Difference between revisions of "Gasoline" - New World Encyclopedia

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[[Image:GasCan.jpg|thumb|The word "Gasoline" is used in North America, as shown on this can, where as "Petrol" is used in most other Commonwealth countries.]]
 
[[Image:GasCan.jpg|thumb|The word "Gasoline" is used in North America, as shown on this can, where as "Petrol" is used in most other Commonwealth countries.]]
  
 
'''Gasoline''' (also called '''gas,''' '''petrol,''' or '''petrogasoline''') 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.
 
'''Gasoline''' (also called '''gas,''' '''petrol,''' or '''petrogasoline''') 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.
 
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== Terminology ==
 
== Terminology ==
 
Except for [[Canada]], most current or former [[Commonwealth of Nations|Commonwealth countries]] use the word "petrol," abbreviated from ''petroleum spirit''. In [[North America]], the word "gasoline" is commonly used, where it is often shortened in [[colloquial]] usage to "[[gas (disambiguation)|gas]]." It is not a genuinely [[gaseous]] fuel like [[liquefied petroleum gas]], which is stored under pressure as a liquid but allowed to return to a gaseous state before combustion.
 
Except for [[Canada]], most current or former [[Commonwealth of Nations|Commonwealth countries]] use the word "petrol," abbreviated from ''petroleum spirit''. In [[North America]], the word "gasoline" is commonly used, where it is often shortened in [[colloquial]] usage to "[[gas (disambiguation)|gas]]." It is not a genuinely [[gaseous]] fuel like [[liquefied petroleum gas]], which is stored under pressure 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]]. In [[British English]] "gasoline" can refer to a different petroleum derivative historically used in lamps, but this is now uncommon.
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''Mogas,'' short for ''motor gasoline,'' distinguishes [[automobile]] fuel from ''aviation gasoline,'' or [[avgas]]. In [[British English]] "gasoline" can refer to a different petroleum derivative historically used in lamps, but this is now uncommon.
  
 
==History==
 
==History==
 
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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]] or as an [[oxygenate]] to reduce emissions. 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>Chromatography Online, [http://www.chromatography-online.org/topics/gasoline/components.html gasoline components.] Retrieved September 9, 2008.</ref>
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]] or as an [[oxygenate]] to reduce emissions. 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.] chromatography-online. Retrieved September 9, 2008.</ref>
 
  
 
===Early uses===
 
===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]].
 
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 [[USA]], 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.  
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In the [[U.S.]], 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.
 
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.
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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]], rumors spread around the city of ''[[pétroleuses]]'', women using bottles of petrol to commit [[arson]] against city buildings.
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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]], rumors spread around the city of ''[[pétroleuses]],'' women using bottles of petrol to commit [[arson]] against city buildings.
  
 
===Etymology===
 
===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" for gasoline was first recorded in American English in 1905 <ref name = etymonline>[http://www.etymonline.com/index.php?search=gasoline Gasoline.] Online Etymology Dictionary. Retrieved September 9, 2008.</ref> and is often confused with the older words gas and gases that have been used since the early 1600s. 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.] Window on State Government. Retrieved September 9, 2008.</ref>
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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" for gasoline was first recorded in American English in 1905 <ref name = etymonline>Online Etymology Dictionary, [http://www.etymonline.com/index.php?search=gasoline Gasoline.] Retrieved September 9, 2008.</ref> and is often confused with the older words gas and gases that have been used since the early 1600s. 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>Window on State Government, [http://www.window.state.tx.us/taxinfo/audit/motorfue/glossary.htm Motor Fuels Tax Audit Procedures Manual—Ch 153—Glossary.] Retrieved September 9, 2008.</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 History.] Petrochem Carless. Retrieved September 9, 2008.</ref>
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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>Petrochem Carless, [http://www.petrochemcarless.com/docs/about_us_history.htm History.] Retrieved September 9, 2008.</ref>
  
Carless's competitors used the term "motor spirit" until the 1930s, but never officially registered it as a trademark.<ref name = etymonline/><ref>Hincks, Ron. 2004. Our Motoring Heritage: Petrol & Oil. ''Chrysler Collector.'' 154:16–20.</ref> It has also been suggested that the word was coined by [[Edward Butler (inventor)|Edward Butler]] in 1887.<ref>[http://www.telegraph.co.uk/motoring/main.jhtml?xml=/motoring/2002/02/01/emrdron02.xml Keeping track: All fired up about `petrol'.] ''[[Daily Telegraph]]''. Retrieved September 9, 2008.</ref>
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Carless's competitors used the term "motor spirit" until the 1930s, but never officially registered it as a trademark.<ref name = etymonline/><ref>Ron Hincks, Our Motoring Heritage: Petrol & Oil, ''Chrysler Collector'' 154 (2004): 16–20.</ref> It has also been suggested that the word was coined by [[Edward Butler (inventor)|Edward Butler]] in 1887.<ref>''Daily Telegraph,'' [http://www.telegraph.co.uk/motoring/main.jhtml?xml=/motoring/2002/02/01/emrdron02.xml Keeping track: All fired up about "petrol."] Retrieved September 9, 2008.</ref>
  
In [[Germany]] and some other European countries and in [[New Guinea Pidgin]] gasoline is called ''Benzin'' ([[German language|German]], [[Danish language|Danish]] and [[Turkish language|Turkish]]), ''Benzine'' in [[Dutch language|Dutch]], ''Bensin'' ([[Swedish language|Swedish]] and [[Norwegian language|Norwegian]]), ''Bensiini'' ([[Finnish language|Finnish]]), ''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.
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In [[Germany]] and some other European countries and in [[New Guinea Pidgin]] gasoline is called ''Benzin'' ([[German language|German]], [[Danish language|Danish]], and [[Turkish language|Turkish]]), ''Benzine'' in [[Dutch language|Dutch]], ''Bensin'' ([[Swedish language|Swedish]] and [[Norwegian language|Norwegian]]), ''Bensiini'' ([[Finnish language|Finnish]]), ''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==
 
==Chemical analysis and production==
[[Image:Refinery.jpg|thumb|[[Oil refinery|Oil refineries]] produce gasoline]]
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[[Image:Refinery.jpg|thumb|[[Oil refinery|Oil refineries]] produce gasoline.]]
[[Image:Nodding donkey.jpg|thumb|A [[United States]] [[nodding donkey]]]]
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[[Image:Nodding donkey.jpg|thumb|A [[United States]] [[nodding donkey]].]]
[[Image:Gulf Offshore Platform.jpg|thumb|An oil rig in the [[Gulf of Mexico]]]]
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[[Image:Gulf Offshore Platform.jpg|thumb|An oil rig in the [[Gulf of Mexico]].]]
[[Image:BP bensinstasjon, Nøtterøy.JPG|thumb|right|Old petrol pumps in Nøtterøy, Norway]]
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[[Image:BP bensinstasjon, Nøtterøy.JPG|thumb|right|Old petrol pumps in Nøtterøy, Norway.]]
 
