Lignite Explained
Lignite (derived from Latin lignum meaning 'wood'), often referred to as brown coal, is a soft, brown, combustible sedimentary rock formed from naturally compressed peat. It has a carbon content around 25–35%[1] and is considered the lowest rank of coal due to its relatively low heat content. When removed from the ground, it contains a very high amount of moisture, which partially explains its low carbon content. Lignite is mined all around the world and is used almost exclusively as a fuel for steam-electric power generation.
Lignite combustion produces less heat for the amount of carbon dioxide and sulfur released than other ranks of coal. As a result, lignite is the most harmful coal to human health.[2] Depending on the source, various toxic heavy metals, including naturally occurring radioactive materials, may be present in lignite and left over in the coal fly ash produced from its combustion, further increasing health risks.[3]
Characteristics
Lignite is brownish-black in color and has a carbon content of 60–70 percent on a dry ash-free basis. However, its inherent moisture content is sometimes as high as 75 percent[4] and its ash content ranges from 6–19 percent, compared with 6–12 percent for bituminous coal.[5] As a result, its carbon content on the as-received basis (i.e., containing both inherent moisture and mineral matter) is typically just 25-35 percent.[1]
The energy content of lignite ranges from 10 to 20 MJ/kg (9–17 million BTU per short ton) 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.[6] The energy content of lignite consumed in Victoria, Australia, averages (8.2 million BTU/ton) on a net wet basis.[7]
Lignite has a high content of volatile matter which makes it easier to convert into gas and liquid petroleum products than higher-ranking coals. Its high moisture content and susceptibility to spontaneous combustion can cause problems in transportation and storage. Processes which remove water from brown coal reduce the risk of spontaneous combustion to the same level as black coal, increase the calorific value of brown coal to a black coal equivalent fuel, and significantly reduce the emissions profile of 'densified' brown coal to a level similar to or better than most black coals.[8] However, removing the moisture increases the cost of the final lignite fuel.
Lignite rapidly degrades when exposed to air. This process is called slacking or slackening.
Uses
Most lignite is used to generate electricity.[1] However, small amounts are used in agriculture, in industry, and even, as jet, in jewelry. Its historical use as fuel for home heating has continuously declined and is now of lower importance than its use to generate electricity.
As fuel
Lignite is often found in thick beds located near the surface, making it inexpensive to mine. However, because of its low energy density, tendency to crumble, 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.[4] [7] It is often burned in power stations near the mines, such as in Australia's Latrobe Valley and Luminant's Monticello plant and Martin Lake plant in Texas. Primarily because of latent high moisture content and low energy density of brown coal, carbon dioxide emissions from traditional brown-coal-fired plants are generally much higher per megawatt-hour generated than for comparable black-coal plants, with the world's highest-emitting plant being Australia's Hazelwood Power Station[9] until its closure in March 2017.[10] The operation of traditional brown-coal plants, particularly in combination with strip mining, is politically contentious due to environmental concerns.[11] [12]
The German Democratic Republic relied extensively on lignite to become energy self-sufficient, and eventually obtained 70% of its energy requirements from lignite.[13] Lignite was also an important chemical industry feedstock via Bergius process or Fischer-Tropsch synthesis in lieu of petroleum,[14] which had to be imported for hard currency following a change in policy by the Soviet Union in the 1970s, which had previously delivered petroleum at below market rates.[15] East German scientists even converted lignite into coke suitable for metallurgical uses (high temperature lignite coke) and much of the railway network was dependent on lignite either through steam trains or electrified lines mostly fed with lignite derived power.[15] As per the table below, East Germany was the largest producer of lignite for much of its existence as an independent state.
