{{Short description|Fuel for heating, cooking and vehicles}} {{Distinguish|text=liquefied natural gas, nor with associated petroleum gas, nor with "condensate" in the sense of natural-gas condensate (natural gas liquids)}} {{SM2|Propane|discuss=Talk:Propane#Proposed move of content from Propane article to LPG article}} {{Use dmy dates|date=August 2019}}

thumb|LPG storage spheres [[File:LPG cylinders.JPG|thumb|Two {{convert|45|kg|lb|abbr=on}} LPG gas cylinders in New Zealand used for domestic supply]] [[File:13-08-09-hongkong-by-RalfR-106.jpg|thumb|LPG minibuses in Hong Kong]] [[File:2011-2013 Ford Falcon (FG II) XT sedan, TriColor taxis (2017-04-22).jpg|thumb|A pure LPG-powered Ford Falcon taxicab in Perth, Australia]] thumb|Tank cars in a Canadian train for carrying liquid petroleum gas by rail

'''Liquefied petroleum gas''', also referred to as '''liquid petroleum gas''' ('''LPG''' or '''LP gas'''), is a fuel gas which contains a flammable mixture of hydrocarbon gases, specifically propane, butane and isobutane. It can also contain some propylene, butylene, and isobutylene.<ref>{{Cite report |url=https://iea.blob.core.windows.net/assets/312383bd-58a2-44bc-bae1-e856a4c61215/WorldEnergyPrices_Documentation.pdf |title=World Energy Prices: Database Documentation |date= |publisher=International Energy Agency |edition=2020 |access-date=February 8, 2024 |archive-url=https://web.archive.org/web/20240208033625/https://iea.blob.core.windows.net/assets/312383bd-58a2-44bc-bae1-e856a4c61215/WorldEnergyPrices_Documentation.pdf |archive-date=February 8, 2024 |url-status=live}}</ref><ref>{{Cite book |last=NFPA |title=Liquefied Petroleum Gas Code |date=2017 |publisher=National Fire Protection Association |isbn=978-1455913879 |edition=2017 |series=NFPA 58 |location=Quincy, Mass. |pages=11, 132 |author-link=National Fire Protection Association}}</ref><ref>{{Cite book |title=Enciclopedia degli idrocarburi |publisher=Eni and Istituto della Enciclopedia Italiana |year=2005 |volume=II |location=Roma, Italy |page=26 |language=Italian |trans-title=Encyclopaedia of Hydrocarbons |oclc=955421604}}</ref><ref>{{cite journal |last1=Shipman |first1=R H |title=14 - Liquefied petroleum gas |journal=Plant Engineer's Reference Book (Second Edition) |date=2002 |pages=14–1 |doi=10.1016/B978-075064452-5/50069-9 |isbn=978-0-7506-4452-5}}</ref><ref>{{cite book |last1=Falkiner |first1=Robert J. |last2=Pickard |first2=Andy |chapter=Chapter 6 Liquefied Petroleum Gas |title=Fuels and Lubricants Handbook: Technology, Properties, Performance, and Testing |date=2019 |publisher=ASTM International |isbn=978-0-8031-7089-6 |url=https://asmedigitalcollection.asme.org/astm-ebooks/book/665/chapter-abstract/27759364/Chapter-6-Liquefied-Petroleum-Gas?redirectedFrom=fulltext |language=en |doi=10.1520/MNL37-2ND-EB}}</ref>

LPG is used as a fuel gas in heating appliances, cooking equipment, and vehicles, and is used as an aerosol propellant<ref>{{cite web|url=https://www.brothersgas.com/aerosol_propellant/|title=Aerosol Propellant {{!}} Aerosol Propellant Gas {{!}} Aerosol Supplies Dubai – Brothers Gas|last=Alvi|first=Moin ud-Din|website=www.brothersgas.com|access-date=2016-06-14|url-status=live|archive-url=https://web.archive.org/web/20161230065341/http://brothersgas.com/aerosol_propellant/|archive-date=30 December 2016}}</ref> and a refrigerant,<ref>{{cite web|url=http://archive.hychill.com.au/pdf/pasolpgr.pdf|archive-url=https://web.archive.org/web/20150310165137/http://archive.hychill.com.au/pdf/pasolpgr.pdf|archive-date=2015-03-10|title=Performance and Safety of LPG Refrigerants}}</ref> replacing chlorofluorocarbons which damage the ozone layer. When specifically used as a vehicle fuel, it is often referred to as autogas or just as gas.

