Review of supercritical CO2 power cycles integrated with CSP

Increasing demand of electricity and severer concerns to environment call for green energy sources as well as efficient energy conversion systems. SCO₂ power cycles integrated with concentrating solar power (CSP) are capable of enhancing the competitiveness of thermal solar electricity. This article makes a comprehensive review of supercritical CO₂ power cycles integrated with CSP. A detailed comparison of four typical CSP technologies is conducted, and the cost challenge of currently CSP technologies is pointed out. The thermophysical properties of sCO₂ and the corresponding two real gas effects are analyzed elaborately to express the features of sCO₂ power cycles. An extensive review of sCO₂ layouts relevant for CSP including 12 single layouts and 1 combined layout is implemented logically. Strengths and weaknesses of sCO₂ power cycles over traditional steam-Rankine cycle generally adopted in current CSP plants are concluded, followed by metal material degration summary in CSP relevant temperature sCO₂ environment, which shows that the nickel-based alloy is a proper structural material candidate for sCO₂-CSP integration. Thermodynamic analyses of sCO₂ power cycles when integrated with CSP are divided into three level of which design-point analysis and off-design modeling are conducted and compared, more researches into the off-design point analysis, dynamic modeling, especially the transient behavior are suggested. Economic analysis of the integrated system is concluded and presents a considerable levelized cost of electricity reduction of 15.6% to 67.7% compared to that of state of art CSP. Taking the thermodynamic and economic analysis into consideration, target designs of sCO₂ power cycles for CSP are summarized in three aspects. Finally, current theoretical and experimental researches of sCO₂ power cycles integrated with CSP for market penetration are introduced. The strengths, weaknesses, and potential solutions to the gaps of three potential pathways (molten salt pathway, particle pathway, and gas phase pathway) to realize the integration of sCO₂ power cycles in the next CSP generation plants up to 700°C are reviewed. In general, the integration of sCO₂ power cycles with CSP technologies exhibits promising expectations for facilitating the competitiveness of thermal solar electricity.