Simulation and exergetic evaluation of CO2 capture in a solid-oxide fuel-cell combined-cycle power plant

The incorporation of fuel cells into power plants can enhance the operational efficiency and facilitate the separation and capture of emissions. In this paper a fuel-cell unit, consisting of solid-oxide fuel-cell stacks, a pre-reformer, and an afterburner is incorporated into a combined-cycle power plant with CO2 capture. The thermodynamic performance of the plant is examined using an exergetic analysis and it is compared with a conventional combined-cycle power plant (reference plant) without CO2 capture, as well as with other plants with CO2 capture. efficiencies of the chemical reactions taking place in the fuel-cell unit are found to be the main source of exergy destruction among the plant components. However, the additional power generated in the fuel-cell stacks and the afterburner enhances the overall efficiency and compensates for the energy needed for the capture and compression of the carbon dioxide. When compared with the reference plant and with alternative capture technologies, the solid-oxide fuel-cell plant with CO2 capture operates more efficiently and appears to be a thermodynamically promising approach for carbon capture.