Business World of Renewable Energy

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Offshore wind: Large-scale Study Delivers Robust Design Guidance for Grouted Connections

Essen, Germany - In the dynamic offshore wind industry, the materials used are playing a major role in reducing costs and shortening construction and maintenance times.

That is why a group of developers and operators of offshore wind farms – innogy SE, SPR/Iberdrola, SSE, EnBW, Ørsted, Statkraft and ORE Catapult – joined forces in 2014 and launched a Joint Industry Partnership as part of the Carbon Trust’s Offshore Wind Accelerators (OWA) to investigate grout connections for offshore wind foundations. The main objective was to develop a comprehensive database of large scale test results to extend and validate design guidelines for grouted connections with geometries relevant for pre-piled jacket structures.

“Seawater mixed neat grout cement connections using Ordinary Portland Cement (OPC) have a long track record in offshore Oil and Gas industry as cost effective, reliable subsea connection type. In the last decade this technology has been transferred to offshore wind – with close to around 100 offshore jackets installed of this type so far. We have particularly emphasised the verification of the use of seawater mixed OPC as it significantly reduces the environmental footprint for these structures. In contrast high strength grouts require freshwater, which offshore adds significant to the cost”, explains Daniel Bartminn, Project Director GOAL (abbreviation for ‘Grouted OPC Connections with Annuli of Large Dimension’).

OPC grouted connections mixed with seawater technology has been used for existing offshore wind farms, for example Thornton Bank (Belgium), Ormonde (United Kingdom) and Alpha Ventus (Germany).

According to innogy SE, who manages the research project, the tests, carried out at KIT Karlsruhe, are the largest consistent tests series for large annuli in full and half scale adding extensive knowledge to further improve existing ISO guidelines. This comprehensive dataset will be analyzed in the upcoming month and summarized in a comprehensive study report, anticipated to be published during Q2 2018.

The research project was funded by the Carbon Trust Offshore Wind Accelerator, a world-leading collaborative research and development programme focused on reducing the costs of offshore wind energy.

Source: IWR Online, 01 Mar 2018