Understanding Chinese energy-environmental efficiency: performance, decomposition, and strategy

Understanding energy-environmental efficiency is important for coordinating economic development and eco-environment protection through energy use; however, vague definitions and conflicting results confuse researchers and policymakers and impact China's high-quality development. After delimiting energy-environmental efficiency, this study employed the intermediate adjustment situation three-stage Slacks-Based Model Data Envelopment Analysis model to explore Chinese provincial energy-environmental efficiencies from 1995 to 2018, and discussed their impacts by regional strategies. The results illustrated that Chinese energy-environmental efficiencies were overestimated, and their national average value dropped from 0.573 to 0.361 after removing the influence of external environmental factors and random interference. Moreover, energy-environmental efficiencies in East China performed significantly better than other regions, with expanding gaps between regions existed. Moreover, China maintained low-scale efficiency and high pure energy-environmental efficiency, and the low-scale efficiency led to the worrisome energy-environmental efficiency. Fortunately, pure energy-environmental efficiencies were promising, but their downward trends that started in 2002 should be a warning. Unexpectedly, the regional strategies held various impacts, they benefitted overall energy-environmental efficiency and scale efficiency, but not help pure energy-environmental efficiency, and the impacts were weak and short time. Policymakers should improve scale efficiency and formulate regional strategies in a timely manner to maintain energy-environmental efficiency improvement.