Gasoline
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2008-07-16T09:00:15Z
Ian Dunster
220513
/* Dye */ Added derivation of DERV
{{Redirect|Petrol}}
[[Image:GasolineContainer.JPG|thumb|A container for storing gasoline used in the [[United States]]; red containers are typically used.]]
'''Gasoline (gas)''' or '''petroleum spirit (petrol)''' is a [[petroleum]]-derived [[liquid]] mixture consisting mostly of [[aliphatic]] [[hydrocarbon]]s, enhanced with [[iso-octane]] or the [[aromatic]] hydrocarbons [[toluene]] and [[benzene]] to increase its [[octane rating]], and is primarily used as [[fuel]] in [[internal combustion engine]]s.
Most [[Commonwealth of Nations|Commonwealth countries]] or former Commonwealth countries (with the exception of [[Canada]]) use the word "petrol", abbreviated from ''petroleum spirit''. "Gasoline" is commonly used in [[North America]], where it is often shortened in [[colloquial]] usage to "[[gas (disambiguation)|gas]]." It is not a genuinely [[gaseous]] fuel used in internal combustion engines such as [[liquefied petroleum gas]], stored pressurised as a liquid but allowed to return to a gaseous state before combustion.
''Mogas'', short for ''motor gasoline'', distinguishes [[automobile]] fuel from ''aviation gasoline'', or [[avgas]]. "Gasoline" in [[British English]] can refer to a different petroleum derivative historically used in lamps, but this is now uncommon.
==History==
Gasoline is a mixture of hydrocarbons, although some may contain significant quantities of ethanol and some may contain small quantities of additives such as [[methyl tert-butyl ether]] as anti-knock agents to increase the octane rating. The hydrocarbons consist of a mixture of n-paraffins, naphthenes, olefins and aromatics. Naphthenes, olefins and aromatics increase the octane rating of the gasoline whereas the n-paraffins have the opposite effect.<ref>[http://www.chromatography-online.org/topics/gasoline/components.html gasoline components<!-- Bot generated title -->]</ref>
===Early uses===
Before gasoline was used as fuel for engines, it was sold in small bottles as a treatment against [[louse|lice]] and their eggs. At that time, the word ''Petrol'' was a [[trade name]]. This treatment method is no longer common because of the inherent fire hazard and the risk of [[dermatitis]].
In the US gasoline was also sold as a cleaning fluid to remove grease stains from clothing. Before dedicated [[filling stations]] were established, early motorists bought gasoline in cans to fill their tanks.
The name ''gasoline'' is similar to that of other petroleum products of the day, most notably [[petroleum jelly]], a highly purified heavy distillate, which was branded ''[[Vaseline]]''. The trademark ''Gasoline'' was never registered, and thus became generic.
Gasoline was also used in kitchen ranges and for lighting, and is still available in a highly purified form, known as ''camping fuel'' or ''[[white gas]]'', for use in lanterns and portable stoves.
During the [[Franco-Prussian War]] (1870–1871), ''pétrole'' was stockpiled in [[Paris]] for use against a possible [[Kingdom of Prussia|German-Prussian]] attack on the city. Later in 1871, during the revolutionary [[Paris Commune]], rumours spread around the city of ''[[pétroleuses]]'', women using bottles of petrol to commit [[arson]] against city buildings.
===Etymology===
The word "gasolene" was coined in 1865 from the word [[gas]] and the chemical suffix [[-ine]]/-ene. The modern spelling was first used in 1871. The shortened form "gas" was first recorded in American English in 1905.<ref name = etymonline>[http://www.etymonline.com/index.php?search=gasoline Online Etymology Dictionary<!-- Bot generated title -->]</ref>
Gasoline originally referred to any liquid used as the fuel for a gasoline-powered engine, other than diesel fuel or liquefied gas; [[methanol]] racing fuel would have been classed as a type of gasoline.<ref>[http://www.window.state.tx.us/taxinfo/audit/motorfue/glossary.htm Motor Fuels Tax Audit Procedures Manual - Ch 153 - Glossary<!-- Bot generated title -->]</ref>
The word "petrol" was first used in reference to the refined substance in 1892 (it was previously used to refer to unrefined petroleum), and was registered as a trade name by British wholesaler Carless, Capel & Leonard at the suggestion of [[Frederick Richard Simms]].<ref>[http://www.petrochemcarless.com/docs/about_us_history.htm Petrochem Carless :: History<!-- Bot generated title -->]</ref> Although it was never officially registered as a trademark, Carless's competitors used the term "motor spirit" until the 1930s.<ref name = etymonline/><ref>{{cite journal | journal = Chrysler Collector | issue = 154 | year = 2004 | pages = 16–20 | author = Ron Hincks | title = Our Motoring Heritage: Petrol & Oil}}</ref> It has also been suggested that the word was coined by [[Edward Butler (inventor)|Edward Butler]] in 1887.<ref>{{cite news | title=Keeping track: All fired up about `petrol' | publisher =[[Daily Telegraph]] | year=2002 | date=2002-02-01 | url=http://www.telegraph.co.uk/motoring/main.jhtml?xml=/motoring/2002/02/01/emrdron02.xml }}</ref>
In [[Germany]] and some other European countries and in [[New Guinea Pidgin]] gasoline is called ''Benzin'' ([[German language|German]] and [[Danish language|Danish]]), ''Bensin'' ([[Swedish language|Swedish]] and [[Norwegian language|Norwegian]]), ''Benzyna'' ([[Polish language|Polish]]), ''Benzina'' ([[Catalan language|Catalan]]), ''Benzină'' ([[Romanian language|Romanian]]), ''Бензин'' ([[Russian language|Russian]]), and other variants of this word. The usage derives from the chemical [[benzene]], not from [[Bertha Benz]], who used chemists' shops to purchase the gasoline for her famous drive from [[Mannheim]] to [[Pforzheim]] in 1888.
