Optimization of electromagnetic-triboelectric wind energy harvester based on coaxial reversed mechanism with tip discharge

In recent years, the development of triboelectric-electromagnetic composite energy harvesters has revolutionized low-power urban devices by providing a cost-effective and high-output energy solution. However, most triboelectric nanogenerators (TENGs) have limited current output in the μA range, restricting their widespread application. Additionally, existing electromagnetic structures lack compactness and portability. To address these challenges, this paper proposes a compact triboelectric-electromagnetic composite wind energy harvester based on a coaxial reversing mechanism and tip discharge. It achieves gas ionization and increases the TENG's output current by utilizing TENG charge accumulation during rotation through a sidewall tip-copper structure. Compared to conventional TENGs, this harvester elevates the current from the μA level to the mA level. Moreover, it improves the output performance of the small volume electromagnetic generator (EMG) structure through the synchronous reversal of the magnet and coil at the same wind speed using two coaxial reversing propellers, intensifying the magnetic flux variation. Notably, the EMG structure outperforms a single rotating coil or magnet, achieving a remarkable 12% increase in output performance. At average urban wind speeds, this wind energy harvester can charge capacitors of 33 μF, 100 μF, and 220 μF to 2.5 V in 1.6 s, 2 s, and 3.6 s. Furthermore, it can power over 500 small LEDs and support the operation of temperature and humidity sensors. With its efficient wind energy harvesting technology, the proposed harvester holds great promise for self-powered Internet of Things (IoT) applications.