When compared to the fuel cell buses which were tested from 2003 within the framework of the CUTE and HyFLEET:CUTE projects, the new Citaro FuelCELL Hybrid boasts some important innovations: hybridisation with energy recovery and storage in lithium-ion batteries, powerful electric motors with 120 kW continuous output in the wheel hubs, electrified ancillary assemblies and enhanced fuel cells. These will deliver an increased service life of at least five years or 12,000 operating hours.
The fuel cell stacks of the new Citaro FuelCELL Hybrid are identical to those of the Mercedes‑Benz B‑Class F‑CELL with a fuel cell drive system.Both stacks are located on the vehicle's roof as was the case with earlier fuel cell buses. The lithium-ion batteries which can store the energy recovered during braking, are a new addition to the roof. The power provided by this energy storage unit means that the new Citaro FuelCELL Hybrid can travel several kilometres on battery-electric power alone. Essentially, the concept of the new FuelCELL bus broadly correlates with the Mercedes‑Benz BlueTec Hybrid buses. The latter still get their electric energy from a diesel generator. On the new FuelCELL buses, in contrast, it is the fuel cells which generate with zero emissions the electrical current for the drive motors.
Thanks to the improved fuel cell components and the hybridisation with lithium-ion batteries, the new Citaro FuelCELL Hybrid saves 50 percent hydrogen in comparison to the previous generation.As a result it was possible to reduce the number of tanks in comparison to the earlier fuel cell buses tested from nine to seven, containing in total 35 kg of hydrogen. The range of the fuel cell bus is over 300 kilometres. With these manifold technical advances, purely electrically-powered buses using fuel cells to produce the energy are a significant step closer to series production capability.