How a suspended cable system could transform offshore wind resilience
An earthquake-resistant offshore wind turbine capable of withstanding earthquakes, hurricane-force winds and massive waves, even when these events occur simultaneously, has been designed by engineers at the University of Technology Sydney (UTS), Australia.
To help offshore wind turbines operate safely in increasingly challenging environments, researchers developed a suspended cable reinforcement system that surrounds the tower. Acting like a structural exoskeleton, the design strengthens the turbine against combined seismic, wind and wave loads without fundamentally changing the tower itself.
According to Professor Behzad Fatahi, who led the research team, “Offshore wind turbines are becoming increasingly larger, and more projects are being proposed in regions where earthquakes are a genuine design concern.”
Where could the new reinforcement system be deployed?
The study highlights the Pacific Ring of Fire, a roughly 40,000 km tectonic belt stretching around the Pacific Ocean and considered the world’s most seismically active region. Asian waters within this zone alone are expected to host more than 100 GW of future offshore wind capacity.
However, seismic risks are not limited to the Pacific. The Mediterranean basin is also tectonically active due to the convergence of the African and Eurasian plates. As offshore wind development expands across Mediterranean countries, the new reinforcement concept could also prove valuable for projects in the region.
“Our research demonstrates that a relatively simple structural reinforcement concept, inspired by cable-stayed bridges and towers, can significantly improve the dynamic performance of offshore wind turbines,” Fatahi added.
Current earthquake protection systems have limitations
Offshore wind farms already employ vibration mitigation technologies. During the devastating 2011 earthquake and tsunami in Japan, the Kamisu offshore wind farm successfully survived the disaster, including the seismic event that contributed to the Fukushima nuclear accident.
Nevertheless, existing systems have inherent limitations. Tuned mass dampers can reduce tower bending, but their effectiveness depends on the reliable operation of mechanical components. Tuned liquid dampers help limit structural oscillations, yet their performance against seismic acceleration varies depending on the earthquake’s frequency characteristics.
The Australian team’s approach instead adopts a well-established engineering solution widely used in cable-stayed bridges: high-strength steel stay cables. These cables increase the tower’s bending stiffness while reducing damaging dynamic responses during extreme loading events.
Simulation results on a 15 MW offshore wind turbine
To evaluate the concept, researchers modelled the suspended reinforcement system on a next-generation 15 MW earthquake-resistant offshore wind turbine, reflecting the industry’s shift toward increasingly larger machines.
According to UTS, numerical simulations showed that the cable-stayed structure substantially reduced tower accelerations, stresses and structural deformation. In several scenarios where a conventional turbine experienced yielding or instability, the reinforced tower remained structurally intact.
The study also found that the stay cables reduce internal forces in the upper sections of the tower, increase overall structural stiffness, limit resonance effects and prevent cross-sectional ovalisation, a deformation mechanism that can contribute to structural instability.
The researchers caution, however, that the concept remains at an early stage. Additional research, validation and testing will be required before the reinforcement system can be deployed in commercial offshore wind projects.
The research, titled Novel cable stay reinforced offshore wind turbine resisting combined seismic, wind and wave loading, was published in the journal Ocean Engineering.