==Chemical analysis and production==
[[Image:BP bensinstasjon, Nøtterøy.JPG|thumb|right|Petrol pumps]]
Gasoline is produced in [[oil refineries]]. Material that is separated from [[crude oil]] via [[distillation]], called virgin or straight-run gasoline, does not meet the required specifications for modern engines (in particular octane rating; see below), but will form part of the blend.
The bulk of a typical gasoline consists of [[hydrocarbon]]s with between 5 and 12 [[carbon]] [[atom]]s per [[molecule]].
Many of these hydrocarbons are considered hazardous substances and are regulated in the United States by [[Occupational Safety and Health Administration]]. The [[Material Safety Data Sheet]] for unleaded gasoline shows at least fifteen hazardous chemicals occurring in various amounts. These include [[benzene]] (up to 5% by volume), [[toluene]] (up to 35% by volume), [[naphthalene]] (up to 1% by volume), [[1,2,4-Trimethylbenzene|trimethylbenzene]] (up to 7% by volume), [[MTBE]] (up to 18% by volume) and about ten others.<ref>[http://firstfuelbank.com/msds/Tesoro.pdf MATERIAL SAFETY DATA SHEET] Tesoro Petroleum Companies, Inc., USA, 2003-02-08</ref>
The various [[Oil refinery|refinery]] streams blended together to make gasoline all have different characteristics. Some important streams are:
*''Reformate'', produced in a [[catalytic reformer]] with a high octane rating and high [[aromatic]] content, and very low olefins ([[alkene]]s).
*''Cat Cracked Gasoline'' or ''Cat Cracked [[Naphtha]]'', produced from a [[Fluid catalytic cracking|catalytic cracker]], with a moderate octane rating, high [[olefin]]s (alkene) content, and moderate aromatics level. ''Here, "cat" is short for "[[catalyst|catalytic]]".''
*''Hydrocrackate'' (Heavy, Mid, and Light), produced from a hydrocracker, with medium to low octane rating and moderate aromatic levels.
*''Virgin or Straight-run Naphtha'' (has many names), directly from [[crude oil]] with low octane rating, low aromatics (depending on the [[crude oil]]), some [[naphthene]]s ([[cycloalkane]]s) and no olefins (alkenes).
*''Alkylate'', produced in an [[alkylation]] unit, with a high octane rating and which is pure [[paraffin]] (alkane), mainly branched chains.
*''Isomerate'' (various names) which is obtained by isomerising the pentane and hexane in light virgin naphthas to yield their higher octane isomers.
(The terms used here are not always the correct chemical terms. They are the [[jargon]] normally used in the oil industry. The exact terminology for these streams varies by refinery and by country.)
Overall a typical gasoline is predominantly a mixture of paraffins ([[alkane]]s), naphthenes (cycloalkanes), and olefins (alkenes). The exact ratios can depend on
* the oil refinery that makes the gasoline, as not all refineries have the same set of processing units.
* the [[crude oil]] feed used by the refinery.
* the grade of gasoline, in particular the octane rating.
Currently many countries set tight limits on gasoline [[aromatic]]s in general, [[benzene]] in particular, and olefin (alkene) content. This is increasing the demand for high octane pure paraffin (alkane) components, such as alkylate, and is forcing refineries to add processing units to reduce the benzene content.
Gasoline can also contain some other [[organic compound]]s: such as [[organic ether]]s (deliberately added), plus small levels of contaminants, in particular [[sulfur]] compounds such as [[disulfides]] and [[thiophene]]s. Some contaminants, in particular [[thiol]]s and [[hydrogen sulfide]], must be removed because they cause corrosion in engines. Sulfur compounds are usually removed by hydrotreating, yielding [[hydrogen sulfide]] which can then be transformed into elemental sulfur via the [[Claus process]].
The density of gasoline is 0.71–0.77 g/cm<sup>3</sup>,<ref>{{cite web | title = Lead-Free Gasoline Material Safety Data Sheet | author = Bell Fuels | publisher = [[NOAA]] | url = http://www.sefsc.noaa.gov/HTMLdocs/Gasoline.htm | accessdate = 2008-07-06}}</ref> (in English units, approx. .026 lb/in<sup>3</sup> or 6.073 lb/gal) which means it floats on water. This may be advantageous in the event of a spill. It is flammable and can burn while floating over water.
===Volatility===
[[Image:Reservekanister.JPG|thumb|A container for storing gasoline used in [[Germany]]]]
Gasoline is more [[volatility (chemistry)|volatile]] than [[diesel]] oil, [[Jet-A]] or [[kerosene]], not only because of the base constituents, but because of the [[Gasoline additive|additives]] that are put into it. The final control of [[volatility (chemistry)|volatility]] is often achieved by blending with [[butane]]. The Reid Vapor Pressure test is used to measure the volatility of gasoline. The desired volatility depends on the ambient temperature: in hotter climates, gasoline components of higher [[molecular weight]] and thus lower volatility are used. In cold climates, too little volatility results in cars failing to start. In hot climates, excessive volatility results in what is known as "[[vapour lock]]" where combustion fails to occur, because the liquid fuel has changed to a gaseous fuel in the fuel lines.
In the United States, volatility is regulated in large urban centers to reduce the emission of unburned hydrocarbons. In large cities, so-called reformulated gasoline that is less prone to evaporation, among other properties, is required. In Australia summer petrol volatility limits are set by State Governments and vary between capital cities. Most countries simply have a summer, winter and perhaps intermediate limit.
