Exploring the nonlinear causal Nexus between industrial robot imports and renewable energy transition: A PSTR model analysis of belt and road countries

Industrial robots play a significant role in promoting the development of renewable energy throughout the production process. However, this mechanism has not yet been systematically explored in existing research. To address this gap, this study focuses on countries along the Belt and Road Initiative, which accounts for over one-third of global industrial robot imports, and constructs a three-dimensional analytical framework. Specifically, energy intensity is used as the threshold variable for endowment capacity, fossil fuel subsidies and financial development for guiding capacity, and R&D intensity for absorptive capacity. Using a panel smooth transition regression (PSTR) model, we empirically examine the nonlinear impact of industrial robot imports on renewable energy transition and its boundary conditions. The quantitative findings reveal four key patterns. First, robot imports have no effect when the energy intensity is below 5.86, hinder the transition when it falls between 5.86 and 6.83, but promote the transition when it exceeds 6.83. Second, for fossil fuel subsidies, the negative effect is less pronounced at medium levels (1.34–15.46 billion USD), but rebounds at high levels. Third, in the case of financial development, the impact is inverted U-shaped: robot imports facilitate the transition when the credit-to-GDP indicator is below 73.82%, but suppress the transition above this threshold. Fourth, when R&D intensity exceeds 1.67%, robot imports are detrimental to the transition due to technological lock-in. These findings provide policy insights for transitions in developing countries.