From carbon reduction to negative carbon: a comprehensive review of regional integrated energy system planning theory and methods

Driven by the global energy transition and the urgent “dual carbon” goals, regional integrated energy system (RIES) planning is undergoing a paradigm shift from carbon reduction to negative carbon emissions. This paper provides a comprehensive review of the theoretical frameworks and technical pathways for RIES planning from a carbon-centric perspective. A key contribution is the proposed Carbon-Energy-Economy (CEE) triple-dimensional governance framework, which endogenizes carbon factors into planning decisions through emission constraints, trading mechanisms, and capture technologies. We first analyze the fundamental characteristics of RIES and their critical role in achieving carbon neutrality, detailing advancements in multi-energy coupling models, energy router concepts, and standardized energy hub modeling. The paper further explores multi-energy flow analysis methods, and systematically compares the applicability and limitations of various planning algorithms, with emphasis on addressing uncertainties from renewable integration. Finally, we highlight the integration of artificial intelligence with traditional optimization methods, offering new pathways for intelligent, adaptive, and low-carbon RIES planning. This review underscores the transition towards data-physical fusion models, cooperative uncertainty optimization, multi-market planning, and innovative zero/negative-carbon technological routes.