Volatility standards may be relaxed (allowing more gasoline components into the atmosphere) during emergency anticipated gasoline shortages. For example, on [[31 August]] [[2005]] in response to [[Hurricane Katrina]], the United States permitted the sale of non-reformulated gasoline in some urban areas, which effectively permitted an early switch from summer to winter-grade gasoline. As mandated by [[United States Environmental Protection Agency|EPA]] administrator [[Stephen L. Johnson]], this "fuel waiver" was made effective through [[15 September]] [[2005]].<ref>{{cite web | title = Week 1: Nationwide fuel waiver issued to bolster fuel supplies | work = Response to 2005 Hurricanes | date = 2005-08-31 | url = http://www.epa.gov/katrina/activities/week1.html#aug31johnson | publisher = [[U.S. Environmental Protection Agency]]}}</ref> Though relaxed volatility standards may increase the atmospheric concentration of volatile organic compounds in warm weather, higher volatility gasoline effectively increases a nation's gasoline supply because the amount of butane in the gasoline pool is allowed to increase.{{Fact|date=February 2008}}
===Octane rating===
{{see details|octane rating}}
An important characteristic of gasoline is its octane rating, which is a measure of how resistant gasoline is to the abnormal combustion phenomenon known as [[detonation]] (also known as knocking, pinging, spark knock, and other names). [[Deflagration]] is the normal type of combustion. Octane rating is measured relative to a mixture of [[2,2,4-Trimethylpentane|2,2,4-trimethylpentane]] (an [[isomer]] of [[octane]]) and n-[[heptane]]. There are a number of different conventions for expressing the octane rating; therefore, the same fuel may be labeled with a different number, depending upon the system used.
The octane rating became important in the search for higher output powers from [[aero engine]]s in the late 1930's and the 1940's as it allowed higher [[compression ratio]]s to be used.
===World War II and octane ratings===
{{Refimprove|date=May 2007}}
During [[World War II]], [[Germany]] received much of its oil from [[Romania]]. From {{convert|2.8|Moilbbl|m3}} in 1938, Romania’s exports to Germany increased to {{convert|13|Moilbbl|m3}} by 1941, a level that was essentially maintained through 1942 and 1943, before dropping by half, due to Allied bombing and [[Naval mine|mining]] of the Danube. Although these exports were almost half of Romania’s total production, they were considerably less than what the Germans expected. Even with the addition of the Romanian deliveries, overland oil imports after 1939 could not make up for the loss of overseas shipments. In order to become less dependent on outside sources, the Germans undertook a sizable expansion program of their own meager domestic oil pumping. After 1938, the Austrian oil fields were made available, and the expansion of Nazi crude oil output was chiefly concentrated there. Primarily as a result of this expansion, the Reich's domestic output of crude oil increased from approximately {{convert|3.8|Moilbbl|m3}} in 1938 to almost {{convert|12|Moilbbl|m3}} in 1944. Even this was not enough.
Instead, Germany had developed a synthetic fuel capacity that was intended to replace imported or captured oil. Fuels were generated from [[coal]], using either the [[Bergius process]] or the [[Fischer-Tropsch process]]. Between 1938 and 1943, synthetic fuel output underwent a respectable growth from {{convert|10|Moilbbl|m3}} to 36 million. The percentage of synthetic fuels compared with the yield from all sources grew from 22% to more than 50% by 1943. The total oil supplies available from all sources for the same period rose from {{convert|45|Moilbbl|m3}} in 1938 to {{convert|71|Moilbbl|m3}} in 1943.
By the early 1930s, automobile gasoline had an octane reading of 40 and aviation gasoline of 75-80. Aviation gasoline with such high octane numbers could only be refined through a process of distillation of high-grade petroleum. Germany’s domestic oil was not of this quality. Only the additive [[tetra-ethyl lead]] could raise the octane to a maximum of 87. The license for the production of this additive was acquired in 1935 from the American holder of the patents, but without high-grade Romanian oil even this additive was not very effective. 100 octane fuel, designated either 'C-2' (natural) or 'C-3' (synthethic) was introduced in late 1939 with the [[Daimler-Benz DB 601|Daimler-Benz DB 601N]] engine, used in certain of the Luftwaffe`s [[Messerschmitt Bf 109#Bf 109E "Emil"|Bf 109E]] and [[Messerschmitt Bf 109#Bf 109F "Friedrich"|Bf 109F]] single-engined fighters, [[Messerschmitt Bf 110#Bf 110 C|Bf 110C]] twin-engined fighters, and several bomber types. Some later combat types, most notably the [[BMW 801|BMW 801D]]-powered [[Focke-Wulf Fw 190|Fw 190A, F and G series]], and later war Bf 109G and K models, used C-3 as well. The nominally 87 octane aviation fuel designated 'B-4' was produced in parallel during the war.
In the [[United States|US]] the oil was not "as good," and the oil industry had to invest heavily in various expensive boosting systems. This turned out to have benefits: the US industry started delivering fuels of increasing octane ratings by adding more of the boosting agents, and the infrastructure was in place for a post-war octane-agents additive industry. Good crude oil was no longer a factor during wartime, and by war's end American aviation fuel was commonly 130 octane, and 150 octane was available in limited quantities for fighters from the summer of 1944. This high octane could easily be used in existing engines to deliver much more power by increasing the pressure delivered by the [[supercharger]]s.
In late 1942, the Germans increased to octane rating of their high-grade 'C-3' aviation fuel to 150 octane. The relative volumes of production of the two grades B-4 and C-3 cannot be accurately given, but in the last war years perhaps two-thirds of the total was C-3. Every effort was being made toward the end of the war to increase [[isoparaffin]] production; more isoparaffin meant more C-3 available for fighter plane use.
A common misapprehension exists concerning wartime fuel octane numbers. There are two octane numbers for each fuel, one for lean mix and one for rich mix, rich being greater. The misunderstanding that German fuels had a lower octane number (and thus a poorer quality) arose because the Germans quoted the lean mix octane number for their fuels while the Allies quoted the rich mix number. Standard German high-grade 'C-3' aviation fuel used in the later part of the war had lean/rich octane numbers of 100/130. The Germans listed this as a 100 octane fuel, the Allies as 130 octane.
After the war the US Navy sent a Technical Mission to Germany to interview German petrochemists and examine German fuel quality. Their report entitled “Technical Report 145-45 Manufacture of Aviation Gasoline in Germany” chemically analyzed the different fuels, and concluded that “Toward the end of the war the quality of fuel being used by the German fighter planes was quite similar to that being used by the Allies.”
