(Invited) Stack Test Facility for PEM Water Electrolysis up to 400 Kilowatt and Lessons Learned at Stack Scale-up
Authors: Janssen Holger , Hehemann Michael , Hoppe Eugen , Zwaygardt Walter , Müller Martin Johannes 
Published: August 2024

A new type of energy system based on renewable energy sources and hydrogen technologies is put into operation at Forschungszentrum Jülich, Germany. The aim of the "Living Lab Energy Campus (LLEC)" project is testing and optimizing the systems interactions. Central components are wind power and PV systems, PEM electrolysis system, conditioning and subsequent gas transport in H2 and O2 pipelines, H2 storage in LOHC reactors and hydrogen use in combined heat and power plants.
The PEM electrolysis system in Fig. 1, left, is an R&D test platform which was jointly configured by Forschungszentrum Jülich (IEK-14) and Greenlight Innovation Corp. and built by Greenlight. It offers a range of different operating modes and system configurations that will be studied embedded into the LLEC:

Equal pressure or differential pressure anode/cathode up to 50 bar(g).

Water circulation on anode and/or cathode side.

Stack cabin with flexible connections for fluid inlets and outlets as well as electrical current. This makes it easy to connect and operate different stacks (also from other manufacturers).

Automated system operation, simulation of load profiles (e.g. wind/PV).

The system is CE-certified and can run continuously under automatic control. Critical system conditions, such as exceeding the H2 concentration limit (currently set at 30 % LEL) in the O2 gas flow, immediately initiate an emergency shutdown program. In the emergency shutdown program, the power supply unit is first switched off and the pressure on the anode and cathode side is reduced to ambient pressure. The reason for the fault leading to the shutdown is stored in the system control unit and can be called up. In addition, all measured values and states of the installed sensors and actuators are recorded by the system control unit and stored with an adjustable time resolution. The measured values can be used to monitor the system behavior and detect problems at an early stage, but also to characterize and balance the overall system, system components and the stack.
For generating large amounts of hydrogen within the LLEC project, IEK-14 initiated the development of a PEM electrolysis stack. The electric design data was taken from the performance data of a laboratory cell (1.75 V at 3 A cm-2, 20 cm² active area) and scaled up. The stack consists of 60 cells with an active cell area of 1056 cm².
The bipolar plate was completely redeveloped. The main features are:

Use of porous layer structures with different degrees of fineness as a flowfield structure.

Welding of all components of the bipolar plate to form a material-locking unit.

Preliminary tests in short stacks with bipolar plates on a smaller scale (100 cm² active cell area) showed promising results. The design and manufacturing process for the bipolar plates have now been patented (EP4128399) and published (Janßen H et al., A facile and economical approach to fabricate a single-piece bipolar plate for PEM electrolyzers, Int. J. of Hydrogen Energy, 2023).
An interesting aspect that will be discussed further in the presentation is the scale-up of both the active cell area and the number of cells. Ultimately, the aim is to understand which parameters (and their fluctuations) are mainly influencing the stack performance during scale-up. A data analysis of component properties and a comparison with operating data should provide initial indications. Fig. 1, right, shows a 60-cell PEM stack with an active cell area of 1056 cm², of which short stacks with 4 cells were also constructed.

Figure 1