Dong project eyes new-look piles

A range of new trimmed-down piles will be tested this year as part of a Dong-led project designed to cut the weight and cost of offshore wind turbine foundations.

The next-generation monopiles, being fabricated for the UK Carbon Trust’s pile soil analysis (Pisa) scheme by Danish contractors NLMK DanSteel and Bladt Industries, will be trialled in Dunkirk in France and at Cowden in England – two sites that mirror North Sea seabed geology.

Dong expects to be able to cut five metres off the length of conventional designs, which should shed over 13% of the weight of a 300-tonne monopile.

“This R&D [research and development] project will contribute to the development of lighter foundations for offshore wind energy, which will bring down costs,” says Dong Energy Wind Power vice president Tove Feld.

“The weight of the foundation is critical to costs, as both the installation and production of modern foundations require very specialised equipment.”

Carbon Trust’s Offshore Wind Accelerator director Jan Matthiesen adds: “We need to urgently cut the costs of offshore wind to ensure its deployment potential is realised. This project is a critical stepping stone to achieving lower weight and lower cost foundations.”

NLMK DanSteel and Bladt have devised new design methodology for “a whole series of different-sized piles” in response to Pisa research carried out at the University of Oxford, Imperial College London and University College Dublin that suggest geotechnical design methods used to-date have been “very conservative”.

Dong’s Pisa project manager Jesper Skov Gretlund notes: “When you think about it, it’s rather extraordinary that companies selling steel structures participate in a project aiming to save steel.

"This goes to show that the entire industry has its mind set on solving common challenges for the benefit of all.”

The Pisa project, which includes developers RWE, Statoil, Statkraft, SSE, ScottishPower and Vattenfall, is looking to cut-price foundation technologies for a “significant contribution” to reducing the cost of offshore wind power by 35-40% by 2020.