Supercritical CO2 as a Heat Transfer and Power Cycle Fluid for CSP Systems

Concentrating Solar Power (CSP) utilizes solar thermal energy to drive a thermal power cycle for the generation of electricity. CSP technologies include parabolic trough, linear Fresnel, central receiver or “power tower,” and dish/engine systems. The parabolic trough is the most common system with nine Solar Electric Generating Stations (SEGS) operating in southern California for over two decades and new plants online in Nevada and Spain. The resurgent interest in CSP has been driven by renewable portfolio standards in southwestern states and renewable energy feed-in tariffs in Spain. CSP has cost advantages versus solar photovoltaic systems for large, centralized power plants. Certain CSP systems, in particular parabolic troughs and power towers, are also amenable to the incorporation of thermal energy storage. Thermal energy storage is much less expensive than electric storage and allows CSP plants to increase capacity factor and dispatch power as needed — for example, to cover an evening demand peak.