A major step was recently taken in the French offshore wind market with the installation of the Fécamp met mast foundation in the English Channel. This marks the first installation of a new type of foundation that may prove of great importance to the offshore wind industry.
MT Højgaard has just 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. MT Højgaard used tugs to transport the 1,760-ton 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. This type of foundation promises to be financially and environmentally advantageous for offshore wind farms at greater sea depths, says Kim R. Andersen, Vice President of Offshore & Steel Bridges at MT Højgaard.
The installation concept can reduce the time it takes to build offshore wind farms, as the foundations are towed into place using tugs and then lowered to the seabed. 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 potential for reducing installation costs is of great importance to the profitability of offshore wind farms.
- 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. 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, says Kim R. Andersen.
The project’s players
The foundation was designed by Seatower and manufactured by Eiffage TP in France, while MT Højgaard performed the installation. The prototype foundation is part of a development project in connection with the planned offshore wind farm “Parc éolien en mer de Fécamp” in France, owned by the French energy company EDF Energies Nouvelles, Danish-based DONG Energy and German-based wpd Offshore.
MT Højgaard installed the foundations for the world’s first offshore wind farm, Vindeby. Since 1992, MT Højgaard has delivered more than 630 foundations for 12 offshore wind farms, equivalent to more than 2 GW of wind power.