View source for Natural gas

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{| class="toccolours" border="1" style="float: right; clear: right; margin: 0 0 1em 1em; border-collapse: collapse;"
! {{chembox header}} | Methane
|-
| align="center" colspan="2" bgcolor="#ffffff" | [[Image:Methane-2D.svg|100px|Natural gas]] [[Image:Methane-3D-space-filling.svg|100px|Natural gas]]
|-
! {{chembox header}} | General
|- 
| Other names || Marsh gas, Swamp gas
|-
| [[Chemical formula|Molecular formula]] || CH<sub>4</sub> 
|-
| Appearance || Clear Gas, Blue Flame
|-
! {{chembox header}} | Properties
|-
| [[Density]] and [[Phase (matter)|phase]] || 0.717 kg/m<sup>3</sup>, gas
|-
| [[Melting point]] || −182.5°C (90.6 K) at 1 [[atmosphere (unit)|atm]]<br>
25 °C (298 K) at 1.5 G[[Pascal (unit)|Pa]]
|-
| [[Boiling point]] || −161.6°C (111.55 K)
|-
| [[Triple point]] || 90.7 K, 0.117 bar
|-
! {{chembox header}} | Hazards <!--  Summary only- MSDS entry provides more complete information -->
|-
| [[Material safety data sheet|External MSDS]] || [["http://praxairmrc.com/praxair.nsf/d63afe71c771b0d785256519006c5ea1/bd40c55346b4930f85256e5f007e8c2a/$FILE/NaturalGas-Canada.pdf"|External MSDS]] <!-- please replace with proper link-->
|-
| [[Directive 67/548/EEC|EU classification]] || Highly flammable ('''F+''')
|-
| [[NFPA 704]] || {{NFPA 704 | Health=1 | Flammability=4 }}
|-
| [[List of R-phrases|R-phrases]] || {{R12}}
|-
| [[List of S-phrases|S-phrases]] || {{S2}}, {{S9}}, {{S16}}, {{S33}}
|-
| [[Flash point]] || −188°C
|-
| [[Autoignition temperature]] || 482-632°C
|-
| Maximum burning <br> temperature: || 2148°C
|-
| [[Explosive limit]]s
| 5&ndash;15%
|-
! {{chembox header}} | Related compounds
|-
| Related [[alkane]]s || [[Ethane]]<br/>[[Propane]]
|-
| Related compounds  || [[Methanol]]<br/>[[Chloromethane]]
|-
| {{chembox header}} | <small>Except where noted otherwise, data are given for<br> materials in their [[standard state|standard state (at 25 °C, 100 kPa)]]<br/>[[wikipedia:Chemical infobox|Infobox disclaimer and references]]</small>
|-
|colspan=3 align=center |<small> ''See [[methane]] for a more complete list.''</small>
|-
|}

'''Natural gas''' is a [[gas]]eous [[fossil fuel]] consisting primarily of [[methane]] but including significant quantities of [[ethane]], [[butane]], [[propane]], [[carbon dioxide]], [[nitrogen]], [[helium]] and [[hydrogen sulfide]].<ref>[http://www.naturalgas.org/overview/background.asp Natural gas overview]</ref> It is found in [[oil field]]s and [[natural gas field]]s, and in [[coal bed]]s (as [[coalbed methane]]). When methane-rich gases are produced by the [[anaerobic decay]] of non-fossil [[organic compound|organic]] material, these are referred to as [[biogas]]. Sources of biogas include [[swamp]]s, [[marsh]]es, and [[landfill]]s (see [[landfill gas]]), as well as [[sewage]] [[sludge]] and [[manure]] by way of [[anaerobic digester]]s, in addition to [[enteric fermentation]] particularly in [[cattle]]. Natural gas is often informally referred to as simply '''gas''', especially when compared to other energy sources such as electricity. Before natural gas can be used as a fuel, it must undergo extensive [[natural gas processing|processing]] to remove almost all materials other than methane. The by-products of that processing include ethane, propane, butanes, [[pentane]]s and higher molecular weight hydrocarbons, elemental sulfur, and sometimes [[helium]] and nitrogen.

