Improving the Efficiency of PEM Electrolyzers through Membrane-Specific Pressure Optimization

Fabian Scheepers, Markus Stähler, Andrea Stähler, Edward Rauls, Martin Müller, Marcelo Carmo and Werner Lehnert
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Fabian Scheepers: Forschungszentrum Juelich GmbH, Institute of Energy and Climate Research, IEK-14, Electrochemical Process Engineering, 52425 Juelich, Germany
Markus Stähler: Forschungszentrum Juelich GmbH, Institute of Energy and Climate Research, IEK-14, Electrochemical Process Engineering, 52425 Juelich, Germany
Andrea Stähler: Forschungszentrum Juelich GmbH, Institute of Energy and Climate Research, IEK-14, Electrochemical Process Engineering, 52425 Juelich, Germany
Edward Rauls: Forschungszentrum Juelich GmbH, Institute of Energy and Climate Research, IEK-14, Electrochemical Process Engineering, 52425 Juelich, Germany
Martin Müller: Forschungszentrum Juelich GmbH, Institute of Energy and Climate Research, IEK-14, Electrochemical Process Engineering, 52425 Juelich, Germany
Marcelo Carmo: Forschungszentrum Juelich GmbH, Institute of Energy and Climate Research, IEK-14, Electrochemical Process Engineering, 52425 Juelich, Germany
Werner Lehnert: Forschungszentrum Juelich GmbH, Institute of Energy and Climate Research, IEK-14, Electrochemical Process Engineering, 52425 Juelich, Germany

Energies, 2020, vol. 13, issue 3, 1-21

Abstract: Hydrogen produced in a polymer electrolyte membrane (PEM) electrolyzer must be stored under high pressure. It is discussed whether the gas should be compressed in subsequent gas compressors or by the electrolyzer. While gas compressor stages can be reduced in the case of electrochemical compression, safety problems arise for thin membranes due to the undesired permeation of hydrogen across the membrane to the oxygen side, forming an explosive gas. In this study, a PEM system is modeled to evaluate the membrane-specific total system efficiency. The optimum efficiency is given depending on the external heat requirement, permeation, cell pressure, current density, and membrane thickness. It shows that the heat requirement and hydrogen permeation dominate the maximum efficiency below 1.6 V, while, above, the cell polarization is decisive. In addition, a pressure-optimized cell operation is introduced by which the optimum cathode pressure is set as a function of current density and membrane thickness. This approach indicates that thin membranes do not provide increased safety issues compared to thick membranes. However, operating an N212-based system instead of an N117-based one can generate twice the amount of hydrogen at the same system efficiency while only one compressor stage must be added.

Keywords: polymer electrolyte membrane electrolyzer; membrane; pressure operation; system optimization; system modelling; functional layer; storage pressure (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (10)

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