* Present: More than 100 fuel cell vehicles in everyday use in demonstration programs worldwide 

    * Future: Series-produced vehicles with fuel cell powertrain will become competitive

Stuttgart/Hamburg--A total of 60 A Class vehicles with fuel cell powertrains are currently in use worldwide. These F Cell test vehicles are being driven by various customers at six locations in Europe, Asia and the United States. In the largest fuel cell fleet test to date, all relevant measured values are sent on a daily basis via radio and the Internet to the DaimlerChrysler researchers and developers in Nabern and Ulm, where the evaluation of the data provides valuable insights for the next generations of fuel cell vehicles.

The experts are busy working on concepts for these pioneering vehicles so that DaimlerChrysler will be able to launch additional fuel cell automobiles on the basis of the B Class in the coming years. It is estimated that the marketing of fuel cell drive systems will commence sometime between 2012 and 2015. About 100 operational vehicles were built with the alternative drive concept in the decade following the presentation of the first fuel cell automobile Necar1 in 1994. Besides the 60 A Classes F Cell used by customers, these vehicles include various concept cars and research vehicles, as well as three Sprinter vans and 36 Citaro urban buses that have been successfully used in regular service by public transit authorities - in some cases since 2003.

Complexity demands a gradual approach

“Fuel cell technology is very complex,” says Dr. Christian Mohrdieck, who is Director of Fuel Cell Dive System Development. “It is an entirely new drive concept, which is not based on thermodynamics as is the case with internal combustion engines, but on electrochemistry.” Twelve years ago, the researchers and developers at DaimlerChrysler entered uncharted territory with the Necar 1. There were plenty of surprises and it was a learning experience for even the most accomplished engineers. The approximately 100 fuel cell vehicles that DaimlerChrysler has built to date demonstrate that the engineers have gained sufficient expertise with the alternative drive system to know where to make future adjustments in order to gradually prepare the technology for the market. As soon as the current field tests with the A Class F Cells are completed, DaimlerChrysler will commence testing the second generation fuel cell powertrain systems in B Class vehicles. The fleet tests will focus on mastering further technical and economic challenges and realizing various improvements. Besides making further enhancements, DaimlerChrysler will be striving in particular to substantially reduce costs in its third generation of fuel cell vehicles.

Simplifying components and cutting costs

On the way to achieving this goal, DaimlerChrysler has set clear objectives for its engineers: First, the entire fuel cell system will have to be made simpler and more robust by reducing the number of components. Fewer components also mean fewer opportunities for faults, which in turn results in lower costs. Another goal is to make existing components smaller in order to save space and reduce weight. Finally, the engineers will also be working to further increase the lifetime and power density of the fuel cell stacks by the time the system is ready for series production. To achieve this goal, the company has developed various programs and technical concepts, with one of the main challenges being a substantial reduction in costs. This is not only a difficult task for automakers, but also for suppliers of important components, who for the most part are also entering uncharted terrain when it comes to mobile fuel cell applications.

Generation 1: Top marks for the F Cell and Citaro

For the current F Cell project, DaimlerChrysler has signed usage contracts with various companies and agencies. The contracts regulate the use of 60 A Classes F Cell over a one to two year period, during which the customers’ employees test the vehicles under demanding everyday conditions in California, Michigan, Berlin, Tokyo and Singapore. Altogether, these vehicles had been driven a total of approximately 800,000 kilometers by the end of June 2006, and had been in operation for more than 24,000 hours. The F Cell vehicles are equipped with a recording device that registers all relevant parameters, from driving speed and the voltage shape in the fuel cells to the pressure in the hydrogen tanks. So far, the engineers have been satisfied with the global field test results: The evaluation of tremendous volumes of collected data clearly shows that the fuel cell system is far less prone to faults than was originally anticipated at the start of the project.

