The CLEANER project, funded by the Clean Hydrogen Partnership, supports the European Green Deal's 2050 climate-neutrality goals by developing cost-effective stationary proton exchange membrane fuel cell (PEMFC) systems that can operate on lower-cost, industrial-grade hydrogen. Unlike high-purity hydrogen, industrial hydrogen may contain impurities such as carbon monoxide (CO) and sulfur, making effective contamination management essential.
Current standards limit CO levels in hydrogen to less than 0.2 ppm because CO rapidly poisons platinum-based anode catalysts. To enable the use of industrial-quality hydrogen, VTT has developed a novel in situ galvanostatic cleaning strategy that removes CO from PEMFC stacks during normal system shutdown.
The method uses a constant current pulse together with an individually controlled bleed resistor connected across each cell. This limits cell voltage to a safe threshold (e.g. 0.85 V), preventing catalyst degradation while fully oxidizing and removing CO. The approach was successfully demonstrated on a four-cell PEMFC stack, and the first results were presented at the 42nd Topical Meeting of the International Society of Electrochemistry in Espoo, Finland, on 24 June 2026.
Cleaning process
- Wait until the PEMFC enters its normal hydrogen-soak shutdown.
- Connect a constant-current source and individual bleed resistors across each cell.
- Set the resistor voltage limit (e.g. 0.85 V).
- Apply a constant current until all cells reach the voltage threshold.
- Disconnect the current source.
The result is a fully regenerated PEMFC stack with minimal impact on catalyst lifetime.
The strategy could enable PEM fuel cells to tolerate significantly higher CO concentrations than currently allowed, reducing hydrogen purification requirements and lowering system costs. VTT has filed a patent application for the technology.
The CLEANER project is now optimising the method using newly developed catalysts and extending it to remove sulfur contaminants, another major challenge for PEM fuel cells and electrochemical hydrogen compressors.
The CLEANER project is supported by the Clean Hydrogen Partnership under Grant Agreement No. 101137799 and is co-funded by the Research Council of Norway and UK Research and Innovation (UKRI).