Varieties of LPG that are bought and sold include mixes that are mostly propane ({{chem|C|3|H|8}}), mostly butane ({{chem|C|4|H|10}}), and, most commonly, mixes including both propane and butane. In the northern hemisphere winter, the mixes contain more propane, while in summer, they contain more butane.<ref name=Totten>{{cite book|editor-last=ed|editor-first=George E. Totten|title=Fuels and lubricants handbook : technology, properties, performance, and testing|year=2003|publisher=ASTM International|location=West Conshohocken, Pa.|isbn=9780803120969|url=https://books.google.com/books?id=J_AkNu-Y1wQC&pg=PA31-IA1|edition=2nd printing.|url-status=live|archive-url=https://web.archive.org/web/20160604011923/https://books.google.com/books?id=J_AkNu-Y1wQC&pg=PA31-IA1|archive-date=4 June 2016}}</ref><ref name=SeasonalMix>{{cite web|last=Unipetrol |title=Analysis of seasonal mixtures – Propane-butane Fuel Mixture (Summer, Winter) |url=http://www.unipetrolrpa.cz/en/our-products/refinery_products/other-refinery-products/propane-butane.html |archive-url=https://web.archive.org/web/20100809101649/http://www.unipetrolrpa.cz/en/our-products/refinery_products/other-refinery-products/propane-butane.html |url-status=dead |archive-date= 9 August 2010 |access-date=29 April 2013 }}</ref> In the United States, mainly two grades of LPG are sold: commercial propane and HD-5. These specifications are published by the Gas Processors Association (GPA)<ref name="GPA Standard 2140-97">{{cite web|title=Liquefied Petroleum Gas Specifications and Test Methods|url=https://www.gpaglobal.org/publications/view/id/36/|publisher=Gas Processors Association|access-date=2012-05-18|url-status=dead|archive-url=https://web.archive.org/web/20130621132551/https://www.gpaglobal.org/publications/view/id/36/|archive-date=21 June 2013}}</ref> and the American Society of Testing and Materials.<ref>{{cite web|title=ASTM D1835 – 11 Standard Specification for Liquefied Petroleum (LP) Gases|url=http://www.astm.org/Standards/D1835.htm|publisher=American Society for Testing & Materials|url-status=live|archive-url=https://web.archive.org/web/20120522150653/http://www.astm.org/Standards/D1835.htm|archive-date=22 May 2012}}</ref> Propane/butane blends are also listed in these specifications.

Propylene, butylenes and various other hydrocarbons are usually also present in small concentrations such as {{chem2|C2H6}}, {{chem2|CH4}}, and {{chem2|C3H8}}. HD-5 limits the amount of propylene that can be placed in LPG to 5% and is utilized as an autogas specification.<ref>{{cite web |title=Propane Fuel Basics |url=https://afdc.energy.gov/fuels/propane-basics |website=Alternative Fuels Data Center |institution=U.S. Department of Energy |access-date=2024-12-28}}</ref> A powerful odorant, ethanethiol, is added so that leaks can be detected easily. The internationally recognized European Standard is EN 589. In the United States, tetrahydrothiophene (thiophane) or amyl mercaptan are also approved odorants,<ref>{{CodeFedReg|49|173|315|(b)(1) Note 2}}</ref> although neither is currently being utilized.

LPG is prepared by refining petroleum or "wet" natural gas, and is almost entirely derived from fossil fuel sources, being manufactured during the refining of petroleum (crude oil), or extracted from petroleum or natural gas streams as they emerge from the ground. It was first produced in 1910 by Walter O. Snelling, and the first commercial products appeared in 1912. It currently provides about 3% of all energy consumed, and burns relatively cleanly with no soot and very little sulfur emission. As it is a gas, it does not pose ground or water pollution hazards, but it can cause air pollution. LPG has a typical specific calorific value of 46.1&nbsp;MJ/kg compared with 42.5&nbsp;MJ/kg for fuel oil and 43.5&nbsp;MJ/kg for premium grade petrol (gasoline).<ref>{{Cite book|title=Automotive Handbook |year=1996 |publisher=Robert Bosch GmbH |location=Stuttgart |isbn=0-8376-0333-1 |editor=Horst Bauer |edition=4th|pages=238–239}}</ref> However, its energy density per volume unit of 26 MJ/L is lower than either that of petrol or fuel oil, as its relative density is lower (about 0.5–0.58&nbsp;kg/L, compared to 0.71–0.77&nbsp;kg/L for gasoline). As the density and vapor pressure of LPG (or its components) change significantly with temperature, this fact must be considered every time when the application is connected with safety or custody transfer operations,<ref>{{Cite journal|last=Zivenko|first=Oleksiy|title=LPG Accounting Specificity During ITS Storage and Transportation|date=2019|journal=Measuring Equipment and Metrology|language=en |volume=80|issue=3|pages=21–27|doi=10.23939/istcmtm2019.03.021|s2cid=211776025|issn=0368-6418|doi-access=free}}</ref> e.g. typical cuttoff level option for LPG reservoir is 85%.

