Scottish Offshore Wind Farm: Monopile Foundations to Go Beyond 50-Metre Depths

Offshore engineering consultancy SLPE has been awarded the contract to provide detailed design of wind turbine foundations for Red Rock Power Limited and ESB’s Inch Cape Offshore Wind Farm.

Inch Cape successfully applied earlier this year to remove the 1 GW capacity cap from its consent, allowing it to select the most powerful turbines on the market.

The wind farm will be located 15-22 kilometres off the Angus coastline in Scotland, with water depths ranging from 43 to 55 metres.

SLPE successfully delivered the turbine foundation concept design for Inch Cape in March this year and, following a period of further design optimisation, has now been awarded the detailed design which is planned to start in early 2022.

“Following the concept design phase, we undertook a refinement phase to further optimise our designs for a number of variables and uncertainties. These studies will contribute to the detailed design of monopiles that will support some of the largest offshore wind turbines in the market today. Inch Cape is also currently the deepest offshore wind farm in which monopile foundations are planned to be deployed,” said Joseph Hilton, Managing Director of SLPE.

In the meantime, SLPE is supporting Inch Cape with further concept refinement work and site investigation support, in order to inform key project decisions and develop high-quality design inputs in preparation for detailed design.

“With water depths of up to 55m, the monopiles for Inch Cape will be among the largest in the world,” said Nick Terry, Head of WTG Substructures.

“Being able to demonstrate the feasibility of monopiles in these water depths has delivered significant cost savings to the project, when compared against jacket foundations. This has been made possible by our in-house iterative design and optimisation software, which enables each location-specific monopile design to be individually optimised for both structural weight and cost-effective fabrication.”

Terry continued: “Our monopile designs also incorporate advanced PISA-type geotechnical design, using full 3D finite element analysis and advanced soil constitutive modelling to simulate the soil-structure behaviour. This results in higher accuracy and considerable weight savings compared to conventional pile design methods. This advanced approach is delivered in partnership with Geowynd, who complement SLPE with their deep expertise in marine geotechnics.”

Inch Cape will feature 72 wind turbines installed across an area of some 150 km2.

The removal of the capacity cap will allow Inch Cape Offshore Limited to deploy more powerful turbines, possibly with ratings in excess of 15 MW within the consented parameters.

Adam Ezzamel, Inch Cape Project Director, said: “We are looking forward to progressing into the next phase of design with SLPE, and are actively seeking similarly innovative and ambitious UK-based companies to support us with the delivery of this exciting project.”