Advances and development trend of carbon dioxide thermodynamic cycles applied in novel energy systems

<p indent="0mm">To develop the novel energy system, it is necessary to break through the efficiency bottleneck of traditional energy systems, and improve the accommodation capacity of clean energy. However, traditional thermodynamic cycles make it difficult to meet the urgent demands of novel energy systems in terms of efficiency, cost, and flexibility. Therefore, the development of novel thermodynamic cycles is of great significance in addressing the challenges of energy utilization. As a natural working medium, carbon dioxide has economic and efficient advantages in energy conversion and energy storage, and the potential of applying carbon dioxide thermodynamic cycles to novel energy systems is being progressively explored. Benefiting from its high density, low viscosity and excellent heat transfer performance, the supercritical carbon dioxide provides high thermal efficiency and enables compact system designs in energy conversion systems. In the field of energy storage, carbon dioxide is easily liquefied, and its density is higher than air under the same state and pressure, which can reduce the storage volume. Therefore, energy storage technology based on carbon dioxide thermodynamic cycles can provide high-density and high-efficiency energy storage solutions for new energy systems. In order to elucidate the application prospects of carbon dioxide thermodynamic cycles, this paper systematically reviews the recent advancements in power generation and energy storage technology based on carbon dioxide thermodynamic cycles, and analyzes its key problems and challenges in the aspects of technology realization, system optimization and engineering application. Firstly, according to the distinct roles of the carbon dioxide working medium in the energy systems, we classify various carbon dioxide thermodynamic cycles and provide a detailed overview of their working principles and characteristics. The technical challenges associated with their application in power generation and large-scale energy storage are analyzed from the perspectives of equipment design, operation control, and engineering demonstration. Secondly, in the field of efficient power generation systems, taking the clean solar thermal power generation system with large installed capacity and traditional coal-fired power generation system as examples, the current status and difficulties of the application of carbon dioxide power cycles are discussed, and the application prospects in novel energy systems are further explored. In the field of large-scale energy storage, the research status and key problems of compressed carbon dioxide energy storage technology are reviewed, supplemented by a discussion on the research progress and development trend in thermodynamic cycle optimization, large-scale storage, and efficient conversion of carbon dioxide. Finally, from the aspects of theory, technology and demonstration application, an outlook on the future research direction of dioxide thermodynamic cycles is put forward.