Coal seam - Revision history

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	[[File:640px-Coal_seam.jpg\|400px\|framed\|right\|Figure 1. Coal seams (darker black bands) in a rock.<ref>Wikimedia Commons. (June 2, 2015). ''Coal Seam'' [Online]. Available: http://upload.wikimedia.org/wikipedia/commons/8/89/Coal_seam.jpg</ref>]]		[[File:640px-Coal_seam.jpg\|400px\|framed\|right\|Figure 1. Coal seams (darker black bands) in a rock.<ref>Wikimedia Commons. (June 2, 2015). ''Coal Seam'' [Online]. Available: http://upload.wikimedia.org/wikipedia/commons/8/89/Coal_seam.jpg</ref>]]

	<onlyinclude>A '''coal seam''' is a dark brown or black banded deposit of [[coal]] that is visible within layers of rock. ~~These~~ seams are located underground and can be mined using either ~~[[deep~~ mining]] or [[strip mining]] techniques depending on their ~~proximity to~~ the surface.</onlyinclude> These seams ~~undergo normal~~ [[coal formation]] and ~~serve as~~ a conventional coal [[resource]]. ~~The~~ [[coal reserve\|reserves]] ~~of coal~~ are immense, and are the largest of all of the [[fossil fuel]]s.<ref name=boyle/>		<onlyinclude>A '''coal seam''' is a dark brown to black, banded deposit of [[coal]] that is visible within layers of rock. Coal seams are located underground and can be mined using either underground mining or [[strip mining\|strip-mining]] techniques, depending on their depth below the surface.</onlyinclude> These seams form through the natural process of [[coal formation]] (coalification) and are considered a conventional coal [[resource]]. Global coal [[coal reserve\|reserves]] are immense and are the largest of all of the [[fossil fuel]]s reserves.<ref name=boyle/>

	~~As well, these~~ seams can act as an [[unconventional resource\|unconventional source]] of [[natural gas]]. When natural gas is ~~obtained~~ from a coal seam, it is known as '''coal seam gas''' or [[coal bed methane]]. This [[gas]] ~~bonds to~~ the surface of underground coal seams, which are ~~generally filled~~ with water. The [[pressure]] of ~~this water makes~~ the ~~gas form a thin film on~~ the surface of the coal. The ~~level~~ of ~~gas bonded to the~~ coal seam depends on the thickness ~~of the coal, the~~ depth of the coal, ~~and the~~ [[permeability]].<ref>Australia Pacific LNG. (June 2, 2015). ''Coal Seam Gas'' [Online]. Available: http://www.aplng.com.au/home/what-coal-seam-gas</ref>		Coal seams can also act as an [[unconventional resource\|unconventional source]] of [[natural gas]]. When natural gas is extracted from a coal seam, it is known as '''coal seam gas''' or [[coal bed methane]]. This [[gas]] is adsorbed onto the surface of underground coal seams, which are typically saturated with water.<ref>Government of South Australia, Department for Energy and Mining. (2019). ''Coal Seam Gas'' [Online]. Available: <nowiki>https://www.energymining.sa.gov.au/industry/energy-resources/geology-and-prospectivity/resource-and-coal-plays/coal-seam-gas</nowiki></ref> The [[pressure]] of the groundwater helps keep the methane adsorbed onto the surface of the coal. The amount of methane adsorbed onto a coal seam depends on factors such as the thickness and depth of the coal seam, its [[permeability]], and the characteristics of the coal itself.<ref>Australia Pacific LNG. (June 2, 2015). ''Coal Seam Gas'' [Online]. Available: http://www.aplng.com.au/home/what-coal-seam-gas</ref>

