There are hundreds of variations in the manner in which coal is formed, and layer upon layer of coal may be found if the processes are repeated more than once in a single area. Additionally, some coal is deeply buried in thick seams hundreds or thousands of metres underground, but elsewhere it might be found only in thin layers near the surface.
Also, the nature of the coal depends very largely on how the original matter was composted and compressed. The hardest coal, anthracite, is up to 94% carbon, while standard cannel or bituminous coal, which makes up most of Britain's coalfields, is 86% to 88% carbon.
Coal accounts for 40% of the fuel used around the world annually to generate power and over 7,000 million tonnes is mined per year.
There are two main types of coal:
Brown Coal/Sub-bituminous (also known as lignite) tend to have a lower calorific value (a measurement of energy per unit of mass) and are not mined in the UK. Most hard coal is bituminous coal and this accounts for the majority of UK Coal's current output.
Hard coal: There are two main types of hard coal:
Steam Coal (also called thermal coal), is mainly used in power stations with some going direct to industry Substitutes for steam coal are oil, gas, nuclear and renewables
Coking Coal (also called met coal), is used to make coke which is an essential raw material for blast furnaces used for steel making. There is no effective substitute for coking coal. Steel producers use blends of coking coal to make coke, with about half being the best type known as hard coking coal.
China
China has been by far the biggest coal producing country over the last three decades. The country produced about 3.6 billion tonnes (Bt) of coal in 2012 accounting for over 47% of the world's total coal output. The country is also a giant consumer of coal accounting for more than half of the world's total coal consumption in 2012, importing 289 million tonnes (Mt) of coal also making it the world's biggest coal importer.
China possesses the world's third biggest coal reserves, estimated at 114.5 Bt as of December 2012 with around 12,000 coal producing mines spread across 28 provinces. Shanxi, Inner Mongolia, Shaanxi and Xinjiang are the biggest coal producing provinces in the country. About half of China's coal is used for power generation, which accounts for over 80% of the country's electricity output.
The United States
The United States, the world's second biggest coal producing country, produced 922 Mt of coal in 2012 accounting for more than 13% of the world's coal production. The US is also the world's second biggest coal consumer, the nation consumed 11% of world's total coal in 2012 and approximately 37% of the country's electricity generation fuelled by coal that year.
Coal mining occurs in 25 states of which Wyoming, West Virginia, Kentucky, Pennsylvania and Texas are the biggest coal producers. The North Antelope Rochelle coal mine located in the Powder River Basin of Wyoming is the world's biggest coal mine and produced 107.7 Mt of thermal coal in 2012. The US also holds the world's biggest coal reserves estimated at over 237 Bt as of December 2012.
India
India produced approximately 605 Mt of coal in 2012 becoming the third biggest coal producer in the world. India was also the third biggest coal consumer accounting for eight percent of the world's coal consumption in the same year. India imported 160 Mt of coal in 2012 becoming the third biggest coal importer after China and Japan. Coal accounts for about 68% of India's electricity generation.
India's proven coal reserves, estimated at 60.6 Bt as of 2013, are the third biggest in the world. The four eastern Indian states Jharkhand, Chhattisgarh, Orissa and West Bengal account for about 70% of the country's coal reserves. Andhra Pradesh, Madhya Pradesh and Maharashtra are the other leading coal producing states in India.
Australia
Australia produced 413 Mt of coal in 2012 ranking as the fourth biggest coal producing country in the world. The country exports approximately 90% of its coal output and is the world's second biggest exporter after Indonesia. Australia exported 383 Mt of coal in 2012 and had proven coal reserves of 76.4 Bt, which rank as fourth biggest in the world.
More than 100 privately-owned coal mines operate in the country with about 74% of the coal output coming from open pit operations. New South Wales and Queensland account for more than 95% of Australia's black coal output where as the country's brown coal reserves are concentrated in Victoria. Peak Downs coal mine in the Bowen Basin of central Queensland and the Mt Arthur coal mine in the Hunter Valley region of New South Wales rank among the world's 10 biggest coal mines.