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.
 
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]].
 
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. Retrieved September 9, 2008.</ref>
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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 percent by volume), [[toluene]] (up to 35 percent by volume), [[naphthalene]] (up to 1 percent by volume), [[1,2,4-Trimethylbenzene|trimethylbenzene]] (up to 7 percent by volume), [[MTBE]] (up to 18 percent by volume) and about ten others.<ref>First Fuel Bank, [http://firstfuelbank.com/msds/Tesoro.pdf Material Safety Data Sheet,] Tesoro Petroleum Companies, Inc., USA. Retrieved September 9, 2008.</ref>
  
 
The various [[Oil refinery|refinery]] streams blended together to make gasoline all have different characteristics. Some important streams are:
 
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).
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*''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]]".''
 
*''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.
 
*''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).
 
*''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.
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*''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.
 
*''Isomerate'' (various names) which is obtained by isomerising the pentane and hexane in light virgin naphthas to yield their higher octane isomers.
  
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Overall a typical gasoline is predominantly a mixture of paraffins ([[alkane]]s), naphthenes (cycloalkanes), and olefins (alkenes). The exact ratios can depend on
 
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.
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* 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.
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* The [[crude oil]] feed used by the refinery
* the grade of gasoline, in particular the octane rating.
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* 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.
 
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]].  
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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&ndash;0.77 g/cm<sup>3</sup>,<ref>[http://www.sefsc.noaa.gov/HTMLdocs/Gasoline.htm Bell Fuels: Lead-Free Gasoline Material Safety Data Sheet.] [[NOAA]]. Retrieved September 9, 2008.</ref> (in English units, approx. 0.026 lb/cu&nbsp;in or 6.073 lb/U.S.&nbsp;gal or 7.29&nbsp;lb/imp&nbsp;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.
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The density of gasoline is 0.71&ndash;0.77 g/cm<sup>3</sup>,<ref>NOAA, [http://www.sefsc.noaa.gov/HTMLdocs/Gasoline.htm Bell Fuels: Lead-Free Gasoline Material Safety Data Sheet.] Retrieved September 9, 2008.</ref> (in English units, approx. 0.026 lb/cu&nbsp;in or 6.073 lb/U.S.&nbsp;gal or 7.29&nbsp;lb/imp&nbsp;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===
 
===Volatility===
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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 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 "[[vapor lock]]" where combustion fails to occur, because the liquid fuel has changed to a gaseous fuel in the fuel lines, rendering the fuel pump ineffective and starving the engine of fuel.  
 
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 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 "[[vapor lock]]" where combustion fails to occur, because the liquid fuel has changed to a gaseous fuel in the fuel lines, rendering the fuel pump ineffective and starving the engine of fuel.  
  
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.  
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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>[http://www.epa.gov/katrina/activities/week1.html#aug31johnson Week 1: Nationwide fuel waiver issued to bolster fuel supplies.] U.S. Environmental Protection Agency. Retrieved September 9, 2008.</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.
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Volatility standards may be relaxed (allowing more gasoline components into the atmosphere) during emergency anticipated gasoline shortages. For example, on August 31, 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 September 15, 2005.<ref>EPA, [http://www.epa.gov/katrina/activities/week1.html#aug31johnson Week 1: Nationwide fuel waiver issued to bolster fuel supplies,] U.S. Environmental Protection Agency. Retrieved September 9, 2008.</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.
  
 
===Octane rating===
 
===Octane rating===
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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 [[engine knocking|detonation]] (also known as knocking, pinking, 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.
 
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 [[engine knocking|detonation]] (also known as knocking, pinking, 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.
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The octane rating became important in the search for higher output powers from [[aero engine]]s in the late 1930s and the 1940s as it allowed higher [[compression ratio]]s to be used.
  
 
===World War II and octane ratings===
 
===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.
 
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.
+
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 percent to more than 50 percent 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' (synthetic) 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.
+
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" (synthetic) 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 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 U.S. 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.
+
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 misconception 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.
+
A common misconception 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.”
+
After the war the U.S. 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==
 
==Energy content==
 
[[Image:GasolineContainer.JPG|thumb|A container for storing gasoline used in the [[United States]]; red containers are typically used.]]
 
[[Image:GasolineContainer.JPG|thumb|A container for storing gasoline used in the [[United States]]; red containers are typically used.]]
  
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 {{convert|19.5|USgal|impgal L}} of gasoline are available from a {{convert|42|USgal|impgal L|sing=on}} 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.<ref>[http://www.gravmag.com/oil.html Oil Industry Statistics from Gibson Consulting.] gravmag.com. Retrieved September 9, 2008.</ref>
+
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/U.S. 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 percent more or less than the average, according to the U.S. EPA. On average, about {{convert|19.5|USgal|impgal L}} of gasoline are available from a {{convert|42|USgal|impgal L|sing=on}} barrel of crude oil (about 46 percent by volume), varying due to quality of crude and grade of gasoline. The remaining residue comes off as products ranging from tar to naptha.<ref>Gravmag, [http://www.gravmag.com/oil.html Oil Industry Statistics from Gibson Consulting.] Retrieved September 9, 2008.</ref>
  
 
<!--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.—>
 
<!--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.] Center for Transportation Analysis/Oak Ridge National Laboratory. Retrieved September 9, 2008.</ref>
+
Volumetric [[energy density]] of some fuels compared with gasoline:<ref name=TEDB>Oak Ridge National Laboratory, [http://www-cta.ornl.gov/data/Appendix_B.html Appendix B, Transportation Energy Data Book,] Center for Transportation Analysis. Retrieved September 9, 2008.</ref>
  
 
{| class="wikitable sortable"
 
