Piezoelectric energy harvesting in railways: Current status and future challenges

With the rapid advancement of intelligent railway systems, the demand for sustainable and distributed power supply for the increasing number of monitoring sensors has become a pressing issue. Piezoelectric energy harvesting, which converts the abundant mechanical vibrations generated in vehicles, rails, sleepers, trackbeds, and bridges into electricity, has emerged as a promising solution due to its high power density, compact design, and ease of integration. This paper provides a comprehensive review of recent progress in piezoelectric energy harvesting for railway applications. First, the fundamental mechanisms of the piezoelectric effect and vibration-to-electricity conversion are introduced, alongside comparisons with other renewable energy harvesting technologies. Then, deployment strategies at different railway locations are examined with representative device structures such as cantilever, stacked, cymbal, and hybrid configurations. The performance, compatibility, and recyclability of key piezoelectric materials, including inorganic, organic, and composites, are further analyzed. In addition, energy conversion and storage circuits, as well as environmental adaptability, are discussed as essential factors for system-level integration. Finally, the paper highlights critical engineering challenges, such as material fatigue, harsh environmental conditions. Future perspectives emphasize the need for multi-scale design optimization, adaptive broadband tuning, sustainable material innovation, and standardized deployment frameworks.