In 2014, about 12 percent of Germany's energy and, specifically, 27 percent of Germany's electricity came from lignite power plants,[16] while in 2014 in Greece, lignite provided about 50 percent of its power needs. Germany has announced plans to phase out lignite by 2038 at the latest.[17] [18] [19] [20] Greece has confirmed that the last coal plant will be shut in 2025 after receiving pressure from the European Union[21] and plans to heavily invest in renewable energy.[22]
Home heating
Lignite was and is used as a replacement for or in combination with firewood for home heating. It is usually pressed into briquettes for that use.[23] [24] Due to the smell it gives off when burned, lignite was often seen as a fuel for poor people compared to higher value hard coals. In Germany, briquettes are still readily available to end consumers in home improvement stores and supermarkets.[25] [26] [27] [28]
In agriculture
An environmentally beneficial use of lignite is in agriculture. Lignite may have value as an environmentally benign soil amendment, improving cation exchange and phosphorus availability in soils while reducing availability of heavy metals,[29] [30] and may be superior to commercial K humates.[31] Lignite fly ash produced by combustion of lignite in power plants may also be valuable as a soil amendment and fertilizer.[32] However, rigorous studies of the long-term benefits of lignite products in agriculture are lacking.[33]
Lignite may also be used for the cultivation and distribution of biological control microbes that suppress plant pests. The carbon increases the organic matter in the soil while the biological control microbes provide an alternative to chemical pesticides.[34]
Leonardite is a soil conditioner rich in humic acids that is formed by natural oxidation when lignite comes in contact with air.[35] The process can be replicated artificially on a large scale.[36] The less matured xyloid (wood-shaped) lignite also contains high amounts of humic acid.
In drilling mud
Reaction with quaternary amine forms a product called amine-treated lignite (ATL), which is used in drilling mud to reduce fluid loss during drilling.[37]
As an industrial adsorbent
Lignite may have potential uses as an industrial adsorbent. Experiments show that its adsorption of methylene blue falls within the range of activated carbons currently used by industry.[38]
In jewellery
Jet is a form of lignite that has been used as a gemstone.[39] The earliest jet artifacts date to 10,000 BCE[40] and jet was used extensively in necklaces and other ornamentation in Britain from the Neolithic until the end of Roman Britain.[41] Jet experienced a brief revival in Victorian Britain.[42]
Geology
Lignite begins as an accumulation of partially decayed plant material, or peat. Peat accumulates most readily in areas where there is ample moisture, slow subsidence of the land surface, and lack of disturbance by rivers or oceans. Peat swamps are otherwise found in a wide variety of climates and geographical settings. Under these conditions, the area remains saturated with water, which covers dead plant material and protects it from degradation by atmospheric oxygen. Anaerobic bacteria may continue to degrade the peat, but this process is slow, particularly in acid water. Once the peat is buried by other sediments, biological degradation essentially comes to a halt, and further changes are a result of increased temperature and pressure from burial.[43]
