Mercedes-Benz Special Trucks and Mörtlbauer Baumaschinen Vertriebs GmbH have jointly presented two innovative prototypes as part of the “WaVe” development project, which aims to research hydrogen combustion engines for special-purpose vehicles. The Unimog test vehicle and crawler showcased their capabilities in both driving and working operations at the Mörtlbauer factory premises.
The demonstration marked the conclusion of the project, which was funded by Germany's Federal Ministry for Economic Affairs and Climate Action. Over the past three years, Mercedes-Benz Special Trucks and Mörtlbauer collaborated with 16 other consortium partners to develop these hydrogen combustion engines. The Unimog implement carrier has been undergoing various tests for over a year, while the dump truck crawler, operational since spring 2024, has also proven effective in initial application-specific tests.
Franziska Cusumano, Head of Mercedes-Benz Special Trucks, said, 'The final event held together with our partner Mörtlbauer on their premises once again demonstrated that both vehicles have reached a development status that we can be very satisfied with, even though this project has run for just three years. After numerous test deployments, emission measurements, and technical fine-tuning, we are convinced that hydrogen combustion for work machines with high power requirements, both for driving and for powering auxiliary drives, is worthwhile, practical, and very low in emissions.”
Armin Mörtlbauer, Managing Director of Mörtlbauer Baumaschinen Vertriebs GmbH, said, 'The fact that our crawler and the Mercedes-Benz Special Trucks Unimog can be easily refueled with gaseous hydrogen and that these vehicles also work reliably when using implements is the result of the outstanding cooperation in this research partnership. We have researched and understood this technology. We now have the corresponding experience and data. However, to apply these in series production, we have to go even further on this path. If the government and society choose to follow the path toward hydrogen combustion engines, we are ready to go.'
During the event, the Unimog U 430 implement carrier transported the crawler on a low loader and demonstrated the refueling process at a mobile hydrogen refueling station. The Unimog also showcased implement operation with a front-mounted sweeper from Schmidt.
Hydrogen Combustion
The prototypes are equipped with medium-duty engines specially converted for hydrogen propulsion. Customised pistons, a hydrogen-compatible intake system, and an optimised ignition system were used. The hydrogen combustion process in these engines produces water, which is expelled as hot steam via the exhaust system.
The Unimog’s four TÜV-certified, 700-bar high-pressure tanks hold about 13 kilograms of gaseous hydrogen, delivering approximately 290 hp / 1000 Nm, comparable to a 300 hp diesel engine. The crawler features a similar engine output and fuel capacity, holding 14.5 kilograms of hydrogen at 700 bar, with a payload capacity of 30 metric tonne and versatile applications thanks to its dozer blade and 360-degree rotating body.
The “WaVe” Development Project
The “WaVe” project, launched in July 2021 and funded by Germany's Federal Ministry for Economic Affairs and Climate Action, brought together 18 industry and science partners. The goal was to develop a hydrogen-based drive system for working machines, potentially replacing conventional diesel engines. The project demonstrated that hydrogen-powered vehicles and machines could be used similarly to current diesel engines with minor drivetrain modifications.
These innovations highlight the potential of hydrogen combustion engines in reducing emissions and enhancing the efficiency of special-purpose vehicles, paving the way for more sustainable industrial applications.
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