Environmental efficiency analysis of Chinese container ports with CO2 emissions: An inseparable input-output SBM model

We adopt an inseparable input-output slack-based measure model to estimate the environmental efficiencies of eight container ports in China during 2005-2014. Empirical results show that the pure technical environmental efficiency (PTEE) of container ports is low with a mean value of 0.567. Small differences are found among the ports in different regions. The Bohai Bay Rim port cluster shows the highest PTEE with a mean value of 0.601, followed by the Southern and Pearl River Delta port cluster, and the Yangtze River Delta port cluster with the lowest efficiency and a mean value of 0.537. The effect of input inefficiency on the PTEE of the eight container ports is greater than that of output inefficiency. CO2 inefficiency is 0.226 in Tianjin port but is as high as 0.206 in Ningbo port. In addition, Guangzhou and Dalian ports show low CO2 inefficiency of below 0.1. Different container ports present dissimilar CO2 emission reduction potentials. Most container ports exhibit excessive CO2 emissions in significantly different levels. Shanghai and Shenzhen ports should reduce 230,644 and 181,828 tons of CO2, respectively. A few target policies for improving the environmental efficiency of China's container ports are also proposed.