Optimizing Solid Oxide Fuel Cell Performance to Re-evaluate Its Role in the Mobility Sector

Abstract

A sustainable, interconnected, and smart energy network in which hydrogen plays a major role cannot be dismissed as a utopia anymore. There are vast international and industrial ambitions to reach the envisioned system transformation, and the decarbonization of the mobility sector is a central pillar comprising a huge economic share. Solid oxide fuel cells (SOFCs) are one of the most promising technologies in the brigade of clean energy devices and have potentially wide applicability for transportation, due to their high efficiencies and impurity tolerance. To uncover future pathways to boost the cell's performance, we propose a detailed multiscale modeling methodology to evaluate the direct impact of cell materials and morphologies on commercial-scale system performance. After acquiring intrinsic electrokinetics decoupled from mass and charge transport of different anode and cathode materials via a half-cell model, a full cell model is employed to identify the most promising electrode combination. Subsequently, a scale-up to the system level is performed by coupling a 3-D kW-stack model to the balance of plant components while focusing on morphological optimization of the membrane electrode assembly (MEA). On optimally tailoring the MEA, model results demonstrate that an advanced cell design comprising a Ni fiber-CGO matrix structured anode and a LSCF-infiltrated CGO cathode could reach a stack power density of 1.85 kW L −1 and a net system efficiency of 52.2% for operation at <700 °C, with manageable stack temperature gradients of <14 K cm −1 . The modeloptimized power density is substantially higher than those of commercial stacks and surpasses industrial targets for SOFC-based range extenders. Thus, with further cell and stack development targeting the performance limiting processes elucidated in the paper, commercial SOFCs could, alongside range extenders, also act as prime movers in larger scale transport applications such as trucks, trains, and ships.

Comparison of a solid oxide cell with nickel/gadolinium‐doped ceria fuel electrode during operation with hydrogen/steam and carbon monoxide/carbon dioxide

“…Among the various types of fuel cells and electrolyzers [1], only solid oxide cells (SOCs) show a high fuel flexibility and can, next to hydrogen (H 2 ), operate on carbon monoxide (CO) and reformate/syngas [2][3][4][5][6]. Physicochemical cell models that are able to simulate the cell behavior within a wide range of technically relevant operating conditions are a useful tool to optimize the cell design, evaluate optimum operating strategies, and simulate the cell behavior on stack and system levels [7][8][9][10][11]. On the cell level, the development of an impedance-based zero-dimensional direct current (dc) performance model was demonstrated for electrolyte-supported cells (ESCs) [12,13], metal-supported cells [14], and anode-supported cells [7,8,15].…”

Integrated Multiscale Modeling of Solid Oxide Electrodes, Cells, Stacks, and Systems

“…The integrated multiscale model framework has been described in detail in my group's previous publications [3][4][5][6][7][8][9] and is only summarized here. In essence, the framework comprises of individual sub-models that provide continuum descriptions of the relevant physico-chemical phenomena at the multiple time and length scales involved.…”

“…However, with recent advancements in electrode design leading to faster dynamics and lower operating temperatures, the suitability of SOFCs as range extenders, as well as prime movers in buses, trains and ships is under reconsideration [17]. Thus, we redesigned the SOFC system from the ground-up based on current state-of-the-art electrode materials and morphologies to re-evaluate its role in the transportation sector [9]. After obtaining intrinsic kinetics for the electrodes from half-cell measurements, an optimal full cell MEA combination was identified.…”

“…Thus, we redesigned the SOFC system from the ground‐up based on current state‐of‐the‐art electrode materials and morphologies to re‐evaluate its role in the transportation sector 9. After obtaining intrinsic kinetics for the electrodes from half‐cell measurements, an optimal full cell MEA combination was identified.…”

“…Sensitivity analysis of the stack volumetric power density to MEA parameters. The analysis was performed at 0.8 V and ∼80 % conversion for operating temperatures of 973.15 K and 1023.15 K by varying each MEA parameter, P , on the y ‐axis ±10 % 9.…”