===Chemical composition===
The primary component of natural gas is [[methane]] ([[carbon|C]][[hydrogen|H]]<sub>4</sub>), the shortest and lightest [[hydrocarbon]] molecule.  It also contains heavier gaseous hydrocarbons such as [[ethane]] ([[carbon|C]]<sub>2</sub>[[hydrogen|H]]<sub>6</sub>), [[propane]] ([[carbon|C]]<sub>3</sub>[[hydrogen|H]]<sub>8</sub>) and [[butane]] ([[carbon|C]]<sub>4</sub>[[hydrogen|H]]<sub>10</sub>), as well as other [[sulfur]] containing gases, in varying amounts, see also [[natural gas condensate]].  Natural gas also contains and is the primary market source of [[helium]]. 

{| border="1" cellpadding="4" cellspacing="0" style="border:1px solid #aaa; border-collapse:collapse"
|- bgcolor="#cccccc"
! '''Component'''
! '''wt. %'''
|-
|| Methane (CH<sub>4</sub>)|| 70-90
|-
|| Ethane (C<sub>2</sub>H<sub>6</sub>) || 5-15 
|-
|| Propane (C<sub>3</sub>H<sub>8</sub>) and Butane (C<sub>4</sub>H<sub>10</sub>) || < 5 
|-
|| CO<sub>2</sub>, N<sub>2</sub>, H<sub>2</sub>S, etc. || balance 
|-
|}

Nitrogen, helium, carbon dioxide and trace amounts of hydrogen sulfide, water and [[odorant]]s can also be present
<ref>[http://www.wps.com/LPG/WVU-review.html WVU's AFVTP - Propane Review], West Virginia University</ref>. [[Mercury (element)|Mercury]] is also present in small amounts in natural gas extracted from some fields<ref>[http://www.gaschem.com/mercur.html Using Gas Geochemistry to Assess Mercury Risk], OilTracers, 2006</ref>. The exact composition of natural gas varies between gas fields.

[[Organosulfur compounds]] and [[hydrogen sulfide]]  are common contaminants which must be removed prior to most uses. Gas with a significant amount of sulfur impurities, such as [[hydrogen sulfide]], is termed [[sour gas]]; gas with sulfur or carbon dioxide impurities is [[acid gas]].  Processed natural gas that is available to end-users is tasteless and odorless, however, before gas is distributed to end-users, it is odorized by adding small amounts of odorants (mixtures of [[t-butyl mercaptan]], [[isopropyl mercaptan]], [[tetrahydrothiophene]], [[dimethyl sulfide]] and other sulfur compounds), to assist in [[gas leak|leak]] detection.  Processed natural gas is, in itself, harmless to the human body, however, natural gas is a simple [[asphyxiant]] and can kill if it displaces air to the point where the oxygen content will not support life.

Natural gas can also be hazardous to life and property through an [[explosion]].  Natural gas is lighter than air, and so tends to escape into the atmosphere.  But when natural gas is confined, such as within a house, gas concentrations can reach explosive mixtures and, if ignited, result in blasts that could destroy buildings.  Methane has a lower [[explosive limit]] of 5% in air, and an upper explosive limit of 15%.

Explosive concerns with compressed natural gas used in vehicles are almost non-existent, due to the escaping nature of the gas, and the need to maintain concentrations between 5% and 15% to trigger explosions.

===Energy content, statistics and pricing===
Quantities of natural gas are measured in [[normal cubic meter]]s (corresponding to 0&deg;C at 101.325  [[atmosphere (unit)|kPaA]]) or in [[standard cubic feet]] (corresponding to 60&deg;F and 14.73 [[PSIA]]).
The [[Higher Heating Value|gross heat of combustion]] of one [[normal cubic meter]] of commercial quality natural gas is around 39&nbsp;[[joule|megajoule]]s (≈10.8&nbsp;[[kWh]]), but this can vary by several percent.
In [[United States customary units|US units]], one [[standard cubic foot]] of natural gas produces around 1,030&nbsp;[[British Thermal Unit]]s (BTUs). The actual heating value when the water formed does not condense is the [[Lower Heating Value|net heat of combustion]] and can be as much as 10% less.

