Molten Carbonate Fuel Cells for Retrofitting Postcombustion CO₂ Capture in Coal and Natural Gas Power Plants

The state-of-the-art conventional technology for postcombustion capture of CO₂ from fossil-fueled power plants is based on chemical solvents, which requires substantial energy consumption for regeneration. A promising alternative, available in the near future, is the application of molten carbonate fuel cells (MCFC) for CO₂ separation from postcombustion flue gases. Previous studies related to this technology showed both high efficiency and high carbon capture rates, especially when the fuel cell is thermally integrated in the flue gas path of a natural gas-fired combined cycle or an integrated gasification combined cycle plant. This work compares the application of MCFC-based CO₂ separation process to pulverized coal fired steam cycles (PCC) and natural gas combined cycles (NGCC) as a “retrofit” to the original power plant. Mass and energy balances are calculated through detailed models for both power plants, with fuel cell behavior simulated using a 0D model calibrated against manufacturers' specifications and based on experimental measurements, specifically carried out to support this study. The resulting analysis includes a comparison of the energy efficiency and CO₂ separation efficiency as well as an economic comparison of the cost of CO₂ avoided (CCA) under several economic scenarios. The proposed configurations reveal promising performance, exhibiting very competitive efficiency and economic metrics in comparison with conventional CO₂ capture technologies. Application as a MCFC retrofit yields a very limited (<3%) decrease in efficiency for both power plants (PCC and NGCC), a strong reduction (>80%) in CO₂ emission and a competitive cost for CO₂ avoided (25–40 €/ton).