1. College of Economics and Management, Tianjin Renai College, Tianjin 301636, China
2. College of Management and Economics, Tianjin University, Tianjin 300072, China
3. Energy Policy Research Group (EPRG), University of Cambridge, Cambridge CB2 1AG, UK
4. Econometric Institute, Erasmus School of Economics, Erasmus University Rotterdam, 3062 Rotterdam, The Netherlands