Hamburg putting its first Citaro FuelCELL Hybrid buses into service

Hamburger Hochbahn AG has acquired four Mercedes-Benz Citaro FuelCELL Hybrids under the German “NaBuZ  demo” scheme to promote sustainable bus systems for the future. Three  more buses are to follow next year. (Earlier post.)

The Citaro FuelCELL Hybrid features a number of key enhancements in  comparison to the fuel cell buses which went into trial operation in  Hamburg in 2003: hybridization with energy recovery and storage in  lithium-ion batteries; electric motors in the wheel hubs offering a  continuous output of 120 kW; electrified auxiliary units; and more  advanced fuel cells. The latter are designed for an extended service  life of at least six 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 fuel cell drive, which  is also being deployed in Hamburg. As on the earlier fuel cell buses,  the two stacks are installed on the vehicle’s roof. They are now  accompanied by the lithium-ion batteries which store energy that is  recovered during braking; the new hybrid is able to run for several  kilometers on battery power alone.

The concept behind the new FuelCELL bus essentially corresponds to  that of the Mercedes-Benz BlueTec Hybrid buses which are in service in  Hamburg. A key difference is that the latter derive their electric power  from a diesel generator, while in the new FuelCELL buses the fuel cells  generate the electricity for the drive motors.

The improved fuel cell components and the hybridization with  lithium-ion batteries result in a reduction of almost 50% in hydrogen  consumption for the new Citaro FuelCELL Hybrid in comparison to the  previous generation: 10–14 kg/100km compared to 20–24 kg/100 km. Overall  fuel cell system efficiency has also been improved from 48–38% in the  previous generation to 58–51% in the Citaro FuelCELL Hybrid. As a  result, it has been possible to reduce the number of tanks from the  total of nine on board the fuel cell buses deployed in earlier trials in  Hamburg to seven on the current vehicles, holding 35 kg of hydrogen in  all. The fuel cell bus has a range of around 250 kilometers.

According to all the forecasts, 20 to 25 years from  now mineral oil and, in turn, diesel will be in short supply and too  expensive to be a viable fuel for buses. From the coming decade on,  Hochbahn thus aims to purchase only electrically driven zero-emission  buses. Commissioning this new generation of buses represents an  important step on the road to electric mobility.

—Günter Elste, CEO of Hamburger Hochbahn AG

Demonstration of the Citaro FuelCELL Hybrid buses as part of the  NaBuZ demo project is to take place on Hochbahn’s regular service  routes. The project is integrated into the Clean Energy Partnership  (CEP).

The NaBuZ project receives funding through the federal transport  ministry’s National Innovation Programme (NIP). NIP is coordinated by  NOW GmbH. There will also be close cooperation with the European CHIC  project, in which 26 fuel cell buses are being run in five European  cities.

Daimler Buses’ involvement in the NaBuZ demo project and the CHIC  project follows on from the European Union’s CUTE and HyFLEET:CUTE  projects which were staged from 2003 to 2009. In the course of these  projects, 36 Mercedes-Benz Citaros fitted with second-generation fuel  cell drives were in operation with twelve transport companies on three  continents, driving over more than 140,000 operating hours covering more  than 2.2 million kilometers.

SOURCE: www.greencarcongress.com