PEM technology employs several water circuits, and fresh water is continuously introduced to compensate for water loss during hydrogen production.
Demineralized water is used as process water, as the membrane would suffer severe damage in a very short time due to minerals and other impurities. For instance, in 100 MW PEM systems, approximately 6,000 to 7,000 cubic meters of process water are circulated per hour and require adequate treatment.
Operating temperatures range between 50°C and 70°C during the process. This can release metallic and organic impurities from system components. For stable hydrogen production and an economical service life of the PEM stack, it is essential to constantly minimize these impurities. LANXESS has designed a special process water treatment using Lewatit UltraPure resins in combination with UV light.
To stabilize the water cycle quality, a partial flow of around 3–6% of the total water volume is continuously purified in a polisher unit. LANXESS recommends an upstream UV lamp to oxidize organic matter (TOC), followed by a combination of anion and cation exchange resins and a final polisher filter.
LANXESS’s Liquid Purification Technologies (LPT) business unit is in talks with renowned gas producers to establish standards for efficient water treatment in PEM electrolysis plants. Hans-Juergen Wedemeyer, Technical Marketing Manager at LPT, explained: “Our technical expertise, combined with our high-performance ion exchange resins, support the water purification process for systems. Preliminary application test results enable the plant conditions to be simulated and the state-of-the-art Lewatit UltraPure ion exchange resins to be optimally used. LANXESS is thus supporting a sustainable, climate-friendly energy supply.”
