The power of institutional innovation in the urban carbon unlocking: A study on collaborative empowerment of digital policy and new energy policy

The coordinated implementation of new energy policy and digital policy is a key institutional innovation for carbon unlocking in China. This study, based on constructing urban carbon unlocking efficiency, conducts a quasi-natural experiment on dual policy coordination empowerment through New Energy Demonstration City Pilots and the "Broadband China" Strategy. Utilizing panel data from 273 prefecture-level cities in China from 2012 to 2022 and dual machine learning models, the research examines the synergistic mechanism and multidimensional effects of dual policy in promoting carbon unlocking efficiency. The findings reveal that the dual policy exhibit a clear synergistic effect on carbon unlocking, with the empowering effect of combined policies being more pronounced compared to singular policies, a conclusion that remains robust after a series test. Moreover, the dual policy indirectly support carbon unlocking through environmental attention, technological innovation, and industrial upgrading. Heterogeneity analysis indicates that the dual policy has a more significant positive impact in central cities, cities with a high level of digital economy, and cities with a focus on environmental protection, underscoring the importance of tailored advancement of dual policy. This research provides valuable insights for governments in achieving the carbon unlocking through enhancing the coordination of "green-digital" policies.