Thermodynamic Insights for Electrochemical Hydrogen Compression with Proton-Conducting Membranes
Journal Article - Open Access
Colorado School of Mines Golden United States
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Membrane electrode assemblies MEA based on proton-conducting electrolyte membranes offer opportunities for the electrochemical compression of hydrogen. Mechanical hydrogen compression, which is more-mature technology, can suffer from low reliability, noise, and maintenance costs. Proton-conducting electrolyte membranes may be polymers e.g., Nafionor protonic-ceramics e.g., yttrium-doped barium zirconates. Using a thermodynamics-based analysis, the paper explores technology implications for these two membrane types. The operating temperature has a dominant influence on the technology, with polymers needing low-temperature and protonic-ceramics needing elevated temperatures. Polymer membranes usually require pure hydrogen feed streams, but can compress H2 efficiently. Reactors based on protonic-ceramics can effectively integrate steam reforming, hydrogen separation, and electrochemical compression. However, because of the high temperature e.g., 600 C needed to enable viable proton conductivity, the efficiency of protonic-ceramic compression is significantly lower than that of polymer-membrane compression. The thermodynamics analysis suggests significant benefits associated with systems that combine protonic-ceramic reactors to reform fuels and deliver lightly compressed H2 e.g., 5 barto an electrochemical compressor using a polymer electrolyte to compress to very high pressure.