Application of MCFCs for active CO2 capture within natural gas combined cycles

AbstractThis paper presents an analysis of the application of Molten Carbonate Fuel Cells (MCFC) in a natural gas fired combined cycle power plant to capture CO2 from the exhaust of the gas turbine. The gas turbine flue gases are used as cathode feeding for a MCFC, where CO2 is transferred from the cathode to anode side, concentrating the CO2 in the anode exhaust. This stream is then sent to a CO2 removal section consisting either in (i) an oxygen combustion of residual fuel compounds, or (ii) a cryogenic CO2 removal section, cooling the exhaust stream in the heat recovery steam generator. The MCFC is based on Ansaldo Fuel Cells experience, fed with natural gas processed by an external reformer which is thermally integrated within the FC module. Differently from more conventional approaches to CO2 capture, it works increasing the plant power output, acting as an active CO2 concentrator. The plant shows the potential to achieve a CO2 avoided ranging between 58 and 68%, depending on the configuration while taking advantage from the introduction of the fuel cell, the final electric efficiency is lower from 0.2 to 0.8 points lower than the original combined cycle (57.8% LHV in the most efficient configuration). The power output increases by about 22%, giving a potentially relevant advantage with respect to competitive carbon capture technologies