Spatial and temporal research on ecological total factor energy efficiency in China: Based on "Ecology-Economy-Geography" heterogeneity framework

Scientific measurement of energy efficiency is the cornerstone of improving energy efficiency and realizing energy transition. Considering that the production technology of each region is restrained by factors including economic development and natural resource endowment, this paper first uses the emergy theory to measure the ecological carrying capacity of each region, and then selects other representative data to construct the "Ecology-Economy-Geography" heterogeneous framework. From the perspective of energy input minimization, the spatial and temporal features of China's ecological total factor energy efficiency (ETFEE) from 2006 to 2019 have been discussed by employing the sequential directional SBM model and Luenberger productivity index. After robustness tests, we conclude that: (a) The grouping results under multidimensional variables are different from the traditional grouping of "East-Central-West"; (b) The meta-frontier Ecological Total Factor Energy Efficiency (METFEE) and group frontier Ecological Total Factor Energy Efficiency (GETFEE) vary in spatial distribution and temporal change; (c) Technological progress is the key to improving METFEE, but part of the improvement will be offset by diminishing returns of "catch-up effect". Finally, policy recommendations to promote the ecological total factor energy efficiency in China are put forward.