1. Introduction
China is currently the world’s largest producer and consumer of energy, and coal is the main energy source, with the highest degree of stability, economy, and independent guarantee in China. For a long time, coal has occupied a dominant position in China’s energy production and consumption structure, which has served as a strong impetus for China‘s rapid economic and social development. According to data from the National Bureau of Statistics of China, from 1949 to the end of 2021, the coal industry generated nearly 96.5 billion tons of coal, with the annual output increasing from 34.32 million tons in 1949 to 680 million tons in 1978 and to 4.07 billion tons in 2021, while China’s gross domestic product (GDP) rose from CNY 364.5 billion in 1978, which was in the early days of reform and the opening of the country to international markets, to CNY 114.4 trillion in 2021. The numerous advantages of coal for China, such as its availability, production capacity, consumption proportion, and low cost, mean that there is unlikely to be a short-term shift in China’s coal-based energy system.
However, given the complex and changeable nature of the international environment, China’s economy has begun to move toward a low-carbon future based on its dual carbon goals (i.e., to reach peak carbon emissions in 2030 and to become carbon neutral by 2060). While China’s energy security strategy is now promoting the development of green and low-carbon technologies, it remains necessary to maintain the role of coal in guaranteeing energy security during this energy transformation. On 22 March 2022, Han Zheng, a member of the Standing Committee of the Political Bureau of the CPC Central Committee and Vice Premier of the State Council, stressed at a symposium on the clean and efficient utilization of coal that “We must persist in promoting clean and efficient utilization of coal from the actual situation of our country, give full play to the role of coal as the bottom guarantee, and ensure the national energy and electricity security”. Thus, it is necessary to clearly understand the dominant position of coal in China’s national energy system, consolidate its role in preserving the energy security of the country, and improve the security of coal supply and demand in order to promote the smooth transition to a more sustainable and environmentally friendly energy system while maintaining a safe and stable supply of energy.
However, China’s coal supply chain and coal market mechanisms are not perfect. In recent years, due to the influence of global energy patterns, international trade friction, coal import policies, spatial changes in coal production and demand, environmental constraints of carbon emissions, and the conflict in supply and demand between coal and electricity, China’s coal supply and demand security has been consistently under threat, particularly with the emergence of coal supply shortages and the imbalance between supply and demand. China’s energy security does not rely only on the energy supply; energy consumption is a major consideration as well. Similarly, coal security concerns both supply and demand. On the one hand, a consistent supply of coal is a basic guarantee for China’s energy security; thus, it is important to identify and address any shortcomings in the coal supply chain and promote the balanced development of the coal market. On the other hand, in response to the requirements for the development of high-quality technologies that can contribute to meeting the dual-carbon target and actively respond to climate change, the impact of coal demand on the economy, society, and the ecological environment also needs to be considered.
In this paper, we study coal security in China by identifying the factors affecting both the supply of and demand for coal and presenting corresponding policy suggestions. This research is important for ensuring the safe and stable supply of coal and coal-generated power in China, promoting the development of the coal industry, maintaining the role of coal in national energy security, and providing solid support for stable and sustainable economic development. Based on the research results, we present policy suggestions that address the weak links in China’s coal supply chain and promote the balance between supply and demand in the coal market. Additionally, this research provides a policy basis for the development of high-quality energy infrastructure, coping with climate change, reducing the adverse impact of coal use on the social ecology, and promoting the security of coal supply and demand in order to support the role of coal in ensuring China’s energy security.
2. Literature Review
The two oil crises in the 1970s threatened the energy security of various countries; thus, energy security has become a focus of many researchers worldwide. Initially, energy security research focused on oil security, with the intention of preventing oil supply interruptions and ensuring oil supply security [
1]. However, in accordance with the constant changes in the global energy structure, research on energy security in various countries has shifted from oil security to overall energy security, encompassing oil, coal, natural gas, and electric power, in addition to individual studies on various energy sources.
