Coal

Coal

Overview
Coal is a combustible
Combustion
Combustion or burning is the sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat and conversion of chemical species. The release of heat can result in the production of light in the form of either glowing or a flame...

 black or brownish-black sedimentary rock
Sedimentary rock
Sedimentary rock are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....

 usually occurring in rock strata
Stratum
In geology and related fields, a stratum is a layer of sedimentary rock or soil with internally consistent characteristics that distinguish it from other layers...

 in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock
Metamorphic rock
Metamorphic rock is the transformation of an existing rock type, the protolith, in a process called metamorphism, which means "change in form". The protolith is subjected to heat and pressure causing profound physical and/or chemical change...

 because of later exposure to elevated temperature and pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...

. Coal is composed primarily of carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

 along with variable quantities of other elements, chiefly hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

, with smaller quantities of sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

, oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 and nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

.
Throughout history, coal has been a useful resource for human consumption.
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Encyclopedia
Coal is a combustible
Combustion
Combustion or burning is the sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat and conversion of chemical species. The release of heat can result in the production of light in the form of either glowing or a flame...

 black or brownish-black sedimentary rock
Sedimentary rock
Sedimentary rock are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....

 usually occurring in rock strata
Stratum
In geology and related fields, a stratum is a layer of sedimentary rock or soil with internally consistent characteristics that distinguish it from other layers...

 in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock
Metamorphic rock
Metamorphic rock is the transformation of an existing rock type, the protolith, in a process called metamorphism, which means "change in form". The protolith is subjected to heat and pressure causing profound physical and/or chemical change...

 because of later exposure to elevated temperature and pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...

. Coal is composed primarily of carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

 along with variable quantities of other elements, chiefly hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

, with smaller quantities of sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

, oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 and nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

.
Throughout history, coal has been a useful resource for human consumption. It is primarily burned as a fossil fuel
Fossil fuel
Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years...

 for the production of electricity and/or heat, and is also used for industrial purposes such as refining metals. Coal forms when dead plant matter is converted into peat
Peat
Peat is an accumulation of partially decayed vegetation matter or histosol. Peat forms in wetland bogs, moors, muskegs, pocosins, mires, and peat swamp forests. Peat is harvested as an important source of fuel in certain parts of the world...

, which in turn is converted into lignite
Lignite
Lignite, often referred to as brown coal, or Rosebud coal by Northern Pacific Railroad,is a soft brown fuel with characteristics that put it somewhere between coal and peat...

, then anthracite. This involves biological and geological processes that take place over a long period of time.

Top hard and brown coal producers in 2010 (2009) were (Mt): China 3,162 (2,971), United States 997 (985), India
Energy in India
Energy in India describes energy and electricity production, consumption and import in India. Energy policy of India describes the politics of India related to energy. Electricity sector in India is the main article of electricity in India....

 571 (571), Australia
Energy in Australia
Energy in Australia describes energy and electricity production, consumption and export in Australia. Energy policy of Australia describes the politics of Australia related to energy....

 420 (399), Indonesia
Energy in Indonesia
Energy in Indonesia describes energy and electricity production, consumption and import in Indonesia. In 2009 Indonesia produced oil, coal, natural gas and palm oil, utilized also as energy raw material in 2010. Renewable energy potential in Indonesia is high: solar, wind, hydro and geothermal...

 336 (301), Russia 324 (297), South Africa
Energy in South Africa
Energy in South Africa describes energy and electricity production, consumption and export in South Africa.South Africa was 6. top hard coal producer in 2009. Hard coal production was 1,620 TWh in 2009 and total energy production 1,995 TWh in 2008. The environmenatal concerns of old abandoned coal...

 255 (247), Poland
Energy in Poland
Energy in Poland describes energy and electricity production, consumption and import in Poland.In 2009, Poland was world's 9th largest hard coal producer...

 134 (135), Kazakhstan
Energy in Kazakhstan
Energy in Kazakhstan describes energy and electricity production, consumption and import in Kazakhstan. Energy policy of Kazakhstan describes the politics of Kazakhstan related to energy.Kazakhstan is net energy exporter...

 111 (101), and Colombia 74 (73).

Formation


Coal begins as layers of plant matter accumulating at the bottom of a body of water. For the process to continue, the plant matter was protected from biodegradation
Biodegradation
Biodegradation or biotic degradation or biotic decomposition is the chemical dissolution of materials by bacteria or other biological means...

 and oxidization, usually by mud or acidic water. This traps the carbon in immense peat
Peat
Peat is an accumulation of partially decayed vegetation matter or histosol. Peat forms in wetland bogs, moors, muskegs, pocosins, mires, and peat swamp forests. Peat is harvested as an important source of fuel in certain parts of the world...

 bog
Bog
A bog, quagmire or mire is a wetland that accumulates acidic peat, a deposit of dead plant material—often mosses or, in Arctic climates, lichens....

s that are eventually covered and deeply buried by sediments. Under this compression the plant material is metamorphosed
Metamorphism
Metamorphism is the solid-state recrystallization of pre-existing rocks due to changes in physical and chemical conditions, primarily heat, pressure, and the introduction of chemically active fluids. Mineralogical, chemical and crystallographic changes can occur during this process...

 into coal: over time, the chemical and physical properties
Physical property
A physical property is any property that is measurable whose value describes a physical system's state. The changes in the physical properties of a system can be used to describe its transformations ....

 of the plant remains are changed by geological action to create a solid material.

The wide shallow seas of the Carboniferous
Carboniferous
The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...

 period provided ideal conditions for coal formation, although coal is known from most geological periods. The exception is the coal gap in the Lower Triassic, where coal is rare: presumably a result of the mass extinction which prefaced this era. Coal is known from Precambrian strata, which predate land plants: this coal is presumed to have originated from algal residues.

Coal, a fossil fuel
Fossil fuel
Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years...

, is the largest source of energy for the generation of electricity
Electricity generation
Electricity generation is the process of generating electric energy from other forms of energy.The fundamental principles of electricity generation were discovered during the 1820s and early 1830s by the British scientist Michael Faraday...

 worldwide, as well as one of the largest worldwide anthropogenic sources of carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

 releases. Gross carbon dioxide emissions from coal usage are slightly more than those from petroleum
Petroleum
Petroleum or crude oil is a naturally occurring, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface. Petroleum is recovered mostly through oil drilling...

 and about double the amount from natural gas
Natural gas
Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...

. Coal is extracted from the ground by mining
Coal mining
The goal of coal mining is to obtain coal from the ground. Coal is valued for its energy content, and since the 1880s has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron from iron ore and for cement production. In the United States,...

, either underground by shaft mining
Shaft mining
Shaft mining or shaft sinking refers to the method of excavating a vertical or near-vertical tunnel from the top down, where there is initially no access to the bottom....

 through the seams or in open pits.

Types


As geological processes apply pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...

 to dead biotic material
Biotic material
Biotic material or biological derived material is any natural material that is originated from living organisms. Most such materials contain carbon and are capable of decay....

 over time, under suitable conditions it is transformed successively into:
  • Peat
    Peat
    Peat is an accumulation of partially decayed vegetation matter or histosol. Peat forms in wetland bogs, moors, muskegs, pocosins, mires, and peat swamp forests. Peat is harvested as an important source of fuel in certain parts of the world...

    , 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
    Lignite
    Lignite, often referred to as brown coal, or Rosebud coal by Northern Pacific Railroad,is a soft brown fuel with characteristics that put it somewhere between coal and peat...

     or brown coal, is the lowest rank of coal and used almost exclusively as fuel for electric power generation. Jet
    Jet (lignite)
    Jet is a geological material and is considered to be a minor gemstone. Jet is not considered a true mineral, but rather a mineraloid as it has an organic origin, being derived from decaying wood under extreme pressure....

     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
    Sub-bituminous coal
    Sub-bituminous coal is a type of coal whose properties range from those of lignite to those of bituminous coal and are used primarily as fuel for steam-electric power generation.- Properties:...

