Published May 28, 2012
By Jeff Cobb
PostAuto Schweiz AG has become the first company in Switzerland to deploy fuel-cell technology for public road transport.
Since the end of 2011, five Mercedes-Benz Citaro FuelCELL Hybrid models have been serving on routes in and around Brugg (in the canton of Aargau) as PostAuto vehicles. Over the next five years, PostAuto will test the new generation fuel-cell drive, using clean hydrogen as fuel.
The dense network of routes operated by PostAuto around Brugg is ideally suited to the test in terms of both topography and routing, with a mixture of city traffic, country roads and village streets. The routes will be operated by the PostAuto company Voegtlin-Meyer AG, which will also service and refuel the five fuel-cell post vehicles at its garage location.
Aargau Canton is supporting the fuel-cell bus project with a subsidy of 1.5 million Swiss francs from the Swisslos lottery fund. PostAuto expects to save some 2 000 tonnes of CO2 during the five-year test phase.
Compared with the fuel-cell omnibuses that were tested from 2003 on as part of the CUTE and HyFLEET:CUTE projects, the new Citaro FuelCELL Hybrid offers significant innovations: hybridisation with energy recovery and storage in lithium-ion batteries, powerful electric motors fitted in the wheel hubs with a continuous output of 120 kilowatt, electrified PTO units and more advanced fuel cells.
These cells will have a service life of at least five years, or 12,000 operating hours.
The fuel-cell stacks in the new Citaro FuelCELL Hybrid are identical to those used in the Mercedes-Benz B-Class FCELL with fuel-cell drive. As in the earlier fuel-cell buses, the two stacks are already installed on the vehicle’s roof. A new addition is lithium-ion batteries, which store energy that is recovered during braking. With the electric power from this energy accumulator, the new Citaro FuelCELL Hybrid is able to run for a number of kilometres on battery power alone.
The concept behind the new FuelCELL bus essentially corresponds to that of the Mercedes-Benz BlueTec hybrid buses. However, these derive their electric power from a diesel generator, whereas in the new FuelCELL buses the fuel cells generate the electricity for the drive motors, without producing any emissions whatsoever.
The improved fuel-cell components and the hybridisation with lithium-ion batteries result in a reduction in hydrogen consumption of almost 50 percent for the new Citaro FuelCELL Hybrid compared with the previous generation.
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 to seven on the current vehicles, holding 35 kg of hydrogen in all. The operating range of the fuel-cell bus is now over 150 miles.
With these diverse technical advances, buses running on electric power alone with fuel cells as energy generators are now a major step closer to production maturity.