Energy security is vital to the economic and social development of all countries. Early research on energy security centered on the security of energy supplies [
2], defining energy security as obtaining an adequate energy supply at a reasonable price. This definition has received widespread recognition from international energy research institutions such as the International Energy Agency (IEA) [
3,
4] and the Asia Pacific Energy Research Center [
5]. With the development of the economy, society, science, and technology, and the rise in public awareness regarding environmental protection and sustainable development, the definition and connotations of energy security have expanded. For example, Radovanovic et al. [
6] pointed out that energy security should include environmental and social perspectives, and the sustainability of energy demand has also become the focus of attention. Consequently, the traditional perspective of supply security has evolved into a comprehensive energy concept aimed at supply and demand security. In particular, Wei et al. [
7] defined energy security as an available, affordable, and sustainable energy supply that meets the needs of national economic development while ensuring that the production and use of this energy will not damage the sustainable development of the ecological environment. In recent years, quantitative research on energy security in China and internationally has steadily increased, and the research methods involved in the evaluation of energy security have diversified [
8]. A summary of significant representative studies on the comprehensive evaluation of energy security both domestically and internationally is presented in
Table 1, with the format and style of the table referring to references [
9].
International quantitative research on the evaluation of energy security has mainly focused on energy security indicators and multi-index comprehensive evaluation systems for global or national energy security, with most targeting oil and natural gas or the energy system in general. In contrast, there have been few studies on coal security. At present, the most widely used energy security indicators include the Shannon–Wiener index, the Herfindahl–Hirschman index, the energy price index, energy dependence on foreign countries, and the energy consumption intensity. Although these indices focus on the key points of the energy security problem, they do not comprehensively and objectively reflect the complexity of energy security in practical applications, and subsequently, cannot be used to comprehensively evaluate energy security [
9]. A multi-index evaluation framework should reflect the multifaceted and complex nature of energy security systems along multiple dimensions and should comprehensively measure and analyze energy security. For example, Cabalu [
10] constructed an index system for natural gas supply security and used it to evaluate the natural gas supply security of seven natural gas-importing countries in Asia. In addition, Prambudia et al. [
11,
12,
17] applied an integrated simulation model and the matrix method to construct an energy security evaluation framework based on different dimensions.
Domestic quantitative research on the evaluation of energy security has mainly developed in two directions: the comprehensive evaluation of China’s energy security as a whole and the assessment of primary energy sources such as coal, oil, and natural gas. Xue et al. [
1,
8,
15,
19,
20,
22] included different types of energy, such as coal, oil, natural gas, and clean energy, in their analysis of energy security and created a comprehensive energy security evaluation index based on different dimensions to evaluate, analyze, and predict national or regional energy security. In contrast, Li et al. [
24] constructed a quantitative analysis framework for the energy security of natural gas only based on different dimensions, whereas Tian et al. [
13,
14,
18,
21] constructed a coal security evaluation index consisting of a number of factors to systematically study the coal supply and demand in China. These assessments have employed a variety of methods for determining weights for their respective indices, including the entropy method, the analytic hierarchy process (AHP), factor analysis, vertical and horizontal grading, set pair analysis, the technique for order of preference by similarity to ideal solution (TOPSIS), and BP neural networks, with one study combining associative group analysis (AGA), the express analytic hierarchy process (EAHP), expectation maximization (EM), grey relational analysis (GRA), and TOPSIS.
Despite the extensive quantitative research that has been conducted on domestic energy security evaluation, this research has a number of shortcomings. First, most of this research, both in China and worldwide, has focused on energy security as a whole, and only a few studies have addressed the security of the coal supply and demand. Second, domestic research on coal safety has mainly focused on the evaluation of coal resources, the market, the economy, society, the environment, and other factors from a macro perspective, or have based their evaluation on the dimensions of availability, sustainability, and technological development. Thus, comprehensive evaluation research that combines the macro and meso perspectives is lacking. Third, research on coal security has primarily investigated the coal supply and production, and few studies have considered current economic and social ecological requirements or comprehensively evaluated the security of the coal supply and demand based on the comprehensive energy view. Finally, there has been little research on the in-depth identification and analysis of factors affecting security levels, especially in the study of coal security.
