Direct integration of supercritical carbon dioxide-based concentrated solar power systems and gas power cycles: Advances and outlook

Abstract

The integration of concentrated solar power systems with supercritical carbon dioxide (sCO₂) power cycles offers a promising pathway for sustainable electricity generation. Despite the growing interest, no comprehensive review has yet been dedicated to this emerging technology, which is still in its early stages of development and requires a systematic evaluation of its technical, economic, and operational challenges to unlock its full potential for sustainable electricity generation. This systematic review examines the current global status of directly integrated sCO₂ power cycles with concentrated solar power, a strategy that eliminates intermediate heat exchangers, reducing thermal losses and enabling higher turbine inlet temperatures (>700 °C). This approach enhances overall thermal efficiency (up to 40 %) and Brayton cycle efficiency (up to 60 %), while lowering plant costs by 3.3–4.7 %. However, achieving these efficiencies requires operating at pressures above 20 MPa, necessitating advanced designs for the solar field, heat exchangers, piping, and storage systems, which increase capital costs. Effective control strategies are also essential for maintaining performance under off-design conditions, fluctuating ambient temperatures, and varying solar irradiance. Thermal energy storage and auxiliary heaters play a crucial role in stabilizing power supply, with thermal storage reducing the levelized cost of energy by 10.4 % compared to auxiliary heaters, though the latter has a lower initial cost. This review evaluates receiver designs, power block configurations, and key technological challenges in direct sCO₂ integration. It highlights research gaps, including the limited study of real-world conditions (e.g., non-uniform irradiance), insufficient exploration of hybrid systems integrating geothermal or biomass heat sources (potentially reducing fossil fuel use by up to 38 %), and underutilization of CO₂ mixtures, which could expand Brayton cycle applications and improve thermal efficiency by up to 7 %. Finally, the review outlines future research directions to advance high-efficiency, low-cost CSP technologies, emphasizing the need for innovative materials, optimized control strategies, and hybrid integration to enhance system viability and scalability.