Comparison of Supercritical CO2 Power Cycles to Steam Rankine Cycles in Coal-Fired Applications

Increasing the efficiency of coal-fired power plants is vital to reducing electricity costs and emissions. Power cycles employing supercritical carbon dioxide (sCO 2 ) as the working fluid have the potential to increase power cycle efficiency by 3 – 5% points over state-of-the-art oxy-combustion steam Rankine cycles operating under comparable conditions. To date, the majority of studies have focused on the integration and optimization of sCO 2 power cycles in waste heat, solar or nuclear applications. The goal of this study is to directly compare optimized cycle efficiencies of sCO 2 power cycles to state-of-the-art steam Rankine cycles using heat source and ambient characteristics of baseline oxy- fired coal plants. This study is designed to demonstrate the potential of sCO 2 power cycles, and quantify the power cycle efficiency gains that can be achieved versus the state-of-the-art steam Rankine cycles employed in oxy-fired coal power plants. Turbine inlet conditions were varied among the sCO 2 test cases and compared with existing DOE/NETL steam base cases. Two separate sCO 2 test cases were considered and the associated flow sheets developed. The turbine inlet conditions for this study were chosen to match conditions in a coal-fired ultra-supercritical