Investigation of the Performance of Piezoelectric Wave Energy Harvesters Using a Buoy Design

Investigation of the Performance of Piezoelectric Wave Energy Harvesters Using a Buoy Design

This study proposes a piezoelectric wave energy harvester (PWEH) that integrates a unidirectional rotation mechanism with piezoelectric power generation components using buoys with added mass. By formulating the structural configuration of the buoy and augmenting the mass of the buoy, the inherent frequency of the buoy is modified to synchronize with the oscillation of the waves. A rotating cam is employed to trigger vibrations in the piezoelectric cantilever beam, resulting in a consistent generation of electrical energy via the piezoelectric phenomenon. The apparatus comprises a buoy, a unidirectional rotation mechanism, and components for piezoelectric power generation. The piezoelectric power generation element, which serves as the primary power generation module within the apparatus, utilizes a compound cantilever beam configuration consisting of a brass base and lead zirconate titanate (PZT) material. Performance measurement of the PWEH was conducted using the wave flume test at the Tainan Hydraulics Laboratory, National Cheng Kung University (THL, NCKU), Taiwan. The device exhibited optimal performance at various sizes and masses of the buoys. The measured Response Amplitude Operator (RAO) values were all greater than 0.55, with a maximum value of 1.209. For Buoy B-3 under wave conditions of a 1-s wave period and 75-mm wave amplitude, the average output shaft speed was 4.602 rad/s, and the open-circuit output voltage was 5.01 V. Through rectification and filtering circuits connected to a load impedance of 10 kΩ and a bypass capacitor of 33 nF, the filtered output root mean square voltage was measured at 4.29 V, with an average electrical power of 1.840 mW.