	==Formation==		==Formation==
	:: [[coal formation\|''main page'']]		:: [[coal formation\|''main page'']]
	Coal seams are formed from dead and decaying ~~organic~~ [[matter]]. Generally, this matter ~~came from~~ ancient peat bogs ~~that died and fell into~~ shallow, stagnant ~~waters~~. As this material ~~decayed~~, it ~~became~~ [[peat]] ~~over time~~. As this peat ~~was~~ buried under [[sediment]], ~~the~~ [[temperature]] ~~increased~~ and ~~the~~ pressure ~~became greater~~. ~~This~~ compression ~~and heating slowly turned~~ the ~~soft~~ peat into ~~harder~~ [[lignite]] coal. With ~~further~~ burial and ~~compression this~~ brown lignite coal became [[sub-bituminous]] coal, then [[bituminous]] coal, and finally [[anthracite]] coal.<ref>Stephen Marshak. (June 2, 2015). ''Earth: Portrait of a Planet'', 3rd ed. New York, NY, U.S.A:W.W. Norton & Company, 2008</ref> Regardless of the size or ~~placement~~ of the coal ~~seam this~~ formation ~~pattern~~ remains the same.		Coal seams are formed from the accumulation of dead and decaying plant [[matter]]. Generally, this plant matter gathered in ancient peat-formed wetlands, such as swamps and peat bogs, where it was buried in shallow, stagnant water. As this plant material partially decomposed in the oxygen-poor environment, it gradually formed [[peat]]. As this peat became buried under layers of [[sediment]], increasing [[temperature]] and pressure caused it to undergo coalification.<ref>U.S. Energy Information Administration. (October 24, 2023). ''Coal Explained'' [Online]. Available: <nowiki>https://www.eia.gov/energyexplained/coal/</nowiki></ref> Over millions of years, this heat and compression transformed the peat into [[lignite]], the lowest rank of coal. With continued burial and increasing heat and pressure, brown lignite coal became [[sub-bituminous]] coal, then [[bituminous]] coal, and finally [[anthracite]] coal, the highest rank of coal.<ref>Stephen Marshak. (June 2, 2015). ''Earth: Portrait of a Planet'', 3rd ed. New York, NY, U.S.A:W.W. Norton & Company, 2008</ref> Regardless of the size or location of a coal seam, the overall process of coal formation remains the same.

	==Location==		==Location==
	The size, ~~location~~, and accessibility of coal seams can vary widely. ~~Due to extreme pressures involved in~~ the ~~compression~~ of the peat ~~in the formation of coal~~, about 10 [[meter]]s of peat ~~will only~~ form ~~around~~ 1 ~~meter~~ of coal. However, the thickness of ~~the~~ coal ~~bands~~ can vary significantly depending on the amount of peat that was initially ~~buried~~. Coal seams ~~have been found that are as small as~~ 30 ~~centimeters~~ (or approximately a [[foot]]) ~~all the way up~~ to more than 30 meters wide.<ref name=boyle>G.Boyle, B.Everett, S.Peake, J.Ramage. (June 2, 2015). ''Energy Systems and Sustainability: Power for a Sustainable Future'', 2nd Ed. Oxford, UK: Oxford University Press, 2012</ref> Additionally, ~~these~~ seams ~~can~~ be buried either very deeply or fairly close to the surface. ~~Most of the time the deeply~~ buried seams are ~~mined~~ using ~~deep~~ mining techniques whereas ~~ones close to the surface~~ are obtained ~~through~~ strip mining.		The size, depth, and accessibility of coal seams can vary widely. During coal formation, the combined effects of heat, pressure, and compaction reduce the thickness of peat substantially, so that about 10 [[meter\|metre]]s of peat typically form approximately 1 metre of coal. However, the thickness of coal seams can vary significantly depending on the amount of peat that was initially deposited and the geological conditions during coal formation. Coal seams can range from less than 30 centimetres (approximately a [[foot]]) wide to more than 30 meters wide.<ref name=boyle>G.Boyle, B.Everett, S.Peake, J.Ramage. (June 2, 2015). ''Energy Systems and Sustainability: Power for a Sustainable Future'', 2nd Ed. Oxford, UK: Oxford University Press, 2012</ref> Additionally, coal seams may be buried either very deeply or fairly close to the surface. Deeply buried coal seams are generally extracted using underground mining techniques, whereas shallow coal seams are generally obtained using surface mining techniques, such as strip mining.