{| class="wikitable sortable"
Line 115: Line 113:
 
| Regular Gasoline
 
| Regular Gasoline
 
| align ="right"|34.8
 
| align ="right"|34.8
| align ="right"|44.4<ref>Thomas, George. 2000. [http://www.eere.energy.gov/hydrogenandfuelcells/pdfs/storage.pdf Overview of Storage Development DOE Hydrogen Program]. Sandia National Laboratories. Retrieved September 9, 2008.</ref>
+
| align ="right"|44.4<ref>George Thomas, [http://www.eere.energy.gov/hydrogenandfuelcells/pdfs/storage.pdf Overview of Storage Development DOE Hydrogen Program,] Sandia National Laboratories. Retrieved September 9, 2008.</ref>
 
| align ="right"|150,100
 
| align ="right"|150,100
 
| align ="right"|125,000
 
| align ="right"|125,000
Line 196: Line 194:
 
| align ="right"|
 
| align ="right"|
 
| align ="right"|
 
| align ="right"|
| align ="right"|130<ref>[http://www.hydrogenassociation.org/general/faqs.asp#octane FAQs.] The National Hydrogen Association. Retrieved September 9, 2008.</ref>
+
| align ="right"|130<ref>The National Hydrogen Association, [http://www.hydrogenassociation.org/general/faqs.asp#octane FAQs.] Retrieved September 9, 2008.</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>
 
<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.
+
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]] (that is, 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&nbsp;kg/m&sup3; (6.175&nbsp;lb/US&nbsp;gal; 7.416&nbsp;lb/imp&nbsp;gal).
 
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&nbsp;kg/m&sup3; (6.175&nbsp;lb/US&nbsp;gal; 7.416&nbsp;lb/imp&nbsp;gal).
  
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 unleaded fuels can vary between 86-87 AKI (91-92 RON) for regular, through 89-90 AKI (94-95 RON) for mid-grade (European Premium), up to 90-94 AKI (95-99 RON) for premium (European Super).
+
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 U.S., octane ratings in unleaded fuels can vary between 86-87 AKI (91-92 RON) for regular, through 89-90 AKI (94-95 RON) for mid-grade (European Premium), up to 90-94 AKI (95-99 RON) for premium (European Super).
  
 
==Additives==
 
==Additives==
Line 211: Line 209:
  
 
===Lead===<!-- This section is linked from [[Lead]] —>
 
===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]]).
+
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 U.S. 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>[http://www.epa.gov/history/topics/lead/02.htm EPA Takes Final Step in Phaseout of Leaded Gasoline.] U.S. Environmental Protection Agency. Retrieved September 9, 2008.</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>Schnaas, Lourdes, Stephen J. Rothenberg, María-Fernanda Flores, Sandra Martínez, Carmen Hernández, Erica Osorio, and Estela Perroni. 2004. [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1247386 Blood Lead Secular Trend in a Cohort of Children in Mexico City (1987–2002).] ''Environ. Health. Perspect.'' 112:10:1110–1115. Retrieved September 9, 2008.</ref><ref>Pino, Paulina, Tomás Walter, Manuel J. Oyarzún, Matthew J. Burden and Betsy Lozoff. 2004. Rapid Drop in Infant Blood Lead Levels during the Transition to Unleaded Gasoline Use in Santiago, Chile. ''Archives of Environmental Health: An International Journal.'' 59:4:182–187.</ref>
+
In the U.S., 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 percent 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>EPA, [http://www.epa.gov/history/topics/lead/02.htm EPA Takes Final Step in Phaseout of Leaded Gasoline,] U.S. Environmental Protection Agency. Retrieved September 9, 2008.</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>Lourdes Schnaas, Stephen J. Rothenberg, María-Fernanda Flores, Sandra Martínez, Carmen Hernández, Erica Osorio, and Estela Perroni, [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1247386 Blood Lead Secular Trend in a Cohort of Children in Mexico City (1987–2002),] ''Environ. Health. Perspect.'' 112(10): 1110–1115. Retrieved September 9, 2008.</ref><ref>Paulino Pino, Tomás Walter, Manuel J. Oyarzún, Matthew J. Burden, and Betsy Lozoff, Rapid Drop in Infant Blood Lead Levels during the Transition to Unleaded Gasoline Use in Santiago, Chile, ''Archives of Environmental Health: An International Journal.'' 59 (4): 182–187.</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]
+
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.
  
 
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.
 
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.
+
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 January 1, 2006. A growing number of countries have drawn up plans to ban leaded gasoline in the near future.
  
 
===MMT===
 
===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.
 
[[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,<ref>[http://www.epa.gov/otaq/regs/fuels/additive/mmt_cmts.htm Comments of the Gasoline Additive MMT.] U.S. Environmental Protection Agency. Retrieved September 9, 2008.</ref> and a large Canadian study concluded that MMT impairs the effectiveness of automobile emission controls and increases pollution from motor vehicles.<ref>[http://cvma.ca/eng/publications/FinalMMTReport.pdf Final Report: Effects of MMT in Gasoline on Emissions from On-Road Motor Vehicles in Canada.] Canadian Vehicle Manufacturers’ Association, and Association of International Automobile Manufacturers of Canada. Retrieved September 9, 2008.</ref>
+
U.S. Federal sources state that MMT is suspected to be a powerful neurotoxin and respiratory toxin,<ref>EPA, [http://www.epa.gov/otaq/regs/fuels/additive/mmt_cmts.htm Comments of the Gasoline Additive MMT,] U.S. Environmental Protection Agency. Retrieved September 9, 2008.</ref> and a large Canadian study concluded that MMT impairs the effectiveness of automobile emission controls and increases pollution from motor vehicles.<ref>CVMA, [http://cvma.ca/eng/publications/FinalMMTReport.pdf Final Report: Effects of MMT in Gasoline on Emissions from On-Road Motor Vehicles in Canada,] Canadian Vehicle Manufacturers’ Association, and Association of International Automobile Manufacturers of Canada. Retrieved September 9, 2008.</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>[http://www.aftonchemical.com/Products/MMT/History+of+MMT%AE.htm History of mmt®.] Afton Chemical. Retrieved September 9, 2008.</ref>
+
In 1977, use of MMT was banned in the U.S. 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 U.S. Court of Appeals ruled that the EPA had exceeded its authority, and MMT became a legal fuel additive in the U.S. MMT is nowadays manufactured by the Afton Chemical Corporation division of Newmarket Corporation.<ref>Afton Chemical, [http://www.aftonchemical.com/Products/MMT/History+of+MMT%AE.htm History of mmt®.] Retrieved September 9, 2008.</ref>
  
 
===Ethanol===
 
===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.
 
