Hydroelectric power is the most important and wildly-used renewable energy source in the environment. In this paper, we propose the concept of using a multi-layered triboelectric nanogenerator (TENG) to effectively harvest the water wave and water drop energy. For a single-layered TENG, interdigital electrodes are incorporated in order to generate multiple electric outputs under one water wave or water drop impact. For the collection of water wave energy, a polyurethane (PU) coated copper rod is used to roll and contact with the polytetrafluoroethylene (PTFE) film covered interdigital electrodes. The surface of the PU and PTFE film are fabricated as porous structures and nanowire arrays, which provide the advantage of large contact area. Under one water wave impact, the single-layered TENG composed of 9 pairs of interdigital electrodes can provide 9 pulses of electric outputs (voltage can reach 52V). The output current density and instantaneous output power density of a 5-layered TENG are 15.3 mA/m2 and 1.5 W/m2, respectively. The rectified electric outputs have been applied to drive light emitting diodes and charge commercial capacitors. In addition, the part of the polytetrafluoroethylene (PTFE) film covered interdigital electrodes has been successfully used to harvest water drop energy, whcih can also generate 9 pulses of electric outputs upon one water drop falling. All these results show the developed TENG has great potential to harvest the hydroelectric power of ocean wave and raindrop in the near future. References: 1. Lin, Z.-H.; Cheng, G.; Lin, L.; Lee, S.; Wang, Z. L. Angew. Chem. Int. Ed. 2013, 52, 12545ï¿½12549. 2. Lin, Z.-H.; Cheng, G.; Lee, S.; Wang, Z. L. Adv. Mater. 2014, 26, 4690ï¿½4698. 3. Lin, Z.-H.; Cheng, G.; Wu, W.; Pradel, K. C.; Wang, Z. L. ACS Nano 2014, 8, 6440ï¿½6448. 4. Cheng, G.; Lin, Z.-H.; Du, Z.; Wang, Z. L. ACS Nano 2014, 8, 1932ï¿½1939.