	==Fires==		==Fires==
	[[File:640px-Pdr_1647.jpg\|400px\|framed\|right\|Figure 2. A portion of a highway destroyed by the Centralia mine fire.<ref>Wikimedia Commons. (June 2, 2015). ''Pdr 1647'' [Online]. Available: http://en.wikipedia.org/wiki/Pennsylvania_Route_61#/media/File:Pdr_1647.jpg</ref>]]		[[File:640px-Pdr_1647.jpg\|400px\|framed\|right\|Figure 2. A portion of a highway destroyed by the Centralia mine fire.<ref>Wikimedia Commons. (June 2, 2015). ''Pdr 1647'' [Online]. Available: http://en.wikipedia.org/wiki/Pennsylvania_Route_61#/media/File:Pdr_1647.jpg</ref>]]
	Coal seams can pose a [[fire hazard]], and ~~as a result~~ sometimes begin to smoulder. ~~Generally, these~~ fires are [[ignition\|ignited]] by ~~above ground~~ [[fire]]s but can continue to smoulder underground for many years. ~~Sometimes these~~ fires can burn for decades or centuries until the [[fuel]] ~~below the surface~~ is used up or the fire is extinguished. One of the most widely known coal seam fires is the Centralia mine fire, which has been burning since 1962.<ref>Roadside America. (June 2, 2015). ''Centralia Mine Fire'' [Online]. Available: http://www.roadsideamerica.com/story/2196</ref> Although ~~dangerous and~~ important to ~~put out,~~ these fires ~~are~~ costly and difficult to extinguish. Internationally, thousands of underground coal fires are burning on every continent except Antarctica.<ref name="RE1">Dan Cray. (June 2, 2015). ''Deep Underground, Miles of Hidden Wildfires Rage'' [Online]. Available: http://content.time.com/time/health/article/0,8599,2006195,00.html</ref> These fires are hazardous as they release ~~toxic fumes -~~ including [[carbon dioxide]], [[methane]], ~~and~~ [[mercury]] - and can spark new ~~above ground~~ fires.<ref name="RE1"/> Global coal fire emissions are estimated to ~~cause~~ 40 tonnes of mercury ~~to enter~~ the atmosphere annually and ~~represent~~ 3% of the world's yearly carbon dioxide [[emission]]s.<ref name="RE1"/>		Coal seams can pose a [[fire hazard]] and may sometimes begin to smoulder. These fires are often [[ignition\|ignited]] by surface [[fire]]s or human activities, but they can continue to smoulder underground for many years. Some coal seam fires can burn for decades or even centuries until the underground [[fuel]] is used up, or the fire is extinguished. One of the most widely known coal seam fires is the Centralia mine fire, which has been burning since 1962.<ref>Roadside America. (June 2, 2015). ''Centralia Mine Fire'' [Online]. Available: http://www.roadsideamerica.com/story/2196</ref> Although it is important to extinguish these fires because of the hazards they pose, doing so is often costly and difficult to extinguish. Internationally, thousands of underground coal fires are burning on every continent except Antarctica.<ref name="RE1">Dan Cray. (June 2, 2015). ''Deep Underground, Miles of Hidden Wildfires Rage'' [Online]. Available: http://content.time.com/time/health/article/0,8599,2006195,00.html</ref> These fires are hazardous because they release harmful gases and pollutants including [[carbon dioxide]], [[methane]], [[mercury]], and often other toxic compounds, and can spark new surface fires.<ref name="RE1"/> Global coal fire emissions are estimated to release about 40 tonnes of mercury into the atmosphere annually and account for approximately 3% of the world's yearly carbon dioxide [[emission]]s.<ref name="RE1"/>

			== For Further Reading ==

			* [[Strip mining]]
			* [[Coal bed methane]]
			* [[Sediment]]
			* [[Peat]]
			* Or explore a [[Special:Random\|random page]]

	==References==		==References==
	{{reflist}}		{{reflist}}
	[[Category:Uploaded]]		[[Category:Uploaded]]

Jmdonev: 1 revision imported

2017-08-29T01:46:45Z

1 revision imported

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Jmdonev at 17:42, 14 July 2017

2017-07-14T17:42:09Z

← Older revision		Revision as of 17:42, 14 July 2017
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	[[File:640px-Coal_seam.jpg\|400px\|framed\|right\|Figure 1. Coal seams (darker black bands) in a rock.<ref>Wikimedia Commons. (June 2, 2015). ''Coal Seam'' [Online]. Available: http://upload.wikimedia.org/wikipedia/commons/8/89/Coal_seam.jpg</ref>]]		[[File:640px-Coal_seam.jpg\|400px\|framed\|right\|Figure 1. Coal seams (darker black bands) in a rock.<ref>Wikimedia Commons. (June 2, 2015). ''Coal Seam'' [Online]. Available: http://upload.wikimedia.org/wikipedia/commons/8/89/Coal_seam.jpg</ref>]]