The price of natural gas varies greatly depending on location and type of consumer, but [[as of 2007]] a price of $7 per 1000 cubic feet is typical in the United States. This corresponds to around $7 per million BTU's, or around $7 per [[gigajoule]]. Natural gas in the United States is traded as a [[futures contract]] on the [[New York Mercantile Exchange]]. Each contract is for 10,000 MMBTU ([[gigajoule]]s), or 10 billion BTU's. Thus, if the price of gas is $7 per million BTU's on the NYMEX, the contract is worth $70,000. In the United States, at retail, natural gas is often sold in units of [[therm]]s (th); 1 therm = 100,000&nbsp;BTU. [[Gas meter]]s measure the volume of gas used, and this is converted to therms by multiplying the volume by the energy content of the gas used during that period, which varies slightly over time. Wholesale transactions are generally done in [[decatherm]]s (Dth), or in thousand decatherms (MDth), or in million decatherms (MMDth). A million decatherms is roughly a billion cubic feet of natural gas.

Natural gas is also traded as a commodity in Europe, principally at the United Kingdom [[National Balancing Point (UK)|NBP]] and related European hubs, such as the [[Title Transfer Facility|TTF]] in the Netherlands.

In the rest of the world, LNG and LPG is traded in metric tons or mmBTU as spot deliveries. Long term contracts are signed in metric tons - and to convert from one system to the other requires should better be described here, than a very isolated market. A cubic foot is a volumetric measure, MT is weight. The LNG and LPG is transported by special ships/containers, as the gas is liquified - LPG cryonic. The specification of each LNG/LPG cargo will usually contain the energy content, but this information is in general not available to the public.

==Natural gas processing==
[[Image:NaturalGasProcessingPlant.jpg|thumb|right|A natural gas processing plant]]

{{main|Natural gas processing}}
The image below is a schematic [[Process flow diagram|block flow diagram]] of a typical natural gas processing plant. It shows the various unit processes used to convert raw natural gas into sales gas pipelined to the end user markets. 

The block flow diagram also shows how processing of the raw natural gas yields byproduct sulfur, byproduct ethane, and natural gas liquids (NGL) propane, butanes and natural gasoline (denoted as [[pentanes]] +).<ref>[http://www.eia.doe.gov/pub/oil_gas/natural_gas/feature_articles/2006/ngprocess/ngprocess.pdf ''Natural Gas Processing: The Crucial Link Between Natural Gas Production and Its Transportation to Market'']</ref><ref>[http://www.uop.com/gasprocessing/6070.html ''Example Gas Plant'']</ref><ref>[http://www.axens.net/upload/presentations/fichier/axens_gpagcc_2004v2.pdf ''From Purification to Liquefaction Gas Processing'']</ref><ref>[http://www.spe.org/specma/binary/files/5804785Syn10682.pdf ''Feed-Gas Treatment Design for the Pearl GTL Project'']</ref><ref>[http://lnglicensing.conocophillips.com/NR/rdonlyres/B78B6727-E5F4-4505-B9C3-96CC94D7B30D/7357/AICHELNGNGLIntegrationPaper.pdf ''Benefits of integrating NGL extraction and LNG liquefaction'']</ref>

[[Image:NatGasProcessing.png|frame|center|Schematic flow diagram of a typical natural gas processing plant]]

==Storage and transport==
[[Image:Polyethylene gas main.jpg|thumb|right|[[Polyethylene]] gas [[main]] being laid in a [[trench]].]]

The major difficulty in the  use of natural gas is [[transport]]ation and [[Natural gas storage|storage]] because of its low density. Natural gas [[pipeline transport|pipelines]] are economical, but are impractical across [[ocean]]s.  Many [[List of North American natural gas pipelines|existing pipelines in North America]] are close to reaching their capacity, prompting some politicians representing colder areas to speak publicly of potential shortages. 

