Cross-provincial electricity allocation and regional energy development: Evidence from China's ultra-high voltage grid expansion

Cross-provincial electricity allocation has expanded in China to address the spatial mismatch between clean power supply and demand. However, its effectiveness depends not only on infrastructure deployment but also on operational coordination and grid utilization across provincial boundaries. Whether such inter-provincial power accessibility improves regional energy development and reshapes spatial interactions is therefore policy-critical for electricity infrastructure governance. Using ultra-high voltage commissioning as an indicator of cross-provincial transmission connectivity and allocation capacity, we employ a Double Machine Learning framework coupled with causal mediation analysis to estimate the impact and heterogeneity of cross-provincial allocation on provincial energy development from 2012 to 2022, measured by a High-Quality Energy Development (HQED) index. To capture spatial interactions, we construct a grid-enhanced spatial weight matrix that integrates interprovincial grid topology with geographic proximity, thereby tracing the structural evolution of the national energy network. Our empirical evidence reveals that cross-provincial allocation exerts a robust positive effect on regional energy development, with greater gains in regions with transmission hub functions and a larger point estimate for less-developed provinces. Mechanism analysis identifies electrification as the most important positive pathway, while also showing that these gains depend on the stringency of total energy consumption constraints. Furthermore, cross-provincial allocation is associated with stronger topology-based spatial linkages in energy technology development, necessitating a paradigm shift in governance from localized, proximity-based coordination toward a nationally integrated framework anchored in topological connectivity. Our findings offer transferable evidence for reducing institutional barriers and strengthening spatial coordination in infrastructure-enabled low-carbon energy transitions.