Supercritical Carbon Dioxide Solar Thermal Power Generation—Overview of the Technology and Microchannel Receiver Development

The supercritical carbon dioxide (sCO₂) power cycle is being considered for solar thermal central receiver systems in the United States. The cycle lends to increased high-temperature input that is expected of the next-generation concentrating solar thermal power (CSP) systems. Power block efficiencies of about 50% can be achieved for recompression cycles at an input temperature of approximately 720 °C. Additionally, the power block is compact and less complex, raising the possibility of using thermal-storage-coupled CSP sCO₂ technologies for modular (~100 MW) peak-load power plants. Three pathways toward providing solar thermal input to the sCO₂ cycle have been proposed by various research groups—the molten salt receiver pathway, the solid particle receiver pathway, and the gas-phase receiver pathway. The first two technologies have the advantage of sensible thermal storage within the solid/fluid medium passing through the receiver. In the gas receiver pathway, there is a need for coupling a sensible or latent heat storage technology. Several key technologies are needed to enable the realization of the sCO₂ solar thermal technology, key among them being the receiver and thermal storage. In this chapter, some of the key gas-phase receiver technologies are discussed. The group’s past and recent work on the development of microchannel solar thermal receivers for sCO₂ is emphasized.