While fixed-bottom developments account for almost every operational capacity in the world today, soaring winds have been announced far into the future – and rightly so.
With fixed-sub-wall builders limited to depths of up to 60 meters, the ability to install turbines independent of ground depth is a game changer in terms of potential offshore generation capacity.
But despite its potential to accelerate the transition to fossil fuels, floating offshore wind presents unique challenges because it requires an understanding and analysis of additional datasets to optimize operation and performance.
A new dataset
While soaring winds may repeat the spectacular cost reduction we have already seen in solid offshore wind-based foundations with large-scale economies – industry and academia are constantly facing data measurement challenges.
Our current understanding of the complex interaction of wind in an offshore wind farm has been achieved by observing and analyzing the performance of fixed sub-turbines. But the interaction of a turbine and a new motion plan on a floating platform is a new area of study and we need to understand the effective balance between the natural behaviors of wind and wave conditions in order to optimize performance.
Floating platforms introduce new types of data to consider. Factors include the motion of the floating platform (which may have its own controller to remove ballast), anchor line voltages, and parameters of the sea such as wave height, frequency, and period, all acting on the pool. The projections of the energy pay must take into account the availability of the floating platform as well as the turbines.
Risks, rewards and opportunities
For companies bringing the floating offshore wind market for the first time, getting ahead with the data is important.
The challenge lies in determining exactly which data are necessary and valuable to optimize the performance of the coupled turbine-floater unit. While turbine OEMs such as Siemens, GE and Vestas have an established structure to deliver operational data and know its pitfalls, manufacturers of floating platforms are still refining what a good quality and well-structured dataset looks like. File integrity must be incorporated from the outset and not overridden in the course of installing the physical structures.
For companies that do not recognize the complexity of this new data plan, it can be an expensive oversight. Failure to manage conflicting sets of requirements entails inherent risks including potential mechanical overload, increasing the fatigue of critical structures and a reduction in the safe operational life of the assets.
Learn from oil and gas
From a data collection perspective, the industry should draw from decades of oil and gas experience, develop and operate floating platforms. Much can be learned from the sector’s knowledge about optimal sensor placement, frequency of data samples and modeling requirements.
However, a bit of caution should be used as floating oil platforms are not designed to accommodate a dynamically loaded structure, or the consequent behavioral changes.
As with traditional offshore wind, data analytics platforms will evolve to meet the demands of floating wind data. These tools help to dissect and interrogate the data in a way that is valuable for better understanding our floating platforms.
Exploration and analysis of new data through the love of experimental sites such as the National Floating Wind Innovation Center in Aberdeen, Scotland will be crucial to determine the optimal combinations before scaling to ensure lower overall costs.
Spar, semi-submersible or tension leg?
In this early phase of development, there is a proliferation of floating offshore platform solutions, such as spare, semi-submersible and tension legs. Each is designed and optimized for a specific range of water depths and ocean conditions. While the interaction of a turbine with a static foundation is universal, this is not so with floating foundations.
The intensive research required to understand and optimize the interaction of both wind and sea states on the coupled turbine and the floating platform must be multiplied by the number of platform solutions.
It has taken the focus of the entire industry to reach our current level of understanding about the behavior of the wind in an offshore wind farm. A comparable effort may be required to get the best out of any type of floating platform. Collaboration and knowledge sharing within the industry will help accelerate the learning curve. However, due to the material differences in the behavior of each floating solution, many teachings apply uniquely to specific floating solutions.
A new horizon
Successful deployment and upscaling of floating wind is made possible by filling the knowledge gaps quickly while managing and optimizing the coupled wind turbine and floater unit. This requires industry cooperation, cross-fertilization and the brightest mind to explain the challenges of the floating wind.
The education of this knowledge will be highly date-driven and getting really useful data is the foundation of analysis and understanding.
Bronwyn Sutton is Offshore Principal at Clir Renewables
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