Due to differences in economic and social development, energy reserves, energy consumption structure and scale, energy policies and systems, ecological and environmental constraints, and the ability to access international resources, individual countries differ in their strategic positions with regard to the security of fossil-based energy sources such as oil, coal, and natural gas. In China, coal remains an irreplaceable source of energy, and it is important to analyze the security of the coal supply and demand. The present study is based on domestic and international research on security evaluation indices for international and domestic energy systems and on primary energy security, such as oil, coal, and natural gas. Given China’s national energy situation and energy reform policies, it is of great theoretical and practical importance to construct a comprehensive evaluation index for coal supply and demand security that encompasses economic, social, environmental, coal market, and coal supply chain dimensions and to identify significant obstacles to coal supply and demand security.
The main goals of the current research are as follows. First, from traditional overall systematic research on energy security to independent research on coal supply and demand security, the current study seeks to enrich energy security research. Second, to extend traditional coal supply security research, this study comprehensively examines the coal supply and demand security and its obstacle factors. Third, in order to understand the changes in the security of China’s coal supply and demand in recent years, the main influencing factors and weak links in the coal supply system, and the adverse effects of coal demand, it is necessary to develop a criteria system and identify obstacles to conduct a quantitative analysis to take effective targeted measures to enhance risk prevention and control coal security. Fourth, because coal is the main energy source in China, it is difficult to change the domestic energy situation in the short term. Therefore, in-depth research on the security of the coal supply and demand will support coal’s role as an important element in the energy transition process.
In the construction of the coal supply and demand security evaluation index system, this study considers coal resource endowment, production, transportation, inventory, and other supply chain links to form a comprehensive evaluation network chain structure. Based on Xue et al.’s [
1,
13,
16,
20] research methods, this study uses the entropy method, which is objectively weighted, and TOPSIS, which is suitable for the comprehensive comparison of a limited number of evaluation objects, multiple evaluation criteria, and multi-objective decisions, to conduct a comprehensive evaluation of the security of the coal supply and demand. Furthermore, to examine the coal security situation in China for the period 2002–2019, this study refers to relevant methods from past studies [
1,
8,
26,
27] and utilizes the obstacle degree method to quantitatively analyze the factors that affect the safety of coal supply and use, and identify and analyze the main influencing factors and weak links. In addition, the GM(1,1) model is used to predict the degree of security and the obstacle degree of the selected criteria for 2020–2021. Past study on the comprehensive evaluation of China’s coal security over the past five years is summarized in
Table 2, with the format and style of the table referring to references [
9,
28].
4. Results and Discussion
4.1. Weight Calculation Results
Using Equations (1)–(6), the entropy weighting method was used to calculate the weights of the individual criteria and each subsystem. It is evident that the subsystems and criteria within these subsystems had different effects on the overall evaluation system. The top five criteria in terms of their weights were the reserve–production ratio of the basic reserves, the proportion of non-coal energy consumption in energy consumption, carbon dioxide emissions, the proportion of coal imports in consumption, and the proportion of total power generation hours from coal (
Table 6).
4.2. Analysis of the Comprehensive Evaluation Results
TOPSIS was used to calculate the Euclidean distance between each evaluation criteria and the positive and negative ideal solutions using Equations (7)–(11). Equation (12) was used to calculate the strength and ranking of China’s coal supply and demand security for the 2002–2019 period (
Table 7), with the overall security level classified according to the evaluation criteria presented in
Table 3. Overall, China’s coal supply and demand security was below the relatively secure level during the study period; it was at a warning level during the 2010–2014 period and at a generally secure level for the remaining years. During the warning period, the reserve–production ratio for China’s coal resources (A2) and the difference in the coal social stock between the beginning and the end of the period were low. In addition, the proportion of coal imports (B2), the natural population growth rate (C2), the contribution of secondary industry to GDP (C4), carbon dioxide emissions (D1), and coal consumption for thermal power generation (D2) were relatively high. Coal supply and demand security for 2002–2019 is shown in
Figure 1.
