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

Abstract

Achieving net-zero or carbon-negative energy systems requires technologies capable of generating power while capturing or utilising CO2 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 CO2-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 O2-fed cathodes. Results show that integrating MCFCs into different plant types significantly affects both plant efficiency and CO2 avoidance cost, with the air-fed NGCC–MCFC configuration demonstrating the most favourable techno-economic balance, while the O2-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 CO2-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.