wind farm. When operational late in 2018, the world’s largest offshore wind farm will be capable of supplying renewable energy to more than half a million households in the United Kingdom. It will contribute to governmental targets to ensure that 15% of the UK’s energy is being produced sustainably by 2020. Offshore installation vessel Aeolus and heavy lift installation vessel Svanen played important roles in the efficient construction of the offshore wind farm.

Logistical and technical challenges

After the successful completion of Burbo Bank Extension offshore wind project in 2016, Van Oord again reached agreement with DONG Energy to build a new offshore wind farm. The project had both logistical and technical challenges. Simply transporting the foundation elements to Belfast from various locations spread across Europe was a logistical puzzle in itself. The monopiles were installed safely by our top duo Svanen and Aeolus well within the tight time schedule. In addition to the traditional method of installing foundations with the Aeolus jacked (standing on legs), the installation vessel accomplished a new first by installing the transition pieces while floating.

Specialised offshore wind equipment

Van Oord’s modern Aeolus was upgraded even further for this project. Thanks to innovative modifications, the vessel can also do its work while afloat. When using this method, it is extremely important to maintain the stability of the vessel throughout the installation cycle. While the Svanen has anchors to keep it in place during floating installation, the Aeolus used Dynamic Positioning (DP) to maintain a stable position. Prior to this project, the Svanen was also modified to the newest standards, engineered by our in-house experts.

The floating installation of the transition pieces was necessary because the soil conditions at most of the locations were inadequate to allow us to use the more conventional installation method of jacking up the vessel. The modifications to both vessels, which were engineered in-house and used on-site, and the experienced team on site contributed to highly efficient installation cycles.

Floren Verweij, Project Manager Van Oord
Floren Verweij, Project Manager Van Oord


The Walney Extension offshore wind farm is expected to be fully commissioned in 2018, at which time it will be the largest offshore wind farm in the world.

By partnering up with Van Oord again after the successful completion of our Burbo Bank Extension offshore wind project enabled us both to optimise our work methods even further.

Jesper Lykke Pedersen, Project Manager at DONG Energy
Additional information
  • Start date
    12 November 2016
  • End date
    11 August 2017
  • Location
    Irish Sea, approximately 19 kilometres off Walney Island, Cumbria, United Kingdom
  • Business Unit
    Offshore Wind
  • Client
    DONG Energy