    , whose properties range from those of lignite to those of bituminous coal, is used primarily as fuel for steam-electric power generation and is an important source of light aromatic hydrocarbon
    Aromatic hydrocarbon
    An aromatic hydrocarbon or arene is a hydrocarbon with alternating double and single bonds between carbon atoms. The term 'aromatic' was assigned before the physical mechanism determining aromaticity was discovered, and was derived from the fact that many of the compounds have a sweet scent...

    s for the chemical synthesis
    Chemical synthesis
    In chemistry, chemical synthesis is purposeful execution of chemical reactions to get a product, or several products. This happens by physical and chemical manipulations usually involving one or more reactions...

     industry.
  • Bituminous coal
    Bituminous coal
    Bituminous coal or black coal is a relatively soft coal containing a tarlike substance called bitumen. It is of higher quality than lignite coal but of poorer quality than Anthracite...

     is 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 used for heat and power applications in manufacturing and to make coke
    Coke (fuel)
    Coke is the solid carbonaceous material derived from destructive distillation of low-ash, low-sulfur bituminous coal. Cokes from coal are grey, hard, and porous. While coke can be formed naturally, the commonly used form is man-made.- History :...

  • Steam coal is a grade between bituminous coal and anthracite, once widely used as a fuel for steam locomotive
    Steam locomotive
    A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...

    s. 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
    Water heating
    Water heating is a thermodynamic process using an energy source to heat water above its initial temperature. Typical domestic uses of hot water are for cooking, cleaning, bathing, and space heating...

  • Anthracite, the highest rank of coal is a harder, glossy, black coal used primarily for residential and commercial space heating
    Space heating
    A space heater is a self-contained device for heating an enclosed area. Space heating is generally employed to warm a small space, and is usually held in contrast with central heating, which warms many connected spaces at once...

    . It may be divided further into metamorphically altered bituminous coal and petrified oil, as from the deposits in Pennsylvania
  • Graphite
    Graphite
    The mineral graphite is one of the allotropes of carbon. It was named by Abraham Gottlob Werner in 1789 from the Ancient Greek γράφω , "to draw/write", for its use in pencils, where it is commonly called lead . Unlike diamond , graphite is an electrical conductor, a semimetal...

    , technically the highest rank is difficult to ignite and is not commonly used as fuel: it is mostly used in pencils and, when powdered, as a lubricant
    Lubricant
    A lubricant is a substance introduced to reduce friction between moving surfaces. It may also have the function of transporting foreign particles and of distributing heat...

    .


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:
German Classification English Designation 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
Cannel coal
Cannel coal, also known as candle coal, is a type of coal, also classified as terrestrial type oil shale, with a large amount of hydrogen, which burns easily with a bright light and leaves little ash....

 (sometimes called "candle coal"), is a variety of fine-grained, high-rank coal with significant hydrogen content. It consists primarily of "exinite
Exinite
Liptinite is an umbrella term used in coal geology, referring to the finely-ground and macerated remains found in coal deposits. It replaced the term Exinite as one of the four categories of kerogen. Liptinites were originally formed by spores, pollen, dinoflagellate cysts, leaf cuticles, and plant...

" maceral
Maceral
A maceral is a component of coal or oil shale. The term 'maceral' in reference to coal is analogous to the use of the term 'mineral' in reference to igneous or metamorphic rocks. Examples of macerals are inertinite, vitrinite and liptinite.- Inertinite :...

s, now termed "liptinite".

Hilt's Law


Hilt's Law
Hilt's Law
A geological term that states the deeper the coal, the deeper its rank . The law holds true if the thermal gradient is entirely vertical, but metamorphism may cause lateral changes of rank, irrespective of depth. Increasing depth of burial results in a decrease in the oxygen content of the coals...

is a geological term that states that, in a small area, the deeper the coal, the deeper its rank (grade). The law holds true if the thermal gradient is entirely vertical, but metamorphism may cause lateral changes of rank, irrespective of depth.

Early uses as fuel




The earliest reference to the use of coal as fuel is from the geological treatise On stones (Lap. 16) by the Greek
Greeks
The Greeks, also known as the Hellenes , are a nation and ethnic group native to Greece, Cyprus and neighboring regions. They also form a significant diaspora, with Greek communities established around the world....

 scientist Theophrastus
Theophrastus
Theophrastus , a Greek native of Eresos in Lesbos, was the successor to Aristotle in the Peripatetic school. He came to Athens at a young age, and initially studied in Plato's school. After Plato's death he attached himself to Aristotle. Aristotle bequeathed to Theophrastus his writings, and...

 (c. 371–287 BC):
Outcrop
Outcrop
An outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth. -Features:Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficial deposits are covered by a mantle of soil and vegetation and cannot be...

 coal was used in Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

 during the Bronze Age
Bronze Age
The Bronze Age is a period characterized by the use of copper and its alloy bronze as the chief hard materials in the manufacture of some implements and weapons. Chronologically, it stands between the Stone Age and Iron Age...

 (3000–2000 BC), where it has been detected as forming part of the composition of funeral
Funeral
A funeral is a ceremony for celebrating, sanctifying, or remembering the life of a person who has died. Funerary customs comprise the complex of beliefs and practices used by a culture to remember the dead, from interment itself, to various monuments, prayers, and rituals undertaken in their honor...

 pyre
Pyre
A pyre , also known as a funeral pyre, is a structure, usually made of wood, for burning a body as part of a funeral rite...

s. In Roman Britain
Roman Britain
Roman Britain was the part of the island of Great Britain controlled by the Roman Empire from AD 43 until ca. AD 410.The Romans referred to the imperial province as Britannia, which eventually comprised all of the island of Great Britain south of the fluid frontier with Caledonia...

, with the exception of two modern fields, "the Romans
Mining in Roman Britain
Mining was one of the most prosperous activities in Roman Britain. Britain was rich in resources such as copper, gold, iron, lead, salt, silver, and tin, materials in high demand in the Roman Empire. The abundance of mineral resources in the British Isles was probably one of the reasons for the...

 were exploiting coals in all the major coalfields in England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 and Wales
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

 by the end of the second century AD". Evidence of trade in coal (dated to about AD 200) has been found at the inland port
Inland port
The term inland port is used in two different but related ways to mean either a port on an inland waterway or an inland site carrying out some functions of a seaport.- As a port on an inland waterway :...

 of Heronbridge
Heronbridge Roman Site
Heronbridge Roman Site is the remains a Roman settlement on both sides of Watling Street, about south of Chester in Cheshire, England, with evidence of industrial activity in the late 1st and 2nd centuries. The site is a Scheduled Ancient Monument....

, near Chester
Chester
Chester is a city in Cheshire, England. Lying on the River Dee, close to the border with Wales, it is home to 77,040 inhabitants, and is the largest and most populous settlement of the wider unitary authority area of Cheshire West and Chester, which had a population of 328,100 according to the...

, and in the Fenlands
The Fens
The Fens, also known as the , are a naturally marshy region in eastern England. Most of the fens were drained several centuries ago, resulting in a flat, damp, low-lying agricultural region....

 of East Anglia
East Anglia
East Anglia is a traditional name for a region of eastern England, named after an ancient Anglo-Saxon kingdom, the Kingdom of the East Angles. The Angles took their name from their homeland Angeln, in northern Germany. East Anglia initially consisted of Norfolk and Suffolk, but upon the marriage of...

, where coal from the Midlands
English Midlands
The Midlands, or the English Midlands, is the traditional name for the area comprising central England that broadly corresponds to the early medieval Kingdom of Mercia. It borders Southern England, Northern England, East Anglia and Wales. Its largest city is Birmingham, and it was an important...

 was transported via the Car Dyke
Car Dyke
The Car Dyke was, and to large extent still is, an eighty-five mile long ditch which runs along the western edge of the Fens in eastern England. It is generally accepted as being of Roman age and, for many centuries, to have been taken as marking the western edge of the Fens...

 for use in drying grain. Coal cinders have been found in the hearths of villa
Roman villa
A Roman villa is a villa that was built or lived in during the Roman republic and the Roman Empire. A villa was originally a Roman country house built for the upper class...

s and military forts
Castra
The Latin word castra, with its singular castrum, was used by the ancient Romans to mean buildings or plots of land reserved to or constructed for use as a military defensive position. The word appears in both Oscan and Umbrian as well as in Latin. It may have descended from Indo-European to Italic...

, particularly in Northumberland
Northumberland
Northumberland is the northernmost ceremonial county and a unitary district in North East England. For Eurostat purposes Northumberland is a NUTS 3 region and is one of three boroughs or unitary districts that comprise the "Northumberland and Tyne and Wear" NUTS 2 region...