==Energy content==
Gasoline contains about 34.8 [[megajoule|MJ]]/[[Liter|l]] or 132 MJ/[[US gallon]]. This is about 9.67 kWh/l or 36.6 kWh/US gallon. This is an average; gasoline blends differ, therefore actual energy content varies from season to season and from batch to batch, by up to 4% more or less than the average, according to the US EPA. On average, about 19.5 gallons of gasoline are available from a 42 gallon barrel of crude oil (about 46% by volume), varying due to quality of crude and grade of gasoline. The remaining residue comes off as products ranging from tar to naptha [http://www.gravmag.com/oil.html].
<!--Note: I modified this table because the values in SI units didn't agree with the values in British or US units. So I used another source, but it did not have MJ/kg, and I did not have the time to try to find accurate densities in order to convert to MJ/kg. If someone can fill in the blanks using good data, it would be useful.-->
Volumetric [[energy density]] of some fuels compared with gasoline:<ref name=TEDB>[http://www-cta.ornl.gov/data/Appendix_B.html Appendix B, Transportation Energy Data Book] from the [[Center for Transportation Analysis]] of the [[Oak Ridge National Laboratory]]</ref>
{| class="wikitable sortable"
! align = "left"|Fuel type
! align ="right"| MJ/[[litre]]
! align ="right"| MJ/kg
! align ="right"| [[British thermal unit|BTU]]/[[gallon|Imp gal]]
! align ="right"| BTU/[[US gallon|US gal]]
! align ="right"| [[octane rating|Research octane<br> number (RON)]]
|-
| Regular Gasoline
| align ="right"|34.8
| align ="right"|44.4<ref>[http://www.eere.energy.gov/hydrogenandfuelcells/pdfs/storage.pdf Thomas, George. Overview of Storage Development DOE Hydrogen Program [pdf]. Livermore, CA. Sandia National Laboratories. 2000.]</ref>
| align ="right"|150,100
| align ="right"|125,000
| align ="right"|Min 91
|-
| Premium Gasoline
| align ="right"|39.5
| align ="right"|
| align ="right"|
| align ="right"|
| align ="right"|Min 95
|-
| [[Autogas]] ([[Liquified petroleum gas|LPG]]) (60% [[Propane]] + 40% [[Butane]])
| align ="right"|26.8
| align ="right"|46
| align ="right"|
| align ="right"|
| align ="right"|108
|-
|[[ethanol fuel|Ethanol]]
| align ="right"|23.5
| align ="right"|31.1<ref>Calculated from heats of formation. Does not correspond exactly to the figure for MJ/l divided by density.</ref>
| align ="right"|101,600
| align ="right"|84,600
| align ="right"|129
|-
| [[Methanol]]
| align ="right"|17.9
| align ="right"|19.9
| align ="right"|77,600
| align ="right"|64,600
| align ="right"|123
|-
| [[Butanol fuel|Butanol]]
| align ="right"|29.2
| align ="right"|
| align ="right"|
| align ="right"|
| align ="right"|91-99
|-
| [[Alcohol fuel|Gasohol]] (10% ethanol + 90% gasoline)
| align ="right"|33.7
| align ="right"|
| align ="right"|145,200
| align ="right"|120,900
| align ="right"|93/94
|-
| [[Diesel]]
| align ="right"|38.6
| align ="right"|45.4
| align ="right"|166,600
| align ="right"|138,700
| align ="right"|25(*)
|-
| [[Aviation gasoline]] (high octane gasoline, not jet fuel)
| align ="right"|33.5
| align ="right"|46.8
| align ="right"|144,400
| align ="right"|120,200
| align ="right"|
|-
| [[Aviation fuel#Energy content|Jet fuel (kerosene based)]]
| align ="right"|35.1
| align ="right"|43.8
| align ="right"|151,242
| align ="right"|125,935
| align ="right"|
|-
| [[Liquefied natural gas]]
| align ="right"|25.3
| align ="right"|~55
| align ="right"|109,000
| align ="right"|90,800
| align ="right"|
|-
| [[Hydrogen]]
| align ="right"|
| align ="right"|121
| align ="right"|
| align ="right"|
| align ="right"|130<ref>[http://www.hydrogenassociation.org/general/faqs.asp#octane|The National Hydrogen Association FAQs]</ref>
|}
<small>(*) Diesel is not used in a gasoline engine, so its low octane rating is not an issue; the relevant metric for diesel engines is the [[cetane number]]</small>
A high octane fuel such as [[Liquefied petroleum gas]] (LPG) has a lower energy content than lower octane gasoline, resulting in an overall lower power output at the regular compression ratio an engine ran at on gasoline. However, with an engine [[engine tuning|tuned]] to the [[Autogas|use of LPG]] (i.e. via higher compression ratios such as 12:1 instead of 8:1), this lower power output can be overcome. This is because higher-octane fuels allow for a higher [[compression ratio]] - this means less space in a cylinder on its combustion stroke, hence a higher cylinder temperature which improves efficiency according to [[Carnot efficiency|Carnot's theorem]], along with fewer wasted hydrocarbons (therefore less pollution and wasted energy), bringing higher power levels coupled with less pollution overall because of the greater efficiency.
The main reason for the lower energy content (per litre) of LPG in comparison to gasoline is that it has a lower [[density]]. Energy content per kilogram is higher than for gasoline (higher [[hydrogen]] to [[carbon]] ratio). The weight-density of gasoline is about 740 kg/m³.
