Conceptual study of a high efficiency coal-fired power plant with CO2 capture using a supercritical CO2 Brayton cycle

Abstract

A concept of coal-fired power plant built around a supercritical CO2 Brayton power cycle and 90% post-combustion CO2 capture have been designed. The power cycle has been adapted to the coal-fired boiler thermal output, this boiler has been roughly designed in order to assess the power cycle pressure drop and its cost, an adapted CO2 capture process has been designed and finally the overall heat integration of the power plant has been proposed. Due to the high complexity of such as plant, this paper does not intend to provide definitive evaluation of the concept but to explore its potential.A coal power plant with CO2 power cycle without carbon capture could achieve a net efficiency of 50% (LHV) with a maximal temperature and pressure of 620 °C and 300 bar, these performances has to be validated but the first results on pilot plant are encouraging. The CO2 capture process use monoethanolamine as solvent and is equipped with vapor recompression systems in order to reduce the heat needed from the CO2 cycle. It achieves around 2.2 GJ/tCO2 of specific boiler duty with 145 kWh/tCO2 of electrical auxiliary consumption including compression to 110 bar. The energetic evaluation of the overall power plant carried out highlights the promising potential of CO2 supercritical cycle. A net power plant efficiency of 41.3% (LHV), with carbon capture and CO2 compression to 110 bar, seem to be achievable with available or close-to-available equipment.A technical-economic evaluation of the designed power plant has been performed. It shows a levelized cost of electricity reduction of 15%, and a cost of avoided CO2 reduction of 45%, without transport and storage, compared to a reference supercritical coal-fired power plant equipped with standard carbon capture process.