Partnerships and investments are driving fuel cell technology advances, and the move from prototype car to everyday use is on the horizon.

CAROLA HANISCH

Although there won't be a fuel cell-powered car in everyone's garage for years to come, the fuel cell revolution is definitely under way in the transportation sector. Ten years ago, no one considered fuel cell cars to be technologically feasible. "Even our top management said things like 'we can run faster than this vehicle will drive,'" recalls Robert Veit, who works on DaimlerChrysler's fuel cell project and is in charge of communications and marketing. But then the company, which was only Daimler at that time, began investing enormous amounts of money in developing the technology.

     The results of DaimlerChrysler's efforts are impressive. Since 1994, the company has produced four prototype vehicles and a prototype bus. Concurrently, other major car companies, including Ford, General Motors (GM), Toyota, and Honda, have been actively engaged in developing this new transportation technology and are themselves racing toward marketplace introduction.

     According to DaimlerChrysler's announcements, within five years, the first fuel cell cars—not just prototypes—will be running on the streets. The company plans to have fuel cell vehicles in limited production by 2004 and will invest more than $1.4 billion on fuel cell technology development by the time the first fuel cell vehicles come to market. This is an incredibly fast pace of development, given that it involves a propulsion system technology completely different from the internal combustion engine of today's cars.

     The rapid stride of technological development is evidenced in the NECAR series of fuel cell-powered prototypes. Daimler-Benz introduced the world's first fuel cell vehicle, NECAR 1, in 1994. NECAR stands for New Electric Car (and also alludes to the river Neckar, which runs through Stuttgart, where Daimler-Benz is located). NECAR 1 was basically a mobile laboratory: a converted Mercedes van, in which the fuel cell system and performance-monitoring equipment took up so much space that there was just enough room left for the driver—the fuel cell power unit alone weighed more than 1760 pounds (800 kg). The second prototype, NECAR 2, introduced in 1996, was a Mercedes V-class vehicle, similar to a conversion van, but with enough room for six passengers.

     Fuel cell transportation technology outgrew the laboratory in early 1997 with the introduction of NEBUS, a city bus powered by fuel cells, which like NECAR 1 and 2, carries its hydrogen fuel on board. NECAR 3, the world's first fuel cell car, followed in mid-1998 (see photo above). It is based on a Mercedes A-class compact car and produces its hydrogen fuel on board from reformation of methanol.

     This March, the equivalent liquid hydrogen-fueled version, NECAR 4, was presented (see photo above). The prototype reaches top speeds of 90 mph (145 kph) and can travel nearly 280 miles (450 km) before refueling. Engineers at Dbb Fuel Cell Engines in Nabern, Germany, have been able to mount the complete fuel cell system in the vehicle floor (see diagram), thereby allowing room for up to five passengers and cargo space. Dbb Fuel Cell Engines is a joint subsidiary set up by Ford Motor Company, Ballard Power Systems of Canada, and DaimlerChrysler. NECAR V, which also runs on hydrogen produced from methanol reformation, is already on the drawing board (see photo below).

The fuel cell assembly is small enough to fit in any size vehicle.

     Other car companies are trying to maintain a similar pace of development. Erhard Schubert, director of GM and Opel's international center for alternative propulsion methods in Mainz, Germany, also announced the planned introduction of a fuel cell car series model by 2004. So far, Opel has only unveiled Zafira, a methanol-fueled compact van. Elsewhere, Toyota has developed a fuel cell demonstration car and hopes to introduce it to market by 2003. According to Veit, Toyota is the biggest competitor.

     Despite all this progress, however, many questions remain. What fuel will be used during the transition time before hydrogen becomes available from renewable energy sources? Will costs come down enough to make fuel cell cars affordable? And is the environmental benefit of using them high enough to justify their cost? Not surprisingly, these questions have generated a wide range of opinions and active debate.

The development impetus
Why should the idea of a fuel cell, of the electrochemical conversion of energy—already about 150 years old—take off now? Alexander Wokaun of the Department of General Energy Research at the Paul Scherrer Institute in Villingen, Switzerland, mentions three triggering events.

