Thermodynamic and economic comparison of supercritical carbon dioxide coal-fired power system with different improvements

The supercritical carbon dioxide (SCO₂) Brayton cycle is expected to become the new generation of power cycle for coal-fired power units. Most previous studies on system and parameter optimizations of SCO₂ power systems aimed to improve thermal performance, and some of them also involved the economic performance evaluation of the configurations they proposed. However, the configurations included in previous economic analyses are limited, and the models used in different papers are different. Although many improved configurations of SCO₂ coal-fired power generation system have been proposed, currently, there is a lack of comparison under the unified thermal-economic evaluation standard. Thus, this study focuses on the economic optimization and comparison of the performances of different advanced configurations of SCO₂ coal-fired power systems under the unified standard. Thermodynamic and economic optimization models are developed, and various configurations are proposed, representing improvements from four aspects (medium-temperature flue gas heat utilization, reheating, waste heat recovery, and main compressor intercooling) based on a recompression system. The system parameters are also economically optimized with the genetic algorithm. Results show that integrating the SCO₂ benchmark cycle, medium temperature economizer, single-reheat, flue bypass, low temperature economizer and main compressor intercooling into the coal-fired power unit yields excellent thermo-economic performance. This configuration has the highest power generation efficiency of 47.93% and the lowest levelized cost of electricity of 0.0540 USD kW⁻¹ hour⁻¹ compared to others. Furthermore, the influences of specific parameters on power generation cost are analyzed.