Energy harvesting in hybrid electric vehicles and railway systems: AI-enabled condition monitoring and emerging trends

Modern electric and hybrid transportation platforms employ numerous sensors, controllers, and communication modules that require continuous power supply. Energy harvesting technologies offer a promising solution to support these auxiliary systems and reduce dependency on the primary battery. This article systematically evaluates major energy harvesting technologies such as Thermoelectric generators (TEGs), Regenerative Braking systems (RBS), Regenerative shock absorbers (RSAs) and other vibration harvesting technologies, as the potential solution to provide the power supply in the onboard auxiliaries and self-sensing modules. A comparative analysis is presented in terms of working principles, energy conversion potential, operational characteristics, and practical implementation in transportation systems. TEGs exploit exhaust-gas thermal gradients, RBS recovers kinetic energy typically discarded as heat and RSAs transform vibrations caused by suspensions to electrical energy without affecting ride comfort. To further the discussion, the review also applies the same to railway applications where bogie, axle-box and track-mounted harvesters enabled self-powered monitoring and predictive maintenance. Adaptive power distribution, autonomous health management, and self-sustaining IoT-based transport (IoTT) further are backed up by the integration of mechanical intelligence and AI-enabled energy management. In general, this review demonstrates the prospect of multi-source hybrid harvesters to eliminate traction battery dependence and to extend the vehicle range and facilitate a fully self-powered cyber-physical transportation platform.