Lignite forms from peat that has not experienced deep burial and heating. It forms at temperatures below 100C,[4] primarily by biochemical degradation. This includes humification, in which microorganisms extract hydrocarbons from the peat and humic acids are formed. The humic acids make the environment more acidic, which slows the rate of further bacterial decay. Humification is still incomplete in lignite, coming to completion only when the coal reaches sub-bituminous rank.[44] The most characteristic chemical change in the organic material during formation of lignite is the sharp reduction in the number of C=O and C-O-R functional groups.[45]
Lignite deposits are typically younger than higher-ranked coals, with the majority of them having formed during the Tertiary period.[4]
Extraction
Lignite is often found in thick beds located near the surface.[4] [7] These are inexpensive to extract using various forms of surface mining, though this can result in serious environmental damage.[46] Regulations in the United States and other countries require that land that is surface mined must be restored to its original productivity once mining is complete.[47]
Strip mining of lignite in the United States begins with drilling to establish the extent of the subsurface beds. Topsoil and subsoil must be properly removed and either used to reclaim previously mined-out areas or stored for future reclamation. Excavator and truck overburden removal prepares the area for dragline overburden removal to expose the lignite beds. These are broken up using specially equipped tractors (coal ripping) and then loaded into bottom dump trucks using front loaders.[48]
Once the lignite is removed, restoration involves grading the mine spoil to as close an approximation as practical of the original ground surface (Approximate Original Contour or AOC). Subsoil and topsoil are restored and the land reseeded with various grasses. In North Dakota, a performance bond is held against the mining company for at least ten years after the end of mining operations to guarantee that the land has been restored to full productivity.[47] A bond (not necessary in this form) for mine reclamation is required in the US by the Surface Mining Control and Reclamation Act of 1977.[49]
Example open cast mine
- Location: Nochten, Germany[50] [51]
- Owner: Lausitz Energie Bergbau AG (LEAG)[50]
- Parent Company: Energetický a průmyslový holding AS [50.0%]; PPF Investments Ltd [50.0%][50]
- Supplies fuel to: Boxberg Power Station and Schwarze Pumpe power station[50]
- Location: near Weißwasser and Boxberg in Saxony, Germany[50]
- GPS Coordinates: 51.457109, 14.574709 (exact)[50]
- Mine Status: Operating[50] [51]
- Production: 14Mt (2020), 16.1Mt (2021), 14.5Mt (2022)[50]
- Coal Type: Lignite[50] [51]
- Mine Size: 107 km2[50]
- Opened in Year: 1968[50]
- Closure Year: 2031 (expected)[50]
- Planned out and constructed: 1966-1968[50]
- Mine type: open cast surface pit mine[50] [51]
Resources and reserves
List of countries by lignite reserves
Top Ten Countries by lignite reserves (2020)[52] Countries | Lignite reserves (billions of tons) |
---|
Russia | 90.447 |
Australia | 73.865 |
Germany | 35.7 |
United States | 29.91 |
Turkey | 19.32[53] |
Pakistan | 17.5[54] |
Indonesia | 14.746 |
China | 8.25 |
Republic of Kosovo | 7.112 |
New Zealand | 6.75 |
Poland | 5.752 | |
Australia
The Latrobe Valley in Victoria, Australia, contains estimated reserves of some 65 billion tonnes of brown coal.[55] The deposit is equivalent to 25 percent of known world reserves. The coal seams are up to thick, with multiple coal seams often giving virtually continuous brown coal thickness of up to . Seams are covered by very little overburden .[55]
A partnership led by Kawasaki Heavy Industries and backed by the governments of Japan and Australia has begun extracting hydrogen from brown coal. The liquefied hydrogen will be shipped via the transporter Suiso Frontier to Japan.[56]
North America