	<onlyinclude>A '''coal seam''' is a dark brown or black banded deposit of [[coal]] that is visible within layers of rock. These seams are located underground and can be mined using either [[deep mining]] or [[strip mining]] techniques depending on their proximity to the surface.</onlyinclude> These seams undergo normal [[coal formation]] and serve as a conventional coal [[resource]]. The [[coal reserve\|reserves]] of coal are immense, and are the largest of all of the [[fossil fuel]]s.<ref name=boyle/>		<onlyinclude>A '''coal seam''' is a dark brown or black banded deposit of [[coal]] that is visible within layers of rock. These seams are located underground and can be mined using either [[deep mining]] or [[strip mining]] techniques depending on their proximity to the surface.</onlyinclude> These seams undergo normal [[coal formation]] and serve as a conventional coal [[resource]]. The [[coal reserve\|reserves]] of coal are immense, and are the largest of all of the [[fossil fuel]]s.<ref name=boyle/>

	As well, these seams can act as an unconventional source of [[natural gas]]. When natural gas is obtained from a coal seam, it is known as '''coal seam gas''' or [[coal bed methane]]. This [[gas]] bonds to the surface of underground coal seams, which are generally filled with water. The [[pressure]] of this water makes the gas form a thin film on the surface of the coal. The level of gas bonded to the coal seam depends on the thickness of the coal, the depth of the coal, and the [[permeability]].<ref>Australia Pacific LNG. (June 2, 2015). ''Coal Seam Gas'' [Online]. Available: http://www.aplng.com.au/home/what-coal-seam-gas</ref>		As well, these seams can act as an [[unconventional resource\|unconventional source]] of [[natural gas]]. When natural gas is obtained from a coal seam, it is known as '''coal seam gas''' or [[coal bed methane]]. This [[gas]] bonds to the surface of underground coal seams, which are generally filled with water. The [[pressure]] of this water makes the gas form a thin film on the surface of the coal. The level of gas bonded to the coal seam depends on the thickness of the coal, the depth of the coal, and the [[permeability]].<ref>Australia Pacific LNG. (June 2, 2015). ''Coal Seam Gas'' [Online]. Available: http://www.aplng.com.au/home/what-coal-seam-gas</ref>

	==Formation==		==Formation==
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	==Fires==		==Fires==
	[[File:640px-Pdr_1647.jpg\|400px\|framed\|right\|Figure 2. A portion of a highway destroyed by the Centralia mine fire.<ref>Wikimedia Commons. (June 2, 2015). ''Pdr 1647'' [Online]. Available: http://en.wikipedia.org/wiki/Pennsylvania_Route_61#/media/File:Pdr_1647.jpg</ref>]]		[[File:640px-Pdr_1647.jpg\|400px\|framed\|right\|Figure 2. A portion of a highway destroyed by the Centralia mine fire.<ref>Wikimedia Commons. (June 2, 2015). ''Pdr 1647'' [Online]. Available: http://en.wikipedia.org/wiki/Pennsylvania_Route_61#/media/File:Pdr_1647.jpg</ref>]]
	Coal seams can pose a fire hazard, and as a result sometimes begin to smoulder. Generally, these fires are [[ignition\|ignited]] by above ground ~~fires~~ but can continue to smoulder underground for many years. Sometimes these fires can burn for decades or centuries until the [[fuel]] below the surface is used up or the fire is extinguished. One of the most widely known coal seam fires is the Centralia mine fire, which has been burning since 1962.<ref>Roadside America. (June 2, 2015). ''Centralia Mine Fire'' [Online]. Available: http://www.roadsideamerica.com/story/2196</ref> Although dangerous and important to put out, these fires are costly and difficult to extinguish. Internationally, thousands of underground coal fires are burning on every continent except Antarctica.<ref name="RE1">Dan Cray. (June 2, 2015). ''Deep Underground, Miles of Hidden Wildfires Rage'' [Online]. Available: http://content.time.com/time/health/article/0,8599,2006195,00.html</ref> These fires are hazardous as they release toxic fumes - including [[carbon dioxide]], [[methane]], and [[mercury]] - and can spark new above ground fires.<ref name="RE1"/> Global coal fire emissions are estimated to cause 40 tonnes of mercury to enter the atmosphere annually and represent 3% of the world's yearly carbon dioxide [[emission]]s.<ref name="RE1"/>		Coal seams can pose a [[fire hazard]], and as a result sometimes begin to smoulder. Generally, these fires are [[ignition\|ignited]] by above ground [[fire]]s but can continue to smoulder underground for many years. Sometimes these fires can burn for decades or centuries until the [[fuel]] below the surface is used up or the fire is extinguished. One of the most widely known coal seam fires is the Centralia mine fire, which has been burning since 1962.<ref>Roadside America. (June 2, 2015). ''Centralia Mine Fire'' [Online]. Available: http://www.roadsideamerica.com/story/2196</ref> Although dangerous and important to put out, these fires are costly and difficult to extinguish. Internationally, thousands of underground coal fires are burning on every continent except Antarctica.<ref name="RE1">Dan Cray. (June 2, 2015). ''Deep Underground, Miles of Hidden Wildfires Rage'' [Online]. Available: http://content.time.com/time/health/article/0,8599,2006195,00.html</ref> These fires are hazardous as they release toxic fumes - including [[carbon dioxide]], [[methane]], and [[mercury]] - and can spark new above ground fires.<ref name="RE1"/> Global coal fire emissions are estimated to cause 40 tonnes of mercury to enter the atmosphere annually and represent 3% of the world's yearly carbon dioxide [[emission]]s.<ref name="RE1"/>

