Harvesting thermoelectric energy from railway track

This study aims to develop a prototype for harvesting thermoelectric energy from railway track. By capturing the existing thermal energy in railway tracks, this technology helps power rail-side sensors in off-grid and remote areas without depleting natural resources. In low latitudes such as southern China, the temperature of railway tracks can reach 57 °C due to solar radiation. However, at a relatively shallow depth (200 mm), the substratum below the track foundation (e.g., soils) has a lower temperature (i.e., 15 °C–26 °C). This temperature difference can be used to generate electricity through a thermoelectric generator (TEG). The proposed approach captures thermal energy from the railway track and transfers the energy to the TEG prototype beneath the bottom of rails. Evaluation of the prototype is conducted by finite volume analysis, field test, and laboratory experiment. The results indicate that the TEG prototype can produce 5.8 mW–316.8 mW of power across a resistant load at thermal gradient from 8 °C to 29.2 °C. A DC-DC buck-booster circuit with lithium battery management is developed to charge the batteries by the harvested thermal energy. The system operates at a low startup voltage of 0.9 V and its conversion efficiency is larger than 60%. •Highlights of the paper:•A prototype was developed for harvesting thermoelectric energy from railway track.•One year temperature data of the railway track infrastructure were measured.•A DC-DC converter with lithium battery management was developed.•The system can charge a cellphone at a temperature gradient of 23.5 °C.