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.
  
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 several states, ethanol is added by law to a minimum level which is currently 5.9 percent. Most fuel pumps display a sticker stating that the fuel may contain up to 10 percent 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 percent 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. Most gasoline (petrol) sold in Sweden has 5% ethanol added.
+
In the EU, 5 percent ethanol can be added within the common gasoline spec (EN 228). Discussions are ongoing to allow 10 percent blending of ethanol. Most countries (fuel distributors) today do not add so much ethanol. Most gasoline (petrol) sold in Sweden has 5 percent 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.
+
In Brazil, the [[Brazilian National Agency of Petroleum, Natural Gas and Biofuels]] (ANP) requires that gasoline for automobile use has 23 percent of ethanol added to its composition.
  
 
===Dye===
 
===Dye===
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===Oxygenate blending===
 
===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 pollutants. 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>[http://www.epa.gov/otaq/rfg_regs.htm#usage Removal of Reformulated Gasoline Oxygen Content Requirement (national) and Revision of Commingling Prohibition to Address Non-0xygenated Reformulated Gasoline (national).] U.S. Environmental Protection Agency. Retrieved September 9, 2008.</ref>
+
[[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 U.S. oxygenate blending is mandated by EPA regulations to reduce smog and other airborne pollutants. For example, in Southern California, fuel must contain 2 percent oxygen by weight, resulting in a mixture of 5.6 percent 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>EPA, [http://www.epa.gov/otaq/rfg_regs.htm#usage Removal of Reformulated Gasoline Oxygen Content Requirement (national) and Revision of Commingling Prohibition to Address Non-0xygenated Reformulated Gasoline (national),] U.S. Environmental Protection Agency. Retrieved September 9, 2008.</ref>
  
MTBE use is being phased out in some states due to issues with contamination of ground water. In some places, such as California, 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 3.4 billion US gallons (2.8&nbsp;billion imp&nbsp;gal/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>[http://www.eere.energy.gov/afdc/fuels/stations_locator.html Alternative Fueling Station Locator.] U.S. Department of Energy. Retrieved September 9, 2008.</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 legally 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.)
+
MTBE use is being phased out in some states due to issues with contamination of ground water. In some places, such as California, 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 percent 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 3.4 billion U.S. gallons (2.8&nbsp;billion imp&nbsp;gal/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>U.S. Department of Energy, [http://www.eere.energy.gov/afdc/fuels/stations_locator.html Alternative Fueling Station Locator.] Retrieved September 9, 2008.</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 legally ferment and distill their own bio-ethanol at present (unlike in the U.S. where getting a [[BATF]] distillation permit has been easy since the 1973 oil crisis.)
  
 
==Health concerns==
 
==Health concerns==
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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.
 
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>Cairney, Sheree. 2005. [http://www.abc.net.au/health/library/stories/2005/11/24/1831506.htm Petrol Sniffing Fact File.] ABC AU. Retrieved September 9, 2008.</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 September 9, 2008.</ref>
+
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>Sheree Cairney, [http://www.abc.net.au/health/library/stories/2005/11/24/1831506.htm Petrol Sniffing Fact File,] ABC AU. Retrieved September 9, 2008.</ref> In response, [[Opal (fuel)|Opal]] fuel has been developed by the [[BP]] [[Town of Kwinana|Kwinana]] Refinery in Australia, and contains only 5 percent [[aromatics]] (unlike the usual 25 percent) which inhibits the effects of inhalation.<ref>BP, [http://www.bp.com/genericarticle.do?categoryId=9012769&contentId=7024904 Fuel technology.] Retrieved September 9, 2008.</ref>
  
 
Like other alkenes, 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 vaporizes 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.
 
Like other alkenes, 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 vaporizes 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.
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{{main|Gasoline usage and pricing|Global warming|Peak oil}}
 
{{main|Gasoline usage and pricing|Global warming|Peak oil}}
  
[[Image:Petrol.png|thumb|UK petrol prices]]
+
The U.S. accounts for about 44 percent of the world’s gasoline consumption.<ref>Michael Renner, [http://www.worldwatch.org/node/5579 Analysis: Nano Hypocrisy?] World Watch Institute. Retrieved September 9, 2008.</ref><ref>Energy Information Administration, [http://www.eia.doe.gov/emeu/international/oilconsumption.html International Petroleum (Oil) Consumption.] Retrieved September 9, 2008.</ref> In 2003, The U.S. consumed {{convert|476.474|GL|USgal impgal}},<ref>Earth Trends, [http://earthtrends.wri.org/text/energy-resources/variable-291.html Motor gasoline consumption Units: Million liters,] Energy and Resources—Transportation. Retrieved September 9, 2008.</ref> which equates to 1.3&nbsp;[[gigalitre]]s of gasoline each day (about 360 million U.S. [[gallon]]s or 300 million imperial gallons). The U.S. used about 510 billion liters (138 billion U.S. gal/115 billion imp gal) of gasoline in 2006, of which 5.6 percent was mid-grade and 9.5 percent was premium grade.<ref>Energy Information Administration, [http://tonto.eia.doe.gov/dnav/pet/pet_cons_prim_dcu_nus_a.htm U.S. Prime Supplier Sales Volumes of Petroleum Products.] Retrieved September 9, 2008.</ref>
 
 
The US accounts for about 44% of the world’s gasoline consumption.<ref>Renner, Michael. 2008. [http://www.worldwatch.org/node/5579 Analysis: Nano Hypocrisy?] World Watch Institute. Retrieved September 9, 2008.</ref><ref>[http://www.eia.doe.gov/emeu/international/oilconsumption.html International Petroleum (Oil) Consumption.] Energy Information Administration. Retrieved September 9, 2008.</ref> In 2003 The US consumed {{convert|476.474|GL|USgal impgal}},<ref>[http://earthtrends.wri.org/text/energy-resources/variable-291.html Motor gasoline consumption Units: Million liters.] EarthTrends: Energy and Resources - Transportation. Retrieved September 9, 2008.</ref> which equates to 1.3&nbsp;[[gigalitre]]s of gasoline each day (about 360 million US [[gallon]]s or 300 million imperial gallons). The US used about 510 billion liters (138 billion US gal/115 billion imp gal) of gasoline in 2006, of which 5.6% was mid-grade and 9.5% was premium grade.<ref>[http://tonto.eia.doe.gov/dnav/pet/pet_cons_prim_dcu_nus_a.htm U.S. Prime Supplier Sales Volumes of Petroleum Products.] Energy Information Administration. Retrieved September 9, 2008.</ref>
 
  
 
Western countries have among the highest usage rates per person.
 