Indonesia
Indonesia produced 386 Mt of coal in 2012 making it the world's fifth largest coal producing country. Indonesia overtook Australia as the biggest coal exporting country in 2011, exporting 309 Mt of coal in 2012. Indonesia uses coal to produce approximately 44% of its electricity.
The East Kalimantan region is the biggest coal producing region and accounts for about two thirds of Indonesia's coal output. The country was estimated to possess 5.5 Bt of proven coal reserves as of December 2012 mostly located in Sumatra, East Kalimantan and South Kalimantan.
Russia
Russia, with 354.8 Mt of coal output in 2012, is the sixth biggest coal producing country in the world. Steam coal accounted for 80% of the total coal output while the rest 20% was coking coal. Russia is the fifth biggest coal consumer and exported 134 Mt of coal in 2012 making it the world's third biggest coal exporter.
The country holds the world's second biggest proven coal reserves, estimated at 157 Bt as of December 2012. The Kuzbass region contributing over 200 Mt of coal output is the biggest coal producing region in Russia followed by the East Siberia, Kansk Achinsk and the Far East regions. Approximately 66% of the country's coal output comes from open pit mining operations. Raspadskaya mine in the Kemerovo region is considered as Russia's biggest coal mine.
South Africa
Coal output, estimated at 280 Mt in 2012, made South Africa the seventh biggest coal producing country. South Africa is also the world's sixth biggest coal exporting country; exporting 74 Mt of coal in 2012. South Africa's coal exports are mostly made to China, India and Europe. The African country depends on coal for more than 90% of its electricity generation.
The Witbank, Highveld and Ermelo coalfields located in the eastern part of South Africa near Swaziland account for majority of the country's coal production. Anglo American, BHP Billiton, Xstrata Coal and Exxaro are among the top coal producing miners in the country. South Africa's proven coal reserves stood at 30.15 Bt as of December 2012.
Germany
The world's eighth biggest coal producing country, Germany produced 196.2 Mt of coal in 2012. The country's brown coal production, estimated at more than 180Mt in 2012, makes it the world's biggest brown coal producer followed by Russia and Australia. Germany's coal consumption exceeds its coal production as witnessed by the country's 2012 coal imports standing at approximately 45 Mt and making it the sixth biggest coal importer. About 43% of Germany's electricity generation is coal-based.
The country holds the world's sixth biggest proven coal reserves, estimated at 40.7 Bt as of December 2012. More than 75% of the country's hard coal production comes from the Ruhr Coal Basin in the North Rhine-Westphalia state and the Saar Basin in the south-west Germany, whereas the Rhineland region hosts the country's biggest lignite deposits. The Garzweiler open-cast coal mine in the North Rhine-Westphalia state is the country's biggest brown coal mine.
Poland
Poland produced 144.1 Mt of coal in 2012 becoming the world's ninth biggest coal producing country and Europe's second biggest coal producer after Germany. Poland consumes almost all of the coal it produces and is the world's eighth biggest coal consumer.
More than 85% of Poland's electricity generation is based on coal. The country operates Europe's biggest coal-fired power plant Belchatow. Kompania Weglowa is Poland's biggest coal mining company followed by Lubelski Wegiel Bogdanka. The country's proven coal reserves by the end of 2012 were 5.7 Bt.
Kazakhstan
Kazakhstan, with 116.6 Mt of coal output in 2012, stands as the world's tenth biggest coal producing country. Kazakhstan was the 12th biggest coal consuming country in the same year. Coal accounted for about 85% of the country's total installed power capacity.
Kazakhstan holds the world's eighth biggest proven coal reserves, estimated at 33.6 Bt as of December 2012. The country possesses more than 400 coal deposits, most of them concentrated in three provinces including Karaganda Oblast in Central Kazakhstan, and the Pavlodar and Kostanay Oblasts in North Kazakhstan. Karaganda and Ekibastuz are the two major coal producing basins in the country. Bogatyr Access Komir is the biggest open cast mining company in Kazakhstan
