1. LSE Cities, London School of Economics and Political Science, Houghton Street, London WC2A 2AE, England
2. EDF R and D Center, Asia Pacific Direction-China Division, Henderson Center, Tower 2, 12th floor, 18 Janguomennei Avenue, 100005 Beijing, China
3. European Institute for Energy Research, Karlsruhe Institute of Technology, Emmy-Noether-Strasse 11, 76131 Karlsruhe, Germany