Comparative analysis of conventional diesel-electric and hypothetical battery-electric heavy haul locomotive operation in terms of fuel savings and emissions reduction potentials

The paper considers a novel approach to heavy-haul of railway freight by means of combined operation of conventional diesel-electric and battery-electric locomotives either in single or joint (tandem) operation. A backward-looking quasi-static model of a battery-electric locomotive is proposed, based on the undercarriage of a decommissioned conventional diesel-electric locomotive equipped with a sufficiently sized battery energy storage system. In order to facilitate power flow control from the battery-electric locomotive and to avoid deep battery discharges a suitable control rule is introduced aimed at modulating the driver power (throttle Notch) command in order to maintain the battery state-of-charge above the safe lower limit during discharging. The effectiveness of the proposed approach has been verified by means of simulations for the considered mountainous railway route driving scenario, including realistic railway track slope and speed limitations. The results show that between 22% and 30% fuel cost savings may be achieved, along with reduced emissions of exhaust gases by using the proposed battery-electric locomotive in combination (tandem) with the conventional diesel-electric one. (c) 2021 Elsevier Ltd. All rights reserved.