Analysis of End-Stop Parameters on the Performance of Heaving Point Absorber Wave Energy Convertors

Wave energy converters (WEC) have the potential to generate a sizeable proportion of Ireland’s energy needs. Although there has been a great deal of research into WEC technology, no commercial devices exist at this time. One reason for this, has been underestimating the forces involved in the marine environment, and thus under designing components, especially power take off (PTO) systems. End stops are a crucial component of all moving body converters, which have rigid connections to PTOs. They are designed to protect the PTO mechanism by restricting the allowable travel distance. End stops, although vital components of WEC technology limit energy generation and thus must be taken into account in initial design. In this paper, a torus shaped point absorber moving against a monopile is numerically modelled in operational conditions using combined potential flow boundary element method and modified Morison's equation viscous drag. Two torus geometries are modelled, varying the radius and draft. The effect of various end-stop parameters on PTO forces and average annual energy generation are analysed. These parameters being; WEC travel distance, end stop distance and stiffness. Two separate Irish sites are analysed, a high energy site off the west coast and a medium energy site off the south coast. This paper aids WEC development by describing the performance effects of end stop design.