At Global Public Transport Summit (GPTS) 2023 from 4 to 7 June 2023, Daimler Buses will be showcasing the first series-production electric bus with fuel cell as a range extender: the Mercedes-Benz eCitaro fuel cell. (Earlier post.)

The new, zero-emissions regular-service bus combines high range with high passenger capacity. In the articulated bus variant, available from June, the eCitaro fuel cell can run for around 350 kilometers without having to recharge, offering space for up to 128 passengers. The eCitaro fuel cell can thus seamlessly replace city buses with combustion engines.

At the same time, it is a suitable option for transport operators with an existing battery-electric fleet aiming to operating their long routes without having to recharge and without having to put on additional buses.

The eCitaro fuel cell is based on a battery-electric drive system with NMC 3 high-performance batteries, while the fuel cell with an output of 60 kW serves as a hydrogen generator to extend the range. This combination enables particularly economical operation because electricity from the grid is available at a lower price than green hydrogen, and the sophisticated electronic control system regulates the mix of battery power and fuel cell operation in the best possible way.

In contrast to a fully fledged hydrogen vehicle with a small buffer battery, the eCitaro fuel cell is also significantly better at completely and usefully storing the energy recovered during braking by recuperation in the large batteries.

The battery capacity of at maximum 392 kWh in the articulated bus also enables high levels of drive output to be used over longer distances—for example on inclines in mountainous terrain—without the fuel cell having to operate in the top, inefficient power range.

Due to the favorable weight distribution of batteries and fuel cells, this technology enables a high passenger capacity. Thanks to the long range, opportunity charging en route is not envisaged; charging is always carried out by plug at the depot.

The development of this technology is supported by the German Federal Ministry for Digital Affairs and Transport with a total of €3.3 million as part of the National Innovation Programme for Hydrogen and Fuel Cell Technology (NOW). The funding guideline is coordinated by NOW GmbH and implemented by the project-executing agency Jülich (PtJ).

Before the launch of series production in June, the eCitaro had to pass numerous endurance and functional tests. The focus was on the new fuel cell and hydrogen system in particular. The hydrogen tanks have already been tested for fire, impact and temperature resistance in accordance with the new UN ECE R 134 standard. All components and also the fastening system on the roof underwent vibration and sled tests to simulate an impact.

The new thermal management system, which profitably uses the heat input from the fuel cell, completed extensive laboratory and practical tests in extremely hot and extremely cold environments. The new components of the eCitaro fuel cell have successfully passed all tests.