In China, coal security issues are strongly linked to national energy security and economic and social stability. Facing environmental protection constraints, research on China’s coal security should analyze both supply and demand security. In this study, 19 criteria were selected for four subsystems (coal supply chain, coal market, economy and demographics, and social ecology) to construct an evaluation system for China‘s coal supply and demand security. Entropy and TOPSIS methods were used to evaluate coal security for 2002–2019. The obstacle factors affecting coal security for each subsystem were determined, and the grey model was used to predict the security and obstacle degree for each subsystem for 2020 and 2021. The results indicate that (1) China’s coal supply and use safety level in the period 2002–2019 was below a relatively safe level, i.e., at a safe early warning level during the period 2010–2014 and at a general safety level in the remaining years. (2) The basic coal reserves, the reserve-production ratio of the basic reserves, the balance of social coal stocks at the beginning and the end of the year, and the proportion of coal imports to consumption, urbanization rate, carbon dioxide emissions, and coal consumption in thermal power generation are the main obstacle factors that affect the safety of coal supply and use in China. (3) The obstacle degree of the coal production and supply evaluation subsystem is higher than that of the other three sub-systems, and the overall change trend during the study period showed a downward trend at first, followed by an upward trend.

The reasonable optimization of energy structures and improvement of energy utilization efficiency are the inevitable way to achieve new progress in ecological civilization construction. The Yangtze River Economic Belt, as the leading demonstration area of China’s ecological civilization construction, is of great significance to take the lead in clarifying its energy efficiency situation under the dual-carbon goal. For this purpose, this paper uses the super-efficiency SBM model, ML index and Tobit model considering undesired output to explore the energy efficiency and the main factors affecting it of nine provincial capitals and two municipalities in the Yangtze River Economic Belt from 2003 to 2019. The results show that: (1) During the investigation period, the energy efficiency values of 11 cities are above 1, with a recent trend of decline, and the energy efficiency difference between regions is still expanding. (2) From 2003 to 2019, the overall energy efficiency of the Yangtze River Economic Belt has gradually improved with an average annual growth rate of 4.7%. Technological progress is the main force behind efficiency improvement, technical efficiency plays a small role, and the growth rate of the scale efficiency change index is only 1.3%, which means that the existing scale system of the Yangtze River Economic Belt still needs to be further improved. (3) The impact of industrial structure and government dominance on energy efficiency is significantly positive, while the degree of opening to the outside world is significantly negative. The relationship between economic development level and energy efficiency is an inverted “U” shape.