41° N/8° W Porto, Portugal, January 2004. “Cisco, don’t forget to tell me when your Prime Minister’s on his way!” Cisco, alias José Cerqueira, manages a wry smile — that’s the third time Martin Rogers has given his local colleague a gentle reminder. Not that Rogers is feeling nervous, of course, what with all the dignitaries he has welcomed in his time in Amsterdam, Barcelona, Madrid and Hamburg. You could be excused for thinking he’s a politician, but actually he’s a fuel cell development engineer, and his job has taken him to almost every city where a hydrogen-powered bus is currently in operation. Rogers’ specialty is installing fuel cells in buses — each of which costs a princely 1.2 million euros, almost five times as much as their diesel-engined counterparts. The European Commission supports the establishment of a hydrogen supply infrastructure via the CUTE (Clean Urban Transport for Europe) project. The remaining costs are met out of national and regional budgets. So it comes as no surprise that the program of testing is attracting plenty of attention from politicians, with a stream of transportation ministers and mayors coming to admire the engineers’ progress. “But,” says Rogers, “this is the first time we’ve had a Prime Minister coming to see us.”

Rogers is standing behind three brand new Citaro buses, taking careful note of how their electric motors are running. Just to be on the safe side, he fires up the diagnostics system on his laptop again for a final check. The buses are lined up outside the streetcar museum in Porto, where the guests invited to the kick-off event are beginning to arrive. The buses really look the part, with a giant blue drop of water painted on each side and, at the back, a white trail of vapor rising from the gleaming stainless-steel “exhaust” pipe on the roof. Beneath it, the slogan “Vapor de Água. Não Poluente” — “Pure Steam. No Pollution” — brings home the message. The driver of the bus on the right depresses the gas pedal, drawing a smile from Martin Rogers. The engine sounds like nothing you have ever heard from the rear end of a bus. From a distance it reminds you of a turbine — there is no roaring, rattling, or shaking. In fact there is little audible indication of anything mechanical at all under the outer skin of the bus. Rogers recalls how, at the kick-off event for the fuel cell Citaro in Barcelona, the mayor had himself lifted up on a platform as far as the exhaust pipe, held his handkerchief into the jet of steam and then wiped his nose with it. He grins at the memory, his eyes still fixed on the back of the bus where the engine is now idling again. Another wisp of steam rises up out of the pipe, accompanied by the merest “ffffffff” from the drive system. “The best thing,” notes Rogers, “is that here we’re doing something 100 percent positive.”
 
  
Ten European cities are taking part in the test program which is scheduled to last two years. In addition to those already mentioned, Reykjavík, Stockholm, Stuttgart, Luxemburg, London and now Porto have all come on board. Three buses and two technicians are dispatched to each city, one of the engineers coming from Canadian fuel cell manufacturer Ballard — in Porto this is Martin Rogers — and the other from EvoBus, the wholly-owned DaimlerChrysler subsidiary that builds the buses. Together, these cities and companies have put in place the world’s largest field test involving the use of hydrogen-powered vehicles for local mass transit. The aim of the exercise is to acquire experience and expose this ground-breaking technology to as wide a range of everyday conditions as possible. The cities involved are all linked to an operations center in Mannheim. The engineers submit daily bulletins and enter diagnosis reports in the database whenever a fault occurs. So details of a loose connector in Stuttgart, for example, might solve a problem in Stockholm the next morning?

The different locations each present their own special challenges. In Reykjavík, for example, the technicians will be looking into the performance of fuel cells in the cool, salty climate. In Stuttgart, the emphasis is on how the system tackles hills, while the Stockholm team will assess the effectiveness of the buses in cold conditions and over long distances. Madrid provides the perfect conditions for charting the effect of dry heat, and Barcelona will subject the buses to the influence of warm weather and sea air. Porto likewise has its own set of challenges in store. Early January, and the city of hills, citadels, wide-open squares and narrow alleys is shrouded in mist and rain. Luckily, this is not a problem. “Fuel cells love moisture,” says Rogers, “as it stops the membranes from drying out.” EvoBus engineer Cisco nods his agreement: “The hills won’t hurt, either. Electric motors have outstanding pulling power at low revs, which makes them ideal for all these inclines. The biggest challenge is the state of the roads,” he observes; “some of them date back to the 14th century.” Rogers, too, is unhappy. “With the cobblestones and slippery streetcar rails, these must be some of the worst roads we’ve seen. And vibrations can really take their toll,” he says, obviously concerned for his fuel cells.
The basic principle behind this exciting new technology is really quite simple. The hydrogen is produced initially by splitting water into hydrogen and oxygen by means of electrolysis, for example. The higher the proportion of the electricity required for this process that is generated from renewable resources, such as the sun, wind, hydroelectric power or biomass, the easier on the environment the whole fuel cell concept becomes. The hydrogen (H2) generated by electrolysis is extremely unstable and reacts readily with oxygen, which makes up 21 percent of the ambient air. In the fuel cell, the hydrogen is brought together with oxygen under controlled conditions. At the heart of the cell is a membrane, which regulates the reaction between the atoms in the two gases in a chemo-electric process. The result is pure water on the one hand — and an electric current ready for use on the other.
In the past, fuel cells have been plagued by their prohibitive size and by issues related to the high pressure required to store sufficient quantities of hydrogen on board a vehicle. The Citaro stores its hydrogen in roof-top tanks at 350 bar. The problem is that the working pressure in the fuel cells is 1 to 2 bar, not much different from the pressure in a bicycle tire.