The largest lignite deposits in North America are the Gulf Coast lignites and the Fort Union lignite field. The Gulf Coast lignites are located in a band running from Texas to Alabama roughly parallel to the Gulf Coast. The Fort Union lignite field stretches from North Dakota to Saskatchewan. Both are important commercial sources of lignite.[57]
Types
Lignite can be separated into two types: xyloid lignite or fossil wood, and 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, and if submitted to the action of a weak solution of potash, it yields a considerable quantity of humic acid.[58] Leonardite is an oxidized form of lignite, which also contains high levels of humic acid.[59]
Jet is a hardened, gem-like form of lignite used in various types of jewelry.[39]
Production
Germany is the largest producer of lignite, followed by China, Russia, and United States. Lignite accounted for 8% of all U.S. coal production in 2019.[1]
1970! data-sort-type="number" 1980 | data-sort-type="number" | 1990 | data-sort-type="number" | 2000 | data-sort-type="number" | 2010 | data-sort-type="number" | 2011 | data-sort-type="number" | 2012 | data-sort-type="number" | 2013 | data-sort-type="number" | 2014 | data-sort-type="number" | 2015 |
---|
align=left | | 261 | 258.1 | 280 | |
align=left | | 108 | 129.9 | 107.6 | 167.7 | 169 | 176.5 | 185.4 | 183 | 178.2 | 178.1 |
align=left | | – | 24.3 | 45.5 | 47.7 | 125.3 | 136.3 | 145 | 147 | 145 | 140 |
align=left | | 145 | 141 | 137.3 | 87.8 | 76.1 | 76.4 | 77.9 | 73 | 70 | 73.2 |
align=left | | | 2.6 | 7.3 | 8.4 | 5.5 | 6.5 | 6.6 | – |
align=left | | 2.5 | 3.4 | 3.8 | 3.8 | – | – | – |
align=left | | 5 | 42.8 | 79.9 | 77.6 | 71.0 | 73.6 | 71.6 | 70.1 | 72.1 | 64.7 |
align=left | | – | 36.9 | 67.6 | 59.5 | 56.5 | 62.8 | 64.3 | 66 | 63.9 | 63.1 |
align=left | | – | 14.5 | 44.4 | 60.9 | 70.0 | 72.5 | 68.1 | 57.5 | 62.6 | 50.4 |
align=left | | – | 32.9 | 46 | 67.3 | 68.8 | 66.7 | 69.1 | 59.9 | 58.0 | 63.0 |
align=left | | – | 23.2 | 51.9 | 63.9 | 56.5 | 58.7 | 61.8 | 54 | 48 | 46 |
align=left | | – | 5 | 14.1 | 24.2 | 37.7 | 42.3 | 43.5 | 45 | 47.2 | 43.9 |
align=left | | – | – | – | – | 40.0 | 51.3 | 60.0 | 65.0 | 60.0 | 60.0 |
align=left | | 82 | 87 | 71 | |
align=left | | | 50.1 | 43.8 | 46.6 | 43.5 | 40 | 38.3 | 38.3 |
align=left | | 3.7 | 2.4 | 2.4 | 2.3 | – | – | – |
align=left | | – | 33.7 | 64.1 | |
align=left | | | 35.5 | 37.8 | 40.6 | 38 | 40.1 | 29.7 | 37.3 |
align=left | | | 8.7 | 9 | 8.7 | 8.2 | 7.2 | 8.2 |
align=left | | 7.5 | 6.7 | 8.2 | 7.5 | – | – | – |
align=left | | 3.4 | 11 | 7.1 | 7 | 6.2 | 6.2 | 6.5 |
align=left | | 3.7 | 4 | 4.1 | 4 | – | – | – |
align=left | | | 1.9 | 2 | 2 | – | – | – |
align=left | | – | 26.5 | 33.7 | 29 | 31.1 | 35.5 | 34.1 | 24.7 | 23.6 | 25.2 |
align=left | | – | 30 | 31.5 | 26.3 | 29.4 | 37.1 | 32.5 | 26.5 | 31.3 | 35.9 |
align=left | | – | 1.4 | 2.1 | 30 | 14 | 9 | 20 | – | – | – |
align=left | | – | 1.5 | 12.4 | 17.8 | 18.3 | 21.3 | 18.3 | 18.1 | 18 | 15.2 |
align=left | | – | 4.4 | 6.6 | 5.1 | 8.5 | 8.3 | 9.9 | – | – | – |
align=left | | – | 6 | 9.4 | 11.2 | 10.3 | 9.7 | 9.5 | 9.0 | 8.5 | 10.5 |
align=left | | – | 22.6 | 17.3 | 14 | 9.1 | 9.6 | 9.3 | 9.6 | 9.6 | 9.3 |
align=left | | – | 10 | 10.6 | 7.2 | 6.7 | 6.8 | 6.8 | 7 | 7 | 7 |
Source: World Coal Association[60] U.S. Energy Information Administration[61] BGR bund.de Energiestudie 2016[62] 1970 data from World Coal (1987)[63] – no data available
| |
---|
See also
External links
Notes and References
- Web site: Coal explained . . 2020-09-26 . 2021-01-31 . https://web.archive.org/web/20210131054008/https://www.eia.gov/energyexplained/coal/ . live .
- Web site: Lignite coal – health effects and recommendations from the health sector . https://ghostarchive.org/archive/20221009/https://www.env-health.org/wp-content/uploads/2018/12/HEAL-Lignite-Briefing-en_web.pdf . 2022-10-09 . live . Health and Environment Alliance . December 2018.