Besides its use as an energy carrier, LPG is also a promising feedstock in the chemical industry for the synthesis of olefins such as ethylene and propylene.<ref>{{Cite web|title=High-purity propylene from refinery LPG|url=https://www.digitalrefining.com/article/1000361/high-purity-propylene-from-refinery-lpg}}</ref><ref>{{Cite book|title=Kinetic studies of propane oxidation on Mo and V based mixed oxide catalysts|year=2011}}</ref>

As its boiling point is below room temperature, LPG will evaporate quickly at normal temperatures and pressures and is usually supplied in pressurized steel vessels, where the gas is liquid due to being stored at pressure. They are typically filled to 80–85% of their capacity to allow for thermal expansion of the contained liquid. The ratio of the densities of the liquid and vapor varies depending on composition, pressure, and temperature, but is typically around 250:1. The pressure at which LPG becomes liquid, called its vapour pressure, likewise varies depending on composition and temperature; for example, it is approximately {{convert|220|kPa|psi}} for pure butane at {{convert|20|°C|°F}}, and approximately {{convert|2200|kPa|psi}} for pure propane at {{convert|55|°C|°F}}. LPG in its gaseous phase is still heavier than air, unlike natural gas, and thus will flow along floors and tend to settle in low spots, such as basements. There are two main dangers to this. The first is a possible explosion if the mixture of LPG and air is within the explosive limits and there is an ignition source. The second is suffocation due to LPG displacing air, causing a decrease in oxygen concentration.

A full LPG gas cylinder contains 86% liquid; the ullage volume will contain vapour at a pressure that varies with temperature.<ref>{{cite web |title=LPG pdf | url= http://www.awsgroup.co.za/data/L.P.G.pdf | archive-url= https://web.archive.org/web/20120523031033/http://www.awsgroup.co.za/data/L.P.G.pdf | archive-date= 23 May 2012 | url-status= dead }}</ref>

==Uses== LPG has a wide variety of uses in many different markets as an efficient fuel container in the agricultural, recreation, hospitality, industrial, construction, sailing and fishing sectors. It can serve as fuel for cooking, central heating and water heating and is a particularly cost-effective and efficient way to heat off-grid homes.

===Cooking=== LPG is used for cooking in many countries for economic reasons, for convenience or because it is the preferred fuel source.

In India, nearly 28.5 million metric tons of LPG were consumed in the 2023–24 financial year in the domestic sector, mainly for cooking.<ref>{{Cite web |title=India: LPG consumption volume in 2023 |url=https://www.statista.com/statistics/1052428/india-lpg-consumption-volume/#:~:text=Consumption%20of%20liquefied%20petroleum%20gas%20across%20India%20was,2023,%20a%20slight%20increase%20from%20the%20previous%20year. |access-date=2024-09-29 |website=Statista |language=en}}</ref> In 2016, the number of domestic connections was 215 million (i.e., one connection for every six people) with a circulation of more than 350 million LPG cylinders.<ref>{{cite web |url=http://ppac.org.in/WriteReadData/Reports/201611231215439693847DataonLPGMarketingOct16.pdf |title=LPG Profile |access-date=30 March 2017 |url-status=live |archive-url=https://web.archive.org/web/20170408171257/http://ppac.org.in/WriteReadData/Reports/201611231215439693847DataonLPGMarketingOct16.pdf |archive-date=8 April 2017 }}</ref> Most of the LPG requirement is imported. Piped city gas supply in India is not yet developed on a major scale. LPG is subsidised by the Indian government for domestic users. An increase in LPG prices has been a politically sensitive matter in India as it potentially affects the middle class voting pattern.

LPG was once a standard cooking fuel in Hong Kong; however, the continued expansion of town gas to newer buildings has reduced LPG usage to less than 24% of residential units. However, other than electric, induction, or infrared stoves, LPG-fueled stoves are the only type available in most suburban villages and many public housing estates.

