How we developed the fuel cells drive system at Daimler.

This article was originally published in the Daimler blog.

It was a sensational premiere: On April 13, 1994 the former Daimler-Benz AG unveiled the NECAR, the first vehicle with a fuel cell drive system that was designed for everyday use. This was the initial spark that ignited a whole series of pioneering developments during the following 25 years.

5 min reading time

by Gerald Hornburg, Mechanical engineer in process engineering
published on April 11, 2019

The current high point of this trend is the Mercedes-Benz GLC F-CELL (combined hydrogen consumption: 0.34 kg/100 km; CO₂ emissions, combined: 0 g/km; combined power consumption: 13.7 kWh/100 km1).

This moment of the world premiere filled me with pride: At last, the vehicle we had developed was standing in the spotlight. In 1994, the NECAR was an absolute sensation. It had a PEM fuel cell as its power supply, and it could be driven for many kilometers under everyday conditions without any problems whatsoever. The designation NECAR stands for “New Electric Car.” Later on it was renamed the NECAR 1, because it was followed by the NECAR 2 as early as 1996 and by other fuel cell vehicles after that. When I say “we” I’m referring to our small and creative team of pioneers, and I’m writing this report mainly from our team’s perspective.

But now let’s go back a bit further to the year 1988 and the predecessor company of Daimler AG: Daimler-Benz. At that time, it was an integrated technology group — it not only manufactured automobiles but also operated in the aerospace sector and the digital and computer electronics industry. I regard that period as a very important phase. The company had an extremely wide range of know-how covering outstanding technological products in many different areas. I was working at Dornier, where we were developing fuel cell systems for manned space flight.

These were still alkaline fuel cells that were exclusively suitable for operation with hydrogen and oxygen. But then a new fuel cell technology appeared — proton exchange membrane (PEM) fuel cells. Fuel cells using this technology could conceivably be used to power electric vehicles — and that’s exactly what we suggested. As happens so often, the idea was turned down at first. Too utopian, they said. We were just ahead of our time with the idea.

“Build a demonstrator”

Things changed in 1991. A new member of the Daimler-Benz board had just taken over the leadership of the research department. He was skeptical as to whether the concept would work, but he was prepared to listen. And then, in November 1991, he said: “Prove that it works. Build a demonstrator.”

High efficiency, zero emissions, a normal filling process, and, in the form of hydrogen, an ideal energy carrier for a long range — those were the factors that convinced him to give the go-ahead for development. These factors are still the irresistible advantages of the fuel cell drive system.

So we got going. With just two years and a four-man team, we had to design and build a fuel cell drive unit that worked reliably as an energy source in a vehicle. The experimental platform for this new type of electric vehicle was constructed in parallel by our colleagues in Untertürkheim. It quickly became clear that the vehicle would be based on an MB 100 van. This was because we knew that we would need sufficient space for the fuel cell system and the hydrogen tank.

Working like in a startup

Apart from that, we didn’t have much on hand. There were no finished components available to buy that would be perfect for a fuel cell vehicle. We had to adapt what was available or order things with exact specifications from suppliers. There were no finished designs lying in a drawer somewhere. Every detail had to be thought out completely from scratch. We bought the cell stacks for converting the hydrogen into electric current from Ballard Power Systems in Vancouver. We didn’t have a CAD (Computer Aided Design) system available for the engineering design either.

We did what we could with a standard office graphics program and made a lot of manual sketches and a wooden model. The days were busy, and the hours long, but it was an exciting time. Now you can imagine roughly how we worked back then. Today you’d call it a startup atmosphere.

And like today’s startups, things started to move fast. Thanks to intensive work, we got the job done and succeeded in building a fuel cell system that supplied the power for an electric vehicle. In mid-November 1993, exactly two years after the start of the project, we brought the system to Untertürkheim in a truck. It weighed 850 kilograms, was two cubic meters in size, and delivered a net output of around 35 kW from a stack rated at 50 kW.

November 1993: NECAR’s maiden drive

A fork lift was used to put the system in the MB 100. It was secured in the load compartment with eight bolts, the high-voltage plug was connected, and the coolant checked. What then happened thrills me to this day: All of the systems worked on the spot — everything was “green.” It was a great job, also on the part of our vehicle colleagues in Untertürkheim. To be on the safe side, we then spent a long day testing everything thoroughly, before the big moment. The ignition key was turned and the gas pedal pressed — NECAR drove for the first time in Untertürkheim, and then it was off immediately to the test ground. That was an emotional moment for us; even some seasoned engineers were doing little dances of joy on the plant grounds.

The fuel cell stack had a rated output of 50 kW and functioned perfectly as a power plant for the 30 kW electric motor built into the MB 100 — without a drive battery. The top speed was 90 km/h and the van had a range of 130 kilometers. Not much by today’s standards. But in 1993 that was a massive breakthrough.

We had finally reached the finish line. And not only that — because with the NECAR we had driven into completely new territory, and we could also see that things were going to be really exciting from then on. You could say without blushing that with our pilot project we had ushered in the age of the fuel cell vehicle.

It was the starting gun for the age of the fuel cell drive

We needed a few months to prepare the NECAR for its premiere in April 1994. For example, the air supply for the fuel cell was still too loud, and we improved the sound insulation. But then we were sure that the vehicle was ready for the public. The presentation to the international press took place in the Ulm Research Center. It was a huge success. The journalists were enthralled, and their reports also got other automakers worldwide thinking about fuel cells. We had carried out real pioneering work.

The NECAR was the initial spark for all of the subsequent fuel cell vehicles from Daimler, for which we continued to develop the technology. There was still a long way to go before series production. But today we’re there, and that’s why I’m also delighted about the GLC F-CELL: It contains a lot of our pioneering know-how. It’s a wonderful fuel cell vehicle, and it even has plug-in hybrid technology.

One last anecdote to close: NECAR needed road approval for further testing, and back then in Germany, that meant a special emissions inspection — known in Germany as an ASU. Of course the vehicle had zero emissions, but it still had to undergo inspection. It was completely crazy, but it was funny to watch the test engineers discover that the air coming out of the back was cleaner than the air that was being drawn in for the fuel cell to use.

[1] The figures for fuel consumption, power consumption, and CO₂ emissions are provisional. They were determined by Technical Services for the certification process according to the provisions of the WLTP test procedure and correlated with the NEDC values. An EU type-approval certificate and a certificate of conformity with official values are not yet available. The figures given above may deviate from the official values.

Gerald Hornburg

Gerald Hornburg is a mechanical engineer specializing in process technology. The fuel cell was and still is a major influence on his career: He was one of the four engineers who built the fuel cell drive system for NECAR, which was presented in 1994. Today he’s the Chief Engineer in Advanced Engineering at Mercedes-Benz Fuel Cell GmbH.

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