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.
+
Based on [[externality|externalities]], some countries, for example, 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 U.S.) when calculated as a ''percentage'' of cost-per-unit, but is actually less variable in ''absolute'' terms.
  
 
==Stability==
 
==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>Alpha Rubicon, [http://www.alpharubicon.com/altenergy/gasstoretg.htm Fuel storage practices.] Retrieved September 9, 2008.</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>PER Notebook, Stale Gasoline Problems.</ref>
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>[http://www.alpharubicon.com/altenergy/gasstoretg.htm Fuel storage practices.] Alpharubicon.com. Retrieved September 9, 2008.</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>[http://www.perr.com/tip1.html Stale Gasoline Problems.] PER Notebook. Retrieved September 9, 2008.</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}}. Retrieved September 9, 2008.</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 --->
 
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}}. Retrieved September 9, 2008.</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}}. Retrieved September 9, 2008.</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 />
+
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}}. Retrieved September 9, 2008.</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}}. Retrieved September 9, 2008.</ref><!---See http://www.patentlens.net/patentlens/structured.cgi?patnum=AU_2000/72399_A1#show if template link fails--->
 
"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}}. Retrieved September 9, 2008.</ref><!---See http://www.patentlens.net/patentlens/structured.cgi?patnum=AU_2000/72399_A1#show if template link fails--->
Line 283: Line 278:
  
 
* Biofuels:
 
* Biofuels:
** [[Biodiesel]], for diesel engines.
+
** [[Biodiesel]], for diesel engines
** [[Biobutanol]], for gasoline engines.
+
** [[Biobutanol]], for gasoline engines
** [[Bioethanol]].
+
** [[Bioethanol]]
** [[Biogasoline]].
+
** [[Biogasoline]]
 
* [[Compressed-air car|Compressed air]]
 
* [[Compressed-air car|Compressed air]]
 
* [[Hydrogen economy|Hydrogen fuel]]
 
* [[Hydrogen economy|Hydrogen fuel]]
Line 296: Line 291:
 
== Bioconversion and biogasoline ==
 
== Bioconversion and biogasoline ==
  
[[XcelPlus Global Holdings]], 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 US$2.70 per US gallon ($3.24/imp&nbsp;gal, 71¢/L).<ref>Navarro, Xavier. 2008. [http://www.autobloggreen.com/2008/05/24/got-some-biodiesel-you-cant-use-convert-it-to-gasoline-with-bi/ Got some biodiesel you can't use? Convert it to gasoline with Biolene.] AutoblogGreen. Retrieved September 9, 2008.</ref>
+
[[XcelPlus Global Holdings]], 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 US$2.70 per U.S. gallon ($3.24/imp&nbsp;gal, 71¢/L).<ref>Xavier Navarro, [http://www.autobloggreen.com/2008/05/24/got-some-biodiesel-you-cant-use-convert-it-to-gasoline-with-bi/ Got some biodiesel you can't use? Convert it to gasoline with Biolene,] AutoblogGreen. Retrieved September 9, 2008.</ref>
  
Companies such as [[Sapphire Energy]] are developing a means to "grow" gasoline, that is, produce it directly from living organisms (i.e. [[algal fuel|algae]]). [[Biogasoline]] has the advantage of not needing any change in vehicle or distribution infrastructure.
+
Companies such as [[Sapphire Energy]] are developing a means to "grow" gasoline, that is, produce it directly from living organisms (that is, [[algal fuel|algae]]). [[Biogasoline]] has the advantage of not needing any change in vehicle or distribution infrastructure.
  
 
== See also ==
 
== See also ==
 
 
* [[Biofuel]]
 
* [[Biofuel]]
 
* [[Diesel]]
 
* [[Diesel]]
Line 315: Line 309:
  
 
== References ==
 
== References ==
 
+
* Blume, David, R., Buckminster (FWS) Fuller, and Michael Winks. 2007. ''Alcohol Can Be a Gas!: Fueling an Ethanol Revolution for the 21st Century.'' Santa Cruz, CA: International Institute for Ecological Agriculture. ISBN 0979043772.
* Blume, David, R. Buckminster (FWS) Fuller, and Michael Winks. 2007. ''Alcohol Can Be a Gas!: Fueling an Ethanol Revolution for the 21st Century.'' Santa Cruz, CA: International Institute for Ecological Agriculture ISBN 0979043778.
+
* Conaway, Charles F. ''The Petroleum Industry: A Nontechnical Guide.'' Tulsa, OK: PennWell, 1999. ISBN 978-0878147632
 
+
* Hyne, Norman J. ''Nontechnical Guide to Petroleum Geology, Exploration, Drilling, and Production,'' 2nd ed. Tulsa, OK: PennWell, 2001. ISBN 087814823X.
* Conaway, Charles F. 1999. ''The Petroleum Industry: A Nontechnical Guide.'' Tulsa, OK: PennWell. ISBN 0878147772.
+
* McCain, William D. ''The Properties of Petroleum Fluids.'' Tulsa, OK: PennWell, 1989. ISBN 0878143351.
 
+
* McKetta, John J. Jr. (ed.). ''Encyclopedia of Chemical Processing and Design: Volume 31—Natural Gas Liquids and Natural Gasoline to Offshore Process Piping: High Performance Alloys ... of Chemical Processing and Design.'' CR Press, 1989. ISBN 082472481X.  
* Hyne, Norman J. 2001. ''Nontechnical Guide to Petroleum Geology, Exploration, Drilling, and Production,'' 2nd ed. Tulsa, OK: PennWell. ISBN 087814823X.
+
* Meyers, Robert A. ''Handbook of Petroleum Refining Processes,'' 3rd ed. McGraw-Hill Handbooks. New York: McGraw-Hill, 2004. ISBN 0071391092.
 