[[LNG carrier]]s can be used to transport [[liquefied natural gas]] (LNG) across oceans, while [[tank truck]]s can carry liquefied or [[compressed natural gas]] (CNG) over shorter distances. They may transport natural gas directly to end-users, or to distribution points such as pipelines for further transport. These may have a higher cost, requiring additional facilities for [[liquefaction of gases|liquefaction]] or [[physical compression|compression]] at the production point, and then [[gasification]] or decompression at end-use facilities or into a pipeline.

In the past, the natural gas which was recovered in the course of recovering [[petroleum]] could not be [[profit]]ably sold, and was simply [[combustion|burned]] at the oil field (known as [[gas flare|flaring]]). This [[waste]]ful practice is now illegal in many countries.  Additionally, companies now recognize that value for the gas may be achieved with LNG, CNG, or other transportation methods to end-users in the future.  The gas is now re-[[Wiktionary:inject|inject]]ed back into the formation for later recovery. This also assists oil [[pump]]ing by keeping underground [[pressure]]s higher. In [[Saudi Arabia]], in the late [[1970s]], a "Master Gas System" was created, ending the need for flaring. The natural gas is used to generate electricity and heat for [[desalinization]].  Similarly, some landfills that also discharge methane gases have been set up to capture the methane and generate electricity.

Natural gas is often stored in underground caverns formed inside depleted gas reservoirs from previous gas wells, [[salt domes]], or in tanks as [[liquefied natural gas]].  The gas is injected during periods of low demand and extracted during periods of higher demand.  Storage near the ultimate end-users helps to best meet volatile demands, but this may not always be practicable.

With 15 nations accounting for 84% of the world-wide production, access to natural gas has become a significant factor in international economics and politics. In this respect, control over the pipelines is a major strategic factor.<ref>[http://www.imi-online.de/2007.php3?id=1589 The Contours of the New Cold War]</ref>

==Use==
===Power generation===
Natural gas is a major source of [[electricity generation]] through the use of [[gas turbine]]s and [[steam]] [[turbines]]. Particularly high efficiencies can be achieved through combining gas turbines with a steam turbine in [[combined cycle]] mode. Natural gas burns cleaner than other [[fossil fuel]]s, such as oil and coal, and produces less carbon dioxide per unit energy released.  For an equivalent amount of heat, burning natural gas produces about 30% less [[carbon dioxide]] than burning [[petroleum]] and about 45% less than burning [[coal]].<ref>[http://www.naturalgas.org/environment/naturalgas.asp#greenhouse/ Natural Gas and the Environment]</ref> Combined cycle power generation using natural gas is thus the cleanest source of power available using fossil fuels, and this technology is widely used wherever gas can be obtained at a reasonable cost. [[Fuel cell]] technology may eventually provide cleaner options for converting natural gas into electricity, but as yet it is not price-competitive. Also, the natural gas supply is expected to peak around the year 2030, 20 years after the peak of oil. It is also projected that the world's supply of natural gas could be exhausted around the year 2085.

=== Hydrogen ===
Natural gas can be used to produce [[hydrogen]], with one common method being the [[hydrogen reformer]]. Hydrogen has various applications: it is a primary feedstock for the chemical industry, a hydrogenating agent, an important commodity for oil refineries, and a fuel source in [[hydrogen vehicle]]s.

===Natural gas vehicles===
[[Image:WMATA 3006.jpg|thumb|right|A [[Metrobus (Washington, D.C.)|Metrobus]] using natural gas]]
[[Compressed natural gas]] ([[methane]]) is used as a clean alternative to other [[automobile]] fuels such as [[gasoline]] (petrol) and [[diesel]]. [[As of 2005]], the countries with the largest number of [[natural gas vehicle]]s were [[Argentina]], [[Brazil]], [[Pakistan]], [[Italy]], [[India]] and [[Bangladesh]].<ref>[http://www.iangv.org/content/view/17/35/ International Statistics] (IANG website page)</ref> The energy efficiency is generally equal to that of gasoline engines, but lower compared with modern diesel engines. Benzine vehicles converted to run on gas suffer of the low-compression ratio their engines have, resulting in a cropping of delivered power while running on natural gas (10%-15%). CNG factory-made engines, however, use a higher compression ratio, due to the high number of [[octane]] (120-130) of this fuel.

