Study of CO2 recovery in a carbonate fuel cell tri-generation plant

Abstract The possibility of separating and recovering CO 2 in a biogas plant that co-produces electricity, hydrogen, and heat is investigated. Exploiting the ability of a molten carbonate fuel cell (MCFC) to concentrate CO 2 in the anode exhaust stream reduces the energy consumption and complexity of CO 2 separation techniques that would otherwise be required to remove dilute CO 2 from combustion exhaust streams. Three potential CO 2 concentrating configurations are numerically simulated to evaluate potential CO 2 recovery rates: 1) anode oxidation and partial CO 2 recirculation, 2) integration with exhaust from an internal combustion engine, and 3) series connection of molten carbonate cathodes initially fed with internal combustion engine (ICE) exhaust. Physical models have been calibrated with data acquired from an operating MCFC tri-generating plant. Results illustrate a high compatibility between hydrogen co-production and CO 2 recovery with series connection of molten carbonate systems offering the best results for efficient CO 2 recovery. In this case the carbon capture ratio (CCR) exceeds 73% for two systems in series and 90% for 3 MCFC in series. This remarkably high carbon recovery is possible with 1.4 MWe delivered by the ICE system and 0.9 MWe and about 350 kg day −1 of H 2 delivered by the three MCFC.