Pilot Free Trade Zones and Renewable Energy-Related Product Exports in China: Evidence from a Staggered Difference-in-Differences Analysis

Institutional opening-up may influence the cross-border supply of technologies used in the energy transition. Using a panel of 31 Chinese provincial-level administrative units from 2008 to 2024, this study examines renewable energy-related product exports following the staggered establishment of pilot free trade zones (PFTZs). The two-way fixed-effects estimate with five controls is 0.394 in units of CNY 10 billion, equivalent to approximately CNY 3.94 billion at current prices, and is significant at the 1% level. A Callaway–Sant'Anna specification with the same five covariates also yields a positive overall estimate. Results differ by outcome scale: the corresponding log-export estimates are not statistically significant. Sensitivity intervals include zero when larger departures from parallel trends are allowed. The restricted wind/PV-related basket yields a positive coefficient significant only at the 10% level and retains multipurpose products. Regressions for green invention patent applications and the business-environment index provide suggestive evidence consistent with the proposed channels, but do not identify indirect causal effects on exports. The business-environment evidence warrants particular caution because 70.59% of its annual observations are interpolated or extrapolated. Formal comparisons indicate overall differences across products and regions, but do not justify a general ranking of all subgroup effects. Destination analysis is restricted to a fixed end-2024 Belt and Road partner list and its complement. The findings provide provincial evidence on institutional opening-up and energy technology-related trade. Their sustainability implications depend on product uses and overseas deployment, which are not directly observed.