Different countries have some variation in what RON (Research Octane Number) is standard for gasoline, or petrol. In the UK, ordinary regular unleaded petrol is 91 RON (not commonly available), premium unleaded petrol is always 95 RON, and super unleaded is usually 97-98 RON. However both Shell and BP produce fuel at 102 RON for cars with hi-performance engines, and the supermarket chain [[Tesco]] began in 2006 to sell super unleaded petrol rated at 99 RON. In the US, octane ratings in fuels can vary between 86-87 AKI (91-92 RON) for regular, through 89-90 (94-95) for mid-grade (European Premium), up to 90-94 (RON 95-99) for premium unleaded or E10 (Super in Europe)
==Additives==
{{main|Gasoline additive}}
===Lead===<!-- This section is linked from [[Lead]] -->
The mixture known as gasoline, when used in high [[Physical compression|compression]] internal combustion engines, has a tendency to autoignite(''detonation'') causing a damaging "[[engine knocking]]" (also called "pinging") noise. Early research into this effect was led by A.H. Gibson and [[Harry Ricardo]] in England and [[Thomas Midgley]] and Thomas Boyd in the United States. The discovery that [[lead]] additives modified this behavior led to the widespread adoption of the practice in the 1920s and therefore more powerful higher compression engines. The most popular additive was [[tetra-ethyl lead]]. However, with the discovery of the environmental and health damage caused by the lead, and the incompatibility of lead with [[catalytic converter]]s found on virtually all newly sold US automobiles since 1975, this practice began to wane (encouraged by many governments introducing differential tax rates) in the 1980s. Most countries are phasing out leaded fuel; different additives have replaced the lead compounds. The most popular additives include [[aromatic hydrocarbon]]s, [[ether]]s and [[alcohol as a fuel|alcohol]] (usually [[ethanol]] or [[methanol]]).
In the US, where lead had been blended with gasoline (primarily to boost octane levels) since the early 1920s, standards to phase out leaded gasoline were first implemented in 1973. In 1995, leaded fuel accounted for only 0.6% of total gasoline sales and less than 2,000 [[short ton]]s of lead per year. From [[January 1]], [[1996]], the [[Clean Air Act]] banned the sale of leaded fuel for use in on-road vehicles. Possession and use of leaded gasoline in a regular on-road vehicle now carries a maximum $10,000 fine in the US. However, fuel containing lead may continue to be sold for off-road uses, including aircraft, racing cars, farm equipment, and marine engines.<ref>{{cite press release | title = EPA Takes Final Step in Phaseout of Leaded Gasoline | date = 1996-01-29 | url = http://www.epa.gov/history/topics/lead/02.htm | publisher = [[U.S. Environmental Protection Agency]]}}</ref> The ban on leaded gasoline led to thousands of tons of lead not being released in the air by automobiles. Similar bans in other countries have resulted in lowering levels of lead in people's [[blood]]streams.<ref>{{cite journal | title = Blood Lead Secular Trend in a Cohort of Children in Mexico City (1987–2002) | author = Lourdes Schnaas, Stephen J. Rothenberg, María-Fernanda Flores, Sandra Martínez, Carmen Hernández, Erica Osorio,1 and Estela Perroni | journal = [[Environ. Health. Perspect.]] | year = 2004 | volume = 112 | issue = 10 | pages = 1110–1115 | doi = 10.1289/ehp.6636 | url = http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1247386 | format = [[Open-access]] full-text reprint | pmid = 15238286}}</ref><ref>{{cite journal | journal = [[Archives of Environmental Health: An International Journal]] | volume = 59 | issue = 4 | year = 2004 | pages = 182–187 | doi = 10.3200/AEOH.59.4.182-187 | title = Rapid Drop in Infant Blood Lead Levels during the Transition to Unleaded Gasoline Use in Santiago, Chile | author = Paulina Pino, Tomás Walter; Manuel J. Oyarzún A3, Matthew J. Burden; Betsy Lozoff}}</ref>
A side effect of the lead additives was protection of the [[poppet valve|valve]] seats from erosion. Many [[classic car]]s' engines have needed modification to use lead-free fuels since leaded fuels became unavailable. However, "Lead substitute" products are also produced and can sometimes be found at auto parts stores. These were scientifically tested and some were approved by the Federation of British Historic Vehicle Clubs at the UK's Motor Industry Research Association (MIRA) in 1999. [http://www.fbhvc.co.uk/fuel/index.htm http://www.fbhvc.co.uk/fuel/index.htm]
Gasoline, as delivered at the pump, also contains additives to reduce internal engine carbon buildups, improve [[combustion]], and to allow easier starting in cold climates.
In some parts of [[South America]], [[Asia]], Eastern [[Europe]] and the [[Middle East]], leaded gasoline is still in use. Leaded gasoline was phased out in [[sub-Saharan Africa]] effective [[1 January]], [[2006]]. A growing number of countries have drawn up plans to ban leaded gasoline in the near future.
===MMT===
[[Methylcyclopentadienyl manganese tricarbonyl]] (MMT) has been used for many years in [[Canada]] and recently in [[Australia]] to boost octane. It also helps old cars designed for leaded fuel run on unleaded fuel without need for additives to prevent valve problems.
US Federal sources state that MMT is suspected to be a powerful neurotoxin and respiratory toxin,{{Fact|date=February 2008}} and a large Canadian study concluded that MMT impairs the effectiveness of automobile emission controls and increases pollution from motor vehicles.<ref>{{cite web | title = Final Report: Effects of MMT in Gasoline on Emissions from On-Road Motor Vehicles in Canada | date = 2002-11-11 | publisher = Canadian Vehicle Manufacturers’ Association, and Association of International Automobile Manufacturers of Canada | url = http://cvma.ca/eng/publications/FinalMMTReport.pdf}}</ref>
In 1977 use of MMT was banned in the US by the Clean Air Act until the Ethyl Corporation could prove that the additive would not lead to failure of new car emissions-control systems. As a result of this ruling, the Ethyl Corporation began a legal battle with the EPA, presenting evidence that MMT was harmless to automobile emissions-control systems. In 1995 the US Court of Appeals ruled that the EPA had exceeded its authority, and MMT became a legal fuel additive in the US. MMT is nowadays manufactured by the Afton Chemical Corporation division of Newmarket Corporation.<ref>{{cite web | publisher = Afton Chemical | title = History of mmt® | url = http://www.aftonchemical.com/Products/MMT/History+of+MMT%AE.htm | accessdate = 2008-02-22}}</ref>
===Ethanol===
In the United States, [[ethanol]] is sometimes added to gasoline but sold without an indication that it is a component. Chevron, 76, Shell, and several other brands market ethanol-gasoline blends.{{Fact|date=May 2007}}
In several states, ethanol is added by law to a minimum level which is currently 5.9%. Most fuel pumps display a sticker stating that the fuel may contain up to 10% ethanol, an intentional disparity which allows the minimum level to be raised over time without requiring modification of the literature/labeling. The bill which was being debated at the time the disclosure of the presence of ethanol in the fuel was mandated has recently passed. This law ([[Energy Policy Act of 2005]]) will require all auto fuel to contain at least 10% ethanol. Many call this fuel mix [[gasohol]].
