Hydrogen produced with the help of regenerative energies is an important energy source for mobility in the future. For this reason, the demand for fuel cell stacks that convert hydrogen into electrical energy will increase rapidly in the coming years. Researchers at Fraunhofer IPA and the Black Forest campus, together with several partners from industry, are now developing an innovative quality check that saves time and money in production.
“Automation in the production of fuel cells is still in its infancy. So far, the production has more of a manufactory character. If the energy transition is to succeed and green hydrogen is to be used as an energy source, especially in heavy-duty traffic, then we need efficient production lines and fast and cost-effective quality checks for fuel cell stacks as soon as possible,” explains Dr. Friedrich-Wilhelm Speckmann, group manager for hydrogen technology at Fraunhofer IPA.
Quality control problem
Quality control has so far been a difficult bottleneck in production. Fuel cells can be stacked on top of each other quickly and precisely by robots, but then each of these stacks, called a stack, has to be connected to various measuring devices and checked. In the FastPeM project - the abbreviation stands for "Accelerated test method for mass production of fuel cell stacks" - Speckmann, together with researchers from the Black Forest campus and industrial partners, now wants to develop a test bench demonstrator with which the electrochemical properties of a stack can be tested using innovative technologies can be determined quickly and efficiently.
"The Black Forest campus is the ideal location for this project, because a fully automatic stacking system is currently being set up here," says Speckmann.
"The research center for intelligent hydrogen recycling economy in the northern Black Forest will provide regional and national companies and municipalities with advantages and expertise in the field of mass-market fuel cell production," says Stefan Bogenrieder, Managing Director of the Black Forest campus.
Faster end-of-line testing
A robotic arm stacks the layers on top of each other in the pilot plant: Each fuel cell consists of two thin electrodes with a membrane in between and a bipolar plate through which hydrogen and atmospheric oxygen are later fed. Within 15 minutes, a package of around 400 cells is created that can be pressed together and braced.
"Since every production step is digitally documented in this demonstrator, we have an extensive wealth of data at our disposal that we can use for quality assurance," says Speckmann.
So far, testing a finished stack has been comparatively time-consuming: First, it has to be tested whether the stack is tight or whether gas that flows into the cells under pressure is escaping. The next task is to determine the power curve, which shows which current density occurs at which voltages.
"In the FastPeM project, we now want to research how these processes can be optimized, for example by combining both steps," explains the engineer.
Time savings through digital twins
Virtual technologies are to play a key role here: the production plant and testing facility are equipped with measurement technology that feeds sensor data into a simulation model in real time. The digital twin that is created in this way not only maps the processes, but also every component in detail. Based on this extensive data set, the electrochemical properties of individual cells and complete stacks can be predicted. »The virtually calculated performance characteristics then only have to be checked by selective measurements. Long series of measurements can be avoided in this way; it is probably sufficient to carry out individual measurements. If these match the predictions, no further tests are required,” explains Speckmann. The time required can be significantly reduced if the implementation is successful.
This time saving would be a real benefit for companies that manufacture fuel cells. Of course, it will still take some time before the results are available: The FastPeM project, which started on June 1, will run until 2027, when the test bench for the mass production of fuel cell stacks should also be ready.