What happens when gravity-based support structures are installed in rough sea conditions? What is the cushioning effect of the soil during touch-down? How will the dynamic response of the foundation be in transport when towed? And what is the impact of the various logistic strategies to the cost of energy?
Transportation of Gravity-based support structure using tugs

A consortium of MARIN, Deltares, Witteveen + Bos, Vuyk Engineering and TNO has set up a Joint Industry Project to investigate the critical aspects in the transportation, installation and project logistics of gravity-based support structures for offshore wind turbines. Gravity-based support structures (GBS) are heavy structures (often concrete) that are sunk and placed onto the seabed to provide support for offshore wind turbines. A group of ten leading industry partners, comprising civil contractors, wind farm developers and foundation designers have joined the project.

Insight in operational limits

Current GBS foundations have mostly been installed in calm seas. The increasing size of future offshore wind farms requires longer spells of favourable weather conditions for the installation of GBS systems. In this project, transportation to the wind farm site and installation is simulated and tested at the wave tanks of MARIN and Deltares for more stringent conditions. This will lead to more insights in the operational weather limits for transport and installation of the foundations. The findings and suggestions will be bundled in a handbook for industry.

Impact on costs

The role of TNO in the project is assessing the impact of the different transport strategies on the costs of energy. TNO developed an offshore installation planning tool ‘ECN Install’ to calculate and improve the installation of the large offshore wind farms. TNO will extend the modelling capabilities of this tool to include analyses on GBS, including the onshore logistics like manufacturing and loadout.


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Koen Hermans, MSc

  • offshore wind support structures
  • wind turbine loads analysis