Cotemporal assessment of wind, wave, and current resources for ocean renewable energy device design and testing

Ocean renewable energy, including offshore wind, wave, and ocean current energy, presents a viable approach to producing renewable power, reducing greenhouse gas emissions, and mitigating climate change. Whilst inherently interconnected, much of the published work focuses on individual metocean environmental assessments. These valuable analyses were insufficient for robust ocean energy system design. This study proposes a methodology to examine the cotemporal characteristics of wave, wind, and current in an open-ocean environment. Based on a 25-year buoy observation dataset collected at a representative open ocean location off the coast of Oregon, USA, the cotemporal distributions of wind-wave and current-wave conditions are investigated over sea state histogram. The results show that the wind-wave magnitude correlation and directional alignment increases as wave height increases or wave period decreases, indicating the strongest wind-wave correlation at wave breaking sea states. The current-wave misalignment demonstrates an inverse relationship with wave period in wind-wave dominated seas but little dependence on wave period in swell-dominantly seas. Representative operational and extreme environmental conditions are identified using k-means clustering method and statistical analysis, respectively. Finally, numerical case studies on a floating ocean platform highlight the need to account for cotemporal environmental conditions in mooring loads and structural hydrodynamics analysis.