Tuesday, September 12, 2006

On the road to a hydrogen-fuelled future

THE latest developments in enviro-friendly fuel-cell technology could find their way into real-world applications within the next decade. DaimlerChrysler, one of the leaders in the research race, has more than 100 fuel-cell vehicles operating around the world, including three Mercedes-Benz Citaro buses in Perth.

A fleet of 30 of the fuel-cell buses — utilising technology that is already largely outdated — has covered more than 500,000km and carried more than 10 million passengers in countries from Europe to China since 2003.

Also circulating in a variety of urban environments is a collection of A-Class and B-Class based fuel-cell models.

Fuel-cell technology has been buzz development for many key manufacturers, with Honda, Nissan and General Motors all having models operating in day-to-day situations.

Honda's FCX is the first of the cars to go to private owners with very limited numbers utilising the "hydrogen highway" filling station infrastructure around Los Angeles.

However, it is the Mercedes-Benz F600 HYGenius that is providing the excitement and advances engineers hope will accelerate the flow to a commercial fuel cell future.

"We want to improve the robustness and service life of the entire system. And the best way to see if we're succeeding is to take the vehicle on test drives over long distances," says Andreas Docter, who was responsible for the construction of the fuel-cell system used in the HYGenius and also heads the fuel-cell systems engineering department at DaimlerChrysler Research.

Technology improvements and refinements give the HYGenius a fuel efficiency equivalent of 2.9 litres of diesel per 100kilometres. Packaging is one of the key areas demonstrated on the HYGenius with the vehicle's entire drive unit tucked away in the vehicle's sandwich floor.

er engineers say one of the most significant innovations on the HYGenius running model is a new fuel tank that can store hydrogen at 700bar, double the pressure of the previous model.

The pressure increase allows up to 4kg of hydrogen to be carried, enough for a 400km journey. Also causing excitement is a new membrane technology for the fuel cells and and a new humidification system consisting of hollow fibres.

Both innovations allow for precise heat and water management, which means water in liquid form no longer collects in the stack.

Water freezing in the stack during winter has previously been a serious stumbling block with severe difficulty in starting the engine.

The new technology allows the HYGenius to start easily at temperatures as low as minus 25 Celsius.

The test-bed HYGenius is also running a new smaller and more powerful electric-drive unit on the rear axle, a lithium ion battery that produces twice the output of the previous nickel metal hydride units, new bipolar plates that replaces graphite with .15mm-thick foil helping to reduce the size of the stack by almost 40 per cent, and a newly developed electric turbocharger, smaller and more efficient to supply oxygen to the cells.

Mercedes-Benz has a strong record of technology transfer from research vehicles to production models.

Since 1981, the company has displayed 11 research models with technologies such as Distronic cruise control, gas-discharge lamps (xenon), active body control, window airbags, corning lights and voice-activated systems making the leap to mainstream production.

Source :- CarGuide