(288c) Modeling the Impact of Degradation on the Cost of Low-Temperature Electrolytic Hydrogen Production

In recent years, hydrogen (H₂) has gained increasing attention for its potential to act as a low-carbon energy vector and a form of long-term chemical energy storage in a deeply decarbonized energy system. Today, H₂is predominantly sourced from fossil fuels, but the increasing demand for energy storage and conversion technologies associated with a future renewables-dominant electric grid necessitates alternative, carbon-free methods of hydrogen production. This has led to significant interest in electricity-driven hydrogen production processes such as low-temperature polymer electrolyte membrane (PEM) electrolysis, with an ambitious scale up of this technology projected over the next decade. Several promising aspects of PEM electrolyzers include their small size compared to traditional alkaline electrolyzers, their ability to operate at high current densities, and their ability to operate with a differential pressure between the anode and cathode, which enables the production of high pressure H₂ product. A number of recent studies have explored how adjusting these characteristics, as well as other operating parameters, affect the long-term performance of PEM electrolyzers. However, in order to optimize the implementation of PEM electrolyzers on a utility scale, it is critical to understand their dynamic operation and the effects of degradation of the stack over time. This presentation will discuss first-principles modeling and techno-economic optimization of PEM electrolysis systems with a specific emphasis on accounting for use-dependent degradation and safety under dynamic operation.

Large-scale electrolyzer projects being contemplated include both “islanded” configurations, where renewable electricity is co-located with the electrolyzer and is the sole source of electricity input, as well as “grid-connected” systems involving using grid electricity as well as on-site or contracted renewable electricity. In both cases, cost-effective operation of the electrolyzer will likely involve operating at much less than 100% capacity utilization to manage fluctuations in available renewable energy [1,2] and grid electricity prices. This partial load operation not only has implications for capital utilization, which has been extensively studied, but also stack lifetime and operating efficiencies that are less well studied. Although there is extensive research on the techno-economic analysis of electrolytic the H₂ supply, for both islanded [3,4] and grid-connected configurations [5], most studies tend to either overlook or abstract out the impact of dynamic operation on stack degradation and lifetime as well as operating efficiency.

In this study we evaluate the factors influencing stack degradation and electrolyzer efficiency at partial loadings and their impact on the levelized cost of H₂ supply via electrolysis in both islanded and grid-connected configurations, using techno-economic modeling. We have developed a first principles electrochemical model for PEM water electrolysis that incorporates an empirical relation for electrolyzer degradation as a function of key operational variables. This model enables characterizing temporal dynamics of production rates but also other key process variables, such as temperature fluctuations and species concentrations at the anode/cathode which are essential for safe operation. The developed model is being incorporated as part of a dynamic optimization model to identify operational routines and design considerations that minimize the levelized cost of hydrogen production considering time-varying electricity prices. Numerical experiments will be shown to demonstrate the value of the proposed model in informing the design and operation of PEM electrolysis systems.

References:

[1] Mallapragada, D.S., Gençer, E., Insinger, P., Keith, D.W., and O’Sullivan, F.M. (2020). Can Industrial-Scale Solar Hydrogen Supplied from Commodity Technologies Be Cost Competitive by 2030? Cell Reports Phys. Sci. 1.

[2] Bødal, E.F., Mallapragada, D., Botterud, A., and Korpås, M. (2020). Decarbonization synergies from joint planning of electricity and hydrogen production: A Texas case study. Int. J. Hydrogen Energy.

[3] Yates, J., Daiyan, R., Patterson, R., Egan, R., Amal, R., Ho-Baille, A., and Chang, N.L. (2020). Techno-economic Analysis of Hydrogen Electrolysis from Off-Grid Stand-Alone Photovoltaics Incorporating Uncertainty Analysis. Cell Reports Phys. Sci. 1, 100209.

[4] Mallapragada, D.S., Gençer, E., Insinger, P., Keith, D.W., and O’Sullivan, F.M. (2020). Can Industrial-Scale Solar Hydrogen Supplied from Commodity Technologies Be Cost Competitive by 2030? Cell Reports Phys. Sci. 1.

[5] Guerra, O.J., Eichman, J., Kurtz, J., and Hodge, B.M. (2019). Cost Competitiveness of Electrolytic Hydrogen. Joule 3, 2425–2443.