Supercritical Carbon Dioxide Power Cycle Integrated with Solar Power Tower and Oxy-Combustor

Abstract

Power cycle that integrates solar power tower (SPT) system with direct oxy-combustion (DOC) supercritical CO2 cycle is proposed and investigated. In the SPT/DOC-sCO2 cycle (Cyc 3), the SPT works as preheater for the DOC/sCO2 system. Two more basic cycles for comparison and validation purposes are investigated including stand-alone intercooled sCO2 power cycle driven by DOC system (Cyc 1) and stand-alone basic SPT system (Cyc 2). Energy, exergy, exergoeconomic, levelized cost of electricity (LCOE) and multi-objective optimization analyses are performed for each cycle over wide range of operating pressures, temperatures and direct normal irradiance. Compared to Cyc 1 and Cyc 2, Cyc 3 has higher thermal efficiency by 6% and 2%, respectively with higher exergy efficiency and is less sensitive to cycle minimum temperature. However, the LCOE of Cyc 3 is higher due to the large capital cost of its individual CSP and DOC systems. From the optimization analyses, it is found that the decision variables of the three cycles tend toward low Pmax, higher Pmin, lower Tmax, and lower Tmin. The multi-objective optimization shows that the thermal efficiency and LCOE are 41.06% at 6.35¢/kWh for Cyc 1,45.56% at 7.86¢/kWh for Cyc 2, and 46.65% at 8.05¢/kWh for Cyc 3.