LPG is the most common cooking fuel in Brazilian urban areas, being used in virtually all households, with the exception of the cities of Rio de Janeiro and São Paulo, which have a natural gas pipeline infrastructure. Since 2001, poor families receive a government grant ("Vale Gás") used exclusively for the acquisition of LPG. Since 2003, this grant is part of the government's main social welfare program ("Bolsa Família"). Also, since 2005, the national oil company Petrobras differentiates between LPG destined for cooking and LPG destined for other uses, establishing a lower price for the former. This is a result of a directive from the Brazilian federal government, but its discontinuation is currently being debated.<ref>{{Cite web|url=http://www1.folha.uol.com.br/mercado/2017/08/1910713-anp-quer-fim-de-diferenca-entre-precos-do-gas-de-botijao.shtml|title=ANP quer fim de diferença entre preços do gás de botijão – 17/08/2017 – Mercado|website=Folha de S.Paulo|access-date=2019-01-25}}</ref>

LPG is commonly used in North America for domestic cooking and outdoor grilling.

===Rural heating=== [[File:Liquefied petroleum gas cylinders.jpg|thumb|200px|right| LPG cylinders in India]] thumb|Liquefied petroleum gas tank on a rural farm Predominantly in Europe and rural parts of many countries, LPG can provide an alternative to electric heating, heating oil, or kerosene. LPG is most often used in areas that do not have direct access to piped natural gas. In the UK about 200,000 households use LPG for heating.

LPG can be used as a power source for combined heat and power technologies (CHP). CHP is the process of generating both electrical power and useful heat from a single fuel source. This technology has allowed LPG to be used not just as fuel for heating and cooking, but also for decentralized generation of electricity.

===Motor fuel=== [[Image:lpg-connector.jpg|thumb|LPG filling connector on a Skoda 120]] {{Main|Autogas}} thumb|White-bordered green diamond symbol used on LPG-powered vehicles in China When LPG is used to fuel internal combustion engines, it is often referred to as autogas or auto propane. In some countries, it has been used since the 1940s as a petrol alternative for spark ignition engines. In some countries, there are additives in the liquid that extend engine life and the ratio of butane to propane is kept quite precise in fuel LPG. Two recent studies have examined LPG-fuel-oil fuel mixes and found that smoke emissions and fuel consumption are reduced but hydrocarbon emissions are increased.<ref name="Zhang">{{Cite journal|doi=10.1243/095440705X6470 |title=A study on an electronically controlled liquefied petroleum gas-diesel dual-fuel automobile |year=2005 |last1=Zhang |first1=Chunhua |last2=Bian |first2=Yaozhang |last3=Si |first3=Lizeng |last4=Liao |first4=Junzhi |last5=Odbileg |first5=N |journal=Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering |volume=219|issue=2 |page=207|s2cid=109657186 }}</ref><ref name="Qi">{{Cite journal|doi=10.1016/j.enconman.2006.06.013 |title=Combustion and exhaust emikon characteristics of a compression ignition engine using liquefied petroleum gas–fuel-oil blended fuel |year=2007 |last1=Qi |first1=D |last2=Bian |first2=Y |last3=Ma |first3=Z |last4=Zhang |first4=C |last5=Liu |first5=S |journal=Energy Conversion and Management |volume=48|issue=2 |page=500}}</ref> The studies were split on CO emissions, with one finding significant increases,<ref name="Zhang"/> and the other finding slight increases at low engine load but a considerable decrease at high engine load.<ref name="Qi"/> Its advantage is that it is non-toxic, non-corrosive and free of tetraethyllead or any additives, and has a high octane rating (102–108 RON depending on local specifications). It burns more cleanly than petrol or fuel-oil and is especially free of the particulates present in the latter.

LPG has a lower energy density per liter than either petrol or fuel-oil, so the equivalent fuel consumption is higher. Many governments impose less tax on LPG than on petrol or fuel-oil, which helps offset the greater consumption of LPG than of petrol or fuel-oil. However, in many European countries, this tax break is often compensated by a much higher annual tax on cars using LPG than on cars using petrol or fuel-oil. Propane is the third most widely used motor fuel in the world. 2013 estimates are that over 24.9 million vehicles are fueled by propane gas worldwide. Over 25 million tonnes (over 9 billion US gallons) are used annually as a vehicle fuel.