[[Liquified petroleum gas]] (a [[propane]] and [[butane]] blend) is also used to fuel vehicles. LPG and CNG vehicle fuel systems are not compatible.  CNG also requires higher pressure tanks which are typically much heavier than those used for LPG.

===Residential domestic use===
Natural gas is supplied to homes, where it is used for such purposes as [[cooking]] in natural gas-powered ranges and/or ovens, natural gas-heated [[clothes dryer]]s, [[HVAC|heating]]/[[air conditioning|cooling]] and [[central heating]].  Home or other building heating may include boilers, [[furnace]]s, and [[water heater]]s.  CNG is used in [[rural]] homes without connections to [[plumbing|pipe]]d-in [[public utility]] services, or with portable [[Grill (cooking)|grill]]s.  However, due to CNG being less economical than LPG, LPG (Propane) is the dominant source of rural gas.

===Fertilizer===

Natural gas is a major feedstock for the production of [[ammonia]], via the [[Haber process]], for use in [[fertilizer]] production.

===Aviation===

[[Russia]]n aircraft manufacturer [[Tupolev]] is currently running a development program to produce LNG- and [[hydrogen]]-powered aircraft.<ref> [http://www.tupolev.ru/English/Show.asp?SectionID=82&Page=1 PSC Tupolev - Development of Cryogenic Fuel Aircraft]</ref> The program has been running since the mid-[[1970s]], and seeks to develop LNG and hydrogen variants of the [[Tupolev Tu-204|Tu-204]] and [[Tupolev Tu-334|Tu-334]] passenger aircraft, and also the [[Tupolev Tu-330|Tu-330]] cargo aircraft. It claims that at current market prices, an LNG-powered aircraft would cost 5,000 [[rouble]]s less to operate per ton, roughly equivalent to 60%, with considerable reductions to [[carbon monoxide]], [[hydrocarbon]] and [[nitrogen oxide]] emissions.

===Other===

Natural gas is also used in the manufacture of [[textile|fabric]]s, [[glass]], [[steel]], [[plastic]]s, [[paint]], and other products.

==Sources==
[[Image:Natural gas production world.PNG|thumb|300px|Natural gas production by country (countries in brown and then red have the largest production)]]
===Natural gas===
Natural gas is commercially produced from [[oil field]]s and [[natural gas field]]s.  Gas produced from oil wells is called casinghead gas or associated gas. The natural gas industry is producing gas from increasingly more challenging [[History of the petroleum industry in Canada (natural gas)#Unconventional gas|resource types]]: sour gas, tight gas, [[shale gas]] and [[coalbed methane]]. 

The world's largest gas field by far is [[Qatar]]'s offshore [[South Pars / North Dome Gas-Condensate field|North Field]], estimated to have 25 trillion cubic metres<ref>[http://www.state.gov/r/pa/ei/bgn/5437.htm Background note: Qatar]</ref> (900<!--1500 needs reference--> trillion cubic feet) of gas in place - enough to last more than 200 years at optimum production levels. The second largest natural gas field is the [[Asalouyeh|South Pars Gas Field]] in [[Iran]]ian waters in the [[Persian Gulf]]. Connected to Qatar's North Field, it has estimated reserves of 8 to 14 trillion cubic metres<ref>{{cite web|url=http://www.pseez.ir/gas-en.html|publisher=Pars Special Economic Energy Zone|accessdate=2007-07-17|title=    	
Pars Special Economic Energy Zone}}</ref> (280-500 trillion cubic feet) of gas; see [[List of natural gas fields]].  

===Town gas===
[[Town gas]] is a mixture of methane and other gases, mainly the highly toxic [[carbon monoxide]], that can be used in a similar way to natural gas and can be produced by treating [[coal]] chemically. This is a historic technology, still used as 'best solution' in some local circumstances, although coal gasification is not usually economic at current gas prices.  However, depending upon infrastructure considerations, it remains a future possibility.

