Bottom Fixed Offshore Wind Turbines in Extreme Waves

An important technology enabling the energy transition from fossil to renewable energy is offshore wind energy. Offshore wind energy can be harvested using both bottom fixed and floating wind turbines. The bottom fixed wind turbine is cheaper than its floating alternative. A lot of the existing capacity in Europe is installed on relatively shallow waters of about 30m. Now, the trend is that bottom fixed wind turbines are planned for deeper waters of about 60m and beyond. To design structures against wave loading, it is crucial to predict accurately the waves at the installation site. This is no easy task; it involves prediction over large distances from deep water to shallower water were the bottom fixed turbines are to be installed. In the B-WAVEs project, advanced algorithms for calculating these waves will be developed and the solutions will be available in open source softwares like REEF3D. The offshore wind industry is quickly adopting larger turbines and expanding their capacity goals. For bottom-fixed wind turbine generators (WTGs). The consequence of this trend are larger structures, more dynamic response and higher resonance periods extending towards frequency of wave loading. The resonance frequency is the natural back-and-forth rhythm which the structure naturally likes to move with when it's bumped or pushed. On the other hand, the waves cause oscillating loads on the structure. If the wave frequency is equal to the natural frequency, the structure may experience large cyclic deformations, which may cause damage. In the B-WAVEs project the problem of determining the accurate wave loading on the wind turbine and through efficient analysis describe the deformations of the structure during its lifetime. Through this work the standards used for design of bottom fixed wind turbines will be challenged which in turn will motivate the design practice of the next generation of bottom fixed wind turbines.

The offshore wind industry is quickly adopting larger turbines and expanding their capacity goals. For bottom-fixed wind turbine generators (WTGs) The consequence of this trend are larger structures, more dynamic response and higher resonance periods extending towards wave frequent loads. Combined with harsh and potentially more complex coastal climates, shifts design focus towards structural responses in extreme sea states. Addressing the above will be important as bottom fixed offshore wind turbines increase in size and concept. However, it also makes the process of reliable and physics-based design against extreme wave loads more complex. Hence, we need more knowledge about extreme waves, what causes them, and how to better implement extreme wave events into design analyses. The B-WAVEs project will address this by merging disciplines such as metocean, wave hydrodynamics, and structural dynamics. The aim is to better identify sea states and quantify subsequent extreme wave loads that potentially may harm offshore wind installations. The value of this project is more accurate extreme response predictions, safer structures, and reduced risk of wave induced damage.