Life-Cycle Low-Carbon Assessment of Overhead Transmission Lines in China: A Combined Approach Using the Analytic Hierarchy Process and Entropy Weighting

Driven by global carbon neutrality targets, the low-carbon transformation of power systems necessitates rigorous carbon evaluation of grid infrastructure. However, existing assessments of overhead transmission lines often exhibit incomplete life-cycle boundaries and lack a coordinated approach to subjective and objective weight allocation. To address these gaps, this study targets overhead transmission lines and constructs a comprehensive low-carbon evaluation index system comprising 14 indicators across four life-cycle stages, namely design, construction, operation, and recycling. A hybrid evaluation model is proposed based on the combined analytic hierarchy process and entropy weighting method. The analytic hierarchy process is utilized to derive expert-based subjective weights, while the entropy weighting method extracts objective data variations from multiple samples, which are then integrated to obtain robust composite weights. An empirical analysis conducted on a 500 kV double-circuit overhead transmission line project in China validates the proposed framework. The results reveal a comprehensive evaluation score of 80.219, corresponding to a “low-carbon” grade. Moreover, the line loss rate (0.234227), operational carbon emissions (0.133978), and steel consumption per unit length (0.122381) are identified as the pivotal indicators dominating the evaluation outcome. This research provides quantitative support and practical criteria for decision-making regarding low-carbon design, green construction, operational loss reduction, and resource-oriented retirement of transmission line projects.