- Web site: Gesundheit: Feiner Staub, großer Schaden. 2022-03-12. 2022-01-17. https://web.archive.org/web/20220117193306/https://www.boell.de/de/2015/06/02/gesundheit-feiner-staub-grosser-schaden. live.
- Kopp, Otto C. "Lignite" in Encyclopædia Britannica
- Book: Ghassemi, Abbas . Handbook of Pollution Control and Waste Minimization . CRC Press . 2001 . 434 . 0-8247-0581-5.
- Web site: Lignite . Glossary . U.S. Energy Information Agency . 4 May 2021.
- Book: Victoria, Australia: A principal brown coal province . July 2010 . Department of Primary Industries Melbourne . 978-1-74199-835-1 . https://web.archive.org/web/20110317032514/http://new.dpi.vic.gov.au/__data/assets/pdf_file/0006/37518/Brown-Coal-050710.pdf . March 17, 2011.
- George, A.M.. State Electricity Victoria, Petrographic Report No 17. 1975; Perry, G.J and Allardice, D.J. Coal Resources Conference, NZ 1987 Proc.1, Sec. 4.. Paper R4.1
- Web site: Hazelwood tops international list of dirty power stations . 2008-10-02 . World Wide Fund for Nature Australia . dead . https://web.archive.org/web/20081013091310/http://www.wwf.org.au/news/n223/ . 2008-10-13 .
- Web site: End of generation at Hazelwood . 2017-06-30 . Engie . https://web.archive.org/web/20170331114514/http://www.ipplc.com.au/media/newsitem/End-of-generation-at-Hazelwood . 2017-03-31 . dead.
- Web site: The Greens Won't Line Up For Dirty Brown Coal In The Valley. Australian Greens Victoria. 2006-08-18. 2007-06-28. 2011-08-13. https://web.archive.org/web/20110813085807/http://vic.greens.org.au/news/media-releases-2006/the-greens-won-t-line-up-for-dirty-brown-coal-in-the-valley. live.
- Web site: Greenpeace Germany Protests Brown Coal Power Stations. Environment News Service. 2004-05-28. 2007-06-28. https://web.archive.org/web/20070930203414/http://www.ens-newswire.com/ens/may2004/2004-05-28-02.asp . 2007-09-30.
- Web site: Irfan . Ulmair . How East Germany Cleaned Up Dirty Power . Scientific American . Springer Nature America, Inc. . 4 May 2021 . 3 November 2014 . 12 November 2020 . https://web.archive.org/web/20201112020134/https://www.scientificamerican.com/article/how-east-germany-cleaned-up-dirty-power/ . live .
- News: Liquid fuel revival . 4 May 2021 . Chemistry and Industry . SCI . 22 . 2009 . 4 May 2021 . https://web.archive.org/web/20210504221020/https://www.soci.org/Chemistry-and-Industry/CnI-Data/2009/22/Liquid-fuel-revival . live .
- Web site: The history of energy in Germany . Planete energies . Total Foundation . 4 May 2021 . 29 April 2015 . 14 June 2021 . https://web.archive.org/web/20210614033353/https://www.planete-energies.com/en/medias/saga-energies/history-energy-germany . dead .
- News: Statistics on energy production in Germany 2014, Department of Energy (in german, lignite = "Braunkohle"). 2014-10-01. 2015-12-10. https://web.archive.org/web/20151206115815/http://www.bmwi.de/BMWi/Redaktion/PDF/E/energiestatistiken-energiegewinnung-energieverbrauch,property=pdf,bereich=bmwi2012,sprache=de,rwb=true.pdf. 2015-12-06. dead.
- Web site: Interview zum Kohlekompromiss: "Damit ist es nicht getan". Tagesschau.de.
- Web site: Was der Kohlekompromiss für Deutschland bedeutet. Erneuerbareenergien.de. 13 August 2019. 8 December 2020. 13 August 2020. https://web.archive.org/web/20200813093944/https://www.erneuerbareenergien.de/was-der-kohlekompromiss-fuer-deutschland-bedeutet. live.
