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
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

 and 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...

. It is considered the lowest rank of coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...

; it is mined in Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

, Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

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

, 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...

, New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

, 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...

 and many European countries
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

, and it is used almost exclusively as a fuel for steam-electric power generation. Up to 50% of Greece's electricity and 24.6% of Germany's comes from lignite power plants.


Lignite is brownish-black in color and has a carbon content of around 25-35%, a high inherent moisture content sometimes as high as 66%, and an ash content ranging from 6% to 19% compared with 6% to 12% for 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...


The energy content of lignite ranges from (9-17 million BTU
British thermal unit
The British thermal unit is a traditional unit of energy equal to about 1055 joules. It is approximately the amount of energy needed to heat of water, which is exactly one tenth of a UK gallon or about 0.1198 US gallons, from 39°F to 40°F...

 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...

) on a moist, mineral-matter-free basis. The energy content of lignite consumed in the United States averages (13 million BTU/ton), on the as-received basis (i.e., containing both inherent moisture and mineral matter). The energy content of lignite consumed in Victoria, Australia averages (6.5 million BTU/ton). When reacted with quaternary amine
Quaternary ammonium cation
Quaternary ammonium cations, also known as quats, are positively charged polyatomic ions of the structure NR4+, R being an alkyl group or an aryl group. Unlike the ammonium ion and the primary, secondary, or tertiary ammonium cations, the quaternary ammonium cations are permanently charged,...

, amine treated lignite (ATL) forms. ATL is used in drilling mud to reduce fluid loss.

Lignite has a high content of volatile matter which makes it easier to convert into gas and liquid petroleum products than higher ranking coals. However, its high moisture content and susceptibility to 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....

 can cause problems in transportation and storage. However, it is now known that efficient processes that remove latent moisture locked within the structure of brown coal will relegate the risk of spontaneous combustion to the same level as black coal, will transform the calorific value of brown coal to a black coal equivalent
Black coal equivalent
Black coal equivalent is a term applied to describe the properties of an export coal product derived from the Coldry Process, a patented coal upgrading technology operated by Environmental Clean Technologies Limited, in Victoria, Australia...

 fuel while significantly reducing the emissions profile of 'densified' brown coal to a level similar to or better than most black coals.


Because of its low energy density and typically high moisture content, brown coal is inefficient to transport and is not traded extensively on the world market compared with higher coal grades. It is often burned in power stations constructed very close to any mines, such as in Australia's Latrobe Valley
Latrobe Valley
The Latrobe Valley is an inland geographical region and urban area of Gippsland in the state of Victoria, Australia. It is east of the City Of Melbourne and nestled between the Strzelecki Ranges to the south and the Great Dividing Range to the north – with the highest peak to the north of the...

 and Luminant
Luminant is a Texas-based electric utility. It is a wholly owned subsidiary of Energy Future Holdings Corporation. Luminant's operations include electricity generation and wholesaling, mining, construction, and development...

's Monticello plant
Monticello Steam Electric Station
The Monticello Steam Electric Station is a three unit coal-fired power plant located in Titus County, Texas. Unit 1 of the Monticello Steam Electric Station began operation in 1974, unit 2 became operational in 1975, and unit 3, became operational in 1978. The plant produces electricity by burning...

 in Texas. Primarily because of latent high moisture content of brown coal, carbon dioxide emissions from traditional brown coal fired plants are generally much higher than for comparable black coal plants, with the world's highest emitting being Hazelwood Power Station, Victoria
Hazelwood Power Station, Victoria
Hazelwood Power Station, in the Latrobe Valley, Victoria, Australia is a brown coal fueled base-load power station built between 1964 and 1971. The power station is of 1,600 megawatt capacity, and supplies up to 25% of Victoria's base load electricity and more than 5% of Australia's total energy...

. The operation of traditional brown coal plants, particularly in combination with strip mining, can be politically contentious due to environmental concerns.


Lignite is geologically younger than higher-grade coals, originating mainly in the Tertiary
The Tertiary is a deprecated term for a geologic period 65 million to 2.6 million years ago. The Tertiary covered the time span between the superseded Secondary period and the Quaternary...


