Indirect-fired supercritical CO2 (sCO2) power cycles are being explored as an attractive alternative to steam Rankine cycles for a variety of heat sources including fossil, concentrated solar power (CSP), nuclear, waste heat etc. Therefore, understanding their performance and cost potential is important for commercialization of the technology. This study presents the techno-economic global optimization results of coal-fired utility scale power plants based on indirect sCO2 power cycles with and without carbon capture and storage (CCS). Four power cycle configurations are considered for optimization – recompression cycle (RC) with and without turbine reheat and partial cooling cycle (PCC) with and without turbine reheat. Several design variables are identified for each power cycle configuration and these design variables are optimized to minimize the levelized cost of electricity (LCOE) for each plant. The optimization design variables included parameters such as turbine inlet temperatures and pressure, sCO2 cooler outlet temperatures, recuperator approach temperatures and pressure drops etc. The optimization is conducted using automated derivative free optimization algorithms available under NETL’s Framework for Optimization and Quantification of Uncertainty and Sensitivity (FOQUS) platform.
For sCO2 power plants both with and without CCS, recompression cycle with reheat (RC with reheat) has the highest plant efficiency and lowest LCOE among the considered power cycle configurations. For plants with CCS, the RC with reheat configuration offered 8 percentage points higher plant efficiency (HHV basis) and 14.6% lower LCOE compared to a state-of-the-art (SOA) PC-fired supercritical steam Rankine plant with CCS. For plants without CCS, the RC with reheat configuration offered 4.7 percentage points higher plant efficiency and 7% lower LCOE compared to a SOA PC-fired supercritical steam Rankine plant without CCS.