Multipath retrofit planning approach for coal-fired power plants in low-carbon power system transitions: Shanxi Province case in China

The low-carbon transition of the power industry plays a critical role for China in achieving carbon neutrality. Technical retrofitting for coal-fired power plants improves their flexibility and reduces carbon emissions. China has a large stock of coal-fired power plants, and the retrofit planning of existing coal-fired power plants is an important part of the decarbonizing power system. In this study, a decision support tool that provides coal-fired power plant retrofit investment decisions in low-carbon power system transition is proposed. First, three retrofit paths are investigated. In addition to flexibility reformation, carbon capture utilization and storage reformation, a novel scheme is introduced to transform retired or aged coal-fired power plants into a Carnot battery, also known as a thermal storage power plant. Then, a multipath retrofit planning model for coal-fired power plants is proposed, in which the embedded operational problem is a unit commitment problem considering flexibility and frequency security constraints. Therefore, the problem of frequency safety and uncertainty caused by the high share of variable renewable energy in the power system is solved. The planning model is solved by hyperplane piecewise linearization and the chance-constrained deterministic transformation method. Finally, based on the Shanxi Provincial power system, the roles of flexibility reformation, carbon capture utilization and storage reformation, and Carnot battery reconstruction are analysed, and coal-fired power plant retrofit planning sug-gestions for the Shanxi power system are provided in this study.