, dated to around AD 400. In the west of England contemporary writers described the wonder of a permanent brazier of coal on the altar of Minerva
Minerva
Minerva was the Roman goddess whom Romans from the 2nd century BC onwards equated with the Greek goddess Athena. She was the virgin goddess of poetry, medicine, wisdom, commerce, weaving, crafts, magic...

 at Aquae Sulis
Aquae Sulis
Aquae Sulis was a small town in the Roman province of Britannia. Today it is known as Bath, located in the English county of Somerset.-Baths and temple complex:...

 (modern day Bath) although in fact easily accessible surface coal from what became the Somerset coalfield
Somerset coalfield
The Somerset Coalfield included pits in the North Somerset, England, area where coal was mined from the 15th century until 1973.It is part of a wider coalfield which covered northern Somerset and southern Gloucestershire. It stretched from Cromhall in the north to the Mendip Hills in the south, and...

 was in common use in quite lowly dwellings locally. Evidence of coal's use for iron-working in the city during the Roman period has been found. In Eschweiler
Eschweiler
Eschweiler is a municipality in the district of Aachen in North Rhine-Westphalia in Germany on the river Inde, near the German-Belgian-Dutch frontier, and about 15 km east of Aachen and 50 km west of Cologne.- History :...

, Rhineland
Rhineland
Historically, the Rhinelands refers to a loosely-defined region embracing the land on either bank of the River Rhine in central Europe....

, deposits of bituminous coal
Bituminous coal
Bituminous coal or black coal is a relatively soft coal containing a tarlike substance called bitumen. It is of higher quality than lignite coal but of poorer quality than Anthracite...

 were used by the Romans for the smelting of iron ore.

There is no evidence that the product was of great importance in Britain before the High Middle Ages
High Middle Ages
The High Middle Ages was the period of European history around the 11th, 12th, and 13th centuries . The High Middle Ages were preceded by the Early Middle Ages and followed by the Late Middle Ages, which by convention end around 1500....

, after about AD 1000. Mineral
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...

 coal came to be referred to as "seacoal" in the 13th century; the wharf where the material arrived in London was known as Seacoal Lane, so identified in a charter of King Henry III
Henry III of England
Henry III was the son and successor of John as King of England, reigning for 56 years from 1216 until his death. His contemporaries knew him as Henry of Winchester. He was the first child king in England since the reign of Æthelred the Unready...

 granted in 1253. Initially the name was given because much coal was found on the shore, having fallen from the exposed coal seams on cliffs above or washed out of underwater coal outcrops, but by the time of Henry VIII
Henry VIII of England
Henry VIII was King of England from 21 April 1509 until his death. He was Lord, and later King, of Ireland, as well as continuing the nominal claim by the English monarchs to the Kingdom of France...

 it was understood to derive from the way it was carried to London by sea. In 1257–59, coal from Newcastle
Newcastle upon Tyne
Newcastle upon Tyne is a city and metropolitan borough of Tyne and Wear, in North East England. Historically a part of Northumberland, it is situated on the north bank of the River Tyne...

 was shipped to London for the smiths and lime-burners building Westminster Abbey
Westminster Abbey
The Collegiate Church of St Peter at Westminster, popularly known as Westminster Abbey, is a large, mainly Gothic church, in the City of Westminster, London, United Kingdom, located just to the west of the Palace of Westminster. It is the traditional place of coronation and burial site for English,...

. Seacoal Lane and Newcastle Lane where coal was unloaded at wharves along the River Fleet
River Fleet
The River Fleet is the largest of London's subterranean rivers. Its two headwaters are two streams on Hampstead Heath; each is now dammed into a series of ponds made in the 18th century, the Hampstead Ponds and the Highgate Ponds. At the south edge of Hampstead Heath these two streams flow...

, are still in existence. (See Industrial processes below for modern uses of the term.)

These easily accessible sources had largely become exhausted (or could not meet the growing demand) by the 13th century, when underground mining from shafts
Shaft mining
Shaft mining or shaft sinking refers to the method of excavating a vertical or near-vertical tunnel from the top down, where there is initially no access to the bottom....

 or adit
Adit
An adit is an entrance to an underground mine which is horizontal or nearly horizontal, by which the mine can be entered, drained of water, and ventilated.-Construction:...

s was developed. The alternative name was "pitcoal," because it came from mines. It was, however, the development of the Industrial Revolution
Industrial Revolution
The Industrial Revolution was a period from the 18th to the 19th century where major changes in agriculture, manufacturing, mining, transportation, and technology had a profound effect on the social, economic and cultural conditions of the times...

 that led to the large-scale use of coal, as the steam engine
Steam engine
A steam engine is a heat engine that performs mechanical work using steam as its working fluid.Steam engines are external combustion engines, where the working fluid is separate from the combustion products. Non-combustion heat sources such as solar power, nuclear power or geothermal energy may be...

 took over from the water wheel
Water wheel
A water wheel is a machine for converting the energy of free-flowing or falling water into useful forms of power. A water wheel consists of a large wooden or metal wheel, with a number of blades or buckets arranged on the outside rim forming the driving surface...

. In 1700, 5/6 of the world's coal was mined in Britain. Without coal, Britain would have run out of suitable sites for watermills by the 1830s. In 1947, there were some 750,000 miners, but by 2004 this had shrunk to some 5,000 miners working in around 20 collieries.

In ancient China, coal was used as fuel by the 4th century AD, but there was little extensive use until the 11th century.

Uses today


Coal as fuel



Coal is primarily used as a solid fuel
Fuel
Fuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air...

 to produce electricity and heat through combustion. World coal consumption was about 6.75 billion short ton
Short ton
The short ton is a unit of mass equal to . In the United States it is often called simply ton without distinguishing it from the metric ton or the long ton ; rather, the other two are specifically noted. There are, however, some U.S...

s in 2006 and is expected to increase 48% to 9.98 billion short tons by 2030. China
Coal power in China
The People's Republic of China is the largest consumer of coal in the world, and is about to become the largest user of coal-derived electricity, generating 1.95 trillion kilowatt-hours per year, or 68.7% of its electricity from coal as of 2006...

 produced 2.38 billion tons in 2006. India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

 produced about 447.3 million tons in 2006. 68.7%
Coal power in China
The People's Republic of China is the largest consumer of coal in the world, and is about to become the largest user of coal-derived electricity, generating 1.95 trillion kilowatt-hours per year, or 68.7% of its electricity from coal as of 2006...

 of China's electricity comes from coal. The USA consumes about 14% of the world total, using 90% of it for generation of electricity.

When coal is used for electricity generation
Electricity generation
Electricity generation is the process of generating electric energy from other forms of energy.The fundamental principles of electricity generation were discovered during the 1820s and early 1830s by the British scientist Michael Faraday...

, it is usually pulverized and then combusted (burned) in a furnace
Furnace
A furnace is a device used for heating. The name derives from Latin fornax, oven.In American English and Canadian English, the term furnace on its own is generally used to describe household heating systems based on a central furnace , and sometimes as a synonym for kiln, a device used in the...

 with a boiler
Boiler
A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications.-Materials:...

. The furnace heat converts boiler water to steam
Steam
Steam is the technical term for water vapor, the gaseous phase of water, which is formed when water boils. In common language it is often used to refer to the visible mist of water droplets formed as this water vapor condenses in the presence of cooler air...

, which is then used to spin turbine
Turbine
A turbine is a rotary engine that extracts energy from a fluid flow and converts it into useful work.The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they move and...

s which turn generator
Electrical generator
In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric charge to flow through an external electrical circuit. It is analogous to a water pump, which causes water to flow...

s and create electricity. The thermodynamic efficiency of this process has been improved over time. Simple cycle steam turbines have topped out with some of the most advanced reaching about 35% thermodynamic efficiency for the entire process. Increasing the combustion temperature can boost this efficiency even further. Old coal power plants, especially "grandfathered" plants, are significantly less efficient and produce higher levels of waste heat
Waste heat
Waste heat sometimes called Secondary heat or Low-grade heat refers to heat produced by machines, electrical equipment and industrial processes for which no useful application is found. Energy is often produced by a heat engine, running on a source of high-temperature heat...

. At least 40% of the world's electricity comes from coal, and in 2008 approximately 49% of the United States' electricity came from coal. The emergence of the supercritical turbine
Steam turbine
A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into rotary motion. Its modern manifestation was invented by Sir Charles Parsons in 1884....

 concept envisions running a boiler at extremely high temperatures and pressures with projected efficiencies of 46%, with further theorized increases in temperature and pressure perhaps resulting in even higher efficiencies.

