Ocean wave energy pitching harvester with a frequency tuning capability

Abstract The research introduces a development of a novel and efficient pitching harvester with capacity of frequency conversion and force magnification to convert the low-frequency ocean wave energy to usable electricity based on the piezoelectric effect. The advantages of the proposed harvester over existing ocean wave energy harvesters are the characteristics of its minimized components and space, which are vital for the survivability and sustainability on harsh ocean conditions. The harvester comprises of four magnetic bar-mass-spring-lever-piezoelectric systems arranged symmetrically. By this smart design, the harvester is able to transform the low-frequency of ocean waves to a higher excitation frequency of motions and to magnify the force magnitude of the piezoelectric transducer for harnessing a higher power. A mathematical model for the harvester taking into account the practical wave-structure pitching interaction is developed to evaluate its efficacy. Subsequently, a generated power of 900 W is able to be tracked at a near-resonance of the harvester by adjusting the dimensions, distances and material properties of the developed harvester with a keel depth, a harvester length, a wave period, and a wave height as d s = 0.25 m , L = 1.5 m , T = 7 s , and H w = 1.5 m , respectively.