The assessment of on-board clean hybrid energy storage systems for railway locomotives and multiple units

Batteries, supercapacitors, and hydrogen fuel cells are energy storage devices that have no emissions at the point of use. The idea of powering railway locomotives using these devices is one that could, theoretically, eliminate emissions from the railway sector. The motivation behind the research work presented in this thesis is to assess the technical feasibility of employing batteries, supercapacitors, and hydrogen fuel cells in a railway vehicle. This is meant to serve as reference to future work regarding the cost-benefit analysis, well-to-wheel emissions analysis, and life-cycle assessment of railway vehicles that employ these power sources. In this thesis, the application of on-board clean energy storage systems to railway vehicles were studied. Simulation models for battery/supercapacitor and hydrogen fuel cell/battery hybrid powertrains were developed in Simulink. These models were then used to conduct simulations for two train trips. The first trip selected was the 14 km Trehafod to Treherbert route, on which the British Class 150 diesel motive unit operates. The second trip was the 432 km London to Newcastle trip, on which the Intercity 125 train operates. Since no data regarding freight trains on freight tracks could be obtained, only passenger trains were simulated. The conclusions made at the end of this thesis could potentially apply to freight trains as well. Based on the case studies considered, it was found out that railway systems are very well suited to run on on-board clean energy storage systems from an energy consumption point of view. Although being slower responding power sources, hydrogen fuel cells proved to be capable of handling dynamic load changes in railway systems to a great extent but still required the assistance of a faster acting power source. Despite having a significantly lower electrochemical efficiency, employing hydrogen fuel cells resulted in increasing the range of travel without refueling/recharging due to the high energy density of hydrogen. Lithium ion batteries proved to be very capable in handling all the required transient power demand. In regeneration, supercapacitors outperformed lithium-ion batteries and reduced the need for frictional brakes.Applied Science, Faculty ofEngineering, School of (Okanagan)Graduat