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Daimler Creates a Practical Fuel Cell Minivan
Developing a viable automobile powered by a hydrogen fuel cell has progressed from a distant dream to a vision that's being achieved in real time. This process has unfolded in small but dedicated steps over many decades. Much progress has been made since the early 1990s when all major automakers began publicizing their fuel cell efforts. Among the early leaders were Daimler-Benz and Canadian fuel cell developer Ballard Power Systems. The most tangible evidence of this progress emerged in the form of the NECAR (New Electric Car) series of developmental vehicles, with the NECAR II example underscoring just how far the technology had progressed. Green Car editors had the opportunity to experience the NECAR II on public roads in Berlin and were very favorably impressed. The article that follows is reprinted just as it ran in Green Car Journal's January 1996 issue to offer a glimpse at how the progress was reported.
NECAR II HYDROGEN VEHICLE ON THE ROAD
For several years, an experimental proton exchange membrane fuel cell (PEMFC) powered Mercedes Benz 180 BZ utility van has undergone testing in Germany to prove the viability of this propulsion concept. The apparatus filled the rear of the van, underscoring the limitations of hydrogen fuel cell state-of-the-art. But that has changed. Now researchers at Daimler-Benz AG, in conjunction with partner Ballard Power Systems, have pointedly illustrated just how far technology can progress in just a very short time.
"In the space of just two years we have been able to improve the power-to-weight ratio of the fuel cell stacks by a factor of five and of the electricity generation system as a whole by a factor of three," says Prof. Dr.-Ing. Hartmut Weule, member of the board of management of Daimler-Benz AG and leader of the company's Technology Division.
This breakthrough was recently demonstrated in Mercedes-Benz' NECAR II (New Electric Car) minivan in Berlin, a research vehicle based on the new V-class model that goes on sale in Europe this fall. Green Car editors had the opportunity to experience this next-generation fuel cell vehicle's ability to negotiate urban mid-day traffic, and were quite impressed.
Perhaps the most important distinction Green Car editors noted is that this minivan seems quite normal with no particular peculiarities. It handles itself well in traffic with more than adequate acceleration. While the usual sound of an internal combustion engine was absent during the drive, the vehicle wasn't truly quiet - the fuel cell's compressor could be heard operating and slight tire and gear noise were evident.
Because this latest-generation fuel cell's design is so compact, all powertrain componentry can be situated so it doesn't interfere with the vehicle's conventional six-place seating. The fuel cell itself is positioned behind the third row of seats in the cargo area. While its height does take up about half of the normal cargo volume, there's still room to store a nominal amount of gear. The balance of the powertrain componentry, including the motor controller, is located beneath the hood.
Propulsion is provided by a 33 kW three-phase asynchronous electric motor coupled to a two-speed, electrically switched transmission. The 50 kW fuel cell uses two compact high-performance stacks and offers an output of 180-280 volts. The research vehicle is capable of moderate speeds somewhat in excess of 60 mph and offers an operating range of 150 miles on two full fuel cylinders. In the NECAR II, hydrogen fuel is stored in carbon fiber-reinforced plastic cylinders beneath an aerodynamic plastic rooftop shell. But that likely will change.
"In the view of Daimler-Benz," says Dr. Weule, "the next crucial step will be to move on from hydrogen tanks to generating hydrogen directly onboard." This will overcome the penalty of carrying hydrogen in heavy and bulky cylinders and also address the safety concerns of storing gaseous hydrogen.
The likely fuel of choice is methanol since it's stored as a liquid and can be readily broken down into hydrogen and carbon dioxide. The amount of carbon dioxide produced during this process is said to be considerably less than that of an internal combustion engine (ICE). As is the norm with fuel cells, the only other emissions are water vapor and waste heat.
Methanol has only about half the energy content of gasoline, which causes methanol-fueled ICE vehicles to only travel about half as far on the same volume of fuel. However, because a fuel cell is far more efficient than an ICE (nearly 40 percent versus 17-20 percent), a fuel cell vehicle is capable of traveling the same distance as a gasoline vehicle on the same amount of fuel.
While Daimler-Benz has cleverly sidestepped the dilemma of a nonexistent hydrogen infrastructure with its plan to fuel future fuel cell variants with methanol, this doesn't provide a total solution. Green Car editors note that an extremely limited methanol refueling infrastructure also exists.
Even California's extensive methanol demonstration program, which in recent years has strived to develop a network of methanol refueling sites throughout the state, has resulted in far fewer than 100 methanol pumps available for pumping this alternative fuel. This is a limitation that Green Car editors dealt with when performing extensive road testing of M85 methanol flexible-fuel vehicles in the past.
That's not to say that a methanol infrastructure couldn't be built. As Metallgesellschaft had pointed out several years ago, independent service stations could benefit by replacing their mid-grade gasoline pumps - which are typically used by only 15 percent of their customers in a typical three-pump regular/mid-grade/premium island - with M85 methanol pumps. It's a straightforward process to add this M85 fueling option, requiring an upgraded underground storage tank and the addition of corrosive-resistant piping between tank and pump, roughly a $50,000 investment.
What's in store next? Probably a fuel cell Mercedes-Benz A-class variant and, no doubt, a few more surprises. It seems that Mercedes-Benz intends to stay ahead of the fuel cell curve.
"To our way of thinking, the fuel cell is the most promising alternative drive technology," says Helmut Werner, president and CEO of Mercedes-Benz. "It can offer a way out of the problems of storing energy in heavy batteries of limited capacity. The combination of fuel cell and electric drive offers excellent efficiency and, if methanol is used, an operating range which matches that of conventional vehicles."
While fuel cell development does seem to be moving forward at an impressive pace, there remains the issue of funding the research and development needed to take fuel cells from the test track to the production line. What would this funding level be? It's difficult to pin down. But when pressed for a funding figure, Ballard's stack development manager E. G. Pow admitted "we're talking in the ballpark of C$100 million" to get it in a production car.
Green Car editors note that while this is indeed a significant amount, it's a relatively small financial commitment in automotive development terms, similar to that being made by Chrysler in its niche-market (projected 5,000 annual sales) Plymouth Prowler roadster. For perspective, Ford spent over $2 billion in the development and production of its all-new Taurus sedan and wagon models.
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