An experimental way of coal combustion is in a form of coal-water slurry fuel
Coal-water slurry fuel
Coal-water slurry fuel is a fuel which consists of fine coal particles suspended in water. Presence of water in CWS reduces harmful emissions into the atmosphere, makes the coal explosion-proof, makes use of coal equivalent to use of liquid fuel Coal-water slurry fuel (CWSF or CWS or CWF) is a...

 (CWS, which was well-developed in Russia (since the Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

 time). CWS
Coal-water slurry fuel
Coal-water slurry fuel is a fuel which consists of fine coal particles suspended in water. Presence of water in CWS reduces harmful emissions into the atmosphere, makes the coal explosion-proof, makes use of coal equivalent to use of liquid fuel Coal-water slurry fuel (CWSF or CWS or CWF) is a...

 significantly reduces emissions saving the heating value of coal. Other ways to use coal are combined heat and power cogeneration
Cogeneration
Cogeneration is the use of a heat engine or a power station to simultaneously generate both electricity and useful heat....

 and an MHD topping cycle.

The total known deposits recoverable by current technologies, including highly polluting, low energy content types of coal (i.e., lignite, bituminous), is sufficient for many years. However, consumption is increasing and maximal production could be reached
Peak coal
Peak coal is the point in time at which the maximum global coal production rate is reached, after which, according to the theory, the rate of production will enter to a terminal decline. Coal is a fossil fuel formed from plant matter over the course of millions of years...

 within decades (see World Coal Reserves, below).

Coking coal and use of coke




Coke is a solid carbonaceous residue derived from low-ash, low-sulfur bituminous coal from which the volatile constituents are driven off by baking in an oven without oxygen at temperatures as high as 1,000 °C (1,832 °F) so that the fixed carbon and residual ash are fused together. Metallurgical coke is used as a fuel and as a reducing agent
Reducing agent
A reducing agent is the element or compound in a reduction-oxidation reaction that donates an electron to another species; however, since the reducer loses an electron we say it is "oxidized"...

 in smelting iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

 ore in a blast furnace
Blast furnace
A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally iron.In a blast furnace, fuel and ore and flux are continuously supplied through the top of the furnace, while air is blown into the bottom of the chamber, so that the chemical reactions...

. The coking coal should be low in sulphur and phosphorus
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...

 so that they do not migrate to the metal. The product is cast iron
Cast iron
Cast iron is derived from pig iron, and while it usually refers to gray iron, it also identifies a large group of ferrous alloys which solidify with a eutectic. The color of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured, due...

 and is too rich in dissolved carbon, and so must be treated further to make steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

.

The coke must be strong enough
Coke strength after reaction
Coke Strength after Reaction refers to coke "hot" strength, generally a quality reference in a simulated reaction condition in an industrial blast furnace. The test is based on a procedure developed by Nippon Steel Corp in the 1970s as an attempt to get an indication of coke performance and is...

 to resist the weight of overburden in the blast furnace, which is why coking coal is so important in making steel using the conventional route. However, the alternative route to is direct reduced iron
Direct reduced iron
Direct-reduced iron , also called sponge iron, is produced from direct reduction of iron ore by a reducing gas produced from natural gas or coal. The reducing gas is a mixture majority of hydrogen and carbon monoxide which acts as reducing agent...

, where any carbonaceous fuel can be used to make sponge or pelletised iron. Coke from coal is grey, hard, and porous and has a heating value of 24.8 million Btu/ton (29.6 MJ/kg). Some cokemaking processes produce valuable by-products that include coal tar
Coal tar
Coal tar is a brown or black liquid of extremely high viscosity, which smells of naphthalene and aromatic hydrocarbons. Coal tar is among the by-products when coal iscarbonized to make coke or gasified to make coal gas...

, ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

, light oils, and "coal gas".

Petroleum coke
Petroleum coke
Petroleum coke is a carbonaceous solid derived from oil refinery coker units or other cracking processes. Other coke has traditionally been derived from coal....

 is the solid residue obtained in oil refining, which resembles coke but contains too many impurities to be useful in metallurgical applications.

Gasification



Coal gasification can be used to produce syngas
Syngas
Syngas is the name given to a gas mixture that contains varying amounts of carbon monoxide and hydrogen. Examples of production methods include steam reforming of natural gas or liquid hydrocarbons to produce hydrogen, the gasification of coal, biomass, and in some types of waste-to-energy...

, a mixture of carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...

 (CO) and hydrogen (H2) gas. This syngas can then be converted into transportation fuels like gasoline and diesel through the Fischer-Tropsch process
Fischer-Tropsch process
The Fischer–Tropsch process is a set of chemical reactions that convert a mixture of carbon monoxide and hydrogen into liquid hydrocarbons. The process, a key component of gas to liquids technology, produces a petroleum substitute, typically from coal, natural gas, or biomass for use as synthetic...

. This technology is currently used by the Sasol
Sasol
Sasol Ltd. is a South African company involved in mining, energy, chemicals and synfuels. In particular, they produce petrol and diesel profitably from coal and natural gas using Fischer-Tropsch process...

 chemical company of South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

 to make gasoline from coal and natural gas. Alternatively, the hydrogen obtained from gasification can be used for various purposes such as powering a hydrogen economy
Hydrogen economy
The hydrogen economy is a proposed system of delivering energy using hydrogen. The term hydrogen economy was coined by John Bockris during a talk he gave in 1970 at General Motors Technical Center....

, making ammonia, or upgrading fossil fuels.

During gasification, the coal is mixed with oxygen and steam (water vapor
Water vapor
Water vapor or water vapour , also aqueous vapor, is the gas phase of water. It is one state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice. Under typical atmospheric conditions, water vapor is continuously...

) while also being heated and pressurized. During the reaction, oxygen and water molecules oxidize the coal into carbon monoxide (CO) while also releasing hydrogen (H2) gas. This process has been conducted in both underground coal mines
Underground Coal Gasification
Underground coal gasification is an industrial process, which converts coal into product gas. UCG is an in-situ gasification process carried out in non-mined coal seams using injection of oxidants, and bringing the product gas to surface through production wells drilled from the surface. The...

 and in coal refineries.
(Coal) + O2 + H2O → H2 + CO


If the refiner wants to produce gasoline, the syngas is collected at this state and routed into a Fischer-Tropsch reaction. If hydrogen is the desired end-product, however, the syngas is fed into the water gas shift reaction
Water gas shift reaction
The water-gas shift reaction is a chemical reaction in which carbon monoxide reacts with water vapor to form carbon dioxide and hydrogen:The water-gas shift reaction is an important industrial reaction. It is often used in conjunction with steam reforming of methane or other hydrocarbons, which is...

 where more hydrogen is liberated.
CO + H2O → CO2 + H2


High prices of oil and natural gas are leading to increased interest in "BTU Conversion" technologies such as gasification
Gasification
Gasification is a process that converts organic or fossil based carbonaceous materials into carbon monoxide, hydrogen, carbon dioxide and methane. This is achieved by reacting the material at high temperatures , without combustion, with a controlled amount of oxygen and/or steam...

, methanation and liquefaction. The Synthetic Fuels Corporation
Synthetic Fuels Corporation
The Synthetic Fuels Corporation was a U.S. government-funded corporation established in 1980 by the Synthetic Fuels Corporation Act to create a financial bridge for the development and construction of commercial synthetic fuel manufacturing plants that would produce alternatives to imported fossil...

 was a U.S. government-funded corporation established in 1980 to create a market for alternatives to imported fossil fuels (such as coal gasification). The corporation was discontinued in 1985.

In the past, coal was converted to make coal gas, which was piped to customers to burn for illumination, heating, and cooking. At present, the safer natural gas is used instead.

Liquefaction


Coal can also be converted into liquid fuels
Synthetic fuel
Synthetic fuel or synfuel is a liquid fuel obtained from coal, natural gas, oil shale, or biomass. It may also refer to fuels derived from other solids such as plastics or rubber waste. It may also refer to gaseous fuels produced in a similar way...

 such as gasoline
Gasoline
Gasoline , or petrol , is a toxic, translucent, petroleum-derived liquid that is primarily used as a fuel in internal combustion engines. It consists mostly of organic compounds obtained by the fractional distillation of petroleum, enhanced with a variety of additives. Some gasolines also contain...

 or diesel by several different processes. In the direct liquefaction processes, the coal is either hydrogenated
Hydrogenation
Hydrogenation, to treat with hydrogen, also a form of chemical reduction, is a chemical reaction between molecular hydrogen and another compound or element, usually in the presence of a catalyst. The process is commonly employed to reduce or saturate organic compounds. Hydrogenation typically...

 or carbonized
Carbonization
Carbonization or carbonisation is the term for the conversion of an organic substance into carbon or a carbon-containing residue through pyrolysis or destructive distillation. It is often used in organic chemistry with reference to the generation of coal gas and coal tar from raw coal...

