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There are different types of electrolyzers

There are many types of electrolyzers and each type uses a slightly different process to produce hydrogen. The two most common types of electrolyzers used in hydrogen production are proton exchange membrane (PEM) and alkaline electrolyzers.1 This fact will briefly describe the most common types of electrolyzers and their relative advantages and disadvantages.

Alkaline electrolyzers use a liquid alkaline electrolyte solution to conduct ions between two electrodes. Alkaline electrolyzers use an alkaline electrolyte to produce hydrogen. In alkaline electrolyzers, the electrolysis process works by passing an electric current through a solution of water and an alkaline electrolyte, which splits the water molecules into hydrogen and oxygen gasses at the respective electrodes. The liquid electrolyte allows for a simpler design, reducing the need for expensive, corrosion-resistant materials.2 Their simplicity, low cost, and high efficiency make them an attractive option for large-scale hydrogen production. 3 However, they have slower dynamic response times compared to some other electrolyzer technologies and they produce low-purity hydrogen which may not be suitable for some end uses.

PEM electrolyzers use a solid polymer electrolyte that conducts protons from the anode to the cathode while separating the gasses. Proton exchange membrane (PEM) electrolyzers utilize a solid polymer electrolyte that conducts protons from the anode to the cathode. In PEM electrolyzers, water is split into hydrogen and oxygen gasses by applying an electric current, with oxygen evolving at the anode and protons moving through the membrane to form hydrogen at the cathode.4 These electrolyzers offer several advantages, including high current densities, rapid response times of about five minutes, and compact system designs, making them suitable for applications requiring dynamic operation and limited space. PEM electrolyzers also produce high-purity hydrogen. 5 However, they also have disadvantages, such as higher production costs due to the need for expensive, corrosion-resistant materials like platinum and iridium for the catalysts. 6

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Footnotes​

  1. Department of Energy. (n.d.). Hydrogen production: Electrolysis. Department of Energy. https://www.energy.gov/eere/fuelcells/hydrogen-production-electrolysis ↩

  2. Accelera. (2023, February 20). What is an electrolyzer and what is it used for?. Accelera. https://www.accelerazero.com/news/what-is-an-electrolyzer-and-what-is-it-used-for ↩

  3. Hydrogen Newsletter. (2022, December 6). PEM (proton exchange membrane) electrolyzers vs AEL (alkaline electrolysis) electrolyzers: What is the best selection for a Green Hydrogen Project? https://www.hydrogennewsletter.com/untitled-2/#google_vignette ↩

  4. Accelera. (2023, February 20). What is an electrolyzer and what is it used for?. Accelera. https://www.accelerazero.com/news/what-is-an-electrolyzer-and-what-is-it-used-for ↩

  5. Kumar, S. S., & Himabindu, V. (2019). Hydrogen production by PEM water electrolysis–A review. Materials Science for Energy Technologies, 2(3), 442-454. https://www.sciencedirect.com/science/article/pii/S2589299119300035 ↩

  6. Hydrogen Newsletter. (2022, December 6). PEM (proton exchange membrane) electrolyzers vs AEL (alkaline electrolysis) electrolyzers: What is the best selection for a Green Hydrogen Project? https://www.hydrogennewsletter.com/untitled-2/#google_vignette ↩