===Biogas===
[[Methanogen|Methanogenic archaea]] are responsible for all biological sources of methane, some in symbiotic relationships with other life forms, including [[termite]]s, [[ruminant]]s, and cultivated crops. Methane released directly into the atmosphere would be considered a [[pollutant]],  however, methane in the atmosphere is oxidised, producing carbon dioxide and water.   Methane in the atmosphere has a half life of seven years, meaning that every seven years, half of the methane present is converted to carbon dioxide and water.

[[Image:U.S. Natural Gas Production 1900-2005.png‎|right|thumb|U.S. Natural Gas Production 1900 - 2005 Source: EIA]]

Future sources of [[methane]], the principal component of natural gas, include landfill gas, biogas and methane hydrate. Biogas, and especially landfill gas, are already used in some areas, but their use could be greatly expanded. Landfill gas is a type of biogas, but biogas usually refers to gas produced from organic material that has not been mixed with other waste. 

[[Landfill gas]] is created from the decomposition of waste in [[landfill]]s. If the gas is not removed, the pressure may get so high that it works its way to the surface, causing damage to the landfill structure, unpleasant odor, vegetation die-off and an [[explosion]] hazard. The gas can be vented to the atmosphere, [[gas flare|flared]] or burned to produce [[electricity]] or [[heat]]. Experimental systems were being proposed for use in parts [[Hertfordshire]], UK and [[Lyon]] in France.    

Once [[water vapor]] is removed, about half of landfill gas is methane. Almost all of the rest is [[carbon dioxide]], but there are also small amounts of [[nitrogen]], [[oxygen]] and [[hydrogen]]. There are usually trace amounts of [[hydrogen sulfide]] and [[siloxane]]s, but their concentration varies widely. Landfill gas cannot be distributed through natural gas pipelines unless it is cleaned up to the same quality. It is usually more economical to combust the gas on site or within a short distance of the landfill using a dedicated pipeline. Water vapor is often removed, even if combusting the gas on site.  If low temperatures  condense out the water from the gas, [[siloxanes]] can be lowered as well because they tend to condense out with the water vapour. Other non-methane components may also be removed in order to meet [[emission standard]]s, to prevent fouling of the equipment or for environmental considerations. Co-firing landfill gas with natural gas improves combustion, which lowers emissions. 

[[Biogas]] is usually produced using agricultural waste materials, such as otherwise unusable parts of plants and [[manure]]. Biogas can also be produced by separating [[organic material]]s from waste that otherwise goes to landfills.  This is more efficient than just capturing the landfill gas it produces. Using materials that would otherwise generate no income, or even cost money to get rid of, improves the profitability and energy balance of biogas production. 

[[Anaerobic lagoon]]s  produce biogas from manure, while biogas reactors can be used for manure or plant parts. Like landfill gas, biogas is mostly methane and carbon dioxide, with small amounts of nitrogen, oxygen and hydrogen. However, with the exception of pesticides, there are usually lower levels of contaminants.

===Hydrates===
A speculative source of enormous quantities of methane is from [[methane clathrate|methane hydrate]], found under sediments in the oceans. However, [[as of 2006]] no technology has been developed to recover it economically.

==Safety==
In any form, a minute amount of [[aroma compound|odorant]] such as t-butyl [[mercaptan]], with a rotting-cabbage-like smell, is added to the otherwise [[color]]less and [[odor]]less gas, so that [[leak]]s can be detected before a fire or [[explosion]] occurs.  Sometimes a related compound, thiophane is used, with a rotten-egg smell.  Adding odorant to natural gas began in the United States after the 1937 [[New London School explosion]].  The buildup of gas in the school went unnoticed, killing three hundred students and faculty when it ignited. Odorants are considered non-toxic in the extremely low concentrations occurring in natural gas delivered to the end user.

In [[mining|mine]]s, where methane seeping from rock formations has no odor, [[sensor]]s are used, and mining apparatuses have been specifically developed to avoid ignition sources, e.g., the [[Davy lamp]].

