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The foundation was designed by Seatower and manufactured by Eiffage TP in France, while MT Højgaard performed the installation. MT Højgaard said that it believes the new Seatower Cranefree foundation could be hugely significant to the offshore wind industry.
MT Højgaard lowered the first Seatower Cranefree foundation to a depth of nearly 30 metres on the seabed of the English Channel, off the French town of Fécamp on the Normandy coast. The foundation was lowered by filling seawater into ballast tanks on the foundation. Prior to lowering the foundation, the seabed was prepared by establishing a level layer of filter stones.
Tugs were used to transport the 1,760-tonne foundation and met mast from Le Havre harbour to the installation site approximately 17km off the coast. This installation method differs from traditional methods, which are typically based on the use of large installation vessels.
"The installation of the met mast foundation is an important milestone for the industry in general, as the installation costs of offshore wind projects must be minimised to make offshore wind energy financially sustainable,” said Kim Andersen, vice president of offshore and steel bridges at MT Højgaard. “This type of foundation promises to be financially and environmentally advantageous for offshore wind farms at greater sea depths.”
The company said that the design allows for faster installation, while the overall installation concept enables installation within a short weather window, even when waves are high. The technology is also suited for foundations at the greater depths where future offshore wind farms will typically be established.
“The project is interesting, as the technology behind the foundation is well-known and based on experiences from the oil and gas, tunnel, and bridge industries,” said Andersen. “However, this is the first time that this type of foundation and installation concept have been utilised on the offshore wind market, and it will be interesting to draw on experience from this project in future large scale projects.”
The prototype foundation is part of a development project in connection with the planned offshore wind farm Parc éolien en mer de Fécamp, owned by the French energy company EDF Energies Nouvelles, Danish-based Dong Energy and German-based Wpd Offshore.
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