     The development became possible as Ballard Power Systems, Inc., of Canada, significantly increased the energy density of so-called proton-exchange membrane (PEM) fuel cells to about 1 kW/kg. In a PEM fuel cell, hydrogen and oxygen react under controlled conditions to generate electricity for powering the vehicle. Second, in December 1997, Daimler-Benz and Ford Motor Co. set up a financially powerful fuel cell vehicle alliance with Ballard. And, at the Kyoto Conference, Framework Convention on Climate Change, also in December 1997, the industrialized countries committed to significantly reducing their CO₂ emissions. As a result, European car producers have promised to reduce the amount of CO₂ emitted from a current level of about 200 g/km to 140 g/km in 2008 and to 120 g/km in 2012. Against these targets, fuel cell cars might be a more effective propulsion system than conventional engines, even when hydrogen is produced from fossil fuels. Finally, expanded interest in fuel cell development is being driven by technological progress, financial support by the car industry, and environmental targets.

     The car companies have strategic reasons for pursuing fuel cell development and applications. In California, beginning in 2003, 10% of newly registered vehicles are required to be zero-emission vehicles. California's urban air quality legislation is known to have repercussions for legislative developments in other U.S. states, as well as on the development of federal standards, so car manufacturers are trying to adapt early.

     Only electric cars are considered zero-emission vehicles. They can be powered by batteries or fuel cells. Car manufacturers first focused on battery-driven cars, but they quickly learned that customers are not willing to accept low driving ranges and long recharging times. "We had bad experiences with battery [powered] cars," explained Veit. "With the fuel cell car, we think we have a solution that is, in terms of performance and usage, equivalent to conventional cars," he said.

     In May, the California Air Resources Board, Ford Motor Co., DaimlerChrysler, Ballard Power Systems, and three oil companies formed the California Fuel Cell Partnership, which will put a fleet of up to 50 fuel cell vehicles on the road between 2000 and 2003. The oil companies involved in the deal—Atlantic Richfield, Shell Oil, and Texaco—will work on the development of methanol and hydrogen fuels and the fueling infrastructure. "You need tests under everyday conditions," said Hans H. Wenck, a press officer at Deutsche Shell AG in Hamburg. "You might, for example, find out that your gas station's tank coating is corroded by methanol. If this happens in 10 years, with thousands of gas stations, you might have to spend hundreds of millions of dollars [to correct the problem]. So you better test it out on a small scale before [this happens]."

     Car manufacturers and some oil companies are also taking a longer view and are thinking about what comes after oil is depleted. The Royal Dutch/Shell Group established the Shell Hydrogen Company this year. "Hydrogen is going to be the most important energy carrier of the 21st century," believes Fritz Vahrenholt, a board member of Deutsche Shell AG in Hamburg. "In the long term, it is going to replace oil and gas. For an energy company like Shell, it is important to take part in the development [effort] early on, in order to establish a leading position in the hydrogen business," he said. This February, an Icelandic consortium, Vistorka hf. (EcoEnergy Ltd.) signed a cooperation agreement with DaimlerChrysler, Norsk Hydro, and the Royal Dutch/Shell Group, setting up a joint venture for replacing fossil fuels in Iceland with hydrogen. They will try to set up the world's first "hydrogen economy." The joint venture ultimately aims to convert both the public and private transportation sectors, including fishing vessels. Iceland has a large potential of renewable energy sources, which so far have only been harnessed to a limited degree—about 67% of its primary energy consumption is currently supplied by hydrothermal and geothermal sources.

An oil substitute
Another major incentive for developing fuel cell technology is the prospect of increasing dependence on OPEC oil. Methanol and hydrogen are nowadays produced from natural gas, a domestic energy source in the United States. But which of the two should dominate until hydrogen from renewable energy sources becomes available? "From the vehicle perspective, hydrogen fuel cell vehicles will be simpler, lower-cost, and more energy-efficient," said Joan Ogden, a research scientist at Princeton University's Center for Energy and Environmental Studies in New Jersey.

     Hydrogen can be used either as a compressed gas or, at a temperature of -253 °C, as a liquid. Used in either form, however, hydrogen's energy density is very low compared to methanol's and even more so compared to gasoline's. It therefore requires a large, heavy tank for on-board storage. Weight, however, increases fuel consumption and CO₂ emissions per kilometer driven, as long as hydrogen is produced from natural gas.