. Hydrogenation processes are the Bergius process
Bergius process
The Bergius Process is a method of production of liquid hydrocarbons for use as synthetic fuel by hydrogenation of high-volatile bituminous coal at high temperature and pressure...

, the SRC-I and SRC-II (Solvent Refined Coal) processes and the NUS Corporation hydrogenation process. In the process of low-temperature carbonization
Carbonization
Carbonization or carbonisation is the term for the conversion of an organic substance into carbon or a carbon-containing residue through pyrolysis or destructive distillation. It is often used in organic chemistry with reference to the generation of coal gas and coal tar from raw coal...

, coal is coked at temperatures between 360 °C (680 °F) and 750 °C (1,380 °F). These temperatures optimize the production of coal tars richer in lighter hydrocarbons than normal coal tar. The coal tar is then further processed into fuels. Alternatively, coal can be converted into a gas first, and then into a liquid, by using the Fischer-Tropsch process
Fischer-Tropsch process
The Fischer–Tropsch process is a set of chemical reactions that convert a mixture of carbon monoxide and hydrogen into liquid hydrocarbons. The process, a key component of gas to liquids technology, produces a petroleum substitute, typically from coal, natural gas, or biomass for use as synthetic...

. An overview of coal liquefaction and its future potential is available.

Coal liquefaction methods involve carbon dioxide (CO2) emissions in the conversion process. If coal liquefaction is done without employing either carbon capture and storage
Carbon capture and storage
Carbon capture and storage , alternatively referred to as carbon capture and sequestration, is a technology to prevent large quantities of from being released into the atmosphere from the use of fossil fuel in power generation and other industries. It is often regarded as a means of mitigating...

 technologies or biomass blending, the result is lifecycle greenhouse gas footprints that are generally greater than those released in the extraction and refinement of liquid fuel production from crude oil. If CCS technologies are employed, reductions of 5-12% can be achieved in CTL plants and up to a 75% reduction is achievable when co-gasifying coal with commercially demonstrated levels of biomass (30% biomass by weight) in CBTL plants. For most future synthetic fuel
Synthetic fuel
Synthetic fuel or synfuel is a liquid fuel obtained from coal, natural gas, oil shale, or biomass. It may also refer to fuels derived from other solids such as plastics or rubber waste. It may also refer to gaseous fuels produced in a similar way...

 projects, Carbon dioxide sequestration is proposed to avoid releasing it into the atmosphere. Sequestration will, however, add to the cost of production. Currently all US and at least one Chinese synthetic fuel projects, include sequestration in their process designs.

Refined coal



Refined coal is the product of a coal-upgrading technology that removes moisture and certain pollutants from lower-rank coals such as sub-bituminous and lignite (brown) coals. It is one form of several pre-combustion treatments and processes for coal that alter coal's characteristics before it is burned. The goals of pre-combustion coal technologies are to increase efficiency and reduce emissions when the coal is burned. Depending on the situation, pre-combustion technology can be used in place of or as a supplement to post-combustion technologies to control emissions from coal-fueled boilers.

Industrial processes


Finely ground bituminous coal, known in this application as sea coal, is a constituent of foundry sand. While the molten metal is in the mould
Molding (process)
Molding or moulding is the process of manufacturing by shaping pliable raw material using a rigid frame or model called a pattern....

 the coal burns slowly, releasing reducing gases
Reducing agent
A reducing agent is the element or compound in a reduction-oxidation reaction that donates an electron to another species; however, since the reducer loses an electron we say it is "oxidized"...

 at pressure and so preventing the metal from penetrating the pores of the sand. It is also contained in mould wash, a paste or liquid with the same function applied to the mould before casting. Sea coal can be mixed with the clay lining (the "bod") used for the bottom of a cupola furnace
Cupola furnace
A Cupola or Cupola furnace is a melting device used in foundries that can be used to melt cast iron, ni-resist iron and some bronzes. The cupola can be made almost any practical size. The size of a cupola is expressed in diameters and can range from . The overall shape is cylindrical and the...

. When heated the coal decomposes and the bod becomes slightly friable, easing the process of breaking open holes for tapping the molten metal.

Cultural usage


Coal is the official state mineral of Kentucky
Kentucky
The Commonwealth of Kentucky is a state located in the East Central United States of America. As classified by the United States Census Bureau, Kentucky is a Southern state, more specifically in the East South Central region. Kentucky is one of four U.S. states constituted as a commonwealth...

 (even though coal is not a mineral) and the official state rock of Utah
Utah
Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...

. Both U.S. state
U.S. state
A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...

s have a historic link to coal mining.

Some cultures uphold that children who misbehave will receive only a lump of coal from Santa Claus
Santa Claus
Santa Claus is a folklore figure in various cultures who distributes gifts to children, normally on Christmas Eve. Each name is a variation of Saint Nicholas, but refers to Santa Claus...

 for Christmas in their stocking
Christmas stocking
A Christmas stocking is an empty sock or sock-shaped bag that children hang on Christmas Eve so that Santa Claus can fill it with small toys, candy, fruit, coins or other small gifts when he arrives. These small items are often referred to as stocking stuffers or stocking fillers...

s instead of presents.

It is also customary and lucky in Scotland and the North of England to give coal as a gift on New Year's Day. It happens as part of First-Foot
First-Foot
In Scottish and Northern English folklore, the first-foot, also known in Manx Gaelic as quaaltagh or qualtagh, is the first person to cross the threshold of a home on New Year's Day and a bringer of good fortune for the coming year....

ing and represents warmth for the year to come.

Coal as a traded commodity


In North America, Central Appalachian coal futures contract
Futures contract
In finance, a futures contract is a standardized contract between two parties to exchange a specified asset of standardized quantity and quality for a price agreed today with delivery occurring at a specified future date, the delivery date. The contracts are traded on a futures exchange...

s are currently traded on the New York Mercantile Exchange (trading symbol QL). The trading unit is 1550 short tons (1,406.1 t) per contract, and is quoted in U.S. dollars and cents per ton. Since coal is the principal fuel for generating electricity in the United States, coal futures contracts provide coal producers and the electric power industry
Electrical power industry
The electric power industry provides the production and delivery of electric energy, often known as power, or electricity, in sufficient quantities to areas that need electricity through a grid connection. The grid distributes electrical energy to customers...

 an important tool for hedging
Hedge (finance)
A hedge is an investment position intended to offset potential losses that may be incurred by a companion investment.A hedge can be constructed from many types of financial instruments, including stocks, exchange-traded funds, insurance, forward contracts, swaps, options, many types of...

 and risk management
Risk management
Risk management is the identification, assessment, and prioritization of risks followed by coordinated and economical application of resources to minimize, monitor, and control the probability and/or impact of unfortunate events or to maximize the realization of opportunities...

.

In addition to the NYMEX contract, the IntercontinentalExchange (ICE)
IntercontinentalExchange
IntercontinentalExchange, Inc., known as ICE, is an American financial company that operates Internet-based marketplaces which trade futures and over-the-counter energy and commodity contracts as well as derivative financial products...

 has European (Rotterdam) and South African (Richards Bay) coal futures available for trading. The trading unit for these contracts is 5000 tonnes (5,511.6 ST), and are also quoted in U.S. dollars and cents per ton.

The price of coal increased from around $30.00 per short ton
Short ton
The short ton is a unit of mass equal to . In the United States it is often called simply ton without distinguishing it from the metric ton or the long ton ; rather, the other two are specifically noted. There are, however, some U.S...

 in 2000 to around $150.00 per short ton as of September 2008. As of October 2008, the price per short ton had declined to $111.50. Prices further declined to $71.25 as of October 2010.

Environmental effects




There are a number of adverse health and environmental effects of coal burning especially in power station
Power station
A power station is an industrial facility for the generation of electric energy....

s, and of coal mining
Coal mining
The goal of coal mining is to obtain coal from the ground. Coal is valued for its energy content, and since the 1880s has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron from iron ore and for cement production. In the United States,...

