14 January 2025

Like many other operators, the Mecklenburgische Bäderbahn (MBB), known for its historic steam locomotives, is facing the challenge of making its operations more environmentally friendly. A current study by Nordhausen University of Applied Sciences is investigating whether and how MBB can switch its steam locomotives, which currently run on hard coal, to alternative, climate-friendly fuels. The aim is to significantly reduce CO2 emissions while preserving the historic character of the locomotives.

Among other things, MBB operates "Molli", the oldest narrow-gauge railway on the Baltic coast, which has been running between Kühlungsborn and Bad Doberan since 1886. All steam locomotives currently run on hard coal, which results in both high operating costs and significant CO₂-pollution. In view of the dwindling availability and rising prices of hard coal, MBB is looking for more environmentally friendly fuels that still fulfil the historical requirements of the locomotives.

In order to examine the possibilities of switching to alternative fuels, MBB commissioned Nordhausen University of Applied Sciences to carry out a feasibility study. The project was led by Dr Pascal Leibbrandt. The study analysed the current energy consumption of the locomotives, which requires around 180 kg of coal and 1.4 m³ of water per journey.

The limited space in the locomotives poses a major challenge. As different fuels take up different amounts of space, the study investigated which ones are suitable for storage in existing locomotives.

The study concludes that the use of hydrogen via various conversion and drive paths for locomotives is not currently practicable. This is due to the technical and economic challenges associated with the storage and handling of hydrogen. Solid fuels, although theoretically an alternative, have different energy contents and combustion characteristics, which leads to insufficient heat generation and could affect the operation of the locomotives. It may therefore be necessary to modify the locomotives in order to utilise these fuels effectively.

Although liquid fuels are easier to handle, they do not always have the desired climate-friendly properties. Under the variants described and the current conditions, however, the use of liquid fuels currently makes the most sense. It is assumed that the climate-damaging components of liquid fuels can be gradually replaced by synthetic or other more climate-friendly components in the future. The study emphasises that MBB cannot adopt the results of the study without further ado, as the specific requirements for the vehicles vary. Gaseous fuels were also analysed, whereby their combustion properties and the necessary modifications to the locomotives were considered. This clearly shows that adjustments with regard to raw material shortages, price fluctuations and CO₂-reduction are necessary.

Wood pellets and pyrolysis coal were identified as promising alternatives. These fuels could not only reduce the environmental impact, but also preserve the historic character of the locomotives. However, the use of these fuels results in extensive measures and consequential problems. The storage of wood pellets in particular is much more complex, as storage must be guaranteed regardless of the weather. Keeping the locomotives warm at night is also made more difficult by the use of wood pellets. In contrast, the use of biomethane or other synthetic fuels, for example, requires extensive adjustments, which entail both technical and economic challenges.

Overall, the study offers various insights for MBB and shows potential ways in which the operation of the historic steam locomotives can be made sustainable and environmentally friendly. The search for the optimum fuel will be continued with the aim of ensuring that the "Molli" and other historic locomotives will continue to run on the Mecklenburgische Bäderbahn lines in the future - ideally with an environmentally friendly drive system.

The in.RET conducts basic and application-orientated energy research in the field of renewable energy technology. In addition to the further development and optimisation of technologies for the use of renewable energies, an important focus of work will be the system integration of these energies, i.e. the question of how renewable energies can be combined with each other in a meaningful way and integrated into the existing supply structures in the heat and electricity market. Numerous interdisciplinary issues from the fields of energy technology, measurement and control technology and economics need to be addressed. The focus of research has developed from individual modules to entire energy systems.