Adaptive dual turbine triboelectric nanogenerator toward self-powered marine buoy

Harvesting ocean wave energy to power distributed ocean sensors has become an important research field in the construction of Marine Internet of Things (MIoTs). Triboelectric nanogenerators (TENGs) have received widespread attention in low-frequency, random, and irregular wave energy harvesting due to their excellent electromechanical conversion efficiency. However, how to efficiently convert the slow, random wave motion to drive the power generation system to generate a smooth electrical energy output is still an urgent problem to be solved. Here, a point absorber-based ocean wave energy harvesting system is designed to realize self-powered marine buoy by combining an adaptive dual-turbine wave energy converter (ADC-WEC) with a phase-shifting triboelectric nanogenerator (PS-TENG). The ADC-WEC, with variable blades, converts the up-and-down motion of the wave into a continuous unidirectional rotation that drives the PS-TENG to generate electricity. The PS-TENG converts rotational mechanical energy into direct current output with low crest factor by means of regular electrode displacements and multi-phase rectification coupling. Results show that at 600 rpm, the crest factor of the PS-TENG is down to 1.077, with a voltage of 400 V and a current of 80 μA. Importantly, the experiment showcased the buoy system harvesting wave energy to power small commercial sensors in a simulated wave environment, demonstrating its ability to build MIoTs as a self-powered marine buoy. This study presents a new solution for the efficient harvesting of wave energy and demonstrates its potential application in constructing the self-powered marine environmental monitoring networks.