Overall, the coal supply and demand security level in China initially declined, followed by an increase, with the inflection point occurring in 2011. From 2002 to 2011, China’s economy developed rapidly, and the GDP growth rate was above 9%. With the continuous and rapid increase in coal consumption, the reserve–production ratio for basic coal reserves dropped rapidly from 214 in 2002 to 82 in 2010. This extensive development also led to significantly higher carbon emissions; thus, the security level of China’s coal supply and demand gradually declined during this period. After 2011, as China’s economic development entered a new stage of high-quality development, economic growth slowed, the industrial structure was improved, and the energy structure was optimized. The government also introduced a series of policies such as coal capacity reduction, output control, long-term guarantees, coal price stabilization, and the development of new energy sources. Consequently, China’s energy sustainability improved, the basic reserves and output ratio for coal resources increased, the proportion of non-coal consumption increased significantly, and the number of coal power generation hours increased.
Constructing the GM(1,1) model, the security score of the coal supply and demand for the 2011–2019 period was used in Equations (17)–(24) to estimate the coal security for 2020 and 2021. The predicted relative closeness for coal supply and demand security in China was 0.5058 in 2020 and 0.5320 in 2021, whereas the mean square deviation ratio of the grey prediction was 0.2709. The accuracy level was classified as Grade I, and the fit to the data was good. Combined with the forecast results, the security level of coal supply and demand in China is expected to further improve in the next few years but remain at the generally secure level.
4.3. Obstacle Factor Analysis
Using the obstacle degree model and Equations (13)–(16), the safety obstacle degree for China’s coal supply and demand from 2002 to 2019 was calculated. The seven evaluation criteria with the highest obstacle degrees for each year were selected as the main obstacle factors (
Table 8). Overall, the main obstacles that affected the security of the coal supply and demand in China during the study period were the basic coal reserves (A1), the reserve–production ratio for basic reserves (A2), the social stock balance of coal at the beginning and end of the year (A7), the ratio of coal imports to consumption (B2), the urbanization rate (C3), carbon dioxide emissions (D1), and coal consumption during thermal power generation (D2).
The reserve–production ratio (A2) for China’s basic coal reserves ranked first among the evaluation criteria for coal supply and demand security from 2004 to 2019. This is an important criterion because it reflects the rate of use of China’s basic coal reserves, and it acts as the strongest constraint on coal supply security. According to the analysis, the reserve–production ratio dropped from 159 in 2004 to its lowest point of 57 in 2011. This can be attributed to the rapid decline in basic reserves due to the rapid increase in coal consumption to meet the rapid economic development. After 2011, with the slowdown in economic growth, the increase in basic coal reserves, and the slowdown in coal consumption, the reserve–production ratio for basic coal reserves increased and has remained above 70 since 2016; however, it remained at a low level during the study period.
The difference in the social stock of coal at the beginning of the year (A7) appeared 13 times in the top seven criteria for the 2002–2019 period, and this was the main obstacle factor affecting the security of the coal supply in China. In particular, the difference in coal’s social stock was positive for only five years (2005, 2006, 2015, 2016, and 2017), and negative for the remaining years, indicating that the coal inventory level in China was generally insufficient during the study period, which had an adverse impact on coal supply security.
