In the sH2unter@ports study, the performance requirements for locomotive in the port areas are being closely examined. For this purpose, a conventional G1000 diesel locomotive is equipped with measuring sensors to check the exact power utilisation. How much power the locomotive needs is determined, among other things, by the total weight of the attached loads, the acceleration during operation and the profile of the route network in the ports. Even small hills for instance increase the starting energy many times.
In addition, the type of operation plays an important role, because the operational flow must not be disturbed by long or frequent refuelling operations. For this reason, it is also determined how much distance the locomotive makes and how the journey and break times are.
The profile of the trips has an influence on the prospective locomotive modification. Locomotives that are used almost exclusively in shunting operations have different requirements for refuelling and the amount of stored hydrogen, for example, than would be the case for mainline locomotives. However, such an implementation is currently still in question due to the high demand for hydrogen.
The test runs in Bremerhaven’s overseas port area have already been successfully completed. The test locomotive is currently in operation in the port of Hamburg. With the results, the project partners plan to determine the most efficient solution for the conversion to hydrogen and make a statement as to whether the locomotive should be a new one, with fuel cell technology, or with a diesel engine converted to burn hydrogen. For this purpose, an overall economic-ecological balance will be drawn up.
Why hydrogen?
Hydrogen can be used as an energy carrier that can store electrical energy in converted form. In the future, electricity surpluses from renewable energies will probably be coupled to the production of hydrogen so that the increasing demand can be met in the future. Electrolysis splits water into its components, oxygen and hydrogen.
Hydrogen can be stored under pressure, in gaseous form, deep-frozen or liquefied. In addition, the hydrogen can be further processed to synthesise climate-neutral fuels. These are molecular chains of different hydrocarbons. If the production energy can also be provided without greenhouse gas emissions, these synthetic fuels will be climate-neutral. Hydrogen can be varied and used in numerous combinations, for fuelling shunting locomotives, but also ships, cranes, carriers, trucks etc. The use of hydrogen is thus advantageous in the port context due to this flexibility.
There are also several possibilities for hydrogen operation of shunting locomotives:
1. Conversion of an existing locomotive
Shunting locomotives are powerful locomotives that are built for a long service life. The average age of existing locomotives in Germany is over 40 years. The stock of locomotives was partly increased 10 years ago. These locomotives now have at least 30 years of service life ahead of them, but are equipped with conventional combustion engines (Pagenkopf et al., 2022). With the demand for sustainability and resource efficiency, alternatives to new construction must be found; a complete replacement of the existing “fleet” is currently neither economical nor ecological.
Therefore, a special research interest of the sH2unter@ports project is to investigate the conversion of diesel locomotives to hydrogen-based propulsion systems.
If the body of the locomotive is preserved, there are various possibilities for converting the drive system.
Converting the locomotive to a fuel cell: Depending on the route and requirement profile, a locomotive can be converted to a fuel cell system. Here, the fuel cell generates electricity during the combustion of hydrogen, which is used to power the locomotive. At the same time, an intermediate battery stores electricity to absorb power peaks. The conversion is very extensive.
In a preliminary study in the port of Duisburg, locomotives converted in this way could be used in pure shunting operations, but during mixed and line haul operations, the operating sequence was affected by frequent refuelling intervals (Konrad et al., 2022).
Conversion to hybrid drives: Hybrid drives are even more versatile for locomotives than for passenger cars. This is because locomotives can also have mixed drives with overhead lines that simultaneously feed into a battery. In this way, lines without overhead lines can theoretically be covered. These forms of drive still require further testing so that the exact requirements for the locomotive in use can be evaluated.
But diesel-electric locomotives can also be converted to hydrogen. So far, the locomotives run with an electric motor that draws its power from a diesel generator. If this is converted to green hydrogen, the locomotives will run climate-neutrally.
The project partner Alstom presented a prototype 2022.
2. Construction of a new shunting locomotive
In the long term, there must be concepts for the new construction of climate-neutral, efficient shunting locomotives. In new planning, the fuel cell is the forward-looking innovation, because the drives have only low energy losses and are more efficient than combustion engines.
The manufacturer Alstom is developing a 4-axle hydrogen-powered shunting locomotive with fuel cell drive on the basis of the TRAXX SHUNTER plattform a 4-axle hydrogen-powered shunting locomotive with fuel cell propulsion, which can be used for heavy shunting operations in ports and industrial plants in Europe from around 2027. If you have any questions, please contact Mr Jörg Schulze at Alstom.
3. Conversion to alternative fuels
Fuels can be produced chemically, i.e. synthesised. The compounds of carbon and hydrogen can be put together in many variants, so there is already synthetic diesel or synthetic methanol. However, these substances are only climate-neutral if the production and supply chains are free of greenhouse gas emissions. The production processes, which are still energy-intensive and not very efficient, could become a milestone in the future, for shipping and land-based heavy-duty transport.
In Bremerhaven’s overseas port, a different alternative is already being used; since March 2023, the locomotives have been refuelled with hydrogenated vegetable oil (Hydrogenated Vegetable Oils, HVO for short). When HVO is burned, CO2 is released that was previously absorbed by the plants from the atmosphere. This is why it is considered climate-neutral. The use of HVOs is a short-term solution. One advantage is that it can be used quickly, because the engines do not have to be converted. However, a permanent and widespread use is questionable due to the high resource and land requirements for the provision of this “biodiesel”.