Abstract
Offshore wind and wave energies are both important and abundant renewable energy resources. Offshore wind turbines have entered the commercial phase, while wave energy converters are far lagging behind. Combined wind and wave energy conversion system have been proposed and investigated in recent years, to effectively use the ocean space and energy by sharing infrastructures. In this review paper, global wind and wave resources and the potential for combined use are firstly discussed, then various types of combined wind-wave systems are summarized with a new categorization method proposed. Then, a review on conceptual developments and synergies of combined systems based on the new categorization is elaborated on. Numerical methods used in the combined concepts are summarized with a special discussion on control strategy, extreme load effects and survivability. Model testing techniques are also discussed, highlighting the issues due to scaling laws. The economic aspects of the combined system are also discussed with a case study.