The ratio of coal imports to consumption (B2) appeared 11 times among the top seven obstacle criteria for the 2002–2019 period, particularly after 2009, indicating that it was one of the main obstacles affecting China’s coal supply security. In 2009, China became a coal importer for the first time. During that year, the coal import volume reached 125.84 million tons, more than three times that in 2002. Since then, the volume of coal imports has continued to expand, with China becoming the largest importer of coal in the world. The ratio of imports to consumption increased from 0.74% in 2002 to 7.46% in 2019 and has been high in recent years, indicating a significant dependence on foreign countries, thus increasing the obstacles to coal supply security.
The urbanization rate (C3) appeared 10 times among the top seven obstacles for 2002–2019, particularly after 2009. The ranking of this obstacle rose consistently during the study period from its lowest ranking of 17th in 2003 to third in 2016, thus increasing its impact on coal demand security in China. After 2009, China’s urbanization rate rose from 46.59% in 2009 to 60.60% in 2019. Urbanization directly leads to a substantial increase in China’s energy demand and coal consumption. Urbanization is inevitable for economic and social development; however, from the perspective of coal supply and demand security, its impact on coal demand security is increasing.
Carbon dioxide emissions (D1) were ranked second for the 2006–2010 and 2013–2019 periods and appeared 15 times in total during the study period. This is the most important factor affecting the security of coal demand in China. From 2002 to 2019, China’s carbon dioxide emissions rose from 3.843 billion tons to 9.811 billion tons, with coal carbon emissions accounting for more than 70% of the total energy carbon emissions. These emissions were primarily from coal consumption, which was the most important obstacle factor affecting the ecological environment and the security of coal use and needs to be a focus for carbon reduction to achieve carbon neutrality.
Coal consumption in thermal power generation (D2) occurred 13 times among the top seven obstacle factors during the 2002–2019 period, starting in 2007. This criterion was ranked between fourth and sixth from 2007 to 2019. From 2002 to 2019, coal consumption for China’s thermal power generation, which is the foundation for industrial electricity demand and ensures the stable operation of the economic and social power supply, increased from 597.98 million tons in 2002 to 2101.59 million tons in 2019. The rapid growth in China’s economy led to a continuous increase in electricity demand, and the power supply structure dominated by thermal power generation subsequently led to a significant increase in coal consumption. This was another main obstacle affecting coal demand security, and the pressure to meet the economic and social electricity demand is increasing under the goal of carbon neutrality.
Of the top seven criteria with the highest obstacle degree during the 2002–2019 period, other criteria with a high frequency included the total wholesale profit of coal and products (A5), the coal transportation volume (A6), the coal supply and demand ratio (B4), the GDP (C1), the proportion of non-coal energy consumption (C5), and the proportion of power generation hours for coal (D3). Of these, the GDP (C1) became a factor after 2015, mainly due to the continuous expansion of China’s economy and the increasing size of the GDP. The other obstacle factors were mostly observed before 2010, and their influence has weakened in recent years. In the future, it will be necessary to monitor the change in the obstacle degree of each individual criteria and combine the overall management of the security of the coal supply and demand with the management of individual criteria to further improve coal security.
Based on the results for the obstacle degree of individual criteria, we further calculated the obstacle degree for the four subsystems associated with China’s coal supply and demand security for the 2002–2019 period and predicted the obstacle degree for each subsystem in 2020 and 2021 using the grey model based on Equations (17)–(24) (
Figure 2). Of the four evaluation subsystems, the obstacle degree of the coal supply chain was higher than that of the other three subsystems. For this subsystem, the obstacle degree decreased and then increased, with an inflection point occurring in 2016. The obstacle degree was predicted to continue to rise in 2020 and 2021, gradually increasing the impact on coal supply security. In contrast, the obstacle degree of the coal market subsystem was the lowest of the four subsystems. During the study period, the obstacle degree fluctuated from 2004 to 2017, but has reduced since then, weakening its impact on coal supply security. Finally, the obstacle degree for the social ecology subsystem and the population economy subsystem remained relatively consistent, though the obstacle degree of the former has increased since 2016, whereas it has decreased for the latter since the same year.