Work has started on the installation of 277 foundations for the Dogger Bank offshore windfarm in the North Sea (source: Dogger Bank)
Work has started on the installation of 277 foundations for the 3.6-GW Dogger Bank offshore windfarm, which is being developed in the UK sector of the North Sea, 80 miles off the Yorkshire coast
The campaign to install the turbine foundations at what will be the world’s largest offshore windfarm saw the first monopile and transition piece installed on the Dogger Bank A segment of the project. The installation campaign is being led by Seaway 7 supported by DEME.
The foundations for Dogger Bank are UK-designed and have a unique split-level transition piece, as well as a world’s-largest 8-m flange – or projecting flat rim – to support the turbine towers.
Installation of GE Renewable Energy’s Haliade-X turbines will commence from Spring 2023.
Steel manufactured by Tata Steel in Wales and processed in Corby and Hartlepool is being used in the supporting components of the transition pieces, while South Tyneside-based Metec and Rochdale-based Granada Material Handling have also won contracts with Smulders to support this innovative and world-leading project.
SSE Renewables project director Steve Wilson said, “These foundations have been designed for what is arguably the most demanding wave environment to be encountered on an offshore windfarm and are a testament to the many companies involved in collaborating to reach this unprecedented milestone.
“As well as the sheer scale of the foundations, we’ve incorporated a unique split-level transition piece which allows safe access for technicians directly into the turbine tower, from service and operations vessels, eliminating thousands of manual handling activities and lifting operations over the lifetime of the assets.”
Designed in the UK by Wood Thilsted, the foundations have been optimised to tackle challenging wave loads in the Dogger Bank area of the North Sea, with installation in water depths of up to 32 m and at a distance of 130 km from shore.
Over the three-year installation programme for the three phases of Dogger Bank, the monopiles and transition pieces will be loaded onto installation vessels in Rotterdam ahead of transfer to the offshore windfarm. Using dynamic positioning technology the vessels will pinpoint the installation site on the seabed at which point a monopile measuring up to 72 m will be upended and transferred to a pile gripper, before being lowered into the seabed.
A hammer will be used to drive the monopile to the design depth in the seabed before a guidance system aligns the installation of the record-breaking 8-m flanges which act as a connection for the transition piece which is then installed onto the monopile. The foundations require 152 M80 bolts to secure them before a cover is inserted onto the top of the transition piece to leave it watertight.
Seaway 7 was awarded the tier one contract for foundation installation on all three phases of Dogger Bank, with sub-contractor DEME deploying its Innovation vessel for installation of the first foundations on Dogger Bank A.
Following Innovation, Seaway Strashnov will deploy on Dogger Bank A to continue the foundation installation.
In November 2020, a consortium Sif and Smulders was awarded a contract to manufacture of all 190 monopiles and transition pieces for the Dogger Bank A and B phases of the wind farm, with a contract for Dogger Bank C’s remaining 87 monopiles and transition pieces awarded to the consortium in 2021.
The project is a joint venture between SSE Renewables (40%), Equinor (40%) and Eni Plenitude (20%). SSE Renewables is lead operator for the development and construction of Dogger Bank and Equinor will be lead operator of the windfarm on completion.