- Web site: Teurer Kohlekompromiss. Zdf.de. 30 June 2022.
- Web site: Kommentar zum Kohleausstieg: Der Kohlekompromiss ist ein Meisterstück. Ksta.de. 26 January 2019.
- Web site: Greece confirms last coal plant will be shut in 2025. Euractiv.com. 26 April 2021.
- Web site: Σκρέκας: Προετοιμάζουμε και σχεδιάζουμε την πράσινη πολιτική της χώρας | ΣΚΑΪ. Skai.gr. 18 May 2021. 20 May 2021. 20 May 2021. https://web.archive.org/web/20210520145727/https://www.skai.gr/news/environment/skrekas-proetoimazoume-kai-sxediazoume-tin-prasini-politiki-tis-xoras. live.
- Book: Francis . Wilfrid . Fuels and fuel technology : a summarized manual . 1980 . Pergamon Press . Oxford . 9781483147949 . 4–5 . 2d (SI).
- Thuβ . U. . Popp . P. . Ehrlich . Chr. . Kalkoff . W.-D. . Domestic lignite combustion as source of polychlorodibenzodioxins and -furans (PCDD/F) . Chemosphere . July 1995 . 31 . 2 . 2591–2604 . 10.1016/0045-6535(95)00132-R. 1995Chmsp..31.2591T .
- Web site: Briketts kaufen bei. Obi.de. 2021-07-29. 2021-07-29. https://web.archive.org/web/20210729151550/https://www.obi.de/search/briketts/#/. live.
- Web site: Briketts kaufen bei. Hornbach.de. 2021-07-29. 2021-07-29. https://web.archive.org/web/20210729151549/https://www.hornbach.de/shop/suche/sortiment/briketts. live.
- Web site: Braunkohlebriketts 10kg bei REWE online bestellen!. Shop.rewe.de. 30 June 2022. 25 May 2022. https://web.archive.org/web/20220525100054/https://shop.rewe.de/p/braunkohlebriketts-10kg/4791800. live.
- Web site: Briketts kaufen bei Bauhaus. Bauhaus.info. 2022-03-09. 2022-04-11. https://web.archive.org/web/20220411073905/https://www.bauhaus.info/brennholz-briketts/c/10001327. live.
- Kim Thi Tran . Cuc . Rose . Michael T. . Cavagnaro . Timothy R. . Patti . Antonio F. . Lignite amendment has limited impacts on soil microbial communities and mineral nitrogen availability . Applied Soil Ecology . November 2015 . 95 . 140–150 . 10.1016/j.apsoil.2015.06.020. 2015AppSE..95..140K .
- Li . Changjian . Xiong . Yunwu . Zou . Jiaye . Dong . Li . Ren . Ping . Huang . Guanhua . Impact of biochar and lignite-based amendments on microbial communities and greenhouse gas emissions from agricultural soil . Vadose Zone Journal . March 2021 . 20 . 2 . 10.1002/vzj2.20105. 2021VZJ....2020105L . free .
- Lyons . Graham . Genc . Yusuf . Commercial Humates in Agriculture: Real Substance or Smoke and Mirrors? . Agronomy . 28 October 2016 . 6 . 4 . 50 . 10.3390/agronomy6040050. free .
- Ram . Lal C. . Srivastava . Nishant K. . Jha . Sangeet K. . Sinha . Awadhesh K. . Masto . Reginald E. . Selvi . Vetrivel A. . Management of Lignite Fly Ash for Improving Soil Fertility and Crop Productivity . Environmental Management . September 2007 . 40 . 3 . 438–452 . 10.1007/s00267-006-0126-9. 17705037 . 2007EnMan..40..438R . 1257174 .
- Patti . Antonio . Rose . Michael . Little . Karen . Jackson . Roy . Cavagnaro . Timothy . Evaluating Lignite-Derived Products (LDPs) for Agriculture – Does Research Inform Practice? . EGU General Assembly Conference Abstracts . 2014 . 10165 . 4 May 2021 . 2014EGUGA..1610165P . 11 April 2022 . https://web.archive.org/web/20220411073905/https://ui.adsabs.harvard.edu/abs/2014EGUGA..1610165P . live .