Not all automobile engines are suitable for use with LPG as a fuel. LPG provides less upper cylinder lubrication than petrol or diesel, so LPG-fueled engines are more prone to valve wear if they are not suitably modified. Many modern common rail diesel engines respond well to LPG use as a supplementary fuel. This is where LPG is used as fuel as well as diesel. Systems are now available that integrate with OEM engine management systems.

Conversion kits can switch a vehicle dedicated to gasoline to using a dual system, in which both gasoline and LPG are used in the same vehicle.

In 2020, BW LPG successfully retrofitted a Very Large Gas Carrier (VLGC) with LPG propulsion technology, pioneering LPG's application in large-scale maritime operations.<ref>{{Cite web |date=2020-10-21 |title=World's first VLGC to be retrofitted with pioneering LPG propulsion technology achieves historic milestone; successfully runs on LPG fuel |url=https://bw-group.com/newsroom/articles/2020/10/worlds-first-vlgc-to-be-retrofitted-with-pioneering-lpg-propulsion-technology-achieves-historic-milestone-successfully-runs-on-lpg-fuel/ |access-date=2024-02-21 |website=BW Group |language=en-US}}</ref> LPG's lowers emissions of carbon dioxide, sulfur oxides, nitrogen oxides, and particulate matter<ref>{{Cite web |title=Benefits of LPG Propulsion |url=https://www.bwlpg.com/vlgc_fleet/lpg-propulsion/benefits-lpg-propulsion/ |access-date=2024-02-21 |website=BW LPG |language=en-US}}</ref><ref>{{Cite web |date=2024-05-01 |title=Liquefied Petroleum Gas (LPG) - What is it? |url=https://www.bwlpg.com/media/articles/what-is-liquefied-petroleum-gas-lpg/ |access-date=2024-05-13 |website=BW LPG |language=en-US}}</ref> align with stricter standards set by the International Maritime Organization (IMO), making LPG a viable transition option as the maritime industry transitions towards net zero carbon emissions.<ref>{{Cite web |date=2023-09-22 |title=Net-zero by 2050: Achieving shipping decarbonization through industry momentum and the new ambition at IMO {{!}} UNCTAD |url=https://unctad.org/news/transport-newsletter-article-no-108-net-zero-by-2050 |access-date=2024-02-21 |website=unctad.org |language=en}}</ref>

===Conversion to gasoline=== LPG can be converted into alkylate which is a premium gasoline blending stock because it has exceptional anti-knock properties and gives clean burning.

===Refrigeration=== LPG is instrumental in providing off-the-grid refrigeration, usually by means of a gas absorption refrigerator.

Blended from pure, dry propane (refrigerant designator '''R-290''') and isobutane (R-600a) the blend "R-290a" has negligible ozone depletion potential, very low global warming potential and can serve as a functional replacement for R-12, R-22, R-134a and other chlorofluorocarbon or hydrofluorocarbon refrigerants in conventional stationary refrigeration and air conditioning systems.<ref>{{cite web |url=http://ec.europa.eu/environment/ozone/pdf/hcfc_technical_meeting_summary.pdf |title=*overview of advantages and disadvantages of alternatives* |work=Technical Meeting on HCFC Phase-Out |date=5-6 April 2008 |publisher=European Commission |access-date=30 July 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090805150605/http://ec.europa.eu/environment/ozone/pdf/hcfc_technical_meeting_summary.pdf |archive-date=5 August 2009 }}</ref>

Such substitution is widely prohibited or discouraged in motor vehicle air conditioning systems, on the grounds that using flammable hydrocarbons in systems originally designed to carry non-flammable refrigerant presents a significant risk of fire or explosion.<ref>{{cite web |url=http://www.epa.gov/ozone/snap/refrigerants/hc12alng.html |title=Detailed Questions About HC-12a ®, OZ-12 ®, DURACOOL 12a ®, EC-12a, and other Flammable Hydrocarbon Refrigerants |work=Ozone Layer Depletion - Alternatives / SNAP |publisher=United States Environmental Protection Agency |access-date=30 July 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090807011843/http://www.epa.gov/Ozone/snap/refrigerants/hc12alng.html |archive-date=7 August 2009 }}</ref><ref>{{cite web |url=http://www.sae.org/news/releases/05hydrocarbon_warning.htm |website=Society of Automotive Engineers |title=A Warm Weather Warning: Stay Away from Flammable Hydrocarbon Refrigerants |date=27 April 2005 |access-date=30 July 2009 |url-status=dead |archive-url=https://web.archive.org/web/20050505030057/http://www.sae.org/news/releases/05hydrocarbon_warning.htm |archive-date=5 May 2005 }}</ref>

