Spatial spillover effects and driving mechanisms of carbon emission reduction in new energy demonstration cities

The new energy demonstration city (NEDC) policy is an important strategic initiative for China to promote the priority development of renewable energy and build an ecological civilization system. Objectively evaluating its impact on carbon emissions is crucial for promoting urban energy transition and low-carbon governance. This study utilized nighttime light remote sensing data fitting to obtain city-level carbon emission data from 2006 to 2019. A spatial difference-in-difference model and a mechanism analysis model were constructed to analyze the spatial spillover effect and driving mechanism of NEDC policy on urban carbon emissions. The results indicate that NEDC policy not only effectively reduces local carbon emissions but also exhibits notable spatial spillover effects, promoting carbon reduction in surrounding cities. The boundary of spatial effect decay is 1000 km. Reducing energy consumption, improving energy efficiency, and promoting technological innovation are effective mechanisms for NEDC policy to reduce urban carbon emissions. Furthermore, NEDC policy also has a significant spatial spillover effect under the urban agglomeration association network, but exhibits heterogeneity across different types of urban agglomerations. Grounded in the context of China's reality, this study provides valuable insights for further advancing the strategic construction of NEDCs and formulating effective urban energy-saving and emission reduction policies.