Coal is a non-renewable energy source that takes millions of years to form. Coal is also the most abundant and geographically distributed fossil fuel in the world. Coal accounts for 70% of the world’s proven fossil energy reserves and far exceeds the reserves of oil and natural gas combined. “Proved Coal Reserves” means the amount of coal inferred from reasonable geological and engineering data that can be mined in the future from known coal seams under current economic and operating conditions. In addition to the Middle East, all major regions of the world have considerable coal resources. Interestingly, about two-thirds of the world’s oil reserves and more than 41% of its natural gas reserves are in the Middle East. There are two internationally recognized methods for assessing the world’s coal reserves: ① Prepared by the German Institute for Geosciences and Natural Resources (BGR) and used by the International Energy Agency (IEA) as the main source of information on coal reserves; ② Prepared by the World Energy Council (WEC) and used by the BP World Energy Statistical Yearbook. Quality and geological properties are important parameters for coal reserves. Coal is a heterogeneous energy source, and its quality is related to characteristic parameters such as heat content, sulfur content and ash content. These characteristic parameters vary considerably in different regions and even within the same coal seam. Premium bituminous or coking coal (used to produce coke needed in the steel industry) is a high-quality coal. The calorific content of coking coal produced in the United States is estimated at 26.3 MBtu/t, and its sulfur content is relatively low, about 0.9% by mass. On the other hand are the low calorific value lignite reserves. In terms of calorific value, the lignite reserves of different calorific values also vary considerably. The data released by the International Energy Agency in 2008 showed that the average calorific value of lignite produced by major lignite producing countries can reach as low as 5.9MBtu/t (Greece) and as high as 13.1MBtu/t (Canada) (US EIA-IEO2011).
Figure 1 shows the regional distribution of the world’s proven coal reserves in 1990, 2000 and 2010. Before 2000, the world’s coal reserves remained basically unchanged. Between 2000 and 2010, the world’s coal reserves decreased by 12.5%.
While nearly every country in the world has coal reserves, only 70 of them have mineable coal. By the end of 2011, the world’s accumulated proven coal reserves were about 861 billion tons (data from BP World Energy Statistical Yearbook 2012). According to the estimation of the World Energy Council (WEC2010), at the current level of coal consumption, coal reserves can only be exploited by humans for 118 years. That is, R/P = reserves/annual production = 118 years (coal reserves remaining at the end of the year divided by the amount of coal mined for the year equals a time measure that represents the time until the coal reserves are depleted if the same amount mined each year is maintained). However, we can discover new coal reserves through existing and improved exploration techniques, relying on advances in mining technology to extract previously unminable coal resources to extend the timeframe in which coal resources can be used by humans.
About 92% of the world’s mineable coal resources are concentrated in 10 countries. The United States leads the pack with 27.6% of the world’s total coal reserves. Russia and China are second and third far behind the United States, with 18.2% and 13.3% of the world’s total coal reserves, respectively. The United States has the world’s largest coal reserves, while Saudi Arabia has the world’s largest oil reserves. As a result, U.S. coal producers are stepping up efforts to facilitate the market situation of coal as the primary source of energy supply.
The ratio of reserves of “anthracite and bituminous coal (hard coal)” to “lignite and sub-bituminous coal” varies from country to country. By mass, anthracite and bituminous coal account for 47% of the world’s mineable coal reserves, sub-bituminous coal 30%, and lignite 23% (US EIA-IEO 2012).