Performance study of a novel supercritical CO2 solar-coal supplementary power generation system

Abstract

• New supercritical CO 2 solar-coal supplementary power generation system is proposed. • The annual solar generating power accounts for 61.29% of the total power output. • Standard coal consumption rate is 161.11 g/kWh lower than pure coal-fired system. • The new system performances with the change of the load rate are revealed. • Effects of solar multiple and thermal energy storage capacity on new system are studied. To reduce the CO 2 emission and improve the solar energy utilization rate, a novel supercritical CO 2 solar-coal supplementary power generation system is proposed. Compared with the previous studies on supplementary systems, the novel system takes solar energy as the main heat source instead of coal, which greatly increases the proportion of solar energy input. The results show that, when the solar multiple (parameter representing the area of the heliostat field) is 3 and the thermal energy storage capacity is 16 h, on the summer and winter solstices, the proportions of solar generating power are 100% and 57.15%, respectively. The novel system can operate steadily during the whole year. The annual solar generating power is 161.07 GWh, accounting for 61.29%. The standard coal consumption rate of the novel system is 101.76 g/kWh, 161.11 g/kWh lower than that of the pure coal-fired system. The exergy efficiency for the novel system increases with an increasing operation load rate. Under 50%, 75%, 100%, and 125% load rates, the exergy efficiencies are 16.7%, 25.0%, 33.4%, and 38.0%, respectively. It is the first time to study the effects of the solar multiple and the thermal energy storage capacity on the energy, exergy, environmental, and economic performances of the supercritical CO 2 solar-coal supplementary power generation system. When the thermal energy storage capacity is 16 h, the solar multiple corresponding to the optimal economic performance is 2.5.