In the EU, 5% ethanol can be added within the common gasoline spec (EN 228). Discussions are ongoing to allow 10% blending of ethanol. Most countries (fuel distributors) today do not add so much ethanol.{{Fact|date=April 2008}} Most gasoline (petrol) sold in Sweden has 5% ethanol added.
In Brazil, the [[Brazilian National Agency of Petroleum, Natural Gas and Biofuels]] (ANP) requires that gasoline for automobile use has 23% of ethanol added to its composition.
===Dye===
{{main|Fuel dyes}}
In the [[United States]] the most commonly used aircraft gasoline, [[avgas]], or aviation gas, is known as 100LL (100 octane, low lead) and is dyed blue. Red dye has been used for identifying untaxed (non-highway use) agricultural diesel.
The UK uses red dye to differentiate between regular diesel fuel, (often referred to as DERV from ''Diesel-Engined Road Vehicle''), which is undyed, and diesel intended for agricultural and construction vehicles like excavators and bulldozers. [[Red diesel]] is still occasionally used on [[Heavy Goods Vehicle|HGV]]s which use a separate engine to power a [[loader crane]]. This is a declining practice however, as many loader cranes are powered directly by the [[tractor unit]].
===Oxygenate blending===
[[Oxygenate]] blending adds oxygen to the fuel in [[oxygen]]-bearing compounds such as [[MTBE]], [[ETBE]] and [[ethanol]], and so reduces the amount of [[carbon monoxide]] and unburned fuel in the exhaust gas, thus reducing smog. In many areas throughout the US oxygenate blending is mandated by EPA regulations to reduce smog and other airborne polutants. For example, in Southern California, fuel must contain 2% oxygen by weight, resulting in a mixture of 5.6% ethanol in gasoline. The resulting fuel is often known as ''reformulated gasoline'' (RFG) or ''oxygenated gasoline''. The federal requirement that RFG contain oxygen was dropped [[May 6]], [[2006]] because the industry had developed VOC-controlled RFG that did not need additional oxygen.<ref>{{cite web | url = http://www.epa.gov/otaq/rfg_regs.htm#usage | title = Removal of Reformulated Gasoline Oxygen Content Requirement (national) and Revision of Commingling Prohibition to Address Non-0xygenated Reformulated Gasoline (national) | date = 2006-02-22 | publisher = [[U.S. Environmental Protection Agency]]}}</ref>
MTBE use is being phased out in some states due to issues with contamination of ground water. In some places it is already banned. Ethanol and to a lesser extent the ethanol derived ETBE are a common replacements. Especially since ethanol derived from biomatter such as corn, sugar cane or grain is frequent, this will often be referred to as ''bio''-ethanol. A common ethanol-gasoline mix of 10% ethanol mixed with gasoline is called [[Ethanol fuel|gasohol]] or E10, and an ethanol-gasoline mix of 85% ethanol mixed with gasoline is called [[E85]]. The most extensive use of ethanol takes place in [[Brazil]], where the ethanol is derived from [[sugarcane]]. In 2004, over 3,400 million US gallons (13 million m³) of ethanol was produced in the United States for fuel use, mostly from [[maize|corn]], and E85 is slowly becoming available in much of the United States. Unfortunately many of the relatively few stations vending E85 are not open to the general public.<ref>{{cite web | url = http://www.eere.energy.gov/afdc/fuels/stations_locator.html | title = Alternative Fueling Station Locator | publisher = [[U.S. Department of Energy]]}}</ref> The use of [[bioethanol]], either directly or indirectly by conversion of such ethanol to ''bio''-ETBE, is encouraged by the European Union [[Directive on the Promotion of the use of biofuels and other renewable fuels for transport]]. However since producing bio-ethanol from fermented sugars and starches involves [[distillation]], ordinary people in much of Europe cannot ferment and distill their own bio-ethanol at present (unlike in the US where getting a [[BATF]] distillation permit has been easy since the 1973 oil crisis.)
==Health concerns==
[[Image:Gasoline-fire.png|thumb|right|250px|Uncontrolled burning of gasoline produces large quantities of [[soot]]. ]]
Many of the non-aliphatic hydrocarbons naturally present in gasoline (especially aromatic ones like [[benzene]]), as well as many anti-knocking additives, are [[carcinogenic]]. Because of this, any large-scale or ongoing leaks of gasoline pose a threat to the [[public health|public's health]] and the environment, should the gasoline reach a public supply of [[drinking water]]. The chief risks of such leaks come not from vehicles, but from gasoline delivery truck accidents and leaks from storage tanks. Because of this risk, most (underground) storage tanks now have extensive measures in place to detect and prevent any such leaks, such as [[sacrificial anode]]s. Gasoline is rather [[Volatility (chemistry)|volatile]] (meaning it readily [[evaporation|evaporates]]), requiring that storage tanks on land and in vehicles be properly sealed. The high volatility also means that it will easily ignite in cold weather conditions, unlike diesel for example. Appropriate venting is needed to ensure the level of pressure is similar on the inside and outside. Gasoline also reacts dangerously with certain common chemicals.
