Mercedes-Benz has a history of introducing various fuel saving technologies to its line of commercial buses. The automaker first began experimenting with fuel cells in bus platforms back in 1997, and has since put 36 units on the road. Recently, the hydrogen component was dropped in favor of a diesel engine to act as a generator for the lithium ion batteries and wheel motors of the electric bus. By adding the electric drive component, MB was able to downsize the diesel engine from 12 liters to 4.8 liters.
Now, the oil-burning powerplant is once again going away completely as Mercedes-Benz has started testing Citaro buses with hydrogen fuel cells. Daimler points to the complete lack of emissions as one reason to choose a hydrogen fuel cell in lieu of an internal combustion engine to keep the batteries topped up. This new Citaro FuelCELL hybrid bus will be officially debuted in June at the UITP World Congress and Mobility & City Transport Exhibition in Vienna.