. These effects include:
  • Coal-fired power plants shortened nearly 24,000 lives a year in the United States, including 2,800 from lung cancer
    Lung cancer
    Lung cancer is a disease characterized by uncontrolled cell growth in tissues of the lung. If left untreated, this growth can spread beyond the lung in a process called metastasis into nearby tissue and, eventually, into other parts of the body. Most cancers that start in lung, known as primary...

  • Generation of hundreds of millions of tons of waste products, including fly ash
    Fly ash
    Fly ash is one of the residues generated in combustion, and comprises the fine particles that rise with the flue gases. Ash which does not rise is termed bottom ash. In an industrial context, fly ash usually refers to ash produced during combustion of coal...

    , bottom ash
    Bottom ash
    Bottom ash refers to part of the non-combustible residues of combustion. In an industrial context, it usually refers to coal combustion and comprises traces of combustibles embedded in forming clinkers and sticking to hot side walls of a coal-burning furnace during its operation. The portion of...

    , flue gas desulfurization
    Flue gas desulfurization
    Sulfur dioxide is one of the elements forming acid rain. Tall flue-gas stacks disperse emissions by diluting the pollutants in ambient air and transporting them to other regions....

     sludge, that contain mercury
    Mercury (element)
    Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...

    , uranium
    Uranium
    Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...

    , thorium
    Thorium
    Thorium is a natural radioactive chemical element with the symbol Th and atomic number 90. It was discovered in 1828 and named after Thor, the Norse god of thunder....

    , arsenic
    Arsenic
    Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...

    , and other heavy metals
    Heavy metals
    A heavy metal is a member of a loosely-defined subset of elements that exhibit metallic properties. It mainly includes the transition metals, some metalloids, lanthanides, and actinides. Many different definitions have been proposed—some based on density, some on atomic number or atomic weight,...

  • Acid rain
    Acid rain
    Acid rain is a rain or any other form of precipitation that is unusually acidic, meaning that it possesses elevated levels of hydrogen ions . It can have harmful effects on plants, aquatic animals, and infrastructure. Acid rain is caused by emissions of carbon dioxide, sulfur dioxide and nitrogen...

     from high sulfur coal
  • Interference with groundwater
    Groundwater
    Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...

     and water table
    Water table
    The water table is the level at which the submarine pressure is far from atmospheric pressure. It may be conveniently visualized as the 'surface' of the subsurface materials that are saturated with groundwater in a given vicinity. However, saturated conditions may extend above the water table as...

     levels
  • Contamination of land and waterways and destruction of homes from fly ash spills such as Kingston Fossil Plant coal fly ash slurry spill
    Kingston Fossil Plant coal fly ash slurry spill
    The TVA Kingston Fossil Plant coal fly ash slurry spill occurred just before 1 a.m. on Monday December 22, 2008, when an ash dike ruptured at an solid waste containment area at the Tennessee Valley Authority's Kingston Fossil Plant in Roane County, Tennessee, USA. of coal fly ash slurry was...

  • Impact of water use on flows of rivers and consequential impact on other land-uses
  • Dust nuisance
  • Subsidence above tunnels, sometimes damaging infrastructure
  • Uncontrollable underground fires which may burn for decades or centuries.
  • Coal-fired power plants without effective fly ash capture are one of the largest sources of human-caused background radiation
    Background radiation
    Background radiation is the ionizing radiation constantly present in the natural environment of the Earth, which is emitted by natural and artificial sources.-Overview:Both Natural and human-made background radiation varies by location....

     exposure
  • Coal-fired power plants emit mercury, selenium, and arsenic which are harmful to human health and the environment
  • Release of carbon dioxide, a greenhouse gas
    Greenhouse gas
    A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...

    , which causes climate change
    Climate change
    Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...

     and global warming
    Global warming
    Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...

     according to the IPCC
    Intergovernmental Panel on Climate Change
    The Intergovernmental Panel on Climate Change is a scientific intergovernmental body which provides comprehensive assessments of current scientific, technical and socio-economic information worldwide about the risk of climate change caused by human activity, its potential environmental and...

     and the EPA
    United States Environmental Protection Agency
    The U.S. Environmental Protection Agency is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress...

    . Coal is the largest contributor to the human-made increase of CO2 in the air

Economic aspects


Coal liquification is one of the backstop
Backstop resources
Backstop resources theory states that as a heavily used limited resource becomes expensive, alternative resources will become cheap by comparison, therefore making the alternatives economically viable options...

 technologies that could potentially limit escalation of oil prices and mitigate the effects of transportation energy shortage that will occur under peak oil
Peak oil
Peak oil is the point in time when the maximum rate of global petroleum extraction is reached, after which the rate of production enters terminal decline. This concept is based on the observed production rates of individual oil wells, projected reserves and the combined production rate of a field...

. This is contingent on liquefaction production capacity becoming large enough to satiate the very large and growing demand for petroleum. Estimates of the cost of producing liquid fuels from coal suggest that domestic U.S. production of fuel from coal becomes cost-competitive with oil priced at around $35 per barrel, with the $35 being the break-even cost. With oil prices as low as around $40 per barrel in the U.S. as of December 2008, liquid coal lost some of its economic allure in the U.S., but will probably be re-vitalized, similar to oil sand projects, with an oil price around $70 per barrel.

United States



Some of the simplest economic costs of coal come in the form of subsidies and tax breaks which are not reflected in the market price of coal (for example the estimated $4.6 billion in coal-related subsidies in the 2009 stimulus package). Coal mining and combustion projects require major investments, and the risks and costs of those investments are often passed on to taxpayers via infrastructure subsidies and loan guarantees. An extreme example of this is the Healy Clean Coal Plant (HCCP), which has cost the State of Alaska and the Federal Government nearly $300 million since the mid 1990s yet is not producing power in return. Similarly, a recent study in Kentucky determined that the government spends $115 million more on subsidies for the coal industry in the state than it receives in taxes or other benefits.

Taxpayers also pay the costs of cleaning up environmental disasters caused by the coal industry. Cleanup of the recent coal ash spill in Tennessee is estimated to cost up to $1 billion, not including pending litigation. Now that the cleanup at this site has been taken over by the EPA under the Superfund law, most of this cost will be borne by the US taxpayer.

The health impacts of coal pollution have enormous economic costs, through health care costs and lost productivity. The Ontario government study estimated these costs as billions of dollars within Ontario alone. A similar recent study in West Virginia found that the cost associated with premature death due to coal mining was five times greater than all measurable economic benefits from the mining.

Other industries depend on the ecosystems coal mining destroys. This economic impact on industries such as recreational fishing, commercial fishing, and tourism is particularly relevant in Alaska. Almost 55,000 direct jobs (full time equivalent basis, FTE) are closely linked to the health of Alaska's ecosystems. These jobs make up more than a quarter of Alaskan FTE employment and produce almost $2.6 billion of income for Alaska workers. These 55,000 ecosystem-dependent jobs dwarf the 350 estimated jobs that would be created by a project such as the Chuitna Coal strip mine.

Negative effects on the economy lead to worse health in the population, which has an impact on health care costs, compounding the economic impact. Some people have used this to argue that coal has additional benefits to society. The argument is that coal provides cheap electricity, which is a boon to the economy, therefore health is improved, and health care costs are lowered. While this additional health effect should indeed be considered, it should be applied after the economic impacts discussed above. Once the costs of pollution, global warming, and habitat destruction are added to the benefits of cheap electricity, the economic impact of coal is no longer positive, and this additional health effect only makes it even more costly.

China


In China, due to an increasing need for liquid energy in the transportation sector, coal liquefaction projects were given high priority even during periods of oil prices below $40 per barrel. This is probably because China prefers not to be dependent on foreign oil, instead utilizing its enormous domestic coal reserves. As oil prices were increasing during the first half of 2009, the coal liquefaction projects in China were again boosted, and these projects are profitable with an oil barrel price of $40.

China is by far the largest producer of coal in the world. It has now become the world's largest energy consumer but relies on coal to supply about 70% of its energy needs. An estimated 5 million people work in China's coal-mining industry.

Among commercially mature technologies, advantages for indirect coal liquefaction over direct coal liquefaction are reported by Williams and Larson (2003).

Energy density



The energy density
Energy density
Energy density is a term used for the amount of energy stored in a given system or region of space per unit volume. Often only the useful or extractable energy is quantified, which is to say that chemically inaccessible energy such as rest mass energy is ignored...

 of coal, i.e. its heating value, is roughly 24 megajoules per kilogram.