	==References==		==References==
	{{reflist}}		{{reflist}}
	[[Category:Uploaded]]		[[Category:Uploaded]]

Jmdonev: 1 revision imported

2017-01-08T23:36:32Z

1 revision imported

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Jmdonev at 03:22, 31 December 2016

2016-12-31T03:22:49Z

← Older revision		Revision as of 03:22, 31 December 2016
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	[[category:371 topics]]		[[category:371 topics]]
	[[Category:Done ~~2015~~-06-11]]		[[Category:Done 2016-12-31]]
	[[File:640px-Coal_seam.jpg\|400px\|framed\|right\|Figure 1. Coal seams (darker black bands) in a rock.<ref>Wikimedia Commons. (June 2, 2015). ''Coal Seam'' [Online]. Available: http://upload.wikimedia.org/wikipedia/commons/8/89/Coal_seam.jpg</ref>]]		[[File:640px-Coal_seam.jpg\|400px\|framed\|right\|Figure 1. Coal seams (darker black bands) in a rock.<ref>Wikimedia Commons. (June 2, 2015). ''Coal Seam'' [Online]. Available: http://upload.wikimedia.org/wikipedia/commons/8/89/Coal_seam.jpg</ref>]]

	<onlyinclude>A '''coal seam''' is a dark brown or black banded deposit of [[coal]] that is visible within layers of rock. These seams are located underground and can be mined using either [[deep mining]] or [[strip mining]] depending on their proximity to the surface.</onlyinclude> These seams undergo normal [[coal formation]] and serve as a conventional coal [[resource]]. The [[coal reserve\|reserves]] of coal are immense, and are the largest of all of the [[fossil fuel]]s.<ref name=boyle/>		<onlyinclude>A '''coal seam''' is a dark brown or black banded deposit of [[coal]] that is visible within layers of rock. These seams are located underground and can be mined using either [[deep mining]] or [[strip mining]] techniques depending on their proximity to the surface.</onlyinclude> These seams undergo normal [[coal formation]] and serve as a conventional coal [[resource]]. The [[coal reserve\|reserves]] of coal are immense, and are the largest of all of the [[fossil fuel]]s.<ref name=boyle/>

