Hydrodynamics of floating offshore OTEC platforms - a review

The global push for clean energy has spurred interest in utilising the vast potential of the ocean, which covers two-thirds of the earth's surface. Ocean Thermal Energy Conversion (OTEC) system research has seen limited growth, but recent advancements in the domain of offshore engineering suggest that floating offshore platforms could efficiently adopt such technology for clean energy generation. One specific issue necessitating attention from researchers is to understand the hydrodynamics of floating offshore structures such as spar and semi-submersibles to support heat exchange systems and associated facilities. This paper aims to present a review of various floating offshore structures, intended for Ocean Thermal Energy Conversion and to discuss the methodology adopted for the experimental and numerical analysis, highlighting the modelling challenges and the key areas for further research. The dependence of moon pool and cold-water pipe (CWP) on the motion responses of floating structures are the focus of this study. The size and behaviour of CWP differ from the risers used in the case of conventional offshore structures, necessitating an elaborate investigation considering environmental loading and the interaction of its motion with the platform's motion. Deploying floating OTEC systems involves complex challenges requiring in-depth study of hydrodynamics, particularly the interactions between the supporting structure, cold water pipe, and moorings. This paper reviews the hydrodynamic behaviour of floating OTEC platforms and highlights the need for comprehensive modelling, coupled numerical methodologies, and experimental validations, emphasising the influence of CWP dynamics on platform stability and performance in normal and extreme oceanic conditions.