Hydrogen combustion engine Unimog in testing

The test vehicle is being used to assess where hydrogen combustion can work to supplement battery electric and fuel cell powertrains.

The prototype has been put to work mowing the verge on a decommissioned section of motorway in Germany between Bayreuth and Bamberg. Data gathered from its mowing efforts, accelerating and refuelling at a public station will be used to inform later testing cycles.

Franziska Cusumano, head of Mercedes-Benz special trucks and custom tailored trucks, said: “We are very happy with the current development status of the test vehicle. After a good two-year project term, we are already in practical testing with the first operational Unimog prototype featuring a hydrogen combustion engine.

“The tests with Autobahn GmbH staff in Upper Franconia are particularly valuable for us because here we can collect important feedback from the practical application for further development work.”

The Mercedes-Benz Unimog drivetrain development is being worked on by 18 partners as part of the publicly funded “WaVe” project. The testing programme will ensure the vehicle is used in low temperatures and varying topography.

The hydrogen engine was converted from a natural gas unit and installed in a Unimog U 430 implement carrier, it has around 290hp and 100Nm of torque and runs quieter than a diesel engine. Behind the cab, hydrogen tanks hold up to 14kg of gas pressurised at 700-bar. The next phase of development will see larger tanks installed to ensure the vehicle can operate for a full working day.

Dr. Günter Pitz, head of powertrain development at Mercedes-Benz Special Trucks, said: “The hydrogen combustion drive concept can serve as a blueprint for power-intensive applications in the specialty vehicle sector. Hydrogen combustion can make it possible to drive and work with very low emissions on construction sites, in municipal or agricultural sectors. To reach series maturity for such vehicles, reliable funding is and will be required.”