Vendors and advocates of hydrocarbon refrigerants argue against such bans on the grounds that there have been very few such incidents relative to the number of vehicle air conditioning systems filled with hydrocarbons.<ref>{{cite web|url=http://www.parliament.nsw.gov.au/prod/parlment/HansArt.nsf/V3Key/LA19971016015 |archive-url=https://web.archive.org/web/20090701025536/http://www.parliament.nsw.gov.au/prod/parlment/HansArt.nsf/V3Key/LA19971016015 |url-status=dead |archive-date= 1 July 2009 |title=Motor Vehicle Hydrocarbons |last1=Iemma |first1=Morris |last2=Lo Po' |first2=Faye |publisher=Parliament of New South Wales |date=16 October 1997 |access-date=30 July 2009 }}</ref><ref>{{cite web|url=http://www.parliament.nsw.gov.au/prod/parlment/hansart.nsf/V3Key/LC20000629051 |archive-url=https://web.archive.org/web/20050522080708/http://www.parliament.nsw.gov.au/prod/parlment/hansart.nsf/V3Key/LC20000629051 |url-status=dead |archive-date=22 May 2005 |title=Hydrocarbon Refrigerants |date=29 June 2000 |first1=J. F. |last1=Ryan |publisher=Parliament of New South Wales |access-date=30 July 2009 }}</ref> One particular test, conducted by a professor at the University of New South Wales, unintentionally tested the worst-case scenario of a sudden and complete refrigerant expulsion into the passenger compartment followed by subsequent ignition. He and several others in the car sustained minor burns to their face, ears, and hands, and several observers received lacerations from the burst glass of the front passenger window. No one was seriously injured.<ref>{{Cite web |date=7 April 2005 |title=Car explosion leads to prosecution against leading hydrocarbon promoter |url=http://www.vasa.org.au/pdf/memberlibrary/hydrocarbons/maclaine-cross.pdf |url-status=dead |archive-url=https://web.archive.org/web/20080719142356/http://www.vasa.org.au/pdf/memberlibrary/hydrocarbons/maclaine-cross.pdf |archive-date=Jul 19, 2008 |access-date=24 May 2012 |website=VASA}}</ref>

===Aerosol propellant=== {{Excerpt|Aerosol spray|Aerosol propellants|paragraphs=2}}

==Storage== [[File:Majuro Energy Company bottling LPG.png|thumb|Bottling LPG in Majuro, the Marshall Islands, for storage]] LPG can be stored in a variety of manners. LPG, as with other fossil fuels, can be combined with renewable power sources to provide greater reliability while still achieving some reduction in CO<sub>2</sub> emissions. However, as opposed to wind and solar renewable energy sources, LPG can be used as a standalone energy source without the expense of electrical energy storage.

==Global production== Global LPG production reached over 292 million metric tons per year (Mt/a) in 2015, while global LPG consumption to over 284 Mt/a.<ref>{{cite web | url=https://www.argusmedia.com/~/media/files/pdfs/white-paper/statistical-review-of-global-lpg-2016.pdf?la=en | title=Statistical Review of Global LPG 2016 |website=Argus Media | access-date=13 January 2017 | url-status=dead | archive-url=https://web.archive.org/web/20170410220041/https://www.argusmedia.com/~/media/files/pdfs/white-paper/statistical-review-of-global-lpg-2016.pdf?la=en | archive-date=10 April 2017 | df=dmy-all }}</ref> 62% of LPG is extracted from natural gas while the rest is produced by petroleum refineries from crude oil.<ref>{{cite web | url=http://www.wlpga.org/wp-content/uploads/2015/12/WLPGA-Annual-Report-2015-Light.pdf |website=World LPG Association | title=WLPGA Annual Report 2015 | access-date=13 January 2017 | url-status=live | archive-url=https://web.archive.org/web/20170410214836/http://www.wlpga.org/wp-content/uploads/2015/12/WLPGA-Annual-Report-2015-Light.pdf | archive-date=10 April 2017 | df=dmy-all }}</ref> 44% of global consumption is in the domestic sector. The U.S. is the leading producer and exporter of LPG.<ref>{{cite web | url=https://www.bpnews.com/index.php/publications/magazine/current-issue/830-u-s-is-world-s-largest-lpg-exporter-but-when-will-market-balance | title=U.S. Is World's Largest LPG Exporter, But When Will Market Balance? |first1=John |last1=Needham |website=Butane Propane News | date=7 April 2016 | access-date=10 April 2017 | url-status=live | archive-url=https://web.archive.org/web/20171230230203/https://www.bpnews.com/index.php/publications/magazine/current-issue/830-u-s-is-world-s-largest-lpg-exporter-but-when-will-market-balance | archive-date=30 December 2017 | df=dmy-all }}</ref>

==Security of supply== Because of the natural gas and the oil-refining industry, Europe is almost self-sufficient in LPG. Europe's security of supply is further safeguarded by: * a wide range of sources, both inside and outside Europe; * a flexible supply chain via water, rail and road with numerous routes and entry points into Europe.

