Small-scale water energy harvesting offers a promising pathway to power the rapidly expanding ecosystem of distributed electronics. The inherent ubiquity and mechanical energy of water make it an ideal resource for sustainable, off-grid power generation. The efficiency and application scope of these energy harvesters are fundamentally governed by their working environment and transduction mechanisms. This review provides a comprehensive overview of small-scale water energy harvesting technologies, covering different forms of water and the corresponding energy transduction mechanisms, including triboelectric, piezoelectric, electromagnetic, and thermoelectric approaches. We highlight the state-of-the-art examples with particular emphasis on recent advances in triboelectric nanogenerators (TENGs)-based of small-scale water energy harvesting, focusing on advances in nanomaterial design, hybrid transduction mechanisms, and interfacial engineering. The diverse applications of these technologies in energy harvesting, self-powered sensors, and self-powered wearable devices are discussed. Finally, we outline future research directions, emphasizing the development of hybrid systems, advanced interfacial engineering, and intelligent power management, aiming to bridge the gap between laboratory innovation and real-world deployment. Small-scale water energy harvesting is crucial for powering distributed electronics sustainably, leveraging water’s ubiquity and mechanical energy. In this Review, the authors discuss advances in nanomaterial design, hybrid transduction mechanisms, and interfacial engineering of triboelectric nanogenerators for energy harvesting, with implications for self-powered sensors and wearables, proposing future research to enhance real-world applications.
Zhou et al. (2026) studied this question.