A Rope-Driven Hybrid Triboelectric-Electromagnetic Generator for Ocean Energy Harvesting and Information Sensing

For the purpose of resource utilization and disaster prevention, ocean energy harvesting and information sensing have been in high demand in recent years. However, at the current stage, ocean energy and information systems are not well integrated, as the ocean power generator and sensor work separately. This work presents an electromagnetic–triboelectric hybrid generator system capable of achieving energy harvesting and information sensing simultaneously, which can be deployed in diverse marine environments such as nearshore zones, reefs, and buoy platforms. The hybrid generator was driven by a rope connected to a buoy, which not only withstands strong wave conditions but also converts vertical wave motion into rotational motion. The harvested ocean energy can be mechanically stored, attributed to the combination of overrunning clutch, flywheel, and coil spring, resulting in elongated one-way operation time. Assisted by a one-way flywheel, a tailored disc-type permanent magnet generator (DPMG) was developed to power electrical appliances, achieving continuous electrical power generation after the environmental motion terminates, owing to the inertial energy storage and release principles. Two symmetrically arranged triboelectric nanogenerators (TENGs) with different properties are developed to monitor ocean wave conditions, where wave motion can be well distinguished by the operational TENG, and the severe wave condition can be alarmed when the pulse number of the TENG exceeds the threshold. The power densities of the DPMG and TENG reached 240.63 W/m3 and 89.52 mW/m3, respectively. The flume and ocean field experiments demonstrate this work as an innovative approach to improve the energy harvesting efficiency and integrate the energy harvesting and information sensing functions into one system, while maintaining high survival capability.