Spatial variation of energy efficiency based on a Super-Slack-Based Measure: Evidence from 104 resource-based cities

Energy efficiency is tied to energy activities and environmental effects and serves as a useful tool for sustainability analysis. Few insights have been acquired for sustainability development from resource-based cities in developed or developing countries. A Super-Slack-Based Measure (Super-SBM) with undesirable outputs is established to account for the total-factor energy efficiency from an energy-economy-environment perspective. Using China as a case study, the spatial variation in energy efficiency from 104 resource-based cities is analysed, furthermore, the results are compared with a scenario that does not consider environmental constraints. Finally, resource-based cities are classified into three categories through K-means clustering technology: high-efficiency region, medium-efficiency region and low-efficiency region. The investigation results show the following: (1) Efficiency disparities exist in resource-based cities under different scenarios, as a whole, the energy efficiency in the scenario two considering by-products of energy activities is obviously lower, which can more truly represent the sustainability of resource-based cities. (2) Most resource-based cities are in low-efficiency zones with substantial room for improvement. Spatial agglomeration effect or spatial spillover effect appears in a few cities. (3) Urban development in developing countries may follow the full life cycle process of local resources. A total of 262 resource-based cities could be roughly categorized into four types. The energy efficiency of growing type is the highest, followed by grow-up type, recessionary type, and regenerative type. (4) The ordering of efficiency in resource-based city is as follows: oil and gas-based > multiple minerals-based > non-metallic-based > nonferrous metal-based > coal-based > forestry-based > ferrous metal-based. The discussion offered in this study for various types of resource-based cities could provide a reference for other cities or developing countries which are in similar industrialization phases and hope for sustainable development