Heave-Enhanced, Wave Energy Converter, with a Circular Sliding Generator

Abstract

At Oceans' 13 in San Diego, we introduced the concept of a Circular Sliding Wave Energy Converter (CS-WEC), where a track was fixed to the inside of a floating “wave-rider” buoy, which pitched and rolled in response to waves. At that time, we envisaged a heavy rotating mass on a circular track connected by a pivot arm to a fixed, but spinning, generator plus electronics at the center of the track. The system was adaptively tuned to changing environmental conditions with an artificial electro-magnetic spring in a control loop. We now propose three enhancements to the original design for efficiency and increased power. First, we move the generator, its associated electronics, and re-chargeable battery, from the center position to be part of the rotating mass, without sacrificing power. This is a more efficient way to conserve and better utilize component weights. Second, we move the hermetically-sealed CS-WEC from inside to the outside of the buoy and attach it by 2 pivot points to allow tilts that are greater than those of the sea surface. Third, we anchor the buoy to the sea bottom in shallow water and add a capability to significantly increase power by artificially increasing the magnitude of the pitch/roll motions by using an external surface float on a moment arm. We show a power improvement up to an order of magnitude in realistic ocean conditions (swell and random seas) by increasing the motion.