Electric buses with H2 mode to hit Stuttgart streets

Daimler Buses announced that Stuttgarter Straßenbahnen AG (SSB) will put 10 Mercedes-Benz eCitaro G fully electric articulated buses with new pure hydrogen drive mode (“H2 mode”) into operation in in 2025. SSB has been a development partner of Daimler Buses for the vehicles, the first of which was handed over on April 14.

The eCitaro G fuel cell electric articulated buses include a pure hydrogen drive mode. (Photo: Daimler Buses)

The eCitaro G fuel cell electric articulated buses equipped with a hydrogen-based fuel cell as a range extender can be operated exclusively with hydrogen as an energy source in certain operating scenarios. The pure hydrogen drive mode makes them independent of stationary charging processes. This increases their operating radius compared to hybrid or purely electric technologies, Daimler Buses stated.

The battery and the fuel cell also serve as the energy source for the drive system in the H2 mode operating strategy. External charging of the batteries on the mains network during stationary phases is no longer necessary, as they are charged by the fuel cell while driving, Daimler Buses explained. The fuel cell is designed to always operates in the efficient operating range between 20 and a maximum of 40 kW, even in H2 mode.

The eCitaro G fuel cell vehicles for SSB are equipped with four NMC3 high-voltage battery packs with a total energy capacity of 392 kWh. The compact fuel cell module has a maximum output of 60 kW and is located on the roof of the rear section directly behind the articulation joint. Six hydrogen tanks each with a total capacity of 30 kg of H2 are located on the roof of the individual articulated buses.

SSB has indicated it will no longer purchase diesel buses. From 2027, it intends to operate in the city center of Stuttgart exclusively with emissions-free buses, with plans to be climate neutral across the entire city bus network from 2035.