Modular scalable energy storage for a sustainable rail passenger transportation
The objective of the project MOSENAS is the development of a battery electric multiple unit for a long-term use on different partly electrified railway routes. The focus is set on the designing of a modularly scalable energy storage system under consideration of operational feasibility, efficiency and compatibility with the surrounding charging infrastructure.
January 2022 until June 2024
Federal Ministry for Digital and Transport
Stadler Rail Group
Institute of Networked Energy Systems
Institute of Vehicle Concepts
Project Management at the Institute of Networked Energy Systems:
Electric propulsion offers significant emission advantages in the rail transport as opposed to a diesel engine. However, the layout of all routes with overhead lines mean economic hurdles, or else, is rather difficult to implement due to local restrictions. Still, the near-term upgrade to renewable energy sources within the rail sector can be realized by means of modern battery technologies.
A scalability of the energy storage allows an ideal adjustment to operating conditions of different route profiles and, therefore, diesel multiple units (DMU) can be replaced by battery electric multiple units (BEMUs). In this context, the reliability of a smooth passenger service presents a particular challenge leading to measures to secure energy supply even over several route cycles, if need be. A hybridisation of the battery system can be a possible approach. On the one hand, local topography, recuperation, air conditioning requirements, passenger numbers as well as the availability of charging infrastructure affect the necessary energy storage and power requirements on the battery system and, on the other hand, the lifetime of the batteries. An underdimensioning of the battery storage can result in insufficient states of charge and therefore breakdowns and cancellation of services. An oversizing requires the binding of an unnecessary amount of mass and construction volume with increased need of operating power. At the same time, extra capital is tied up.
In order to address the question on how much battery capacity is needed and which combination of cells is most suitable to secure a safe and efficient operation, a systematic analysis on battery ageing is carried out in the framework of the project. The analysis is supported by a battery measurement campaign. On the basis of battery ageing models, the cellular chemistry, configuration and dimensioning of a hybrid battery system are being optimised for the purpose of operating a BEMU.
The identification of suitable innovative battery systems and the development of lifetime extending operating strategies are jointly elaborated on with the DLR-Institute of Vehicle Concepts.
Long times in the driving mode and comparatively short stays at the charging points, for example in stations or depots, require a quick supply of large of electrical energy and a selective enhancement of the charging infrastructure. This shall be guaranteed by appropriate concepts of local grid supplied power, sector integration and the highest possible inclusion of renewable energy.
A further focus of the project lies on the analysis of potential electrification, particularly supplementary electrification of route sections and catenary island systems, and on the optimised system solutions for infrastructure and vehicle combinations. The integration of second use batteries in stationary storage facilities for the purpose of facilitating an economic and robust operation with mitigated effects is examined in this context. A full electrification of the routes serves as a comparing reference. These routes are fully equipped with overhead lines which does not make the operation of a BEMU necessary. However, it causes a significant outlay to upgrade the infrastructure.
In order to increase the use of renewable energy sources within the transport sector, a direct integration of the charging infrastructure with regenerative generation plants (direct and through public grid) is being analysed.