Gasoline is also one of the sources of pollutant gases. Even gasoline which does not contain [[lead]] or [[sulfur]] [[Chemical compound|compounds]] produces [[carbon dioxide]], [[nitrogen oxide]]s, and [[carbon monoxide]] in the [[exhaust]] of the [[engine]] which is running on it. Furthermore, unburnt gasoline and [[Automobile emissions control#Evaporative emissions control|evaporation from the tank]], when in the atmosphere, react in sunlight to produce [[photochemical smog]]. Addition of ethanol increases the volatility of gasoline.
Through misuse as an [[inhalant]], gasoline also contributes to damage to health. [[Petrol sniffing]] is a common way of obtaining a high for many people and has become epidemic in some poorer communities and indigenous groups in America, Australia, Canada, New Zealand and some Pacific Islands.<ref>[http://www.abc.net.au/health/library/stories/2005/11/24/1831506.htm Petrol Sniffing Fact File] Sheree Cairney, www.abc.net.au, Published 24/11/2005. Retrieved [[2007-10-13]], a modified version of [http://www.abc.net.au/health/library/petrol_ff.htm the original article], now archived [http://web.archive.org/web/20070615215918/http://www.abc.net.au/health/library/petrol_ff.htm here]</ref> In response, [[Opal (fuel)|Opal]] fuel has been developed by the [[BP]] [[Town of Kwinana|Kwinana]] Refinery in Australia, and contains only 5% [[aromatics]] (unlike the usual 25%) which inhibits the effects of inhalation.<ref>[http://www.bp.com/genericarticle.do?categoryId=9012769&contentId=7024904 Fuel technology] www.bp.com. Retrieved [[2007-06-08]].</ref>
Like other alkanes, gasoline burns in the vapor phase and, coupled with its volatility, this makes leaks highly dangerous when sources of ignition are present. Many accidents involve gasoline being used in an attempt to light bonfires; rather than helping the material on the bonfire to burn, some of the gasoline vaporises quickly after being poured and mixes with the surrounding air, so when the fire is lit a moment later the vapor surrounding the bonfire instantly ignites in a large fireball, engulfing the unwary user. The vapor is also heavier than air and tends to collect in garage inspection pits.
==Usage and pricing==
{{main|Gasoline usage and pricing|Global warming|Peak oil}}
[[Image:Petrol.png|thumb|UK gasoline prices]]
The US accounts for about 44% of the world’s gasoline consumption.<ref>http://www.worldwatch.org/node/5579 , http://www.eia.doe.gov/emeu/international/oilconsumption.html </ref> In 2003 The US consumed 476,474,000,000 litres (476.474 gigalitres),<ref>[http://earthtrends.wri.org/text/energy-resources/variable-291.html EarthTrends: Energy and Resources - Transportation: Motor gasoline consumption
Units: Million liters]</ref> which equates to 1.3 [[gigalitre]]s of gasoline each day (about 360 million US liquid [[gallon]]s). The US used about 510 billion litres (138 billion gallons) of gasoline in 2006, of which 5.6% was mid-grade and 9.5% was premium grade.<ref>{{cite web|url=http://tonto.eia.doe.gov/dnav/pet/pet_cons_prim_dcu_nus_a.htm|title=U.S. Prime Supplier Sales Volumes of Petroleum Products|publisher=United States Energy Information Administration|accessdate=2007-10-24}}</ref>
Western countries have among the highest usage rates per person.
Based on [[externality|externalities]], some countries, e.g. in Europe and Japan, impose heavy [[fuel tax]]es on fuels such as gasoline. Because a greater proportion of the price of gasoline in the United States is due to the cost of oil, rather than taxes, the price of the retail product is subject to greater fluctuations (vs. outside the US) when calculated as a ''percentage'' of cost-per-unit, but is actually less variable in ''absolute'' terms.
Fuel prices have been rising steadily since the start of 2008, especially in the UK <ref>[http://www.whatgas.com/unleaded-graph.aspx Whatgas: Unleaded Petrol Price Trend]</ref>, Europe, Canada ,India and the USA. The UK has seen an increase of approximately 20p per litre in one year and Romania has seen a 30% increase of the gasoline price in the same year.
==Stability==
When gasoline is left for a period of time, gums and varnishes may build up and precipitate in the gasoline, causing "stale fuel." This will cause gums to build up in the fuel tank, lines, and carburetor or fuel injection components making it harder to start the engine. Motor gasoline may be stored up to 60 days in an approved container. If it is to be stored for a longer period of time, a fuel stabilizer may be used. This will extend the life of the fuel to about 1-2 years, and keep it fresh for the next uses. Fuel stabilizer is commonly used for small engines such as lawnmower and tractor engines to promote quicker and more reliable starting. Users have been advised to keep gasoline containers and tanks more than half full and properly capped to reduce air exposure, to avoid storage at high temperatures,<ref>{{cite web|url=http://www.alpharubicon.com/altenergy/gasstoretg.htm|title=Fuel storage practices}}</ref> to run an engine for ten minutes to circulate the stabilizer through all components prior to storage, and to run the engine at intervals to purge stale fuel from the [[carburetor]].<ref>{{cite web|url=http://www.perr.com/tip1.html|title=PER Notebook}}</ref>
Gummy, sticky resin deposits result from [[oxidation|oxidative]] degradation of gasoline. This degradation can be prevented through the use of [[antioxidant]]s such as [[phenylenediamine]]s, [[alkylenediamine]]s ([[diethylenetriamine]], [[triethylenetetramine]], etc), and [[alkylamine]]s ([[diethylamine]], [[tributylamine]], [[ethylamine]]). Other useful additives include gum inhibitors such as N-substituted [[alkylaminophenol]]s and color stabilizers such as N-(2-aminoethyl)piperazine, N,N-diethylhydroxylamine, and triethylenetetramine.<ref name=EP0534668>{{patent|EP|0534668|Stabilization of gasoline mixtures}}</ref><!--- I am using this patent's review of several others for a quick description of common compounds, but this section could be expanded by looking through the sources it references --->
By 1975, improvements in refinery techniques have generally reduced the reliance on the catalytically or thermally cracked stocks most susceptible to oxidation.<ref>{{patent|US|3994698| Gasoline additive concentrate composition}}</ref> Gasoline containing acidic contaminants such as [[naphthenic acid]]s can be addressed with additives including strongly basic organo-amines such as [[N,N-diethylhydroxylamine]], preventing metal corrosion and breakdown of other antioxidant additives due to acidity. Hydrocarbons with a [[bromine number]] of 10 or above can be protected with the combination of unhindered or partially hindered phenols and oil soluble strong amine bases such as [[monoethanolamine]], N-(2-aminoethyl)piperazine, [[cyclohexylamine]], 1,3-cyclohexane-bis(methylamine), 2,5-[[dimethylaniline]], 2,6-dimethylaniline, [[diethylenetriamine]] and [[triethylenetetramine]].<ref name=EP0534668 />
"Stale" gasoline can be detected by a [[colorimetric]] [[enzymatic]] test for [[organic peroxide]]s produced by oxidation of the gasoline.<ref>{{patent|AU|2000/72399 A1|Gasoline test kit}}</ref><!---See http://www.patentlens.net/patentlens/structured.cgi?patnum=AU_2000/72399_A1#show if template link fails--->
== Alternatives ==
{{main|Alternative fuel}}
Many of these alternatives are less damaging to the environment than gasoline, but the [[first generation biofuels]] are still not 100 percent clean.
