Innovative energy recovery system design for locomotives: advancing technology management for sustainable rail transportation

Abstract

In Sri Lankan railway, dynamic braking energy from Diesel-Electric Multiple Units (DEMUs) are currently wasted as heat, unlike electrified railways around the world, which recover and reuse this energy. This research proposes to design an innovative and sustainable system to harvest and reuse dynamic braking energy in S14 DEMUs operating on the upcountry railway line, planning to reduce operational costs and support environmental sustainability. Based on past research studies, energy losses during a 20-hour round trip from Badulla to Colombo were estimated around 3.5 MWh. Braking intervals and energy peaks were analyzed to identify optimal energy recovery points. A Lithium Iron Phosphate (LFP) battery system was selected for its proven safety, reliability and feasibility in transport applications. The suggested innovative design integrates a 1 MWh battery pack, capable of utilizing dynamic braking energy, primarily during the downhill section. The stored energy is then reused to power up the auxiliary systems during the return journey. This solution provides significant economic benefits. Over a 10-year period of battery lifetime, each train could save more than Rs. 87 million and reduce diesel consumption by approximately 550,800 liters. These savings not only reduce fuel costs but also reduce carbon emissions, contributing to a greener, more sustainable rail transport system. This novel system's expansion over the upcountry railway fleet could have a multiplied positive impact on the economy and environment. The results show that innovative energy recovery in non-electrified railroads is both economically feasible and ecologically sound.