A recently completed pile testing campaign by DONG Energy and ESG shows cost reduction potential for the offshore wind industry.

Pile testing by DONG Energy and ESG shows cost reduction for the offshore wind industry. Source: DONGPile testing by DONG Energy and ESG shows cost reduction for the offshore wind industry. Source: DONGThe piles under test are made of a cylindrical steel tube and their depth is adjustable to suit environmental and seabed conditions. The piles are one of the most commonly used foundations in the offshore wind market based on ease of installation in a variety of water depths.

The two testing sites, located in Cowden, England, and in Dunkirk, France, carried out tests on 28 piles. The purpose was to assess and validate new design methods development by a joint industry project PISA (pile soil analysis) for offshore wind farms. The PISA academic working group included Oxford University, Imperial College London and University College Dublin. The group supervised testing as the 28 piles were pulled sideways into the soil until failure occurred.

The two test sites involved feature diverse soils—clay till in Cowden and dense sand in Dunkirk, representative of surface soil conditions in the North Sea. Previous oil and gas engineering pile testing at both sites provided field and laboratory soil data. Results confirm that traditional design methods are conservative and that by reducing the quantity of steel in the foundation it may potentially reduce electricity production costs.

The testing was undertaken as part of the PISA research project and carried out by industry working group headed by DONG Energy including EDF, RWE, Statoil, Statkraft, SSE, Scottish Power, Vattenfall, Alstom and Van Oord. PISA operates under the framework of the Carbon Trust Offshore Wind Accelerator (OWA).

The PISA academic working group will analyze the data and deliver a final report to project partners in early 2016.

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