- Jones. Richard. Petit. R. Taber. R. Lignite and stillage:carrier and substrate for application of fungal biocontrol agents to soil. 10.1094/Phyto-74-1167. Phytopathology. 1984. 74. 10. 1167–1170.
- Web site: Youngs, R.W. & Frost, C.M. 1963. Humic acids from leonardite – a soil conditioner and organic fertilizer. Ind. Eng. Chem., 55, 95–99. https://ghostarchive.org/archive/20221009/http://www.anl.gov/PCS/acsfuel/preprint%20archive/Files/07_1_CINCINNATI_01-63_0012.pdf . 2022-10-09 . live. 30 June 2022.
- Gong . Guanqun . Xu . Liangwei . Zhang . Yingjie . Liu . Weixin . Wang . Ming . Zhao . Yufeng . Yuan . Xin . Li . Yajun . Extraction of Fulvic Acid from Lignite and Characterization of Its Functional Groups . ACS Omega . 3 November 2020 . 5 . 43 . 27953–27961 . 10.1021/acsomega.0c03388. 33163778 . 7643152 .
- Elgibaly . A. . Farahat . M. . Abd El Nabbi . M. . The Optimum Types and Characteristics of Drilling Fluids Used During Drilling in The Egyption Western Desert . Journal of Petroleum and Mining Engineering . 1 December 2018 . 20 . 1 . 89–100 . 10.21608/jpme.2018.40453. free .
- Qi . Ying . Hoadley . Andrew F.A. . Chaffee . Alan L. . Garnier . Gil . Characterisation of lignite as an industrial adsorbent . Fuel . April 2011 . 90 . 4 . 1567–1574 . 10.1016/j.fuel.2011.01.015. 2011Fuel...90.1567Q .
- Book: Glossary of Geology . 5th . American Geological Institute . Neuendorf . K. K. E. Jr. . Mehl . J. P. . Jackson . J. A.. 2005 . Alexandria, Virginia . 344.
- Web site: Venus figures from Petersfels. 9 August 2016. live. https://web.archive.org/web/20160929213049/http://donsmaps.com/petersfels.html. 29 September 2016.
- Book: Allason-Jones, Lindsay . Lindsay Allason-Jones . 1996. Roman Jet in the Yorkshire Museum. The Yorkshire Museum . 8–11 . 0905807170.
- Book: Muller, Helen . 1987 . Jet. Butterworths . 59–63 . 0408031107.
- Schweinfurth . Stanley P. . Finkelman . Robert P. . Coal – A complex natural resource . U.S. Geological Survery Circular . 2002 . 1143 . 10.3133/cir1143. free . 2027/umn.31951d02181642b . free .
- Web site: Coal types, formation, and methods of mining . Eastern Pennsylvania Coalition for Abandoned Mine Reclamation . 5 May 2021 . 2016 . 17 July 2020 . https://web.archive.org/web/20200717042100/http://epcamr.org/home/content/reference-materials/coal-types-formation-and-methods-of-mining . live .
- Ibarra . JoséV. . Muñoz . Edgar . Moliner . Rafael . FTIR study of the evolution of coal structure during the coalification process . Organic Geochemistry . June 1996 . 24 . 6–7 . 725–735 . 10.1016/0146-6380(96)00063-0. 1996OrGeo..24..725I .
- Web site: Turgeon . Andrew . Morse . Elizabeth . Coal . 22 December 2012 . National Geographic . 25 September 2021 . 25 September 2021 . https://web.archive.org/web/20210925182608/https://www.nationalgeographic.org/encyclopedia/coal/ . live .
- Web site: Reclamation Process . Mining Lignite Coal for our Energy Future . BNI Coal . 25 September 2021 . 25 September 2021 . https://web.archive.org/web/20210925182556/http://www.bnicoal.com/about/reclamation-process . live .
