Comparison study on different SOFC hybrid systems with zero-CO2 emission

Based on a traditional SOFC (solid oxide fuel cell) hybrid power system, three different SOFC hybrid power systems with zero-CO2 emission are proposed in this paper and their performances are analyzed and compared. The anode outlet gas of SOFC burns with the pure oxygen and the concentration of CO2 is greatly increased. In order to maintain the appropriate turbine inlet temperature, three different measures (steam injection, CO2 gas injection and heat exchange layout) are taken. Because the outlet flue gas of the afterburner mainly consists of CO2 and steam, the CO2 in the flue gas can be captured easily by the condensation method after the recovery of work and heat. With the exergy analysis method, this paper studies the exergy loss distributions of every unit of SOFC hybrid systems with CO2 capture and reveals the variation rules of exergy loss distributions. The effects of the main operating parameters on the overall performances of SOFC hybrid systems with CO2 capture are also investigated. The results show that the zero CO2 emission SOFC hybrid systems still have higher efficiencies, which only decrease about 3–4% compared with that of the basic SOFC hybrid system without CO2 capture.