+
* Wendel, C.H. ''American Gasoline Engines Since 1872.'' Osceola, WI: Motorbooks International, 1999. ISBN 0760307849.
* McCain, William D. 1989. ''The Properties of Petroleum Fluids.'' Tulsa, OK: PennWell. ISBN 0878143351.
 
 
 
* McKetta, John J. Jr. ed. 1989. ''Encyclopedia of Chemical Processing and Design: Volume 31 - Natural Gas Liquids and Natural Gasoline to Offshore Process Piping: High Performance Alloys ... of Chemical Processing and Design.'' New York, NY: Dekker. ISBN 082472481X.  
 
 
 
* Meyers, Robert A. 2004. ''Handbook of Petroleum Refining Processes,'' 3rd ed. McGraw-Hill Handbooks. New York: McGraw-Hill. ISBN 0071391096.
 
 
 
* Wendel, C.H. 1999. ''American Gasoline Engines Since 1872.'' Osceola, WI: Motorbooks International. ISBN 0760307849.
 
  
 
== External links ==
 
== External links ==
 +
All links retrieved May 23, 2017.
  
* [http://zfacts.com/p/35.html Graph of inflation-corrected historic prices, 1970-2005. Highest in 2005.] Retrieved September 10, 2008.
+
* [http://www.straightdope.com/columns/041008.html What's the difference between premium and regular gas?] (from The Straight Dope).
* [http://www.epa.gov/otaq/regs/fuels/additive/mmt_cmts.htm MMT-US EPA.] Retrieved September 10, 2008.
+
* [http://www.energytrendsinsider.com/2007/09/14/refining-101-winter-gasoline/ Refining 101: Winter Gasoline]  
* An [http://www.gasresources.net/Introduction.htm introduction to the modern petroleum science], and to the Russian-Ukrainian theory of deep, [[abiotic petroleum]] origins. Retrieved September 10, 2008.
+
* [http://journeytoforever.org/biofuel_library/ethanol_motherearth/me2.html#table Durability of various plastics: Alcohols vs. Gasoline.]  
* [http://www.straightdope.com/columns/041008.html What's the difference between premium and regular gas?] (from [[The Straight Dope]]). Retrieved September 10, 2008.
+
* [http://money.cnn.com/pf/features/lists/global_gasprices/ CNN/Money: Gas prices around the world.]  
* [http://i-r-squared.blogspot.com/2006/09/here-comes-winter-gasoline.html "Here Comes Winter Gasoline" R-Squared Energy Blog] September 14, 2006. Retrieved September 10, 2008.
+
* [http://cta.ornl.gov/data/index.shtml Transportation Energy Data Book.]  
* [http://www.gtz.de/en/themen/umwelt-infrastruktur/transport/10285.htm International Fuel Prices 2005] with diesel and gasoline prices of 172 countries. Retrieved September 10, 2008.
+
* [http://www.energysupplylogistics.com/terminals Energy Supply Logistics Searchable Directory of US Terminals.]  
* [http://tonto.eia.doe.gov/oog/info/gdu/gasdiesel.asp EIA - Gasoline and Diesel Fuel Update.] Retrieved September 10, 2008.
+
* [http://www.archive.org/movies/details-db.php?collection=prelinger&collectionid=19334&from=collectionSpotlight Down the Gasoline Trail]. Handy (Jam) Organization, 1935. (Movie journey of gasoline in an automobile.)  
*[http://soc.hfac.uh.edu/artman/publish/article_375.shtml World Internet News: "Big Oil Looking for Another Government Handout," April 2006.] Retrieved September 10, 2008.
 
* [http://journeytoforever.org/biofuel_library/ethanol_motherearth/me2.html#table Durability of various plastics: Alcohols vs. Gasoline.] Retrieved September 10, 2008.
 
* [http://www.gasresources.net/DisposalBioClaims.htm Dismissal of the Claims of a Biological Connection for Natural Petroleum.] Retrieved September 10, 2008.
 
* [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. Retrieved September 10, 2008.
 
* [http://money.cnn.com/pf/features/lists/global_gasprices/ CNN/Money: Global gas prices.] Retrieved September 10, 2008.
 
* [http://cta.ornl.gov/data/index.shtml Transportation Energy Data Book.] Retrieved September 10, 2008.
 
* [http://www.energysupplylogistics.com/terminals Energy Supply Logistics Searchable Directory of US Terminals.] Retrieved September 10, 2008.
 
* [http://www.archive.org/movies/details-db.php?collection=prelinger&collectionid=19334&from=collectionSpotlight Down the Gasoline Trail]. Handy (Jam) Organization, 1935. (Movie journey of gasoline in an automobile.) Retrieved September 10, 2008.
 
  
 
[[Category:Physical sciences]]
 
[[Category:Physical sciences]]

Revision as of 07:53, 23 January 2023


The word "Gasoline" is used in North America, as shown on this can, where as "Petrol" is used in most other Commonwealth countries.

Gasoline (also called gas, petrol, or petrogasoline) is a petroleum-derived liquid mixture consisting mostly of aliphatic hydrocarbons, 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 engines.

Terminology

Except for Canada, most current or former Commonwealth countries use the word "petrol," abbreviated from petroleum spirit. In North America, the word "gasoline" is commonly used, where it is often shortened in colloquial usage to "gas." It is not a genuinely gaseous fuel like liquefied petroleum gas, which is stored under pressure 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. In British English "gasoline" 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 or as an oxygenate to reduce emissions. 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.[1]

Early uses

Before gasoline was used as fuel for engines, it was sold in small bottles as a treatment against 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 U.S., 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 German-Prussian attack on the city. Later in 1871, during the revolutionary Paris Commune, rumors 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" for gasoline was first recorded in American English in 1905 [2] and is often confused with the older words gas and gases that have been used since the early 1600s. 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.[3]

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.[4]

Carless's competitors used the term "motor spirit" until the 1930s, but never officially registered it as a trademark.[2][5] It has also been suggested that the word was coined by Edward Butler in 1887.[6]

In Germany and some other European countries and in New Guinea Pidgin gasoline is called Benzin (German, Danish, and Turkish), Benzine in Dutch, Bensin (Swedish and Norwegian), Bensiini (Finnish), Benzyna (Polish), Benzina (Catalan), Benzină (Romanian), Бензин (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

File:Refinery.jpg
Oil refineries produce gasoline.
A United States nodding donkey.
An oil rig in the Gulf of Mexico.
Old petrol pumps in Nøtterøy, Norway.