Similar results have been delivered since May 2003 by the 36 fuel cell buses, which DaimlerChrysler has delivered to ten major European cities as well as to Beijing, China and Perth, Australia. The buses had been driven a total of about 1.4 million kilometers by the end of June 2006. During this time, some of the fuel cell stacks had been in operation for more than 3,000 hours — another result that far surpassed all expectations. The two projects funded by the European Union (EU) — Clean Urban Transport for Europe (CUTE) and Ecological City Transport System (ECTOS) — showed that the fuel cell drive systems in the Citaro worked reliably even under the rigorous conditions of everyday use. As a result of this success, the EU decided to hold a follow-up project called HyFLEET:CUTE, which was launched in January 2006. Although the test results for lifetime and operational reliability were extremely encouraging, the fuel cell bus still poses several technical hurdles that will have to be overcome. These include the need to achieve a higher rate of efficiency, improvements in noise, vibration and harshness (NVH) values, and, in particular, significant cost reductions.

Generation 2: B Class with freeze-start capability and high range

For its next generation of F Cell vehicles, DaimlerChrysler will equip B Class automobiles with fuel cell powertrains. Compared to the current A Class F Cell, the B Class vehicles feature a number of improvements that are essential in order to bring the technology further toward the series-production stage and which have been installed as prototypes in the F 600 HYGENIUS research vehicle (see press information: Input from the F600 HYGENIUS research vehicle).

The car’s primary improvements are its cold-start capability, which guarantees problem-free operation even at freezing temperatures, and the increased range of more than 400 kilometers, which was made possible through the use of 700-bar pressurized tanks. In another improvement, the all-new fuel cell stack generates 40 percent more output and has a higher power/weight ratio.

During fleet tests of the B Classes F Cell, the engineers plan to evaluate these components and use the results to improve the stacks’ lifetime, for example. In addition, they want to simplify the overall system to make it even more reliable and robust.

In addition to being installed in the B Class, the new, freezable fuel cell stack also will be used in a twin prototype arrangement to propel the prototype of a next generation fuel cell bus. As is the case with a building block system, the bus program will involve various development steps, making it possible to represent several output levels.

Future generations: Drastically lower costs will be a prerequisite for larger fleets

Not until costs have been substantially reduced will it become economical to produce more vehicles than are required for the technical development process. Appropriate production technologies will also have to be employed during this phase. In order to pave the way for further developments, the specialists in Nabern and Ulm are now cooperating closely with colleagues at the Production and Material Technology department of the Sindelfingen plant. This is because all new technical concepts need to be compatible to production processes from the very start. Improvements need to be made in particular to the fuel cell stack, so that painstaking manufacture by hand, which will also characterize the next generation, can progress to the series production stage.

“Over the long-term it will be possible to create fuel cell powertrains at an acceptable cost,” says Mohrdieck about DaimlerChrysler’s assessment of the technology. “However, attaining this goal will require us to take certain steps and pursue a long-term plan that we have defined in a roadmap for future implementation.” The successful marketing of fuel cell drives will require that the unit costs of each new technology generation never increase or at least remain unchanged.

On the way to sustainable mobility

Necar 1, DaimlerChrysler’s first fuel cell vehicle, was a test unit in which the drive system weighed 800 kilograms and filled the Mercedes-Benz van’s entire cargo area. Ten years later, the first F Cell’s powertrain system has been so well integrated into a series production A Class that the car’s entire interior and luggage compartment are available for use. By the time this new technology is ready for market launch between 2012 and 2015, only 18 years will have elapsed since Necar 1’s introduction.

DaimlerChrysler Research recognized early on that the technology would be introduced in the near future, which is why it began working on fuel cell vehicles back in 1991. The Necar 1 of 1994 was followed by a long series of other concept and research vehicles: Necar 2 (1996), Necar 3 (1997), Nebus bus (1997), Necar 4 (1999), Jeep Commander (1999), Necar 5 (2000), Jeep Commander 2 (2000), Sprinter van (2001), Town & Country Natrium van (2001), and Citaro city bus (2002).

The researchers and developers used these vehicles to evaluate various energy sources for the fuel cells. In addition to liquid and gaseous hydrogen, these fuels included gasoline, methanol and sodium borohydride, which release hydrogen as a result of chemical processes. DaimlerChrysler will be working with the same determination to develop the successors to today’s fuel cell vehicles and make a crucial contribution to achieving sustainable mobility.