Peak-Shaving of the Oxy-Fuel Power Plant Coupled with Liquid O2 Storage

Integrating a high proportion of intermittent renewable energy provides a solution for the higher peak-shaving capacity of coal-fired power plants.Oxy-fuel combustion is one of the most promising carbon reduction technologies for coal-fired power plants.This study has proposed a novel oxy-fuel power plant that is coupled with both liquid O2storage and cold energy recovery systems in order to adapt to the peak-shaving requirements.The liquid O2storage system uses cheap valley electricity to produce liquid O2for a later use in the peak period to enhance the peak-shaving capacity.Meanwhile,the cold energy recovery system has been introduced to recover the physical latent energy during the phase change of liquid O2to increase the power generation in the peak period.Technical economies of three power plants,i.e.a 330 MW(e) oxy-fuel power plant as reference(Case 1),the same power plant coupled with only liquid O2storage system(Case 2),and the same power plant coupled with both liquid O2storage and cold energy recovery systems(Case 3),have been analyzed and compared.Thermodynamic performance analysis indicates that the peaking capacity of Case 3 can reach the range of 106.03 to 294.22 MW(e),and the maximum peak-shaving coefficient can be as high as 2.77.Exergy analysis demonstrates that the gross exergy efficiency of Cases 2 and 3 reaches 32.18% and 33.57%,respectively,in the peak period,which are significantly higher than that of 26.70% in Case 1.Economic analysis shows that through selling the liquid O2and liquid CO2,combined with carbon trading,the levelized cost of electricity(LCOE) of the three cases have been greatly reduced,with the lowest one of 30.90 USD/MWh shown in Case 3.For a comprehensive consideration,Case 3 can be considered a future reference of oxy-fuel power plant with the best thermodynamic and economic performance.