According to 2010–12 estimates, proven world reserves of natural gas, from which most LPG is derived, stand at 300 trillion cubic meters (10,600 trillion cubic feet). Production continues to grow at an average annual rate of 2.2%.

==Comparison with natural gas== {{more citations needed section|date=November 2025}} LPG is composed mainly of propane and butane, while natural gas is composed of the lighter methane and ethane. LPG, vaporised and at atmospheric pressure, has a higher calorific value (46&nbsp;MJ/m<sup>3</sup> equivalent to 12.8&nbsp;kWh/m<sup>3</sup>) than natural gas (methane) (38&nbsp;MJ/m<sup>3</sup> equivalent to 10.6&nbsp;kWh/m<sup>3</sup>), which means that LPG cannot simply be substituted for natural gas. In order to allow the use of the same burner controls and to provide for similar combustion characteristics, LPG can be mixed with air to produce a synthetic natural gas (SNG) that can be easily substituted. LPG/air mixing ratios average 60/40, though this is widely variable based on the gases making up the LPG. The method for determining the mixing ratios is by calculating the Wobbe index of the mix. Gases having the same Wobbe index are held to be interchangeable.<ref>{{cite web |title=Difference Between LPG Gas and Natural Gas - What is LPG |url=https://www.elgas.com.au/elgas-knowledge-hub/residential-lpg/lpg-vs-natural-gas/ |access-date=2025-05-13 |website=Elgas}}</ref>

LPG-based SNG is used in emergency backup systems for many public, industrial and military installations, and many utilities use LPG peak shaving plants in times of high demand to make up shortages in natural gas supplied to their distributions systems. LPG-SNG installations are also used during initial gas system introductions when the distribution infrastructure is in place before gas supplies can be connected. Developing markets in India and China (among others) use LPG-SNG systems to build up customer bases prior to expanding existing natural gas systems.

LPG-based SNG or natural gas with localized storage and piping distribution network to the households for catering to each cluster of 5000 domestic consumers can be planned under the initial phase of the city gas network system. This would eliminate the last mile LPG cylinders road transport which is a cause of traffic and safety hurdles in Indian cities. These localized natural gas networks are successfully operating in Japan with feasibility to get connected to wider networks in both villages and cities.

==Environmental effects== Commercially available LPG is currently derived mainly from fossil fuels. Burning LPG releases carbon dioxide, a greenhouse gas. The reaction also produces some carbon monoxide. LPG does, however, release less {{chem|CO|2}} per unit of energy than does coal or oil, but more than natural gas. It emits 81% of the {{chem|CO|2}} per kWh produced by oil, 70% of that of coal, and less than 50% of that emitted by coal-generated electricity distributed via the grid.<ref>{{Cite book|title=Green Finance and Investment Promoting Clean Urban Public Transportation and Green Investment in Kazakhstan |url=https://books.google.com/books?id=pgk7DwAAQBAJ&pg=PA124 |publisher=OECD Publishing|year=2017|isbn=978-9264279643|pages=124}}</ref> Being a mix of propane and butane, LPG emits less carbon per joule than butane but more carbon per joule than propane.

LPG burns more cleanly than higher molecular weight hydrocarbons because it releases less particulate matter.<ref>{{Cite book|url=https://books.google.com/books?id=QxtdDgAAQBAJ&q=LPG+burns+more+cleanly+than+hydrocarbons+because+it+releases+less+particulates.&pg=PA649|title=Chemical Energy from Natural and Synthetic Gas|last=Shah|first=Yatish T.|date=2017-03-16|publisher=CRC Press|isbn=9781315302348|language=en}}</ref>

