A comprehensive review of road mechanical energy harvesting technologies

The growing prominence of energy shortages and environmental challenges has intensified global attention toward renewable energy utilization, with an urgent demand for energy transition in the transportation sector. Roads, as one of the important transportation infrastructures, contain a large amount of utilizable mechanical energy, and their energy harvesting technology is currently one of the hotspots in research.This study presents a comprehensive review of road mechanical energy harvesting technologies. First, three categories of road mechanical energy harvesting systems suitable for different application scenarios are summarized and analyzed, including speed bumps, flat-plate, embedded or integrated. Subsequently, from the four technical approaches of hydraulic/pneumatic, electromagnetic, piezoelectric, and TENGs, the principles, methodological frameworks, and research outcomes of various energy harvesting technologies are comprehensively reviewed. The key performance metric of energy output for these four technologies is compared and summarized, along with evaluations of their advantages and disadvantages. Furthermore, the integration and development of road mechanical energy harvesting technologies with smart road systems are introduced. Finally, the key challenges currently hindering the real-world implementations of road mechanical energy harvesting technologies are discussed, including energy harvesting efficiency, material performance, cost and return, regulatory issues, among others. Predictions and recommendations for future development are proposed, aiming to provide assistance for further research and large-scale applications.