Thermodynamic investigation of an integrated near-zero CO2 emission power generation system with SOFC, MGT, SCO2BC, and CO2 capture

Abstract

In response to the imperative to reduce carbon emissions in power generation, a novel near-zero CO2 emission power generation system integrating solid oxide fuel cell (SOFC), micro gas turbine (MGT), supercritical carbon dioxide recompression Brayton cycle (SCO2BC) and CO2 capture (CC) is proposed and investigated. The innovation lies in the utilization of oxy-combustion for CO2 capture from the anode off-gas and the strategic harnessing of waste heat from the cathode off-gas through sequential MGT and SCO2BC processes. A comprehensive mathematical model is developed to assess the thermodynamic performance of the integrated system. The results indicate that the electrical efficiencies of the individual components, SOFC, SOFC-MGT, and SCO2BC, are 56.52%, 66.00%, and 40.76%, respectively, and the integrated system demonstrates an impressive overall efficiency of 70.15% under a current density of 5000 A/m2. The efficiency penalty incurred by CC on the integrated system is approximately 2%. A sensitivity analysis of key parameters highlights the potential for optimizing individual components to enhance power output or efficiency. Notably, the optimal overall efficiency is achieved when the SOFC operates at 0.25 MPa, the fuel utilization ratio is 85%, and the SCO2BC compressor pressure ratio is 2.6. This research not only establishes the viability of the proposed integrated system but also provides insights into optimizing its components for improved performance in power output and efficiency.