Germany scores hybrid goal

Germany showed why it still leads automotive technology with this week’s launch of a zero-emission hybrid bus

Germany scores hybrid goal
Germany scores hybrid goal

August 19, 2011

Germany’s intent to reduce carbon emissions and push automotive technology to newer heights has manifested this week with the launch of the Mercedes-Benz Citaro fuel cell hybrid bus.

The maker Daimler claims the new hybrid is an advance on previous electric-diesel hybrid buses in that these vehicles are emission-less, can run longer distances on battery power, and are virtually maintenance-free.

German public transport operator Hamburger Hochbahn AG (HHA) has acquired four Mercedes-Benz Citaro FuelCELL Hybrids under the German ‘NaBuZ demo project’ which promotes emerging sustainable bus systems.

The four Citaros went into service this week in Hamburg’s public transport system.

HHA’s CEO Günter Elste says in 20 to 25 years from now diesel will be in short supply and too expensive to be a viable fuel for buses.

"From the coming decade on, HHA aims to purchase only electrically driven zero-emission buses."

He says commissioning this new generation of bus represents an important step on the road to electric mobility.

Daimler Buses CEO Hartmut Schick says HHA is a company that displays a commitment to sustainability in all areas, from the generation of energy to its sustainable use.

"We at Daimler Buses have similarly defined sustainability as a leading corporate objective," Schick says.

"With the new FuelCELL Hybrid vehicles, Hamburg is once again assuming a pioneering role in this field," he says.

Schick says HHA has made a name for itself across Europe through its trials of fuel cell buses from previous hybrid generations.

Given Citaro’s low noise levels, coupled with zero emissions, Schick believes passengers and drivers will be ‘delighted’ with the new technology.

The Citaro FuelCELL Hybrid features a number of key innovations in comparison to the fuel cell buses which went into trial operation in Hamburg in 2003.

The Citaro features hybridisation 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 fuel cells 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 FCELL with fuel cell drive, which is also being put to the test in Hamburg.

As on the earlier fuel cell buses, the two fuel cell stacks are installed on the vehicle's roof, unlike other hybrids trialled in Australia and elsewhere with battery cells at the rear of the vehicle or attached near the chassis.

Lithium-ion batteries store energy recovered during braking.

With the electric power from this energy accumulator, the new Citaro FuelCELL hybrid is able to run for several kilometres 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 its electric power from a diesel generator, while in the new FuelCELL buses the fuel cells generate the electricity for the drive motors, without producing any emissions.

The improved fuel cell components and the hybridisation with lithium-ion batteries result in a reduction of almost 50 percent in hydrogen consumption for the new Citaro FuelCELL Hybrid in comparison to 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 in Hamburg to seven on the current vehicles, holding 35 kg of hydrogen.

The fuel cell bus has a range of around 250 kilometres.

Daimler claim the drive system with the fuel cells is virtually maintenance-free with a long service life.

HHA will place three more Citaro buses into the Hamburg fleet next year.

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