	As well, these seams can act as an unconventional source of [[natural gas]]. When natural gas is obtained from a coal seam, it is known as '''coal seam gas''' or [[coal bed methane]]. This [[gas]] bonds to the surface of underground coal seams, which are generally filled with water. The [[pressure]] of this water makes the gas form a thin film on the surface of the coal. The level of gas bonded to the coal seam depends on the thickness of the coal, the depth of the coal, and the [[permeability]].<ref>Australia Pacific LNG. (June 2, 2015). ''Coal Seam Gas'' [Online]. Available: http://www.aplng.com.au/home/what-coal-seam-gas</ref>		As well, these seams can act as an unconventional source of [[natural gas]]. When natural gas is obtained from a coal seam, it is known as '''coal seam gas''' or [[coal bed methane]]. This [[gas]] bonds to the surface of underground coal seams, which are generally filled with water. The [[pressure]] of this water makes the gas form a thin film on the surface of the coal. The level of gas bonded to the coal seam depends on the thickness of the coal, the depth of the coal, and the [[permeability]].<ref>Australia Pacific LNG. (June 2, 2015). ''Coal Seam Gas'' [Online]. Available: http://www.aplng.com.au/home/what-coal-seam-gas</ref>
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	==Formation==		==Formation==
	:: [[coal formation\|''main page'']]		:: [[coal formation\|''main page'']]
	Coal seams are formed from dead and decaying organic matter. Generally, this matter came from ancient peat bogs that died and fell into shallow, stagnant waters. As this material decayed, it became [[peat]] over time. As this peat was buried under sediment, the [[temperature]] increased and the pressure became greater. This compression and heating slowly turned the soft peat into harder [[lignite]] coal. With further burial and compression this brown lignite coal became [[sub-bituminous]] coal, then [[bituminous]] coal, and finally [[anthracite]] coal.<ref>Stephen Marshak. (June 2, 2015). ''Earth: Portrait of a Planet'', 3rd ed. New York, NY, U.S.A:W.W. Norton & Company, 2008</ref> Regardless of the size or placement of the coal seam this formation pattern remains the same.		Coal seams are formed from dead and decaying organic [[matter]]. Generally, this matter came from ancient peat bogs that died and fell into shallow, stagnant waters. As this material decayed, it became [[peat]] over time. As this peat was buried under [[sediment]], the [[temperature]] increased and the pressure became greater. This compression and heating slowly turned the soft peat into harder [[lignite]] coal. With further burial and compression this brown lignite coal became [[sub-bituminous]] coal, then [[bituminous]] coal, and finally [[anthracite]] coal.<ref>Stephen Marshak. (June 2, 2015). ''Earth: Portrait of a Planet'', 3rd ed. New York, NY, U.S.A:W.W. Norton & Company, 2008</ref> Regardless of the size or placement of the coal seam this formation pattern remains the same.

	==Location==		==Location==
	The size, location, and accessibility of coal seams can vary widely. ~~Because of~~ extreme pressures involved in the compression of the peat in the formation of coal, about 10 [[meter]]s of peat will only form around 1 meter of coal. However, the thickness of the coal bands can vary significantly depending on the amount of peat that was initially buried. Coal seams have been found that are as small as 30 centimeters (or ~~around~~ a foot) all the way up to more than 30 meters wide.<ref name=boyle>G.Boyle, B.Everett, S.Peake, J.Ramage. (June 2, 2015). ''Energy Systems and Sustainability: Power for a Sustainable Future'', 2nd Ed. Oxford, UK: Oxford University Press, 2012</ref> Additionally, these seams can be buried either very deeply or fairly close to the surface. Most of the time the deeply buried seams are mined using deep mining techniques whereas ones close to the surface are obtained through strip mining.		The size, location, and accessibility of coal seams can vary widely. Due to extreme pressures involved in the compression of the peat in the formation of coal, about 10 [[meter]]s of peat will only form around 1 meter of coal. However, the thickness of the coal bands can vary significantly depending on the amount of peat that was initially buried. Coal seams have been found that are as small as 30 centimeters (or approximately a [[foot]]) all the way up to more than 30 meters wide.<ref name=boyle>G.Boyle, B.Everett, S.Peake, J.Ramage. (June 2, 2015). ''Energy Systems and Sustainability: Power for a Sustainable Future'', 2nd Ed. Oxford, UK: Oxford University Press, 2012</ref> Additionally, these seams can be buried either very deeply or fairly close to the surface. Most of the time the deeply buried seams are mined using deep mining techniques whereas ones close to the surface are obtained through strip mining.

