A Variety of different concepts of multi-axis wave conversion devices, most of which belongs to the so-called point absorber wave energy converters, have been proposed over the years aiming to harvest more wave energy and improve the efficiency. This paper considers a multi-axis concept device named TALOS that has been initially proposed and developed by Lancaster University. TALOS is a point absorber wave energy converter, with a fully-enclosed hull containing all the internal reaction mechanisms. The internal power take-off system consists of an inertial mass with secondary transmission mechanism, which can be hydraulic cylinders or other types of components, connecting the mass to the solid outer hull. In this paper, a full-scale device (based on a sea trial prototype width of 3 m, expected to be deployed in the East China Sea) is studied numerically and a 1/4th scale model is tank tested at Zhejiang University. A new form of power take-off (PTO) design is introduced, which is that the inertial mass is connected to rotary DC generators by screw drive mechanisms. A numerical model is firstly built with the help of open-source software WEC-Sim and is used to estimate the system's dynamics. Subsequently, further tank tests are carried out to obtain experimental results. Also, based on the current research progress, some design that can be improved in the future are summarized and introduced.
As a clean and renewable resource, wave energy has the significant potential to make a contribution to meet the world's energy demand. In the past few decades, various concepts of wave energy converters have been proposed and developed with the goal of approaching the economically competitive level compared to other resources. One of the most popular devices is the oscillating-body type, which is classified according to working principle. Under ideal conditions, an oscillating-body type wave energy converter can convert all available energy of ocean waves into electricity through linear or rotational oscillation. Recent reviews on current research progress and stages of such devices can be found in (Falcão, 2010). Famous examples include Wavebob (Weber et al., 2009), PowerBuoy (PowerBuoy, 2013) and Archimedes wave swing (AWS) (Cruz and Sarmento, 2007).
