Toward Extending the Life of a Floating Offshore Wind Turbine Using Sheltering From Upstream Wave Energy Converters

Abstract

Offshore renewable energy, derived from wind and waves, is increasingly being considered in many world regions. Co-location of offshore wind turbine and wave energy converter arrays allows the shared use of space and offers beneficial interaction, leading to efficient utilization of marine resources and more sustainable ocean energy solutions. By extracting energy from waves, wave energy converters can reduce hydrodynamic loads on downstream floating offshore wind turbines through sheltering effects, enhancing the structural reliability of the floating offshore wind turbine and extending its service life. To quantify such extension in service life, a comprehensive reliability analysis framework is proposed that incorporates metocean data analysis, fatigue damage assessment, and an integrated reliability-based fatigue life estimation. We employ power take-off matrices of alternative wave energy devices to approximate absorbed wave power in encountered sea states. A metocean data analysis establishes representative sea states for the incident waves and lee waves estimated by subtracting absorbed wave power from the incident power. The open-source time-domain simulation tool, openfast, is employed to compute loads on a downstream floating offshore wind turbine, for sea states of interest. Using selected output stress response time series, fatigue damage is assessed; an extended service life due to effective sheltering for the floating offshore wind turbine is evaluated through the proposed fatigue reliability analysis. Considering three alternatives, our analysis indicates that a 14–25% extension in service life can be achieved using wave energy devices that offer the benefits of sheltering.