Balancing performance and reliability in ammonia-fuelled SOFCs

Ammonia is increasingly positioned as a carbon-free fuel for solid oxide fuel cells (SOFCs). However, direct ammonia feeding can induce nickel nitriding at the anode, accelerating stack degradation. Current work explores some countermeasures, including anti-nitriding coatings, alternative anode materials, and changes in system design. The latter is particularly attractive among these options since system-level redesign can protect the stack and improve efficiency. Accordingly, this paper evaluates the reliability of four SOFC system designs that combine two key measures: anode off-gas recirculation (AOR) to enhance performance, and ammonia pre-cracking to limit nitride formation. The present study integrates Reliability Block Diagrams with Weibull analysis to quantify how each configuration affects overall system reliability and the contribution of critical subsystems. Results indicate that combining AOR with a pre-cracker yields the highest reliability; pre-cracking alone increases reliability but entails an efficiency penalty; and AOR alone, although performance-enhancing, does not provide a reliability justification. To complement these findings, a cost-effectiveness perspective is included to indicate the relative cost implications of moving between configurations. In this way, a balanced view of performance, reliability, and cost is presented. This work therefore provides practical guidance for the design of ammonia-fuelled SOFC systems and supports viable technology selections that extend stack lifetime without compromising system performance.

Keywords: Reliability Block Diagram (RBD), Weibull analysis, solid oxide fuel cell (SOFC), nickel nitriding, reliability assessment.