     Another consideration is that although liquefaction improves energy density, it uses a lot of energy. "As a rule of thumb, one-third of the hydrogen fuel's energy content is lost during liquefaction," said Angelika Heinzel, head of the Department for Energy Technology at Fraunhofer Institute for Solar Energy Technology in Freiburg, Germany. Baldur Eliasson, head of the Energy and Global Change section of ABB in Baden, Switzerland, believes, "We will not use hydrogen on a large scale. Storage and transportation are too expensive and too difficult." DaimlerChrysler considers that using hydrogen as a fuel in the short term is only possible for fleet applications like buses, taxis, or parcel (delivery) services, which run only in cities and can be refueled centrally.

     Using methanol solves some of these problems. It can be reformed on board to generate the hydrogen needed by the fuel cell. Compared to hydrogen, this simplest alcohol has the advantages of being a liquid at room temperature and having a higher energy density. Also, it can be used like gasoline, so customers don't have to change their habits. "From our point of view now, methanol is really the best fuel," said Veit.

     But using methanol also has some disadvantages. One major disadvantage is that the whole process of reforming and cleanup of reform gases consumes a lot of energy, reducing propulsion system efficiency. Although tank size can be smaller than in hydrogen-powered fuel cell cars, weight is still a problem because a methanol-powered car carries on board a small chemical-reforming factory. Moreover, in terms of local air pollution, a methanol-powered car is not a zero-emission vehicle, but only a super ultralow-emission vehicle (SULEV).

     "Both methanol and hydrogen involve similar off-vehicle infrastructure costs," Ogden said. "The distribution system is less costly for methanol than for hydrogen. But it is more expensive to produce methanol from natural gas than hydrogen because energy conversion efficiency is lower for methanol and the [required] production plant is more complex and expensive," Ogden explained.

     A much better solution would be to convert methanol directly (electrochemically) in a fuel cell without going through the reforming process. "But so far the methanol fuel cell doesn't achieve satisfying performance density in terms of watts per kilogram," said Heinzel. For fuel cells, use of methanol presents a special problem because its oxidation in the cell poisons the catalytic electrode surface.

     Another option being investigated is on-board reforming of gasoline. Shell is engaged in a cooperative research effort with Dbb Fuel Cell Engines to develop a CPO (catalytic partial oxidation) reactor that can produce hydrogen from gasoline. "We consider both methanol and gasoline as transition fuels on the way toward hydrogen from renewable energy sources," said Wenck. Gasoline has the advantage of an existing infrastructure, but the gasoline reforming process is very difficult, and significant technological problems remain to be solved.

Cost containment
The major challenge for fuel cell car development is cost. "Cost reduction of all components by more than a factor of 10 is the main challenge," said Wokaun. In the United States, three big car manufacturers (DaimlerChrysler, Ford, and GM) and the federal government initiated the Partnership for a New Generation of Vehicles (PNGV). The initiative aims to develop a fuel-efficient concept car having a fuel economy of 80 miles per gallon (2.9 L per 100 km) by 2004 and is investigating fuel cell cars as one promising option. Their target cost is $50 per kilowatt for the entire propulsion system.

     The standing committee to review the PNGV's research program sees "significant cost reductions to be within reach" (1). It cites a study by Ford/Directed Technologies, Inc. (DTI) that projects costs of $77 per kilowatt based on "known but not implemented" processes. The PNGV review committee calls these projections very encouraging compared with its own estimate of $500 per kilowatt from 1998 (2). The methods and assumptions used by Ford/DTI are not disclosed in detail.

     What environmental benefit will be realized at this cost target if it is met? The Berlin-based German Federal Environmental Agency, Umweltbundesamt (UBA), analyzed costs and benefits in a study released in May (3). UBA is a scientific agency that advises the government in formulating legislation. Reinhard Kolke, the study's author, compared fuel cell cars with high-efficiency, low-emitting gasoline combustion engine cars—ultralow-emission vehicles (ULEVs) or EURO 4-Standard vehicles, which are practically equivalent. He concluded that fuel cell cars are not a cost-effective means to achieve emission reductions.

     It is UBA's opinion that, in terms of urban air quality, future European legislation for fuel quality and exhaust emission limits is strict enough to reach the World Health Organization's (WHO's) air quality goals in Germany for benzene, particulates, and NO_x emissions within 10 years. UBA doesn't consider further reductions—which could be achieved with electric cars such as fuel cell cars—to be necessary to reach WHO and European Community targets.

