Co-Electrolysis CFY-Stack Operation and Integration for Carbon Capture and Utilization

Kusnezoff, Mihails; Rix, Christopher; Adam, Paul; Reichelt, Erik; Herz, Gregor; Jahn, Matthias; Trofimenko, Nikolai; Michaelis, Alexander

doi:10.1149/09101.2579ecst

Cited by 6 publications

(5 citation statements)

References 13 publications

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“…A 10-cell stack of the Mk35x design with metallic CFY (∼94 mol % Cr, 5 mol% Fe, ∼1 mol% Y 2 O 3 ) interconnects developed by IKTS was operated in steam electrolysis. 8,16,17,19,21 The stack was manufactured at the IKTS pilot line and had a cross flow design with internal fuel gas and open-air manifolds. Figure 1 shows the exploded view of the stack components and their assembly.…”

Section: Methodsmentioning

confidence: 99%

“…7 The MK35x stack platform developed by IKTS is based on electrolyte supported cells (ESC) with chromium-iron-yttrium (CFY) interconnects. 8,[16][17][18][19][20][21] The stacks were initially developed for SOFC operation where they showed an average voltage decrease of 0.7%/kh for more than 20,000 h and are commercially available. 18 Here, the durability behavior of MK35x stacks tuned for operation in electrolysis mode is investigated in detail for more than 3000 h in order to obtain an in-depth understanding of the voltage evolution over time of the individual repeat units in the stack.…”

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confidence: 99%

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Electrochemical Analysis of an Electrolyte-Supported Solid Oxide Cell-Based MK35x Stack during Long-Term Electrolysis Operation

Riegraf,

Szabo,

Lang

et al. 2024

J. Electrochem. Soc.

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The currently ongoing scale-up of high-temperature solid oxide electrolysis (SOEL) requires an understanding of the underlying dominant degradation mechanisms to enable continuous progress in increasing stack durability. In the present study, the degradation behavior of SOEL stacks of the type ‘MK35x’ with chromium-iron-yttrium (CFY) interconnects and electrolyte-supported cells (ESC) developed at Fraunhofer IKTS was investigated. For this purpose, the initial electrochemical performance of a 10-cell stack was characterized in various operating conditions in both fuel cell and electrolysis mode. Degradation was evaluated during galvanostatic steady-state steam electrolysis operation for more than 3000 h at an oxygen side outlet temperature of 816°C and a current density of -0.6 A cm-2 and showed an average voltage evolution rate of -0.3 %/kh demonstrating high stability. Initial and final characterization at the part load operating point at -0.39 A cm-2 and 800°C led to the determination of a positive overall degradation rate of 0.4 %/kh showing a considerable impact of the operating conditions on the degradation rate. By means of electrochemical impedance spectroscopy analysis it was shown that the stack’s ohmic resistance increased whereas the polarization resistance decreased most likely due to an enhancement in LSMM’/ScSZ oxygen electrode performance.

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Electrochemical Analysis of an Electrolyte-Supported Solid Oxide Cell-Based MK35x Stack during Long-Term Electrolysis Operation

Riegraf,

Szabo,

Lang

et al. 2024

J. Electrochem. Soc.

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“…More details on stack design and general performance can be found in literature. [11][12][13] The stack module was designed for a nominal input power of P el,stack,nom,DC = 12 kW at a standard current density of i = 600 mA cm À2 .…”

Section: Methodsmentioning

confidence: 99%

“…To provide reliable data for upscaling of hydrogen or syngas production facilities, such models need to be validated under relevant conditions. For that purpose, the results from the small-scale demonstration plant are compared with models derived in earlier works of the authors, [10][11][12] showing a good applicability not only of the stack model but also of the assumptions chosen for the modeling of SOEL systems.…”

Section: Introductionmentioning

confidence: 99%

Small‐Scale Demonstration of a High‐Temperature Coelectrolyzer—Experimental Results and Model Validation

et al. 2023

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High‐temperature electrolysis is known to offer a huge potential for efficient generation of hydrogen and syngas. However, experimental data on technically relevant electrolyzer systems are scarce. Herein, experimental data on a coelectrolyzer with a nominal electric input power of Pel,stack,nom,DC = 12 kW will be presented. The electrolyzer is operated for over 500 h in H2O and coelectrolysis mode under full‐ and part‐load operation. The results not only prove the viability of the chosen system approach and the high efficiency that can be reached with this electrolysis technology, but they are also applied to validate a 0D solid oxide electrolysis model.

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“…A ten-cell stack of the Mk35x design with metallic CFY interconnects developed by IKTS was operated in steam electrolysis (4)(5)(6)(7)(8). The stack has a cross flow design with internal fuel gas and open-air manifolds.…”

Section: Methodsmentioning

confidence: 99%

Degradation Behavior of MK35x Stacks with Chromium-Based Interconnects in Steam Electrolysis Operation

Riegraf,

Szabo,

Lang

et al. 2023

Meet. Abstr.

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The currently ongoing commercialization of high-temperature solid oxide electrolysis (SOEL) requires the understanding of the underlying dominant degradation mechanisms to enable continuous progress in reducing stack degradation rates. In the present study, the degradation behavior of stacks with chromium-based interconnects (MK35x) and electrolyte-supported cells (ESC) developed at Fraunhofer IKTS is investigated. For this purpose, the initial electrochemical performance of 10-layer stacks was extensively characterized in various operating conditions in both fuel cell and electrolysis mode by electrochemical impedance spectroscopy (EIS). Degradation was evaluated during galvanostatic steady-state steam electrolysis operation over >3000 h in the temperature range of 800-825°C at a current density of -0.6 A cm-2, corresponding to a steam conversion rate of 75%. EIS analysis was used to separate the different loss contributions in the stack and showed that the ohmic resistance increase was the dominating performance degradation phenomenon. Moreover, electrochemical degradation rates in steady-state SOEL mode are compared to the ones in reversible mode with a daily cycling between electrolysis and fuel cell operation. Post-mortem analysis was carried out with scanning electron microscopy (SEM) to correlate the observed degradation phenomena with microstructural and morphological changes. The observed low degradation rates demonstrate that MK35x are ready for scale-up, and the present work gives guidance for operation strategies and stack design to extend their lifetime even further.

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Co-Electrolysis CFY-Stack Operation and Integration for Carbon Capture and Utilization

Cited by 6 publications

References 13 publications

Electrochemical Analysis of an Electrolyte-Supported Solid Oxide Cell-Based MK35x Stack during Long-Term Electrolysis Operation

Electrochemical Analysis of an Electrolyte-Supported Solid Oxide Cell-Based MK35x Stack during Long-Term Electrolysis Operation

Small‐Scale Demonstration of a High‐Temperature Coelectrolyzer—Experimental Results and Model Validation

Degradation Behavior of MK35x Stacks with Chromium-Based Interconnects in Steam Electrolysis Operation

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