Correlation and synergy analysis of urban economy–energy–environment system—A case study of Beijing

The coordination of economy, energy, and environment plays an important role for cities seeking green transformation and sustainable development. However, poor information and equivocal data are what often face the related analysis. In this paper, the correlation and synergy of the urban economy–energy–environment system are analyzed. First, the Grey relational analysis and entropy weight method are combined and introduced to analyze the correlation degree in the indicator level and the subsystem level of the 3E system. Then, the concepts of ordinal parameter and comprehensive correlation degree are introduced, to evaluate the ordering degree of subsystems and the synergy degree of compound systems. Finally, the data of Beijing from 2008 to 2017 are used for empirical study. Results suggest that a fluctuating tendency of low synergy or none synergy is observed in the Beijing 3E system. Furthermore, the improvement of the energy subsystem displays dominant effects on the coordinated development of compound systems, and the technological innovation and structural optimization in industries could help to improve the Beijing economy–energy–environment system.