From Porto to Hamburg
 
 
Karl-Heinz Rothgaenger
The difference in pressure is the subject of careful consideration at the German end of the fuel cell bus network, too. “The drop in pressure has to be carefully controlled, and it only has a couple of meters in which to take place. If as much as a single function fails, the chain is broken,” explains Karl-Heinz Rothgaenger, an engineer with mass transit operator Hamburger Hochbahn — another of those involved in the test program. The scene has changed from the streetcar museum in Porto to a bus depot near Hamburg, Germany — one of the local operator’s five bases. Rothgaenger is standing in front of a typical hydrogen filling station, its pressure chambers, hoses and other equipment covered by a structure that looks very much like a huge, blue Lego brick. It certainly adds a splash of color on a cold, wet January day. Rothgaenger talks us through the electrolyzer system: “You fill up on one side with normal tap water, switch on the electric current and store the hydrogen extracted by means of electrolysis in those long narrow tanks.” The special thing about this particular system is that the electricity it consumes is all generated using renewable resources, which has made the bright blue filling station something of an environmental trademark for the City of Hamburg in European bus circles.
It’s not hard to tell that Rothgaenger is a big fan of these new buses, although his cool northern temperament forbids him to be too enthusiastic. Today is the first time a bus has had to be towed back to the depot, after a burst cooling hose stopped it in its tracks. The engineer sets about checking the whole system, while back at headquarters in Mannheim it looks as if the fault has already been identified. Breakdowns do happen from time to time. “It’s not really surprising,” says Rothgaenger, “when you think that the on-board electronics cover 2,000 measuring points. If just one of them fails, the bus may be out of action for a while.” Alternatively, the driver might find that his display panel is advising him to return to the depot immediately. “Even so, we get 85 percent of normal performance out of our fuel cell buses,” notes the engineer. “And I would never have thought we would get this far.“
 
  
Horst Opitz steers his bus into the depot. Since October he has been driving one of the new Citaro buses on the number 24 route through the flat and featureless countryside to the north of the city. It’s a quiet route, and the bus really fills up with passengers when the giant furniture store opposite the depot is having a sale, says Opitz, but that doesn’t mean people don’t like it. The driver recounts how one passenger will step back from the stop when a diesel-engined bus turns up, preferring to wait for his “steam engine.” Either that or he’ll check the departure times on the Internet before leaving home — a nice piece of marketing on the part of the Hamburg operating company.

Following the introduction of the new timetable in June 2004, the hydrogen-powered buses will also have to cope with Hamburg’s busy downtown routes along the main shopping streets. That’s where the driver’s problems start to multiply — although they have nothing to do with technology. “The real headache are the pedestrians who step off the sidewalk without looking left or right!” says Opitz. He has no worries as far as the fuel cells are concerned. “These buses will handle downtown work all right,” he says, with the relaxed smile of a man who has looked into the future, and likes what he sees.

Practical testing has just begun on the first series production Mercedes “F-Cell” compact car fitted with fuel cell technology — a two-year test process that will span the globe.

Report: Silke Dierkes
  
“We’re now entering the next phase,” announced Andreas Truckenbrodt, and for the “F-Cell” that means a far-reaching program of field tests. Over the next two years, the fuel cell powered Mercedes-Benz A-Class will be gaining valuable experience from the hills of San Francisco or the hot asphalt of Los Angeles to the heavy traffic of Tokyo, Singapore and Berlin. The scale of the tests is important because gasoline engine technology has a 100-year head start over the fuel cell. Even so, Truckenbrodt, who is Head of the Center for Fuel Cell Vehicles and Alternative Drive Systems at DaimlerChrysler, remains true to the corporation’s bold goal of bringing commercial fuel cell vehicles to market by 2010.

To help accelerate the process towards market maturity for the zero-emissions vehicle, 60 “F-Cells” are to be tested over a two-year period by customers in Japan, Germany, Singapore and the USA, where the world’s first near-series-production fuel cell powered passenger car will go into regular use. “This will give us a broad base of empirical evidence,” says Truckenbrodt. The road data will expose any weaknesses and give valuable insights into consumption, life span and the operational strategy of the hydrogen powered cars. One problem that remains, for example, is starting the vehicles at sub-zero temperatures.

“We have selected our customers with great care,” explains Andreas Schell at DaimlerChrysler in Auburn Hills, the man charged with looking after the projects in the USA. “It’s not much use to us if we give a car to a celebrity, who then leaves it in the garage.” The main thing is that the cars get some miles on the clock. There should be no problems on that score for UPS in Ann Arbor, Michigan, where the F-Cell cars will see service with the company’s express delivery fleet. And in Tokyo, Tokyo Gas Co. and Bridgestone Corp. employees will be taking to the streets in these innovative low-noise vehicles, emitting only water vapor and helping reduce the burden on the atmosphere in this city of eight million people. 

The two companies are partners in the “Japan Hydrogen & Fuel Cell Demonstration Project” launched with DaimlerChrysler, whose involvement in such cooperative ventures is international. In 1999 the company helped found the “California Fuel Cell Partnership,” while in Berlin, DaimlerChrysler is a major partner in the “Clean Energy Partnership” fuel cell project. Thus, automakers and technology companies are joining the energy industry and politicians in a drive to boost the acceptance of fuel cell powered passenger cars and the use of hydrogen as an energy source. A number of problems remain unsolved, however, and the framework conditions are not yet in place. There is no widespread network of hydrogen filling stations, for example, and fuel cell cars are still much too expensive. Moreover, if the drive system is to be 100 percent environmentally compatible, then ways must be found to derive hydrogen exclusively from renewable sources. “Only by working in partnership on this technology of the future can we hope to succeed,” says Truckenbrodt. The whole fuel cell idea, he explains, is far too important to be just the focus of one company.