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 hydrocarbons with between 5 and 12 carbon atoms 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 percent by volume), toluene (up to 35 percent by volume), naphthalene (up to 1 percent by volume), trimethylbenzene (up to 7 percent by volume), MTBE (up to 18 percent by volume) and about ten others.[7]

The various 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 (alkenes).
  • Cat Cracked Gasoline or Cat Cracked Naphtha, produced from a catalytic cracker, with a moderate octane rating, high olefins (alkene) content, and moderate aromatics level. Here, "cat" is short for "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 naphthenes (cycloalkanes) 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 (alkanes), 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 aromatics 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 compounds: Such as organic ethers (deliberately added), plus small levels of contaminants, in particular sulfur compounds such as disulfides and thiophenes. Some contaminants, in particular thiols 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/cm3,[8] (in English units, approx. 0.026 lb/cu in or 6.073 lb/U.S. gal or 7.29 lb/imp 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

A container for storing gasoline used in Germany

Gasoline is more volatile than diesel oil, Jet-A or kerosene, not only because of the base constituents, but because of the additives that are put into it. The final control of 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 "vapor lock" where combustion fails to occur, because the liquid fuel has changed to a gaseous fuel in the fuel lines, rendering the fuel pump ineffective and starving the engine of fuel.

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 August 31, 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 EPA administrator Stephen L. Johnson, this "fuel waiver" was made effective through September 15, 2005.[9] 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.

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, pinking, 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 (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 engines in the late 1930s and the 1940s as it allowed higher compression ratios to be used.

World War II and octane ratings

During World War II, Germany received much of its oil from Romania. From 2.8 million barrels (450,000 m³) in 1938, Romania’s exports to Germany increased to 13 million barrels (2,100,000 m³) by 1941, a level that was essentially maintained through 1942 and 1943, before dropping by half, due to Allied bombing and 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 3.8 million barrels (600,000 m³) in 1938 to almost 12 million barrels (1,900,000 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 10 million barrels (1,600,000 m³) to 36 million. The percentage of synthetic fuels compared with the yield from all sources grew from 22 percent to more than 50 percent by 1943. The total oil supplies available from all sources for the same period rose from 45 million barrels (7,200,000 m³) in 1938 to 71 million barrels (11,300,000 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" (synthetic) was introduced in late 1939 with the Daimler-Benz DB 601N engine, used in certain of the Luftwaffe`s Bf 109E and Bf 109F single-engined fighters, Bf 110C twin-engined fighters, and several bomber types. Some later combat types, most notably the BMW 801D-powered 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 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 U.S. 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 superchargers.

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 misconception 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 U.S. 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

A container for storing gasoline used in the United States; red containers are typically used.

Gasoline contains about 34.8 MJ/L or 132 MJ/US gallon. This is about 9.67 kWh/L or 36.6 kWh/U.S. 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 percent more or less than the average, according to the U.S. EPA. On average, about 19.5 US gallons (16.2 imp gal/74 L) of gasoline are available from a Template:Convert/LoffAoffDbSonUSre barrel of crude oil (about 46 percent by volume), varying due to quality of crude and grade of gasoline. The remaining residue comes off as products ranging from tar to naptha.[10]

Volumetric energy density of some fuels compared with gasoline:[11]

Fuel type      MJ/litre      MJ/kg     BTU/Imp gal     BTU/US gal     Research octane
number (RON)
Regular Gasoline 34.8 44.4[12] 150,100 125,000 Min 91
Premium Gasoline 39.5 Min 95
Autogas (LPG) (60% Propane + 40% Butane) 26.8 46 108
Ethanol 23.5 31.1[13] 101,600 84,600 129
Methanol 17.9 19.9 77,600 64,600 123
Butanol 29.2 91-99
Gasohol (10% ethanol + 90% gasoline) 33.7 145,200 120,900 93/94
Diesel 38.6 45.4 166,600 138,700 25(*)
Aviation gasoline (high octane gasoline, not jet fuel) 33.5 46.8 144,400 120,200
Jet fuel (kerosene based) 35.1 43.8 151,242 125,935
Liquefied natural gas 25.3 ~55 109,000 90,800
Hydrogen 121 130[14]

(*) 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

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 tuned to the use of LPG (that is, 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'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 (6.175 lb/US gal; 7.416 lb/imp gal).

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 U.S., octane ratings in unleaded fuels can vary between 86-87 AKI (91-92 RON) for regular, through 89-90 AKI (94-95 RON) for mid-grade (European Premium), up to 90-94 AKI (95-99 RON) for premium (European Super).

Additives

Lead

The mixture known as gasoline, when used in high 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 converters found on virtually all newly sold U.S. 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 hydrocarbons, ethers and alcohol (usually ethanol or methanol).

In the U.S., 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 percent of total gasoline sales and less than 2,000 short tons 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.[15] 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 bloodstreams.[16][17]

A side effect of the lead additives was protection of the valve seats from erosion. Many classic cars' 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.

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 January 1, 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.

U.S. Federal sources state that MMT is suspected to be a powerful neurotoxin and respiratory toxin,[18] and a large Canadian study concluded that MMT impairs the effectiveness of automobile emission controls and increases pollution from motor vehicles.[19]

In 1977, use of MMT was banned in the U.S. 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 U.S. Court of Appeals ruled that the EPA had exceeded its authority, and MMT became a legal fuel additive in the U.S. MMT is nowadays manufactured by the Afton Chemical Corporation division of Newmarket Corporation.[20]

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.

In several states, ethanol is added by law to a minimum level which is currently 5.9 percent. Most fuel pumps display a sticker stating that the fuel may contain up to 10 percent 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 percent ethanol. Many call this fuel mix gasohol.

In the EU, 5 percent ethanol can be added within the common gasoline spec (EN 228). Discussions are ongoing to allow 10 percent blending of ethanol. Most countries (fuel distributors) today do not add so much ethanol. Most gasoline (petrol) sold in Sweden has 5 percent ethanol added.

In Brazil, the Brazilian National Agency of Petroleum, Natural Gas and Biofuels (ANP) requires that gasoline for automobile use has 23 percent of ethanol added to its composition.

