A SOFC-based integrated gasification fuel cell cycle with CO₂ capture

The application of solid oxide fuel cells (SOFC) in gasification-based power plants would represent a turning point in the power generation sector, allowing to considerably increase the electric efficiency of coal-fired power stations. Pollutant emissions would also be significantly reduced in integrated gasification fuel cell cycles (IGFC) considering the much lower emissions of conventional pollutants (NO_x, CO, SO_x, and particulate matter) typical of fuel cell-based systems. In addition, SOFC-based IGFCs appear particularly suited to applications in power plants with CO₂ capture. This is evident by considering that SOFCs operate as air separators and partly oxidized fuel exiting the fuel cell does not contain nitrogen from air, such as in conventional oxyfuel processes. The aim of this paper is the thermodynamic analysis of a SOFC-based IGFC with CO₂ capture. In the assessed plant, syngas produced in a high efficiency Shell gasifier is used in SOFC modules after heat recovery and cleaning. Anode exhausts, still containing combustible species, are burned with oxygen produced in the air separation unit, also used to generate the oxygen needed in the gasifier; the product gas is cooled down in a heat recovery steam generator before water condensation and CO₂ compression. The plant layout is carefully designed to best exploit the heat generated in all the processes and, apart from the fuel cell exotic components, far from industrial state-of-the-art, are not included. Detailed energy and mass balances are presented for a better comprehension of the obtained results.