Instrumentation agency Vaisala explains how its refractometers have supported the event of electrolysers for the technology of hydrogen, highlighting their position in enabling correct, real-time monitoring of electrolyte focus in demanding alkaline electrolysis environments
The technology of inexperienced hydrogen by water electrolysis represents an thrilling decarbonisation alternative. Nevertheless, the efficiency of electrolyzers is closely impacted by the traits and stability of the electrolyzer’s parts. A gaggle of engineers in Germany is due to this fact growing a take a look at bench for alkaline electrolysis.
A key issue affecting the success of this mission is the flexibility to precisely and reliably monitor electrolytes in an especially aggressive answer. Following a worldwide seek for appropriate applied sciences, the researchers discovered that Vaisala’s inline refractometers have been capable of meet their stringent necessities.
The mission companions are the engineering providers supplier iChemAnalytics GmbH, the electroplating expertise specialist Dr.-Ing. Max Schlötter GmbH & Co. KG, and the coating professional WHW Hillebrand.
Background
Hydrogen represents an thrilling alternative because the world seeks to decarbonise its power infrastructure within the pursuit of a Web Zero purpose. It’s because hydrogen has a excessive calorific worth and its combustion merchandise don’t comprise any greenhouse gases which can be thought-about main contributors to international warming. Nevertheless, hydrogen is at present largely produced from fossil-fuel intensive processes, producing ‘gray hydrogen’ which globally accounts for round 2% of carbon emissions.
The place hydrogen is generated from the electrolysis of water, powered by renewable power, the ensuing ‘inexperienced hydrogen’ provides a major alternative for decarbonisation, so there’s a excessive stage of curiosity in environment friendly, sustainable electrolyzers.
Alkaline hydrogen electrolyzers use an electrical present to separate water into hydrogen and oxygen utilizing a liquid alkaline answer equivalent to potassium hydroxide (KOH) because the electrolyte. Usually, the answer is 15 to 30% KOH, which may be very aggressive. The electrolyte is contained between two electrodes, sometimes nickel-based, separated by a porous diaphragm or membrane. Hydrogen gasoline is produced on the cathode, and oxygen gasoline is produced on the anode. The diaphragm separates the gases and transports hydroxide ions from the cathode to the anode to finish the circuit.
Venture goals
Work started in 2023 with a completion goal in mid-2026. The principle goals have been:
- Create a working, absolutely automated take a look at bench for electrolyzer stacks
- Develop a brand new electrode coating which is secure for over 80,000 hours
- Consider prototype coatings over a spread of various working circumstances
Why measure electrolyte energy?
Both sides of the membrane within the take a look at bench electrolyzer incorporates a 30% KOH answer – a extremely concentrated, robust, and corrosive alkaline liquid that’s 30% potassium hydroxide and 70% water by weight. Throughout electrolysis the ratio of KOH % on both facet of the membrane modifications. That is essential for a number of causes. The service lifetime of the parts and the part boundary reactions throughout the cells change negatively, which additionally has a direct affect on cell voltage, getting old results and response effectivity.
Electrolyte measurement expertise
The mission workforce performed a worldwide seek for a expertise that will be capable to function in such a difficult surroundings, delivering correct and dependable KOH measurements. The flexibility to function in 30% KOH at temperatures as much as 80°C and pressures as much as 5bar (mounted in-line) dominated out many of the choices, leaving both handbook laboratory evaluation or a small variety of applied sciences based mostly on refractometry or ultrasonics.
Explaining the choice to make use of Vaisala’s inline refractometers, Kristian Macke COO at iChemAnalytics stated: “Laboratory evaluation was dominated out instantly due to the time taken to derive outcomes, which might render course of management, and due to this fact effectivity, not possible to realize.” The mission workforce due to this fact evaluated the continual measurement choices. “We have been significantly impressed by the help from Vaisala’s distributor, Bühler Applied sciences,” Kristian defined. “They lent us a Vaisala refractometer for a brief interval in order that we might conduct a fast take a look at in our laboratory. They offered CAD information to assist combine the Vaisala system into our take a look at bench, and so they offered written affirmation that the refractometer is proof against KOH completely.”
Two Vaisala PR53AC inline refractometers have been put in on the take a look at bench, offering real-time KOH focus measurements on each side of the membrane. Kristian says: “This was a major funding for us, however we now have been completely delighted with the efficiency of the Vaisala probes. They have been delivered factory-calibrated and have been virtually plug-and-play. All we needed to do was combine their 4-20 mA output with our PLC.”
Vaisala’s refractometers measure the angle of refraction of sunshine within the course of medium, utilizing an LED gentle supply. A sensor frequently detects the essential angle at which the overall reflection of sunshine commences, and this has a direct relationship with KOH focus. Vaisala refractometry is extensively utilized in demanding industrial processes – from chemical substances and pulp & paper to meals and prescribed drugs — the place accuracy, chemical resistance, and uptime are essential.
Along with their skill to function in harsh circumstances, one of many foremost benefits of Vaisala’s refractometers is that they aren’t affected by suspended particles, bubbles or color, and with the choice of automated prism wash with steam or high-pressure scorching water, they aren’t affected by scaling or fouling.
Venture progress
The event of a dependable take a look at bench has allowed the mission workforce to concentrate on the principle goals. Completely different electrode coatings and electrolyte options are present process accelerated stress testing in a spread of temperatures, and Kristian says: “The outcomes of a 4-week trial have been lately printed at a convention in Berlin (ZVO Oberflächentage 2025), the place we demonstrated extraordinarily good efficiency information for a brand new coating.”
Wanting ahead
As extra sustainable coatings are being developed, the brand new absolutely automated take a look at bench will enable the workforce to optimize electrolysis gear, supplies and circumstances within the pursuit of course of effectivity. “KOH focus measurement with Vaisala refractometers is performing a critically essential position within the take a look at bench,” Kristian says. “Clearly, the final word purpose is to develop new high-performance electrolyzer stacks with high-performance floor coatings, and the flexibility to routinely monitor and management the KOH ratio can be important for optimizing electrolyzer parts and effectivity.”
This mission showcases how superior measurement expertise helps innovation in clear power, and accelerates the transition towards low-carbon options.
