Upscale - Building knowledge on the future generation of floating substructures for very large wind turbines.

Wind turbines are increasing in size, they are moving offshore and they are beginning to be mounted on floating platforms. With increased focus towards climate change, CO2 emission reduction and renewable energy, and considering the vast areas of ocean available, floating wind is clearly placed in a strategic place. While some technological challenges are still unsolved, projects like HiWind (Equinor, 2009) and WindFloat (Principle Power , 2010) proved that wind turbines are capable of operating on a floating structure, and opened the road for a plethora of new research projects. The results are now starting to be implemented in floating wind farms (HiWind Tampen) and, with further cost reduction, floating wind will become the preferred choice for harvesting energy from wind.

Since the beginning of the wind energy industry, turbines have bigger rotors, higher hub heights, longer blades and larger rated power capacity with the longest blades exceeding 100m in length and the largest rotors reaching 12MW in produced power. In addition, blade producers are positive in seeing blades reaching 200m in length. In order achieve such a goal, the industry needs steep improvements and key innovations in multiple areas: progress in production, transportation and installation techniques, high-strength and low-cost material combinations, and advanced aerodynamic blade control features and control systems to reduce loads. However, the offshore wind energy industry seems to agree that the market will see 20MW+ OWTs with 300m+ rotor radius operating in the future. Floating supporting structures for OWTs will facilitate the rotor upscaling process by reducing the limitations related to assembly and installation, allowing rotors to be assembled in harbor and the whole structure to be towed in place. However, key issues will have to be solved in order to be able to manufacture and optimize structures that were initially thought for smaller rotors. Passive and active load mitigation techniques need to be developed and studied. Engineering models, which might be applied outside their validity range, need to be tested and possibly validated against models of higher complexity.