Ultra-low-frequency and high-power Mag-Boost mechanism for ocean wave energy harvesting

Ocean wave energy is a highly promising renewable energy source that plays a significant role in advancing sustainable development. However, the ultra-low-frequency and random characteristics of ocean waves pose significant challenges to efficient and high-power energy harvesting. This paper introduces an innovative Mag-Boost mechanism that ingeniously leverages sudden magnetic-torque variation in orthogonal magnetic fields to convert ultra-low excitation below 1 Hz into high-frequency oscillations exceeding 50 Hz in the power-magnet without direct contact. The energy conversion efficiency can be as high as 89.3 %. By integrating four Mag-Boost units into a circular array, this study presents a high-power wave energy harvester with ultra-low-frequency response capabilities. At a frequency of 1 Hz and an inclination angle of 25°, the harvester achieved a high output performance with a power of 1.79 W and a power density of 1.88 kW/m³, which is an order of magnitude higher than previously reported results. During offshore tests in the Yellow Sea, the wave energy harvester reached a peak open-circuit voltage of 10 V, providing a stable power supply for wireless temperature and humidity sensors. Furthermore, the Mag-Boost mechanism also demonstrates considerable potential for harvesting other forms of low-frequency environmental energy, including wind, vibration, and human kinetic energy.