Triboelectric-electromagnetic hybrid generator with Savonius flapping wing for low-velocity water flow energy harvesting

Low-velocity water flow exists generally in open channel environments, and harvesting energy from these water flows remains a challenge. Herein, a savonius flapping wing triboelectric-electromagnetic hybrid generator (SFW-TEHG) is proposed to harvest the low-velocity water flow energy by the reciprocating flapping of the savonius flapping wing. Whereafter, the reciprocating flapping is converted into the high-frequency rotating of the energy conversion part by the symmetrical distributed ratchet-gear-rack compound transmission mechanism, thus realizing the conversion of hydrokinetic energy into electricity. Under the water flow velocity of 0.21 m/s, the open-circuit voltage peak and the short-circuit current peak of the TENG reach 1.57 kV and 30.94 mu A, and that of the EMG reach 6.24 V and 3.76 mA, respectively. In application demonstration, the SFW-TEHG can drive wireless sensors to monitor the environment. The SFW-TEHG furnishes a solution for the difficulty of harvesting low-velocity water flow energy and powering microsensors installed widely.