The energy density of coal can also be expressed in kilowatt-hours
Watt-hour
The kilowatt hour, or kilowatt-hour, is a unit of energy equal to 1000 watt hours or 3.6 megajoules.For constant power, energy in watt hours is the product of power in watts and time in hours...

, the units that electricity is most commonly sold in, per units of mass to estimate how much coal is required to power electrical appliances. One kilowatt-hour is 3.6 MJ, so the energy density of coal is 6.67 kW·h/kg. The typical thermodynamic efficiency of coal power plants is about 30%, so of the 6.67 kW·h of energy per kilogram of coal, 30% of that—2.0 kW·h/kg—can successfully be turned into electricity; the rest is waste heat. So coal power plants obtain approximately 2.0 kW·h per kilogram of burned coal.

As an example, running one 100-watt lightbulb for one year requires 876 kW·h (100 W × 24 h/day × 365 day/year = 876000 W·h = 876 kW·h). Converting this power usage into physical coal consumption:

For a coal power plant with a 40% efficiency, it takes 325 kg (714 lb) of coal to power a 100 W lightbulb for one year. One should also take into account transmission and distribution losses caused by resistance and heating in the power lines
Electric power transmission
Electric-power transmission is the bulk transfer of electrical energy, from generating power plants to Electrical substations located near demand centers...

, which is in the order of 5–10%, depending on distance from the power station and other factors.

Carbon intensity


Commercial coal has a carbon content of at least 70%. Coal with a heating value of 6.67 kWh per kilogram as quoted above has a carbon content of roughly 80%, which is , where 1 mol
Mole (unit)
The mole is a unit of measurement used in chemistry to express amounts of a chemical substance, defined as an amount of a substance that contains as many elementary entities as there are atoms in 12 grams of pure carbon-12 , the isotope of carbon with atomic weight 12. This corresponds to a value...

 equals to NA (Avogadro Number) atoms.

Carbon combines with oxygen in the atmosphere during combustion, producing carbon dioxide, with an atomic weight of (12 + 16 × 2 = 44 kg/kmol). The CO2 released to air for each kilogram of incinerated coal is therefore.

This can be used to calculate an emission factor
Emission factor
An emission intensity is the average emission rate of a given pollutant from a given source relative to the intensity of a specific activity; for example grams of carbon dioxide released per megajoule of energy produced, or the ratio of greenhouse gas emissions produced to GDP...

 for CO2 from the use of coal power. Since the useful energy output of coal is about 30% of the 6.67 kWh/kg(coal), the burning of 1 kg of coal produces about 2 kWh of electrical energy. Since 1 kg coal emits 2.93 kg CO2, the direct CO2 emissions from coal power are 1.47 kg/kWh, or about 0.407 kg/MJ.

The U.S. Energy Information Agency's 1999 report on CO2 emissions for energy generation, quotes a lower emission factor of 0.963 kg CO2/kWh for coal power. The same source gives a factor for oil power in the U.S. of 0.881 kg CO2/kWh, while natural gas has 0.569 kg CO2/kWh. Estimates for specific emission from nuclear power
Nuclear power
Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity...

, hydro, and wind energy
Wind power
Wind power is the conversion of wind energy into a useful form of energy, such as using wind turbines to make electricity, windmills for mechanical power, windpumps for water pumping or drainage, or sails to propel ships....

 vary, but are about 100 times lower.

Underground fires



There are thousands of coal fires burning around the world. Those burning underground can be difficult to locate and many cannot be extinguished. Fires can cause the ground above to subside, their combustion gases are dangerous to life, and breaking out to the surface can initiate surface wildfire
Wildfire
A wildfire is any uncontrolled fire in combustible vegetation that occurs in the countryside or a wilderness area. Other names such as brush fire, bushfire, forest fire, desert fire, grass fire, hill fire, squirrel fire, vegetation fire, veldfire, and wilkjjofire may be used to describe the same...

s. Coal seams can be set on fire by spontaneous combustion
Spontaneous combustion
Spontaneous combustion is the self-ignition of a mass, for example, a pile of oily rags. Allegedly, humans can also ignite and burn without an obvious cause; this phenomenon is known as spontaneous human combustion....

 or contact with a mine fire
Mine fire
A coal seam fire or mine fire is the underground smouldering of a coal deposit, often in a coal mine. Such fires have economic, social and ecological impacts...

 or surface fire. Lightning strikes are an important source of ignition, the coal continues to burn slowly back into the seam until oxygen (air) can no longer reach the flame front. A grass fire in a coal area can set dozens of coal seams on fire. Coal fires in China burn 109 million tons of coal a year, emitting 360 million metric tons of CO2. This contradicts the ratio of 1:1.83 given earlier, but it amounts to 2-3% of the annual worldwide production of CO2 from fossil fuels. In Centralia, Pennsylvania
Centralia, Pennsylvania
Centralia is a borough and ghost town in Columbia County, Pennsylvania, United States. Its population has dwindled from over 1,000 residents in 1981 to 12 in 2005, 9 in 2007, and 10 in 2010, as a result of a mine fire burning beneath the borough since 1962...

 (a borough
Borough
A borough is an administrative division in various countries. In principle, the term borough designates a self-governing township although, in practice, official use of the term varies widely....

 located in the Coal Region
Coal Region
The Coal Region is a term used to refer to an area of Northeastern Pennsylvania in the central Appalachian Mountains comprising Lackawanna, Luzerne, Columbia, Carbon, Schuylkill, Northumberland, and the extreme northeast corner of Dauphin counties....

 of the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

), an exposed vein of coal ignited in 1962 due to a trash fire in the borough landfill, located in an abandoned anthracite
Anthracite coal
Anthracite is a hard, compact variety of mineral coal that has a high luster...

 strip mine
Surface mining
Surface mining , is a type of mining in which soil and rock overlying the mineral deposit are removed...

 pit. Attempts to extinguish the fire were unsuccessful, and it continues to burn underground to this day. The Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

n Burning Mountain
Burning Mountain
Burning Mountain, the common name for Mount Wingen, is a hill near Wingen, New South Wales, Australia, approximately north of Sydney just off the New England Highway. It takes its name from a smouldering coal seam running underground through the sandstone...

 was originally believed to be a volcano, but the smoke and ash comes from a coal fire that has been burning for some 6,000 years.

At Kuh i Malik in Yagnob Valley
Yagnob Valley
Yagnob Valley North West Tajikistan, is situated between the southern slope of the Zarafshan Range and the northern slope of the Gissar Range. The valley is formed by the Yagnob River and belongs to the Zarafshan basin...

, Tajikistan
Tajikistan
Tajikistan , officially the Republic of Tajikistan , is a mountainous landlocked country in Central Asia. Afghanistan borders it to the south, Uzbekistan to the west, Kyrgyzstan to the north, and China to the east....

, coal deposits have been burning for thousands of years, creating vast underground labyrinths full of unique minerals, some of them very beautiful. Local people once used this method to mine ammoniac. This place has been well-known since the time of Herodotus
Herodotus
Herodotus was an ancient Greek historian who was born in Halicarnassus, Caria and lived in the 5th century BC . He has been called the "Father of History", and was the first historian known to collect his materials systematically, test their accuracy to a certain extent and arrange them in a...

, but European geographers misinterpreted the Ancient Greek descriptions as the evidence of active volcanism
Volcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...

 in Turkestan
Turkestan
Turkestan, spelled also as Turkistan, literally means "Land of the Turks".The term Turkestan is of Persian origin and has never been in use to denote a single nation. It was first used by Persian geographers to describe the place of Turkish peoples...

 (up to the 19th century, when the Russian army invaded the area).

The reddish siltstone rock that caps many ridges and buttes in the Powder River Basin
Powder River Basin
The Powder River Basin is a geologic region in southeast Montana and northeast Wyoming, about east to west and north to south, known for its coal deposits. The region supplies about 40 percent of coal in the United States. It is both a topographic drainage and geologic structural basin...

 (Wyoming
Wyoming
Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High...

