Power production from wave-induced oscillations of a submerged plate

This paper investigates power production from a submerged wave energy device in shallow water. The energy device consists of a fully submerged, horizontal plate, which is restricted to vertical motions only. The plate undergoes vertical oscillations due to the wave-induced loads. Oscillations of the submerged plate are converted into electricity by use of a direct-drive power take-off (PTO) system. The plate oscillations are controlled by use of a spring and the damping effect of the PTO. Interaction of non-linear shallow-water waves with the submerged plate is studied by coupling the Green–Naghdi equations for the fluid motion with the equation of the vertical motion of the horizontal plate. Particular attention is given to the power production from the oscillations of the plate through the direct-drive PTO system, and its impact on the overall performance of the device under various wave conditions. Optimised configuration of the PTO for a given wave–plate condition is achieved by performing a parametric study over a range of involved variables. It is found that the proposed wave energy device with a direct-drive PTO has very good energy production efficiency and that it is a suitable concept for power production from the ocean waves.