Investigation on the integration of supercritical CO2 cycle with natural gas oxy-fuel combustion power plant

Abstract

The utilization of LNG cold energy is promising to offset the energy penalty of oxy-fuel combustion technology and achieve efficient carbon emissions reduction. In this paper, natural gas oxy-fuel power systems utilizing LNG cold energy are investigated. Supercritical and transcritical CO2 cycles are adopted to deeply recover flue gas waste heat. Results show that the thermal efficiency of the supercritical CO2 recompression cycle is 6% higher than that of the regenerative cycle, whereas the net power output of the recompression cycle is lower. With transcritical CO2 cycle as the secondary subsystem, the efficiency of both integrated systems is enhanced by approximately 9%. Meanwhile, 95% CO2 is captured with the power consumption of 0.07 kWh/kg-CO2. The total investment costs of the integrated regenerative and recompression cycle are 53.96 M$ and 54.62 M$. The levelized cost of electricity of the two integrated systems is 3.21 $/MWh and 3.24 $/MWh, indicating great financial availability. Therefore, applying supercritical and transcritical CO2 cycles contributes to efficient energy conversion and carbon capture. The research could provide meaningful information on the oxy-fuel combustion power system integrated with supercritical and transcritical CO2 cycles from thermodynamic and economic insights.