Ecowende is testing alternative monopile installation methods at its offshore wind farm in the Dutch North Sea, working with CAPE Holland and GBM Works. The trials focus on vibro-based techniques intended to reduce underwater noise during the installation of large-diameter monopiles. As offshore wind turbines increase in size, monopiles have become larger and heavier, increasing the underwater noise associated with conventional impact pile driving. Such noise can affect marine mammals, including harbour porpoises, even where mitigation measures are applied. The project is assessing whether vibro-based installation methods can reduce these effects while remaining technically viable in dense seabed conditions.
Installation activities began in early December, using Van Oord’s offshore installation vessel Boreas. At six test locations, CAPE Holland’s Vibro Lifting Tool is being used to apply vertical vibrations that reduce soil resistance, allowing monopiles to penetrate the seabed under their own weight. The technology has previously been used on offshore wind projects but has not been widely tested in the dense sands typical of the Dutch North Sea.
At three of these locations, GBM Works’ VibroJet technology is being combined with vibro-driving. This method adds controlled water jetting inside the monopile to further reduce soil resistance, with the aim of achieving full installation depth while limiting underwater noise.
The project will compare vibro-based installations with conventional impact hammer methods. Measurements will include installation performance, pile stresses and underwater sound levels. The data will be used to assess the suitability of these techniques for future projects and to support the development of predictive models for pile behaviour and noise generation.
Image credit Ecowende
