Here, we present a methodology for the generalized quantification of the carbon (C)-formation risk in hydrocarbon mixtures based on the normalized chemical activity. An open-source computational thermodynamics tool is coupled to a solid oxide fuel cell (SOFC) stack model to apply and validate this approach with literature data based on methane-fueled SOFC systems with anode off-gas recirculation. Two- and three-dimensional C-formation risk maps valid for all C-H-O mixtures are proposed for a practical, accurate, and meaningful assessment of the trade-off between C-deposition risk and SOFC performance. Compared to conventional risk evaluation methods such as steam-to-carbon ratio (SCR), oxygen-to-carbon ratio (OCR), or C-H-O ternary-phase diagrams, this approach allows a system-agnostic evaluation of different designs operated at varying conditions at a constant C-formation risk margin. The generalized formulation allows integration into process optimization workflows to obtain high-performance system designs with extended stack operating windows.

With a growing energy demand in a carbon-constrained society, fuels cells powered by renewable fuels, and specifically solid waste, are seen as interesting contributors to the energy portfolio. The alternative energy industry needs to reduce costs, enhance efficiency, and demonstrate durability and reliability to be economically feasible and attractive. This paper addresses biomass waste gasification in distributed energy systems, using a solid oxide fuel cell (SOFC) to produce electricity and heat. The potential and optimal plant efficiency and layout (i.e., anode off-gas (AOG) recirculation point via small-scale turbomachinery and heat exchanger network) are analyzed through a multi-stage approach that includes scenario evaluation and multi-objective optimization via a hybrid optimization strategy with heuristics and mathematical programming. The results in this paper summarize the most convenient operating conditions and provide an optimized heat exchanger network (HEN). The AOG recirculation toward the gasifier combustor is the preferred option; the electrical and thermal efficiencies can separately go up to 49 and 47%, respectively. The combined total efficiency ranges between 76 and 82%, and the area of heat exchange, which corresponds to an amount of heat exchanged between 91 and 117 kW, is within 6–14 m ².