     The main challenge for road transport pollution abatement will be CO₂ reduction. Here, regarding CO₂ emissions and primary energy consumption, fuel cell cars are not (or only moderately) better than ULEV cars if natural gas is used as the primary energy source. Moreover, fuel cell cars are much more expensive—Kolke calculates costs of $20-$260 to avoid 1 metric ton of CO₂ emissions. Using an efficient ULEV car, the same CO₂ reduction could be achieved at negative costs: a financial benefit of $60. This is because low fuel consumption makes long-term usage of a highly efficient ULEV car cheap compared with a conventional car (comparisons were made with a 73-mpg gasoline prototype vehicle).

     Car and oil industry stakeholders pursuing fuel cell development argue against the UBA study, stating that efforts to develop all new technologies can be discouraged using cost arguments. But Kolke insists that for the foreseeable future, fuel cell cars are unfavorable (against other options) from an environmental point of view. Instead, he believes that the development of high-efficiency gasoline-fueled ULEV cars on the one hand, and fuel cells in stationary applications on the other hand, should be promoted. Kolke regards fuel cells in stationary applications as a very promising option for achieving sustainable CO₂ emission and energy reduction targets.

     As far as Kolke's price estimates are concerned, there is broad range for discussion: Future cost reductions are very difficult to estimate. Right now, however, it is clear that taken as a whole, fuel cell cars powered with hydrogen produced from fossil fuels do not yield significant CO₂ reductions—although the fuel cell propulsion system itself is much more energy-efficient than the combustion engine, a lot of energy is lost in first producing the methanol or hydrogen fuel. Alois Amstutz, a senior scientist at the Swiss Federal Institute of Technology in Zürich, forecasted similar CO₂ emissions outcomes (4) based on use of computer models to analyze energy conversion cycles of advanced internal combustion engine and fuel cell cars.

     Even Veit admits, "If you compare the whole energy chain nowadays, methanol-reforming technology is a little bit worse than a modern diesel engine and a little bit better than a gasoline one." But, he argues, fuel cell technology is very young compared with the 100-year-old combustion engine, so there is huge potential for improvement of fuel cells.

     Kolke, however, isn't the only environmental expert who is not entirely satisfied with fuel cell car technology. "In seeking to reach CO₂ mitigation targets for 2005 or 2010, hydrogen-based fuel cell technology won't be able to contribute in a noticeable manner. But efficient combustion engine cars can!" asserted Harald Diaz-Bone, from the Wuppertal Institute in Germany. Diaz-Bone is coauthor of a recently published book (5) on 3-L cars—cars that have highly efficient, three-liter engines. "By showing its 'green leaf' fuel cell, the automobile industry distracts from its inaction in improving energy efficiency in the overall car fleet," criticized Diaz-Bone. Kolke agrees, "Car manufacturers seem to think that a fuel cell car is more thrilling than an ordinary 3-L car."

     Currently, hydrogen-based fuel cell cars are unable to contribute significantly to climate protection. But in terms of urban air quality, they are unbeatable; everybody agrees on that. What future role are they going to play? Customers will decide that—and when.

References

(1) Review of the Research Program of the Partnership for a New Generation of Vehicles, Fifth Report; Board on Energy and Environmental Systems and Transportation Research Board, National Research Council, National Academy Press: Washington, DC, 1999.

(2)  Review of the Research Program of the Partnership for a New Generation of Vehicles, Fourth Report; Board on Energy and Environmental Systems and Transportation Research Board, National Research Council, National Academy Press: Washington, DC, 1998.

(3)  Technische Optionen zur Verminderung der Verkehrsbelastungen. Brennstoffzellenfahrzeuge im Vergleich zu Fahrzeugen mit Verbrennungsmotoren; Nr. 3399; Texte des Umweltbundesamt: Berlin, 1999.

(4)  Amstutz, A.; Guzella, G. Fuel Cells for Transportation—An Assessment of its Potential Role for CO₂ Reduction. In Greenhouse Gas Control Technologies, Proceedings of the 4th International Conference on Greenhouse Gas Control Technologies, Interlaken, Switzerland, Aug 30-Sept 2, 1998; Pergamon Press: Elmsford, NY, 1999; pp. 905-910.

(5)  Petersen, R.; Diaz-Bone, H. Das Drei-Liter-Auto; Birkhaeuser Verlag: Basel, Switzerland, 1998.

Carola Hanisch is a freelance writer based in Freiburg, Germany. Germany.