Polycentric spatial structure and energy efficiency: Evidence from China's provincial panel data

Against the background of the increasing number of large and medium-sized cities and the improvement of the intercity transportation infrastructure, a polycentric urban network is gradually emerging in China. Based on panel data of 23 provinces of China over the period of 1998-2018, the dynamic impact of the polycentric spatial structure on the energy efficiency and the mechanism of this impact are explored in this paper. First, the results reveal that there exists an inverted U-shaped relationship between the polycentric spatial structure and the energy efficiency. Nevertheless, the polycentric spatial structure has not yet reached the optimal level in all provinces. Second, the market integration and factor flow are important paths for the polycentric spatial structure to affect the energy efficiency. Third, the inverted U-shaped impact of the polycentric spatial structure on the energy efficiency is mainly reflected in the eastern and central regions, while the phenomenon is not significant in the western region. Finally, the distances between cities and the level of the transportation infrastructure have significant non-linear moderating effects in the process of the polycentric spatial structure affecting the energy efficiency. These findings provide empirical evidence for the coordinated development of China's regional space planning and energy efficiency.