Integrated hydrogen and battery energy systems as emergency backup in electric trains

Abstract

Moving towards sustainable transport by adopting alternative energy sources to traditional ones is, in these times more than ever, of fundamental importance for humanity. In this paper, the possibility of using fuel cell- and/or battery-based energy systems to replace the Diesel engine of a conventional electric train (the Hitachi Blues), is studied.Four different system configurations are proposed, all satisfying the common characteristic of being perfectly placed in rooms previously occupied by Diesel engines. Their sizing, layout and weight have been thoroughly discussed in the paper.Furthermore, to analyze the application limits of these configurations, their installation on an electric train running along a real railway line in the Calabria region (Italy) was simulated. To size the components and define the layout of the plant, computer-aided design software (CAD 3D) was used, starting from the original construction drawings of the railway carriages. Numerical and dynamic zero-dimensional simulations were implemented to evaluate the performance rating of the systems. Among the tested powertrains, two of the proposed configurations (a full-battery and a hybrid fuel cell-battery systems) have proved to be more than adequate to replace the overhead line, reaching an average driving range of about 100 km. Moreover, two different overhead line malfunction scenarios were assumed to evaluate the train performance. In each case, the innovative powertrains allow the train to travel the entire journey. In detail, the overhead line provides more than half of the energy, while the fuel cell reaches almost 25 % of the overall energy demand, consuming the whole amount of hydrogen stored on board, approximately 24 kg. The battery supplies a maximum of 545 kWh (roughly 40 %), conserving a 45 % State of Charge, and up to 165 kWh (over 10 %) can be recovered through regenerative braking strategies.