As it is much less polluting than most traditional solid-fuel stoves, replacing cookstoves used in developing countries with LPG is one of the key strategies adopted to reduce household air pollution in the developing world.<ref name=WHO2016>{{Cite book|last=World Health Organization|url=https://www.who.int/airpollution/publications/burning-opportunities/en/|archive-url=https://web.archive.org/web/20171124101534/http://www.who.int/airpollution/publications/burning-opportunities/en/|url-status=dead|archive-date=November 24, 2017|title=Burning opportunity : clean household energy for health, sustainable development, and wellbeing of women and children|year=2016|location=Geneva, Switzerland |publisher=WHO}}</ref>

==Fire/explosion risk and mitigation== {{More citations needed section|date=September 2009}} [[File:Esferas Horton, factoría Repsol Butano, Gijón.jpg|thumb|LPG Horton sphere tanks at a Repsol Butano facility in Gijón, Spain]] In a refinery or gas plant, LPG must be stored in pressure vessels. These containers are either cylindrical and horizontal (sometimes referred to as bullet tanks) or spherical (of the Horton sphere type). Typically, these vessels are designed and manufactured according to some code. In the United States, this code is governed by the American Society of Mechanical Engineers (ASME).

LPG containers have pressure relief valves, such that when subjected to exterior heating sources, they will vent LPGs to the atmosphere or a flare stack.

If a tank is subjected to a fire of sufficient duration and intensity, it can undergo a boiling liquid expanding vapor explosion (BLEVE). This is typically a concern for large refineries and petrochemical plants that maintain very large containers. In general, tanks are designed so that the product will vent faster than pressure can build to dangerous levels.

One remedy that is utilized in industrial settings is to equip such containers with a measure to provide a fire-resistance rating. Large, spherical LPG containers may have up to a 15&nbsp;cm steel wall thickness. They are equipped with an approved pressure relief valve. A large fire in the vicinity of the vessel will increase its temperature and pressure. The relief valve on the top is designed to vent off excess pressure in order to prevent the rupture of the container itself. Given a fire of sufficient duration and intensity, the pressure being generated by the boiling and expanding gas can exceed the ability of the valve to vent the excess. Alternatively, if, due to continued venting, the liquid level drops below the area being heated, the tank structure can be overheated and subsequently weakened in that area. If either occurs, the container may rupture violently, launching pieces of the vessel at high velocity, while the released products can ignite as well, potentially causing catastrophic damage to anything nearby, including other containers.<ref>{{cite journal |last=Johnson |first=R. |date=2006 |title=The Effect of Pressure Relief Valve Blowdown and Fire Conditions on LPG Pressure Vessels |journal=Journal of Pressure Vessel Technology |volume=128 |issue=3 |pages=467–473 |doi=10.1115/1.2184608}}</ref>

People can be exposed to LPG in the workplace by breathing it in, skin contact, and eye contact. The Occupational Safety and Health Administration (OSHA) has set the legal limit (Permissible exposure limit) for LPG exposure in the workplace as 1000 ppm (1800&nbsp;mg/m<sup>3</sup>) over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 1000 ppm (1800&nbsp;mg/m<sup>3</sup>) over an 8-hour workday. At levels of 2000 ppm, 10% of the lower explosive limit, LPG is considered immediately dangerous to life and health (due solely to safety considerations pertaining to risk of explosion).<ref>{{cite web|title = CDC – NIOSH Pocket Guide to Chemical Hazards – L.P.G.|url = https://www.cdc.gov/niosh/npg/npgd0679.html|website = www.cdc.gov|access-date = 28 November 2015|url-status = live|archive-url = https://web.archive.org/web/20151208124058/http://www.cdc.gov/niosh/npg/npgd0679.html|archive-date = 8 December 2015|df = dmy-all}}</ref>

==See also== {{Portal|Energy}} * Compressed natural gas (CNG) * Filling carousel * Gasoline gallon equivalent * Industrial gas * Intumescent * POL valve

==References== {{Reflist|30em}} {{Cite web |title=Calorific value of Different Fuels |url=http://www.ces.iisc.ernet.in/energy/paper/alternative/calorific.html |url-status=dead |archive-url=https://web.archive.org/web/20200219063035/http://www.ces.iisc.ernet.in/energy/paper/alternative/calorific.html |archive-date=19 February 2020 |website=Centre for Ecological Sciences |publisher=IISc |access-date=21 July 2018 }}

==External links== * [https://www.cdc.gov/niosh/npg/npgd0679.html NIOSH Pocket Guide to Chemical Hazards] – Centers for Disease Control and Prevention

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{{DEFAULTSORT:Liquefied Petroleum Gas}} Category:Liquefied petroleum gas Category:Petroleum production Category:Fossil fuels