Unimog on the road with hydrogen engine

Mercedes-Benz has tested a Unimog with a hydrogen combustion engine in real-life operation. On a disused section of highway between Bayreuth and Bamberg, the engineers used the test vehicle to collect measurement data while mowing the grass verge, accelerating and refuelling at a public fuel pump, which will be used for further vehicle development. Employees of Autobahn GmbH accompanied the tests.

The prototype is part of the "WaVe" (hydrogen combustion engine) development project, in which 18 partners are working together on the hydrogen combustion engine drive concept. The Unimog U 430 implement carrier is equipped with a specially converted gas engine for alternative propulsion using hydrogen technology. The wheelbase and platform length are dimensioned so that the hydrogen tanks can be mounted behind the driver's cab. The four TÜV-approved 700-bar high-pressure tanks hold a total of around 14 kilograms of gaseous hydrogen. They are combined into two double tanks, each of which is operated independently with a tank control unit. In the next stage of development, the volume is to be increased to cover a regular working day. The engine produces around 290 hp (213 kW) and 1000 Newton meters. It is quieter than its diesel counterpart. The prototype was equipped with a front mower with two mowing heads in order to gain further insights during operation.

The aim of the Wa-Ve project is to test the extent to which the conventional diesel engine can be replaced by a hydrogen-powered combustion engine as a multi-energy distributor for the traction drive and all power take-offs. After the first successful practical application, the development team has a remaining project period of six months to make further adjustments and improvements.

In principle, Daimler Truck is focusing on battery-electric drives and hydrogen-powered fuel cells. However, hydrogen combustion can be another option for decarbonizing the powertrain portfolio alongside these two technologies. Initial results show that the hydrogen combustion engine could be a sensible solution for special applications. This alternative could be particularly useful for the Unimog due to the limited installation space and the high power required for work.

Dr. Günter Pitz, Head of Powertrain Development at Mercedes-Benz Special Trucks, believes it makes sense to continue the project: "The hydrogen combustion drive concept can serve as a blueprint for power-intensive applications in the special vehicle sector. On construction sites, in the municipal or agricultural sector, it could be used to drive and work with very low emissions. In order to make such vehicles ready for series production, we need continued financial predictability through targeted funding." (aum)