Types of Coal

As geological processes apply pressure to dead biotic material over time, under suitable conditions it is transformed successively into:

  • Peat, considered to be a precursor of coal, has industrial importance as a fuel in some regions, for example, Ireland and Finland. In its dehydrated form, peat is a highly effective absorbent for fuel and oil spills on land and water
  • Lignite, also referred to as brown coal, is the lowest rank of coal and used almost exclusively as fuel for electric power generation. Jet is a compact form of lignite that is sometimes polished and has been used as an ornamental stone since the Upper Palaeolithic
  • Sub-bituminous coal, whose properties range from those of lignite to those of bituminous coal are used primarily as fuel for steam-electric power generation. Additionally, it is an important source of light aromatic hydrocarbons for the chemical synthesis industry.
  • Bituminous coal, dense sedimentary rock, black but sometimes dark brown, often with well-defined bands of bright and dull material, used primarily as fuel in steam-electric power generation, with substantial quantities also used for heat and power applications in manufacturing and to make coke
  • Steam coal is a grade between bituminous coal and anthracite, once widely used as a fuel for steam locomotives. In this specialized use it is sometimes known as sea-coal in the U.S. Small steam coal (dry small steam nuts or DSSN) was used as a fuel for domestic water heating
  • Anthracite, the highest rank; a harder, glossy, black coal used primarily for residential and commercial space heating. It may be divided further into metamorphically altered bituminous coal and petrified oil, as from the deposits in Pennsylvania
  • Graphite, technically the highest rank, but difficult to ignite and is not so commonly used as fuel: it is mostly used in pencils and, when powdered, as a lubricant.

The classification of coal is generally based on the content of volatiles. However, the exact classification varies between countries. According to the German classification, coal is classified as follows:

Name Volatiles % C Carbon % H Hydrogen % O Oxygen % S Sulfur % Heat content kJ/kg
Braunkohle (Lignite) 45-65 60-75 6.0-5.8 34-17 0.5-3 <28470
Flammkohle (Flame coal) 40-45 75-82 6.0-5.8 >9.8 ~1 <32870
Gasflammkohle (Gas flame coal) 35-40 82-85 5.8-5.6 9.8-7.3 ~1 <33910
Gaskohle (Gas coal) 28-35 85-87.5 5.6-5.0 7.3-4.5 ~1 <34960
Fettkohle (Fat coal) 19-28 87.5-89.5 5.0-4.5 4.5-3.2 ~1 <35380
Esskohle (Forge coal) 14-19 89.5-90.5 4.5-4.0 3.2-2.8 ~1 <35380
Magerkohle (Non baking coal) 10-14 90.5-91.5 4.0-3.75 2.8-3.5 ~1 35380
Anthrazit (Anthracite) 7-12 >91.5 <3.75 <2.5 ~1 <35300
Percent by weight

The middle six grades in the table represent a progressive transition from the English-language sub-bituminous to bituminous coal, while the last class is an approximate equivalent to anthracite, but more inclusive (the U.S. anthracite has < 6% volatiles).

Cannel coal (sometimes called "candle coal"), is a variety of fine-grained, high-rank coal with significant hydrogen content. It consists primarily of "exinite" macerals, now termed "liptinite".

Largest Coal Importers by Country

Countries with annual import higher than 30 million tonnes are shown.

Imports of Coal by Country and year (million short tons)
Country 2006 2007 2008 2009 Share
Japan 199.7 209.0 206.0 182.1 17.5%
China 42.0 56.2 44.5 151.9 14.5%
South Korea 84.1 94.1 107.1 109.9 10.6%
India 52.7 29.6 70.9 76.7 7.4%
Taiwan 69.1 72.5 70.9 64.6 6.2%
Germany 50.6 56.2 55.7 45.9 4.4%
United Kingdom 56.8 48.9 49.2 42.2 4.1%
Total 991.8 1,056.5 1,063.2 1,039.8 100%

Largest Coal Exporters by Country

Countries with annual export higher than 10 million tonnes are shown.

Exports of Coal by Country and year (million short tons)
Country 2007 2008 2009 Share
Australia 268.5 278.0 288.5 26.5%
Indonesia 221.9 228.2 261.4 24.0%
Russia 112.2 115.4 130.9 12.0%
Colombia 74.5 74.7 75.7 6.9%
South Africa 72.6 68.2 73.8 6.8%
USA 60.6 83.5 60.4 5.5%
China 75.4 68.8 38.4 3.5%
Canada 33.4 36.5 31.9 2.9%
Vietnam 35.1 21.3 28.2 2.6%
Kazakhstan 32.8 47.6 25.7 2.4%
Poland 20.1 16.1 14.6 1.3%
Total 1,073.4 1,087.3 1,090.8 100%

Coal Production by Country

The reserve life is an estimate based only on current production levels and proved reserves level for the countries shown, and makes no assumptions of future production or even current production trends. This is a list of countries by coal production in 2009 based mostly on Statistical Review of World Energy 2010 published in 2010 by BP ranks countries with coal production larger than 100 millions tonnes.

