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Application of a Temporal Multiscale Method for Efficient Simulation of Degradation in PEM Water Electrolysis under Dynamic Operation

Dayron Chang Dominguez, An Phuc Dam, Thomas Richter, Kai Sundmacher, Shaun M. Alia

Abstract

Hydrogen is vital for sectors like chemicals and others, driven by the need to reduce carbon emissions. Proton Electrolyte Membrane Water Electrolysis (PEMWE) is a key technology for the production of green hydrogen under fluctuating conditions of renewable power sources. However, due to the scarcity of noble metal materials, the stability of the anode catalyst layer under dynamic operating conditions must be better understood. Model-aided investigation approaches are essential due to the back-box nature of the electrochemical system and the high costs of experimental long-term testing. In this work, a temporal multiscale method based on a Heterogeneous technique is applied to reduce the computational effort of simulating long-term degradation, focused on catalyst dissolution. Such an approach characterizes the problem in fast locally periodic processes, influenced by the dynamic operation and slow processes attributed to the gradual degradation of the catalyst layer. A mechanistic model that includes the oxygen evolution reaction, catalyst dissolution and hydrogen permeation from the cathode to the anode side is hypothesized and implemented. The multiscale approach notably reduces computational effort of simulation from hours to mere minutes. This efficiency gain is ascribed to the limited evolution of Slow-Scale variables during each period of time of the Fast-Scale variables. Consequently, simulation of the fast processes is required only until local periodicity is achieved within each Slow-Scale time step. Thus, the developed temporal multiscale approach proves to be highly effective in accelerating parameter estimation and predictive simulation steps, as could be verified through the results of this article. In this way, the method can support systematic model development to describe degradation in PEMWE under dynamic operating conditions.

Application of a Temporal Multiscale Method for Efficient Simulation of Degradation in PEM Water Electrolysis under Dynamic Operation

Abstract

Hydrogen is vital for sectors like chemicals and others, driven by the need to reduce carbon emissions. Proton Electrolyte Membrane Water Electrolysis (PEMWE) is a key technology for the production of green hydrogen under fluctuating conditions of renewable power sources. However, due to the scarcity of noble metal materials, the stability of the anode catalyst layer under dynamic operating conditions must be better understood. Model-aided investigation approaches are essential due to the back-box nature of the electrochemical system and the high costs of experimental long-term testing. In this work, a temporal multiscale method based on a Heterogeneous technique is applied to reduce the computational effort of simulating long-term degradation, focused on catalyst dissolution. Such an approach characterizes the problem in fast locally periodic processes, influenced by the dynamic operation and slow processes attributed to the gradual degradation of the catalyst layer. A mechanistic model that includes the oxygen evolution reaction, catalyst dissolution and hydrogen permeation from the cathode to the anode side is hypothesized and implemented. The multiscale approach notably reduces computational effort of simulation from hours to mere minutes. This efficiency gain is ascribed to the limited evolution of Slow-Scale variables during each period of time of the Fast-Scale variables. Consequently, simulation of the fast processes is required only until local periodicity is achieved within each Slow-Scale time step. Thus, the developed temporal multiscale approach proves to be highly effective in accelerating parameter estimation and predictive simulation steps, as could be verified through the results of this article. In this way, the method can support systematic model development to describe degradation in PEMWE under dynamic operating conditions.

Paper Structure

This paper contains 10 sections, 14 equations, 8 figures, 1 table, 1 algorithm.

Table of Contents

  1. Anode Catalyst Layer degradation model
  2. Iridium dissolution model
  3. Transport of hydrogen through the membrane
  4. Temporal Multiscale Method for solving the degradation model
  5. Temporal Multiscale Method
  6. Numerical implementation
  7. Results and discussion
  8. Temporal Multiscale simulation
  9. Parameter fitting
  10. Evaluation of the Model Performance with Experimental Data

Figures (8)

  • Figure 1: Theoretical schema of the processes of the PEMWE that are taken into consideration in the proposed model.
  • Figure 2: Theoretical representation of the electrochemical model for corrosion of the material in the ACL.
  • Figure 3: The sketch shows a section of the PEMWE consisting of the membrane at the center and the ACL and the CCL at the sides. In the cathode catalyst layer most of the evolved hydrogen is transported to the cathode outlet. However, a small fraction of hydrogen permeates into the other direction towards the anode side. In the ACL oxygen is evolved and a small volumetric fraction is constituted by hydrogen.
  • Figure 4: Schema of the temporal multiscale method.
  • Figure 5: Experimental data of five test profiles acquired from alia_electrolyzer_2019. They are named from left to right: hold, triangle-wave, square-wave, sawtooth-up and sawtooth-down profiles.
  • ...and 3 more figures