	==Fires==		==Fires==
	[[File:640px-Pdr_1647.jpg\|400px\|framed\|right\|Figure 2. A portion of a highway destroyed by the Centralia mine fire.<ref>Wikimedia Commons. (June 2, 2015). ''Pdr 1647'' [Online]. Available: http://en.wikipedia.org/wiki/Pennsylvania_Route_61#/media/File:Pdr_1647.jpg</ref>]]		[[File:640px-Pdr_1647.jpg\|400px\|framed\|right\|Figure 2. A portion of a highway destroyed by the Centralia mine fire.<ref>Wikimedia Commons. (June 2, 2015). ''Pdr 1647'' [Online]. Available: http://en.wikipedia.org/wiki/Pennsylvania_Route_61#/media/File:Pdr_1647.jpg</ref>]]
	Coal seams can pose a fire hazard, and as a result sometimes begin to smoulder. Generally, these fires are [[ignition\|ignited]] by above ground fires but can continue to smoulder underground for many years. Sometimes these fires can burn for decades or centuries until the [[fuel]] below ~~ground~~ is used up or the fire is extinguished. One of the most widely known coal seam fires is the Centralia mine fire, which has been burning since 1962.<ref>Roadside America. (June 2, 2015). ''Centralia Mine Fire'' [Online]. Available: http://www.roadsideamerica.com/story/2196</ref> Although dangerous and important to put out, these fires are costly and difficult to extinguish. Internationally, thousands of underground coal fires are burning on every continent except Antarctica.<ref name="RE1">Dan Cray. (June 2, 2015). ''Deep Underground, Miles of Hidden Wildfires Rage'' [Online]. Available: http://content.time.com/time/health/article/0,8599,2006195,00.html</ref> These fires are hazardous as they release toxic fumes - including [[carbon dioxide]], [[methane]], and [[mercury]] - and can spark new above ground fires.<ref name="RE1"/> Global coal fire emissions are estimated to cause 40 tonnes of mercury to enter the atmosphere annually and represent 3% of the world's yearly carbon dioxide [[emission]]s.<ref name="RE1"/>		Coal seams can pose a fire hazard, and as a result sometimes begin to smoulder. Generally, these fires are [[ignition\|ignited]] by above ground fires but can continue to smoulder underground for many years. Sometimes these fires can burn for decades or centuries until the [[fuel]] below the surface is used up or the fire is extinguished. One of the most widely known coal seam fires is the Centralia mine fire, which has been burning since 1962.<ref>Roadside America. (June 2, 2015). ''Centralia Mine Fire'' [Online]. Available: http://www.roadsideamerica.com/story/2196</ref> Although dangerous and important to put out, these fires are costly and difficult to extinguish. Internationally, thousands of underground coal fires are burning on every continent except Antarctica.<ref name="RE1">Dan Cray. (June 2, 2015). ''Deep Underground, Miles of Hidden Wildfires Rage'' [Online]. Available: http://content.time.com/time/health/article/0,8599,2006195,00.html</ref> These fires are hazardous as they release toxic fumes - including [[carbon dioxide]], [[methane]], and [[mercury]] - and can spark new above ground fires.<ref name="RE1"/> Global coal fire emissions are estimated to cause 40 tonnes of mercury to enter the atmosphere annually and represent 3% of the world's yearly carbon dioxide [[emission]]s.<ref name="RE1"/>

	==References==		==References==
	{{reflist}}		{{reflist}}
	[[Category:Uploaded]]		[[Category:Uploaded]]

J.williams: 1 revision imported

2015-08-26T21:30:55Z

1 revision imported

← Older revision	Revision as of 21:30, 26 August 2015
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J.williams at 16:52, 12 August 2015

2015-08-12T16:52:55Z

New page

[[category:371 topics]]
[[Category:Done 2015-06-11]]
[[File:640px-Coal_seam.jpg|400px|framed|right|Figure 1. Coal seams (darker black bands) in a rock.<ref>Wikimedia Commons. (June 2, 2015). ''Coal Seam'' [Online]. Available: http://upload.wikimedia.org/wikipedia/commons/8/89/Coal_seam.jpg</ref>]]

