Review of supercritical CO2 technologies and systems for power generation

Thermal-power cycles operating with supercritical carbon dioxide (sCO2) could have a significant role in future power generation systems with applications including fossil fuel, nuclear power, concentrated-solar power, and waste-heat recovery. The use of sCO2 as a working fluid offers potential benefits including high thermal efficiencies using heat-source temperatures ranging between approximately 350°C and 800°C, a simple and compact physical footprint, and good operational flexibility, which could realise lower levelised costs of electricity compared to existing technologies. However, there remain technical challenges to overcome that relate to the design and operation of the turbomachinery components and heat exchangers, material selection considering the high operating temperatures and pressures, in addition to characterising the behaviour of supercritical CO2. Moreover, the sensitivity of the cycle to the ambient conditions, alongside the variable nature of heat availability in target applications, introduce challenges related to the optimal operation and control. The aim of this paper is to provide a review of the current state-of-the-art of sCO2 power generation systems, with a focus on technical and operational issues. Following an overview of the historical background and thermodynamic aspects, emphasis is placed on discussing the current research and development status in the areas of turbomachinery, heat exchangers, materials and control system design, with priority given to experimental prototypes. Developments and current challenges within the key application areas are summarised and future research trends are identified.