The Latrobe Valley
Latrobe Valley
The Latrobe Valley is an inland geographical region and urban area of Gippsland in the state of Victoria, Australia. It is east of the City Of Melbourne and nestled between the Strzelecki Ranges to the south and the Great Dividing Range to the north – with the highest peak to the north of the...

 in the state of Victoria
Victoria (Australia)
Victoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....

, Australia contains estimated reserves of some 200,000 million tonnes (Mt) of brown coal. The deposit is equivalent to 25% of known world reserves. The coal seams are generally of considerable thickness (to 300 metres) and are covered by very little overburden
Overburden is the material that lies above an area of economic or scientific interest in mining and archaeology; most commonly the rock, soil, and ecosystem that lies above a coal seam or ore body. It is also known as 'waste' or 'spoil'...

 (2 to 5 metres).


Lignite can be separated into two types. The first is xyloid lignite or fossil wood
Fossil wood
Fossil wood is wood that is preserved in the fossil record. Over time the wood will usually be the part of a plant that is best preserved...

 and the second form is the compact lignite or perfect lignite.

Although xyloid lignite may sometimes have the tenacity and the appearance of ordinary wood it can be seen that the combustible woody tissue has experienced a great modification. It is reducible to a fine powder by trituration
Trituration is the name of several different methods of processing materials. Trituration is also the name of the process for reducing the particle size of a substance by grinding, as by grinding of powders in a mortar with a pestle. Trituration additionally refers to the production of a...

 and if submitted to the action of a weak solution of potash
Potash is the common name for various mined and manufactured salts that contain potassium in water-soluble form. In some rare cases, potash can be formed with traces of organic materials such as plant remains, and this was the major historical source for it before the industrial era...

 it yields a considerable quantity of ulmic acid
Humic acid
Humic acid is a principal component of humic substances, which are the major organic constituents of soil , peat, coal, many upland streams, dystrophic lakes, and ocean water. It is produced by biodegradation of dead organic matter...



Lignite mined in millions of metric tons
Country 1970 1980 1990 2000 2001 2011
 Germany 369.3 388.0 356.5 167.7 175.4
 Russia 127.0 141.0 137.3 86.4 83.2
 United States 5.4 42.3 82.6 83.5 80.5
 Australia 24.2 32.9 46.0 65.0 67.8
 Greece 8.1 23.2 51.7 63.3 67.0
 Poland 32.8 36.9 67.6 61.3 59.5
 Turkey 4.4 15.0 43.8 63.0 57.2
 Czech Republic 67.0 87.0 71.0 50.1 50.7
 People's Republic of China 13.0 22.0 38.0 40.0 47.0
 Socialist Federal Republic of Yugoslavia 26.0 43.0 60.0 - -
 Serbia and Montenegro - - - 35.5 35.5
 Kingdom of Romania 14.1 27.1 33.5 17.9 29.8
 North Korea 5.7 10.0 10.0 26.0 26.5
Total 804.0 1,028.0 1,214.0 877.4 894.8

See also

  • 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...

  • 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...

  • Energy value of coal
    Energy value of coal
    The energy value of coal, or the fuel content, raj is the amount of potential energy in coal that can be converted into actual heating ability. The value can be calculated and compared with different grades of coal or even other materials...

  • Orders of magnitude (specific energy density)
    Orders of magnitude (specific energy density)
    This is a table of specific energy densities by magnitude. Unless otherwise noted, these values assume standard ambient temperature and pressure....

  • 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...

  • Karrick process
    Karrick process
    The Karrick process is a low-temperature carbonization and pyrolysis process of carbonaceous materials. Although primarily meant for coal carbonization, it also could be used for processing of oil shale, lignite or any carbonaceous materials. These are heated at to in the absence of air to...

  • Leonardite
    Leonardite is a soft waxy, black or brown, shiny, vitreous mineraloid that is easily soluble in alkaline solutions. It is an oxidation product of lignite, associated with near-surface mining...

  • List of CO2 emitted per million Joule of energy from various fuels

External links

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