* [[Biodiesel]], for diesel engines.
* [[Biobutanol]], for gasoline engines.
* [[Bioethanol]].
* [[CNG]] (Compressed Natural Gas)
* [[Hydrogen economy|Hydrogen fuel]]
* [[Battery electric vehicle]]s
* Petroleum [[Diesel|Diesel fuel]]
== Vegoil and biodiesel to gasoline ==
XcelPlus Global Holdings<ref>http://xcelplusglobal.com/</ref> working in conjunction with [[Maverick BioFuels]] developed the technology in which a fuel compatible with [[internal combustion gasoline engine]]s is derived from natural renewable oils like [[soybean]], other vegetable oils and biodiesel. Initial marketing efforts will focus on an additive package for converting ordinary Biodiesel into gasoline, adding the Biolene additive package. The additive is expected to be on the market later this year. Home blenders can expect final pump-grade fuel to cost approximately $2.70 per gallon.<ref>http://www.autobloggreen.com/2008/05/24/got-some-biodiesel-you-cant-use-convert-it-to-gasoline-with-bi/</ref>
Companies such as [http://sapphireenergy.com Sapphire Energy] are developing a means to "grow" gasoline, that is, produce it directly from living organisms, i.e. algae. Biogasoline has the advantage of not needing any change in vehicle or distribution infrastructure.
== See also ==
{{portal|Energy}}
<div style="-moz-column-count:3; column-count:3;">
* [[Comparison of automobile fuel technologies]]
* [[Ethanol fuel]]
* [[Diesel]]
* [[Filling station]]
* [[List of automotive fuel brands]]
* [[Internal combustion engine]]
* [[Diesel engine]]
* [[Oil price increases since 2003]]
* [[Aviation fuel]]
* [[Aftermarket fuel economy device]]
* [[Octane rating]]
* [[Drip gas]]
</div>
==Notes==
{{reflist|2}}
== References ==
* [http://zfacts.com/p/35.html Graph of inflation-corrected historic prices, 1970-2005. Highest in 2005]
* [http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm FTC: The Low-Down on High Octane Gasoline]
* [http://www.epa.gov/otaq/regs/fuels/additive/mmt_cmts.htm MMT-US EPA]
* An [http://www.gasresources.net/Introduction.htm introduction to the modern petroleum science], and to the Russian-Ukrainian theory of deep, [[abiotic petroleum]] origins.
* [http://www.straightdope.com/columns/041008.html What's the difference between premium and regular gas?] (from [[The Straight Dope]])
* [http://i-r-squared.blogspot.com/2006/09/here-comes-winter-gasoline.html "Here Comes Winter Gasoline" R-Squared Energy Blog] [[September 14]], [[2006]]
* [http://www.gtz.de/en/themen/umwelt-infrastruktur/transport/10285.htm International Fuel Prices 2005] with diesel and gasoline prices of 172 countries
* [http://tonto.eia.doe.gov/oog/info/gdu/gasdiesel.asp EIA - Gasoline and Diesel Fuel Update]
*[http://soc.hfac.uh.edu/artman/publish/article_375.shtml World Internet News: "Big Oil Looking for Another Government Handout," April 2006.]
* [http://journeytoforever.org/biofuel_library/ethanol_motherearth/me2.html#table Durability of various plastics: Alcohols vs. Gasoline]
* [http://www.gasresources.net/DisposalBioClaims.htm Dismissal of the Claims of a Biological Connection for Natural Petroleum.]
* [http://www.epa.gov/OMSWWW/rfgecon.htm Fuel Economy Impact Analysis of RFG] i.e. reformulated gasoline. Has lower heating value data, actual energy content is higher see [[higher heating value]]
== External links ==
{{commons|Gasoline}}
{{Wiktionarypar|gasoline}}
* [http://money.cnn.com/pf/features/lists/global_gasprices/ CNN/Money: Global gas prices]
* [http://cta.ornl.gov/data/index.shtml Transportation Energy Data Book]
* [http://www.energysupplylogistics.com/terminals Energy Supply Logistics Searchable Directory of US Terminals]
* [http://www.whygaspricesaresohigh.info Commentary and history on High Gas Prices]
* [http://www.benzin.sk Definition of basic terms, Graphs of Gas prices. all in Slovak language]
'''Images'''
*"''[http://www.archive.org/movies/details-db.php?collection=prelinger&collectionid=19334&from=collectionSpotlight Down the Gasoline Trail]''" Handy Jam Organization, 1935 (Cartoon)
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