Production of Coal by Country and year (million tonnes)
Country 2007 2008 2009 Share Reserve Life (years)
China 2526.0 2782.0 3050.0 45.6 % 38
USA 1040.2 1062.8 973.2 15.8 % 245
India 478.4 521.7 557.6 6.2 % 105
EU 593.4 587.7 536.8 4.6 % 55
Australia 399.0 401.5 409.2 6.7 % 186
Russia 314.2 326.5 298.1 4.3 % 150+
Indonesia 217.4 229.5 252.5 3.6 % 17
South Africa 247.7 250.4 250.0 3.6 % 122
Germany 201.9 192.4 183.7 2.6 % 37
Poland 145.9 143.9 135.1 1.7 % 56
Kazakhstan 97.8 111.1 101.5 1.5 % 308
Total World 6,421.2 6,781.2 6,940.6 100 % 119

World Coal Reserves

The 930 billion short tons of recoverable coal reserves estimated by the Energy Information Administration are equal to about 4,116 BBOE (billion barrels of oil equivalent). The amount of coal burned during 2007 was estimated at 7.075 billion short tons, or 133.179 quadrillion BTU's. This is an average of 18.8 million BTU per short ton. In terms of heat content, this is about 57,000,000 barrels (9,100,000 m3) of oil equivalent per day. By comparison in 2007, natural gas provided 51,000,000 barrels (8,100,000 m3) of oil equivalent per day, while oil provided 85,800,000 barrels per day.

BP, in its 2007 report, estimated at 2006 end that there were 909,064 million tons of proven coal reserves worldwide, or 147 years reserves-to-production ratio. This figure only includes reserves classified as "proven"; exploration drilling programs by mining companies, particularly in under-explored areas, are continually providing new reserves. In many cases, companies are aware of coal deposits that have not been sufficiently drilled to qualify as "proven". However, some nations haven't updated their information and assume reserves remain at the same levels even with withdrawals. Collective projections generally predict that global peak coal production may occur sometime around 2025 at 30 percent above current production in the best case scenario, depending on future coal production rates.

Of the three fossil fuels, coal has the most widely distributed reserves; coal is mined in over 100 countries, and on all continents except Antarctica. The largest reserves are found in the USA, Russia, China, India and Australia. Note the table below.

Proved recoverable coal reserves (million tons (teragrams))
Country Bituminous & Anthracite SubBituminous Lignite TOTAL Percentage of World Total
United States 108,501 98,618 30,176 237,295 22.6
Russia 49,088 97,472 10,450 157,010 14.4
China 62,200 33,700 18,600 114,500 12.6
Australia 37,100 2,100 37,200 76,500 8.9
India 56,100 0 4,500 60,600 7.0
Germany 99 0 40,600 40,699 4.7
Ukraine 15,351 16,577 1,945 33,873 3.9
Kazakhstan 21,500 0 12,100 33,600 3.9
South Africa 30,156 0 0 30,156 3.5
Serbia 9 361 13,400 13,770 1.6
Colombia 6,366 380 0 6,746 0.8
Canada 3,474 872 2,236 6,528 0.8
Poland 4,338 0 1,371 5,709 0.7
Indonesia 1,520 2,904 1,105 5,529 0.6
Brazil 0 4,559 0 4,559 0.5
Greece 0 0 3,020 3,020 0.4
Bosnia and Herzegovina 484 0 2,369 2,853 0.3
Mongolia 1,170 0 1,350 2,520 0.3
Bulgaria 2 190 2,174 2,366 0.3
Pakistan 0 166 1,904 2,070 0.3
Turkey 529 0 1,814 2,343 0.3
Uzbekistan 47 0 1,853 1,900 0.2
Hungary 13 439 1,208 1,660 0.2
Thailand 0 0 1,239 1,239 0.1
Mexico 860 300 51 1,211 0.1
Iran 1,203 0 0 1,203 0.1
Czech Republic 192 0 908 1,100 0.1
Kyrgyzstan 0 0 812 812 0.1
Albania 0 0 794 794 0.1
North Korea 300 300 0 600 0.1
New Zealand 33 205 333-7,000 571-15,000 0.1
Spain 200 300 30 530 0.1
Laos 4 0 499 503 0.1
Zimbabwe 502 0 0 502 0.1
Argentina 0 0 500 500 0.1
All others 3,421 1,346 846 5,613 0.7
Total world 404,762 260,789 195,387 860,938 100