A Critical Review of Gyroscopic Wave Energy Conversion Systems

Exception made for tidal and offshore wind systems, the enormous energy potential of the marine environment is largely unexploited, mainly owing to the lack of technically mature and economically sustainable conversion technologies. For over a century, the possibility of exploiting wave energy has been the objective of academic speculation and inventors’ creative efforts. Still, at this date, only a handful of examples of pilot-scale and low-power experimental installations are available worldwide. Given that wave energy is correlated to its height, most of the experimental sites are located in the oceans, while closed seas, such as the Mediterranean, are considered to be unsuited to traditional wave energy converter configurations. However, the Gyroscopic Wave Energy Converter (G-WEC) concept, seems to be promising even in low-wave height environments, as it relies on the time derivative of the wave flank inclination instead of the wave amplitude. While the concept of G-WEC is not new, as some earlier patents can be traced to the 80s of the twentieth century, and an engineering feasibility analysis of a practical G-WEC system has been performed in the 1995-2000 period, experimental development of G-WECs was started only around 2007 and first offshore pilot plants have been installed since 2016. Overall, the literature about G-WECs is comparatively scarce with respect to more traditional configurations of wave energy conversion devices. In order to fill this gap, in the paper, following a historical review of the G-WEC concept development, a thorough literature review is performed in order to define the current state of the art, while the characteristics of the various proposed configurations of G-WECs are critically compared. Afterwards, the overall design criteria of a G-WEC system are outlined highlighting the interplay between the different variables within the design space. Finally, the advantages and limitations of this type of WEC are discussed.