Explosions caused by natural [[gas leak]]s occur a few times each year.  Individual [[home]]s, [[small business]]es and [[boats]] are most frequently affected when an internal leak builds up gas inside the structure.  Frequently, the blast will be enough to significantly damage a building but leave it standing.  In these cases, the people inside tend to have minor to moderate [[injury|injuries]].  Occasionally, the gas can collect in high enough quantities to cause a deadly explosion, disintegrating one or more buildings in the process.  The gas usually dissipates readily outdoors, but can sometimes collect in dangerous quantities if [[weather]] conditions are right.  However, considering the tens of millions of structures that use the fuel, the individual [[risk]] of using natural gas is very low.

Some gas fields yield [[sour gas]] containing [[hydrogen sulfide]] (H<sub>2</sub>S).  This untreated gas is [[toxic]].  [[Amine gas treating]], an industrial scale process which removes [[acidic]] [[gas]]eous components, is often used to remove hydrogen sulfide from natural gas.
<ref>[http://www.naturalgas.org/naturalgas/processing_ng.asp NaturalGas.org - Processing Natural Gas]</ref>

Extraction of natural gas (or oil) leads to decrease in [[pressure]] in the [[oil reservoir|reservoir]]. This in turn may lead to [[subsidence]] at ground level. Subsidence may affect [[ecosystem]]s, [[waterway]]s, [[sewer]] and  [[water supply]] systems, [[foundation (architecture)|foundation]]s, etc.

Natural Gas heating systems are the leading cause of carbon monoxide deaths in the United States, according to the U.S. Consumer Product Safety Commission. When a natural gas heating system malfunctions, it produces odorless carbon monoxide. With no fumes or smoke to give warning, poisoning victims are easily asphyxiated by the carbon monoxide.

==See also==
{{EnergyPortal}}
<div class="references-small" style="-moz-column-count:2; column-count:2;">
*[[abiogenic petroleum origin]]
*[[Carbon dioxide]] (CO<sub>2</sub>)
*[[Compressed natural gas]] (CNG)
*[[Fuel station]]
*[[Future energy development]]
*[[Hydrogen vehicle]]
*[[Liquefied natural gas]] (LNG)
*[[Natural gas storage]]
*[[List of North American natural gas pipelines]]
*[[Natural gas prices]]
*[[Natural gas processing]]
*[[North American natural gas crisis]]
*[[Steam reforming]]
*[[World energy resources and consumption]]
</div>

==External links==
*[http://www.aga.org American Gas Association - distributor trade group]
*[http://cera.ecnext.com/coms2/browse_RS_GAS_ CERA - Energy research group's Natural Gas Research]
*[http://tonto.eia.doe.gov/oog/info/ngw/ngupdate.asp DOE/EIA Natural Gas Data Page]
*[http://eh.net/encyclopedia/article/castaneda.gas.industry.us Economic History - Manufactured and Natural Gas Industry]
*[http://www.ingaa.org/ Interstate Natural Gas Association of America - pipeline trade group]
*[http://www.naturalgas.org Natural Gas Supply Association - producer trade group]
*[http://www.touchoilandgas.com Oil and Gas Directory]
*[http://www.oilandgaseurasia.com Oil and Gas Eurasia - Oil and Gas News, Technology and Analysis]
*[http://platts.com/Natural%20Gas/Resources/ Platt's - Natural Gas Industry News]
*[http://www.infoplease.com/ipa/A0872966.html Top 20 Greatest Natural Gas Reserves by Country]

===Natural gas vehicles===
*[http://www.cngforum.com/cgi-bin/yabb2/YaBB.pl CNG Forum]
*[http://www.iangv.org International Association for Natural Gas Vehicles]
*[http://www.naftc.wvu.edu National Alternative Fuels Training Consortium - Alternative Fuel Vehicle Training] 
*[http://www.nesea.org/greencarclub/factsheets_naturalgas.pdf#search='explosion%20ratio%20natural%20gas Northeast Sustainable Energy Association - Natural Gas Factsheet] (PDF)

==References==
{{reflist|2}}

<br>
{{Sustainability and energy development group}}

[[Category:Natural gas| ]]
[[Category:Methane]]
[[Category:Fuels]]
[[Category:Energy sources]]

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