Cross‐System Comparative Techno‐Economic and Environmental Evaluation of MCFC Integration in Power and Biogas Upgrading Systems

Achieving net‐zero or carbon‐negative energy systems requires technologies capable of generating power while capturing or utilising CO 2 without significant efficiency losses. Molten carbonate fuel cells (MCFCs) offer such potential, yet their techno‐economic competitiveness across different energy systems remains insufficiently quantified. Beyond conventional power‐plant integration, this study explores a new application of MCFCs in biogas upgrading, where their electrochemical CO 2 ‐transfer capability is harnessed to purify raw biogas to near‐pipeline‐quality biomethane (BM) while simultaneously generating electricity. A process‐simulation‐informed, bottom‐up techno‐economic and environmental assessment was conducted to evaluate MCFC integration within natural gas combined cycle (NGCC), integrated gasification combined cycle (IGCC) and biogas‐upgrading systems, each operated with air‐ or O 2 ‐fed cathodes. Results show that integrating MCFCs into different plant types significantly affects both plant efficiency and CO 2 avoidance cost, with the air‐fed NGCC–MCFC configuration demonstrating the most favourable techno‐economic balance, while the O 2 ‐fed IGCC–MCFC system provides superior environmental performance in centralised applications. In decentralised settings, MCFC‐assisted biogas upgrading can achieve cost‐neutral or revenue‐positive operation when stack costs fall below 1000 ·kW −1, highlighting its potential as a self‐sustaining CO 2 ‐removal route. These findings establish a unified cross‐system performance map identifying where MCFCs are most competitive across centralised and decentralised energy systems, highlighting their potential as dual‐function units for power decarbonisation and renewable‐gas production.