4.6 Global coal reserves and their life expectancy
In 2003, global proven coal reserves were estimated at 984.5 × 109 t, of which slightly over half (52.7%) was anthracite and bituminous coal and the rest (47.3%) was sub-bituminous coal and lignite.
Figure 37 shows the breakdown of global reserves by continental regions. North America has 26% of total global coal reserves, South Asia and the Pacific (mainly Australia) have 30%, Europe 20%, and the Russian Federation 16%. The relatively sparse distribution of coalfields elsewhere (Figure 35) is borne out by far less significant reserves in Africa and the Middle East (6%), and in South and Central America (2%).
Table 4 shows known global reserves as of 2003, ranked in order of the countries with the highest annual production. However, current reserves represent a snapshot in time; what is considered a reserve depends on current extraction technology, and reserves are depleted as coal is mined. Moreover, coal is a high-volume, low-value resource, and so reserves are highly sensitive to economics, the more so because at the start of the 21st century there is a glut of easily mined coal worldwide.
Resource figures are also given in Table 4, however such data are not available for all countries, including many of the world's major producers.
Compare the USA and China in terms of reserves versus coal production in 2003.
China has less than half the reserves of the USA, and yet annually it produces 1.5 times more coal. Clearly if this rate is maintained, China's coal will be exhausted before that of the USA.
This is in fact a recent phenomenon. Since 2000, China has increased production of coal by over 40%, overtaking the USA, which was the world's largest producer between 1999 and 2001.
Comparisons between the sustainability of coal production in different countries are made easier in Table 4 by calculating the ratio of proved reserves in the ground (R) to the annual production (P). This R/P ratio has dimensions of tonnes divided by tonnes per year, which is equal to years (t/(t yr−1) = 1/yr−1 = yr). The R/P ratio is therefore a measure of how long the coal reserve (or that of any other fossil fuel or non-renewable resource) will last, if the current annual production figure is maintained into the future.
Would you expect the R/P ratio to remain reasonably constant for decades?
The pace of exploration and evaluation continually adds to reserves, so they are often maintained at a constant level for many years. However, economics also plays a role — if costs of mining go up or the price of coal goes down some reserves will be lost from the inventory (Sheldon, 2005).
Annual consumption figures and R/P ratios for 2003 are also given in Table 4. Some interesting facts underlie the data given in this table.
Despite producing 21.9% of the world's coal, the USA has to import coal to satisfy its demand, even though coal supplies less than a quarter of its primary energy requirement.
By contrast, China has four times the population of the USA, yet coal supplies two-thirds of its primary energy requirement.
The very high R/P ratio of the Russian Federation (>500 years) is a consequence of the recent fall in industrial coal consumption following the break-up of the Soviet Union.
India has the world's fourth largest reserves, but needs to import about a quarter of its coking coal for the country's steel industry.
Australia is by far the world's largest exporter (as you can judge from its high production yet low consumption), selling coal to over 30 countries. About half the exports go to Japan (the world's largest coal importer).
The figures for the UK reflect the widespread closures of mines in the 1990s that effectively reduced reserves enormously (Section 5).
In years to come, as reserves begin to run low, global coal prices may increase. More coal resources would then become economic to mine, to be reclassified as reserves. This would in turn raise the R/P ratio. It is therefore important to include the future conversion of resources to reserves when considering how long coal will last as a source of energy. However, the current lack of coal resource data for many countries, together with uncertainties associated with predicting future changes in global coal prices make such calculations rather speculative. Of course, such speculations presuppose that coal continues to be favoured despite its contribution to global warming.
In Table 4, the R/P ratio for the USA is given as 258 years. If half of the coal currently considered a resource, but not a reserve, was to become a reserve in future, how long would this coal last (assuming no change in production figures)?
For the USA, reserves = 250.0 × 109t, and resources = 457.5 × 109 t. Converting half of the coal currently considered a resource only to a reserve:
0.5 × (457.5 × 109 − 250.0 × 109) t = 103.8 × 109 t
Therefore total future reserves = 250.0 × 109 t + 103.8 × 109 t = 353.8 × 109 t
R/P ratio = 353.8 × 109 t/970.0 × 106 t yr−1 = 365 years
Table 4 shows that global coal reserves could last into the 23rd century without any further reserves being identified, if production were to be stabilized at present-day levels. However, coal is mined in over 100 countries, and in the absence of any cartels that might control production (as OPEC does with oil), constraining future global coal production is unlikely. Therefore, this R/P ratio will most likely change with time. As you will see in the next section, R/P ratios for individual countries can vary dramatically too.