Optimizing economy-energy-environment (3Es) policy mixes for decarbonization: Synergies, trade-offs, and regional implementation in China

To promote effective carbon reduction, this study explores the synergies and trade-offs of policy mixes related to the economy, energy, and environment (3Es). To address the gap in current research, we constructed a multi-policy decarbonization effect evaluation model, while employing Spatial Durbin and Autocorrelation models with difference-in-differences method (SDM-DID/SAC-DID), to assess seven policy mixes and identify implementation priorities at the provincial level. The results revealed: (1) 3Es policy mixes showed both synergies and trade-offs, with triple-policy combinations outperforming single policies. (2) Regional disparities exist, as prioritizing implementation in northern regions can boost decarbonization by 38.45-52.88%. (3) The optimal policy paths varied across provinces, based on their 3Es transformation levels. (4) Pilot policy implementation may lead to carbon leakage, which can be mitigated by multi-policy mix. To maximize decarbonization effects, China should: (1) Integrate national strategies with provincial advantages, leveraging provincial strengths instead of adopting a “one-size-fits-all” approach. (2) Strengthen regional coordination and policy linkages to prevent carbon leakage. (3) Elevating the policy-driven transformation level, shifting from “dual control of energy consumption” to “dual control of carbon emissions” and encouraging provinces to seize opportunities in the digital economy and green finance.