58865 - Optimized Performance and Cost Potential for Indirect Supercritical Co2 Coal Fired Power Plants 

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, 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 analysis (TEA) optimization results of coal-fired utility scale power plants based on indirect sCO₂ power cycles both with and without carbon capture and storage (CCS). Four power cycle configurations were considered for the optimization – the recompression cycle with and without turbine reheat and the partial cooling cycle with and without turbine reheat. Several design variables were identified for each power cycle configuration and these design variables were optimized to minimize the levelized cost of electricity (LCOE) for each plant. The optimization design variables include parameters such as turbine inlet temperatures and pressure, sCO₂ cooler outlet temperatures, recuperator approach temperatures and pressure drops etc. The total number of optimization design variables ranged from 12 – 17, depending on the power cycle configuration. The optimization was conducted using automated derivative-free optimization (DFO) algorithms available under NETL’s Framework for Optimization and Quantification of Uncertainty and Sensitivity (FOQUS) platform.

For sCO₂ plants both with and without CCS, the recompression cycle with reheat (RC with reheat) had the highest plant efficiency and lowest LCOE among the considered power cycle configurations. For plants with CCS, RC with reheat offered 8 percentage points higher plant efficiency (HHV basis) and 14.6% lower LCOE compared to a reference PC-fired supercritical steam plant with CCS. For plants without CCS, RC with reheat offered 4.7 percentage points higher plant efficiency and 7% lower LCOE compared to a reference PC-fired supercritical steam plant without CCS.

Keywords:  supercritical CO2 (sCO2), recompression cycle, partial cooling cycle, levelized cost of electricity (LCOE), automated derivative free optimization (DFO)

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ACKNOWLEDGEMENT

Team KeyLogic’s contributions to this work were funded by the US Department of Energy’s Office of Energy Efficiency and Renewable Energy under the Mission Execution and Strategic Analysis contract (DE-FE0025912) for support services. The authors would like to thank Travis Shultz (NETL) and Eric Liese (NETL) for their support and assistance in performing this work.