), and in western North Dakota
North Dakota
North Dakota is a state located in the Midwestern region of the United States of America, along the Canadian border. The state is bordered by Canada to the north, Minnesota to the east, South Dakota to the south and Montana to the west. North Dakota is the 19th-largest state by area in the U.S....

 is called porcelanite, which also may resemble the coal burning waste "clinker" or volcanic "scoria
Scoria
Scoria is a volcanic rock containing many holes or vesicles. It is most generally dark in color , and basaltic or andesitic in composition. Scoria is relatively low in mass as a result of its numerous macroscopic ellipsoidal vesicles, but in contrast to pumice, all scoria has a specific gravity...

". Clinker is rock that has been fused by the natural burning of coal. In the Powder River Basin approximately 27 to 54 billion tons of coal burned within the past three million years. Wild coal fires in the area were reported by the Lewis and Clark Expedition
Lewis and Clark Expedition
The Lewis and Clark Expedition, or ″Corps of Discovery Expedition" was the first transcontinental expedition to the Pacific Coast by the United States. Commissioned by President Thomas Jefferson and led by two Virginia-born veterans of Indian wars in the Ohio Valley, Meriwether Lewis and William...

 as well as explorers and settlers in the area.

Production trends




In 2006, China was the top producer of coal with 38% share followed by the USA and India, according to the British Geological Survey
British Geological Survey
The British Geological Survey is a partly publicly funded body which aims to advance geoscientific knowledge of the United Kingdom landmass and its continental shelf by means of systematic surveying, monitoring and research. The BGS headquarters are in Keyworth, Nottinghamshire, but other centres...

.

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
Barrel of oil equivalent
The barrel of oil equivalent is a unit of energy based on the approximate energy released by burning one barrel of crude oil. The US Internal Revenue Service defines it as equal to 5.8 × 106 BTU...

). 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 57000000 barrels (9,062,275,815 l) of oil equivalent per day. By comparison in 2007, natural gas provided 51000000 barrels (8,108,352,045 l) of oil equivalent per day, while oil provided 85800000 barrels (13,641,109.9 m³) per day.

BP
BP
BP p.l.c. is a global oil and gas company headquartered in London, United Kingdom. It is the third-largest energy company and fourth-largest company in the world measured by revenues and one of the six oil and gas "supermajors"...

, in its 2007 report, estimated at 2006 end that there were several billion tons of proven coal reserves worldwide, or 147 years reserves-to-production ratio
Reserves-to-production ratio
The Reserves-to-production ratio is the remaining amount of a non-renewable resource, expressed in years. While applicable to all natural resources, the RPR is most commonly applied to fossil fuels, particularly petroleum and natural gas...

. 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. Speculative projections predict that global peak coal
Peak coal
Peak coal is the point in time at which the maximum global coal production rate is reached, after which, according to the theory, the rate of production will enter to a terminal decline. Coal is a fossil fuel formed from plant matter over the course of millions of years...

 production may occur sometime around 2025 at 30 percent above current production, 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 at end-2008 (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
 Mainland 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
 Kingdom of 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

Major coal producers



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. Countries with annual production higher than 100 million tonnes are shown. For comparison, data for the European Union is also shown.
Shares are based on data expressed in tonnes oil equivalent.
Production of Coal by Country and year (million tonnes)
Country 2003 2004 2005 2006 2007 2008 2009 2010 Share Reserve Life (years)
 Mainland China 1834.9 2122.6 2349.5 2528.6 2691.6 2802.0 2973.0 3240.0 48.3 % 35
 United States 972.3 1008.9 1026.5 1054.8 1040.2 1063.0 975.2 984.6 14.8 % 241
 India 375.4 407.7 428.4 449.2 478.4 515.9 556.0 569.9 5.8 % 106
 European Union 637.2 627.6 607.4 595.1 592.3 563.6 538.4 535.7 4.2 % 105
 Australia 350.4 364.3 375.4 382.2 392.7 399.2 413.2 423.9 6.3 % 180
 Russia 276.7 281.7 298.3 309.9 313.5 328.6 301.3 316.9 4.7 % 495
 Indonesia 114.3 132.4 152.7 193.8 216.9 240.2 256.2 305.9 5.0 % 18
 South Africa 237.9 243.4 244.4 244.8 247.7 252.6 250.6 253.8 3.8 % 119
 Germany 204.9 207.8 202.8 197.1 201.9 192.4 183.7 182.3 1.2 % 223
 Poland 163.8 162.4 159.5 156.1 145.9 144.0 135.2 133.2 1.5 % 43
 Kazakhstan 84.9 86.9 86.6 96.2 97.8 111.1 100.9 110.8 1.5 % 303
Total World 5,301.3 5,716.0 6,035.3 6,342.0 6,573.3 6,795.0 6,880.8 7,273.3 100 % 118

Major coal exporters


Countries with annual export higher than 10 million tonnes are shown.
Exports of Coal by Country and year (million short tons)
Country 2003 2004 2005 2006 2007 2008 2009 Share
 Australia 238.1 247.6 255.0 255.0 268.5 278.0 288.5 26.5%
 Indonesia 107.8 131.4 142.0 192.2 221.9 228.2 261.4 24.0%
 Russia 41.0 55.7 98.6 103.4 112.2 115.4 130.9 12.0%
 Colombia 50.4 56.4 59.2 68.3 74.5 74.7 75.7 6.9%
 South Africa 78.7 74.9 78.8 75.8 72.6 68.2 73.8 6.8%
 United States 43.0 48.0 51.7 51.2 60.6 83.5 60.4 5.5%
 Mainland China 103.4 95.5 93.1 85.6 75.4 68.8 38.4 3.5%
 Canada 27.7 28.8 31.2 31.2 33.4 36.5 31.9 2.9%
 Vietnam 6.9 11.7 19.8 23.5 35.1 21.3 28.2 2.6%
 Kazakhstan 30.3 27.4 28.3 30.5 32.8 47.6 25.7 2.4%
 Poland 28.0 27.5 26.5 25.4 20.1 16.1 14.6 1.3%
Total 713.9 764.0 936.0 1,000.6 1,073.4 1,087.3 1,090.8 100%

Major coal importers


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%
 Mainland 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%
 Republic of China 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%


See also



  • Asphaltene
  • Biochar
    Biochar
    Biochar or terra preta is charcoal created by pyrolysis of biomass. Biochar is under investigation as an approach to carbon sequestration via bio-energy with carbon capture and storage. Biochar thus has the potential to help mitigate climate change, via carbon sequestration...

  • Carbochemistry
    Carbochemistry
    Carbochemistry is the branch of chemistry that studies the transformation of coals into useful products and raw materials.-See also:* Petrochemistry* Coal* Coke * coal-gas* coal-tar...

  • Coal assay
    Coal assay
    Coal Analysis techniques are specific analytical methods designed to measure the particular physical and chemical properties of coals. These methods are used primarily to determine the suitability of coal for coking, power generation or for iron ore smelting in the manufacture of steel.-Chemical...

  • Coal dust
    Coal dust
    Coal dust is a fine powdered form of coal, which is created by the crushing, grinding, or pulverizing of coal. Because of the brittle nature of coal, coal dust can be created during mining, transportation, or by mechanically handling coal.-Explosions:...

  • Coal Measure (stratigraphic unit)
  • Coal mining
    Coal mining
    The goal of coal mining is to obtain coal from the ground. Coal is valued for its energy content, and since the 1880s has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron from iron ore and for cement production. In the United States,...

  • Coal phase out
    Coal phase out
    A fossil fuel phase-out are plans for transport electrification, decommissioning of operating fossil fuel-fired power plants and prevention of the construction of new fossil-fuel-fired power stations. The purpose of this is to decrease the high concentration of greenhouse gas emissions, which are...

  • Coal-tar
  • Coalbed methane
    Coalbed methane
    Coalbed methane or Coal Bed Methane, coalbed gas or coal mine methane is a form of natural gas extracted from coal beds. In recent decades it has become an important source of energy in United States, Canada, and other countries...

  • Fluidized bed combustion
    Fluidized bed combustion
    Fluidized bed combustion is a combustion technology used in power plants. Fluidized beds suspend solid fuels on upward-blowing jets of air during the combustion process. The result is a turbulent mixing of gas and solids. The tumbling action, much like a bubbling fluid, provides more effective...

  • Major coal producing regions
  • Mountaintop removal mining
  • The Coal Question
    The Coal Question
    The Coal Question; An Inquiry Concerning the Progress of the Nation, and the Probable Exhaustion of Our Coal Mines was a book by economist William Stanley Jevons that explored the implications of Britain's reliance on coal. Given that coal was a finite, non-renewable energy resource, Jevons raised...

  • World Coal Association


External links