With the world's rising concern about climate change and sustainability, renewable energy technologies evolved substantially over the past few years as result of increasing political and financial support. The US government, for example, has recently announced a 30GW target for offshore wind energy deployment by 2030 and 110GW by 2050. As the size of offshore renewable energy deployments increases, a proper understanding of the risks associated with offshore technology deployment becomes of utmost importance for continuing economic interest in the renewable ocean energy sector. While marine hydrokinetic devices can contribute to a more diversified offshore renewable energy portfolio in the future, the vulnerability of these technologies to hurricane damage has not been thoroughly studied. Although fragility curves have been developed for wind turbines, transmission and distribution lines, and conventional power plants, no such curves exist for ocean current energy. This existing research gap inhibits our ability to analyze the susceptibility of marine hydrokinetic devices to damage from hurricanes.
The work presented herein develops fragility curves for ocean current devices moored by buoyancy and thrust mooring. The focus is on Sandia reference model 4 (RM4), utilizing ocean current velocities off the coast of North Carolina. This research used statistical analyses and mechanical model simulations using the Ansys-AQWA software to construct fragility curve estimates for ocean current devices, focusing on the thrust mooring system. The ocean current velocities and their variability are assumed as random variables, and the fragility curve is assessed in view of the mooring lines' tension exceeding ultimate limit states for various risk class categories.