Ask an electrolyser developer where the PFAS are, and the answer is usually "in the membrane and the ionomer". That is where the largest quantities sit in a PEM stack, and it is where most substitution work has concentrated. On 17 June 2026, researchers and industry experts from three EU projects met in Castelvetro di Modena, Italy, and came away with a broader view.
The workshop was hosted by the EU project FASTCH2ANGE and brought together HYScale, the AEM electrolysis project we coordinate, and PROMISERS. The HYScale recap and session recordings are public. Here are the messages we think matter most for anyone specifying or buying electrolysers.
Why PFAS are on the agenda at all
PFAS (per- and polyfluoroalkyl substances) are prized in electrochemistry for their chemical and thermal stability. The same stability makes them persistent in the environment. A proposal to restrict PFAS broadly across the EU is being evaluated by the European Chemicals Agency. Whatever the final scope and transition periods, manufacturers who plan stacks for 10 to 20 years of service cannot ignore the direction of travel.
Message 1: PFAS substitution goes beyond the membrane
The clearest point from the day: replacing PFAS must extend past membranes and ionomers. Fluorinated materials can also be found in gaskets, seals, coatings, tubing and other auxiliary components. A stack marketed as "PFAS-free" because of its membrane may still contain fluorinated materials elsewhere.
For buyers, this changes the question. Don't ask "is the membrane PFAS-free?". Ask for a component-by-component declaration covering the stack and the balance of plant.
Message 2: durability decides whether alternatives survive
A PFAS-free material that degrades twice as fast is not a substitute. Participants agreed that PFAS-free alternatives will only succeed if they hold their performance under demanding conditions for long periods.
That is why durability data sit at the centre of our own AEM work. Our PFAS-free AionFLX™ membranes and ionomers have been tested for thousands of hours, with AionFLX™ Plus past 8,000 hours, and we report degradation rates, not just start-of-life polarisation curves. The details are in our membrane durability article.
Message 3: scale-up is more than electrochemistry
A result in a small cell says little about industrial readiness. The workshop listed material availability, manufacturability, reproducibility, component lifetime and system integration as equally important. In HYScale, that meant moving the membrane from lab films to semi-automated sheets for the 100 kW system. We describe that process separately.
Message 4: we need harmonised testing
Comparing PFAS-free and fluorinated materials across projects is still hard. Test benches, operating conditions and reporting methods differ. The three projects called for more harmonised testing and benchmarking protocols. This matters to buyers too: without them, two datasheets that both say "2 A/cm²" may not be comparable at all.
When you compare suppliers, ask for:
- The protocol. EU harmonised test protocols exist for low-temperature electrolysis.
- The conditions. Temperature, electrolyte concentration and pressure during the test.
- The scale. Cell area, and whether the result was reproduced at stack level.
- The degradation rate over a stated number of hours, with any interruptions reported.
Message 5: build sustainability assessment in from the start
Finally, participants stressed that life cycle assessment (LCA), techno-economic assessment (TEA) and Safe-and-Sustainable-by-Design (SSbD) approaches should be applied early. A PFAS-free replacement that needs a hazardous solvent, or that takes far more energy to make, may not be a real improvement. HYScale is building an LCA model of its 100 kW AEM electrolyser for exactly this reason.
Where CENmat stands
We work on AEM and PEM electrolysis, from materials to stacks and systems, and we are open about what is PFAS-free today:
- AEM: AionFLX™ membranes and ionomers are PFAS-free and are used with our CRM-free OXYGN™ and H2GN™ electrodes.
- Bipolar and PFAS-free proton exchange membranes: these are in development in the REDHy project, where a PFAS-free, CRM-free bipolar membrane has been scaled beyond 400 cm². Read the REDHy article.
- PEM: our focus is ultra-low iridium catalysts, which address the other big materials risk in PEM stacks.
For a side-by-side view of the materials questions across technologies, see alkaline vs PEM vs AEM electrolysis. If you are working through PFAS questions for an electrolyser project, talk to us. We are happy to share what we have learned about materials, testing and documentation.
Funded by the European Union. HYScale has received funding from the Clean Hydrogen Partnership and its members under grant agreement No 101112055. Views and opinions expressed are those of the author(s) only and do not necessarily reflect those of the European Union or the Clean Hydrogen Partnership.