Compared with the fuel cell buses which were being tested as part of the CUTE and HyFLEET:CUTE projects from 2003 onwards, the new Citaro FuelCELL Hybrid provides several significant new features: hybridisation with energy recuperation and storage in lithium-ion batteries, powerful electric motors with 120 kW of continuous output in the wheel hubs, electrified power take-off units and further enhanced fuel cells. These should achieve an extended 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 FCELL with fuel cell drive. As with the previous fuel cell buses, the two stacks are located on the vehicle roof. These are now joined by the lithium-ion batteries which, for example when braking, can store recovered energy. With the electricity from this energy storage unit the new Citaro FuelCELL Hybrid can drive several kilometres on battery operation alone. In general the design of the new FuelCELL buses is broadly the same as that of the Mercedes-Benz BlueTec Hybrid buses; these buses also get electrical energy from a diesel generator. In the new FuelCELL buses, however, fuel cells generate the power for the drive motors in a totally emissions-free process.
Thanks to the improved fuel cell components and the hybridisation using lithium ion batteries, the new Citaro FuelCELL Hybrid saves 50 percent on hydrogen over the previous generation. For this reason, compared to the previously tested fuel cell buses, it was possible to reduce the number of tanks from nine to seven, giving a total of 35 kg of hydrogen. The range of a fuel cell bus is now over 250 kilometres. With these many and varied technical advances, purely electric buses with fuel cells as energy producers take a clear step closer to series production capability.