- Web site: Mining Process . Mining Lignite Coal for our Energy Future . BNI Coal . 25 September 2021.
- Web site: Reclamation Bonds . Office of Surface Mining Reclamation and Enforcement . 2022-03-18 . 2022-03-02 . https://web.archive.org/web/20220302211054/https://www.osmre.gov/resources/reclamation-bonds . live .
- Web site: Nochten Coal Mine . 2024-04-19 . 2024-04-19 . https://web.archive.org/web/20240419141452/https://www.gem.wiki/Nochten_Coal_Mine . live .
- Web site: On the Road to Green Energy, Germany Detours on Dirty Coal. Yale E360. 2024-04-19. 2024-04-19. https://web.archive.org/web/20240419141452/https://e360.yale.edu/features/on_the_road_to_green_energy_germany_detours_on_dirty_coal. live.
- Web site: Leading countries based on lignite reserves 2020. en. Statista. February 2022. 2022-07-30. 2022-05-20. https://web.archive.org/web/20220520012919/https://www.statista.com/statistics/264778/countries-with-the-largest-soft-brown-coal-reserves/. live.
- While the Statista review reports 10975 million tonnes for Turkey, the 2005-2019 surveys of the Mineral Research and Exploration General Directorate of Turkey has almost doubled this value. Web site: Kömür Arama Araştırmaları . tr . 2022-07-30 . MTA Genel Müdürlüğü . Coal Surveying Studies.
- Web site: Yep . Eric . 4 April 2019 . Analysis: Pakistan's Thar wager pits coal against LNG in its power mix . S&P Global . 8 February 2024 . 8 February 2024 . https://web.archive.org/web/20240208115457/https://www.spglobal.com/commodityinsights/en/market-insights/latest-news/natural-gas/040419-analysis-pakistans-thar-wager-pits-coal-against-lng-in-its-power-mix . live .
- Department of Primary Industries, Victorian Government, Australia, ‘Victoria Australia: A Principle Brown Coal Province’ (Fact Sheet, Department of Primary Industries, July 2010).
- Web site: Kawasaki Heavy says liquefied hydrogen carrier departs Japan for Australia . Asia Pacific . Reuters . 24 December 2021 . 24 December 2021 . 24 December 2021 . https://web.archive.org/web/20211224105754/https://www.reuters.com/world/asia-pacific/kawasaki-heavy-says-liquefied-hydrogen-carrier-departs-japan-australia-2021-12-24/ . live .
- Schobert . Harold H. . Chapter 1 The principal lignite deposits of North America . Coal Science and Technology . 1995 . 23 . 1–50 . 10.1016/S0167-9449(06)80002-9. 9780444898234 .
- Book: Mackie, Samuel Joseph . The Geologist . Reynolds . 1861 . Original from Harvard University . 197–200 .
- Book: Tan, Kim H.. Humic Matter in Soil and the Environment: Principles and Controversies. 22 April 2003. CRC Press. 9780203912546 . 30 June 2022. Google Books.
- Web site: Resources. World Coal Association. 2014. 2015-12-22. 2015-12-23. https://web.archive.org/web/20151223074452/http://www.worldcoal.org/resources/statistics/. dead.
- Web site: Production of Lignite Coal. U.S. Energy Information Administration. 2012. 2015-12-23. 2015-12-24. https://web.archive.org/web/20151224103800/http://www.eia.gov/cfapps/ipdbproject/iedindex3.cfm?tid=1&pid=14&aid=1&cid=regions&syid=1980&eyid=2012&unit=TST. live.
- Web site: Archived copy . 2017-04-19 . 2017-10-20 . https://web.archive.org/web/20171020084706/http://www.bgr.bund.de/DE/Themen/Energie/Downloads/Energiestudie_2016_Tabellen.xlsx?__blob=publicationFile&v=1 . dead .
- Book: Gordon, Richard. 1987. World coal: economics, policies and prospects. 44. Cambridge. Cambridge University Press. 0521308275. 506249066.