<onlyinclude>A '''coal seam''' is a dark brown or black banded deposit of [[coal]] that is visible within layers of rock. These seams are located underground and can be mined using either [[deep mining]] or [[strip mining]] depending on their proximity to the surface.</onlyinclude> These seams undergo normal [[coal formation]] and serve as a conventional coal [[resource]]. The [[coal reserve|reserves]] of coal are immense, and are the largest of all of the [[fossil fuel]]s.<ref name=boyle/>

As well, these seams can act as an unconventional source of [[natural gas]]. When natural gas is obtained from a coal seam, it is known as '''coal seam gas''' or [[coal bed methane]]. This [[gas]] bonds to the surface of underground coal seams, which are generally filled with water. The [[pressure]] of this water makes the gas form a thin film on the surface of the coal. The level of gas bonded to the coal seam depends on the thickness of the coal, the depth of the coal, and the [[permeability]].<ref>Australia Pacific LNG. (June 2, 2015). ''Coal Seam Gas'' [Online]. Available: http://www.aplng.com.au/home/what-coal-seam-gas</ref>

==Formation==
:: [[coal formation|''main page'']]
Coal seams are formed from dead and decaying organic matter. Generally, this matter came from ancient peat bogs that died and fell into shallow, stagnant waters. As this material decayed, it became [[peat]] over time. As this peat was buried under sediment, the [[temperature]] increased and the pressure became greater. This compression and heating slowly turned the soft peat into harder [[lignite]] coal. With further burial and compression this brown lignite coal became [[sub-bituminous]] coal, then [[bituminous]] coal, and finally [[anthracite]] coal.<ref>Stephen Marshak. (June 2, 2015). ''Earth: Portrait of a Planet'', 3rd ed. New York, NY, U.S.A:W.W. Norton & Company, 2008</ref> Regardless of the size or placement of the coal seam this formation pattern remains the same.

==Location==
The size, location, and accessibility of coal seams can vary widely. Because of extreme pressures involved in the compression of the peat in the formation of coal, about 10 [[meter]]s of peat will only form around 1 meter of coal. However, the thickness of the coal bands can vary significantly depending on the amount of peat that was initially buried. Coal seams have been found that are as small as 30 centimeters (or around a foot) all the way up to more than 30 meters wide.<ref name=boyle>G.Boyle, B.Everett, S.Peake, J.Ramage. (June 2, 2015). ''Energy Systems and Sustainability: Power for a Sustainable Future'', 2nd Ed. Oxford, UK: Oxford University Press, 2012</ref> Additionally, these seams can be buried either very deeply or fairly close to the surface. Most of the time the deeply buried seams are mined using deep mining techniques whereas ones close to the surface are obtained through strip mining.

==Fires==
[[File:640px-Pdr_1647.jpg|400px|framed|right|Figure 2. A portion of a highway destroyed by the Centralia mine fire.<ref>Wikimedia Commons. (June 2, 2015). ''Pdr 1647'' [Online]. Available: http://en.wikipedia.org/wiki/Pennsylvania_Route_61#/media/File:Pdr_1647.jpg</ref>]]
Coal seams can pose a fire hazard, and as a result sometimes begin to smoulder. Generally, these fires are [[ignition|ignited]] by above ground fires but can continue to smoulder underground for many years. Sometimes these fires can burn for decades or centuries until the [[fuel]] below ground is used up or the fire is extinguished. One of the most widely known coal seam fires is the Centralia mine fire, which has been burning since 1962.<ref>Roadside America. (June 2, 2015). ''Centralia Mine Fire'' [Online]. Available: http://www.roadsideamerica.com/story/2196</ref> Although dangerous and important to put out, these fires are costly and difficult to extinguish. Internationally, thousands of underground coal fires are burning on every continent except Antarctica.<ref name="RE1">Dan Cray. (June 2, 2015). ''Deep Underground, Miles of Hidden Wildfires Rage'' [Online]. Available: http://content.time.com/time/health/article/0,8599,2006195,00.html</ref> These fires are hazardous as they release toxic fumes - including [[carbon dioxide]], [[methane]], and [[mercury]] - and can spark new above ground fires.<ref name="RE1"/> Global coal fire emissions are estimated to cause 40 tonnes of mercury to enter the atmosphere annually and represent 3% of the world's yearly carbon dioxide [[emission]]s.<ref name="RE1"/>

==References==
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