Dye

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 HGVs 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 U.S. oxygenate blending is mandated by EPA regulations to reduce smog and other airborne pollutants. For example, in Southern California, fuel must contain 2 percent oxygen by weight, resulting in a mixture of 5.6 percent 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.[21]

MTBE use is being phased out in some states due to issues with contamination of ground water. In some places, such as California, 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 percent ethanol mixed with gasoline is called 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 3.4 billion U.S. gallons (2.8 billion imp gal/13 million m³) of ethanol was produced in the United States for fuel use, mostly from 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.[22] 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 legally ferment and distill their own bio-ethanol at present (unlike in the U.S. where getting a BATF distillation permit has been easy since the 1973 oil crisis.)

Health concerns

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'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 anodes. Gasoline is rather volatile (meaning it readily 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 compounds produces carbon dioxide, nitrogen oxides, and carbon monoxide in the exhaust of the engine which is running on it. Furthermore, unburnt gasoline and 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.[23] In response, Opal fuel has been developed by the BP Kwinana Refinery in Australia, and contains only 5 percent aromatics (unlike the usual 25 percent) which inhibits the effects of inhalation.[24]

Like other alkenes, 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 vaporizes 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

The U.S. accounts for about 44 percent of the world’s gasoline consumption.[25][26] In 2003, The U.S. consumed Template:Convert/GL,[27] which equates to 1.3 gigalitres of gasoline each day (about 360 million U.S. gallons or 300 million imperial gallons). The U.S. used about 510 billion liters (138 billion U.S. gal/115 billion imp gal) of gasoline in 2006, of which 5.6 percent was mid-grade and 9.5 percent was premium grade.[28]

Western countries have among the highest usage rates per person.

Based on externalities, some countries, for example, in Europe and Japan, impose heavy fuel taxes 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 U.S.) when calculated as a percentage of cost-per-unit, but is actually less variable in absolute terms.

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,[29] 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.[30]

Gummy, sticky resin deposits result from oxidative degradation of gasoline. This degradation can be prevented through the use of antioxidants such as phenylenediamines, alkylenediamines (diethylenetriamine, triethylenetetramine, etc), and alkylamines (diethylamine, tributylamine, ethylamine). Other useful additives include gum inhibitors such as N-substituted alkylaminophenols and color stabilizers such as N-(2-aminoethyl)piperazine, N,N-diethylhydroxylamine, and triethylenetetramine.[31]

By 1975, improvements in refinery techniques have generally reduced the reliance on the catalytically or thermally cracked stocks most susceptible to oxidation.[32] Gasoline containing acidic contaminants such as naphthenic acids 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.[31]

"Stale" gasoline can be detected by a colorimetric enzymatic test for organic peroxides produced by oxidation of the gasoline.[33]

Other fuels

Many of these alternatives are less damaging to the environment than gasoline, but the first generation biofuels are still not 100 percent clean.

  • Biofuels:
    • Biodiesel, for diesel engines
    • Biobutanol, for gasoline engines
    • Bioethanol
    • Biogasoline
  • Compressed air
  • Hydrogen fuel
  • Electricity
  • Fossil fuels:
    • CNG (Compressed Natural Gas)
    • Petrodiesel

Bioconversion and biogasoline

XcelPlus Global Holdings, working in conjunction with Maverick BioFuels, developed the technology in which a fuel compatible with internal combustion gasoline engines 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 US$2.70 per U.S. gallon ($3.24/imp gal, 71¢/L).[34]

Companies such as Sapphire Energy are developing a means to "grow" gasoline, that is, produce it directly from living organisms (that is, algae). Biogasoline has the advantage of not needing any change in vehicle or distribution infrastructure.

See also

Notes

  1. Chromatography Online, gasoline components. Retrieved September 9, 2008.
  2. 2.0 2.1 Online Etymology Dictionary, Gasoline. Retrieved September 9, 2008.
  3. Window on State Government, Motor Fuels Tax Audit Procedures Manual—Ch 153—Glossary. Retrieved September 9, 2008.
  4. Petrochem Carless, History. Retrieved September 9, 2008.
  5. Ron Hincks, Our Motoring Heritage: Petrol & Oil, Chrysler Collector 154 (2004): 16–20.
  6. Daily Telegraph, Keeping track: All fired up about "petrol." Retrieved September 9, 2008.
  7. First Fuel Bank, Material Safety Data Sheet, Tesoro Petroleum Companies, Inc., USA. Retrieved September 9, 2008.
  8. NOAA, Bell Fuels: Lead-Free Gasoline Material Safety Data Sheet. Retrieved September 9, 2008.
  9. EPA, Week 1: Nationwide fuel waiver issued to bolster fuel supplies, U.S. Environmental Protection Agency. Retrieved September 9, 2008.
  10. Gravmag, Oil Industry Statistics from Gibson Consulting. Retrieved September 9, 2008.
  11. Oak Ridge National Laboratory, Appendix B, Transportation Energy Data Book, Center for Transportation Analysis. Retrieved September 9, 2008.
  12. George Thomas, Overview of Storage Development DOE Hydrogen Program, Sandia National Laboratories. Retrieved September 9, 2008.
  13. Calculated from heats of formation. Does not correspond exactly to the figure for MJ/l divided by density.
  14. The National Hydrogen Association, FAQs. Retrieved September 9, 2008.
  15. EPA, EPA Takes Final Step in Phaseout of Leaded Gasoline, U.S. Environmental Protection Agency. Retrieved September 9, 2008.
  16. Lourdes Schnaas, Stephen J. Rothenberg, María-Fernanda Flores, Sandra Martínez, Carmen Hernández, Erica Osorio, and Estela Perroni, Blood Lead Secular Trend in a Cohort of Children in Mexico City (1987–2002), Environ. Health. Perspect. 112(10): 1110–1115. Retrieved September 9, 2008.
  17. Paulino Pino, Tomás Walter, Manuel J. Oyarzún, Matthew J. Burden, and Betsy Lozoff, Rapid Drop in Infant Blood Lead Levels during the Transition to Unleaded Gasoline Use in Santiago, Chile, Archives of Environmental Health: An International Journal. 59 (4): 182–187.
  18. EPA, Comments of the Gasoline Additive MMT, U.S. Environmental Protection Agency. Retrieved September 9, 2008.
  19. CVMA, Final Report: Effects of MMT in Gasoline on Emissions from On-Road Motor Vehicles in Canada, Canadian Vehicle Manufacturers’ Association, and Association of International Automobile Manufacturers of Canada. Retrieved September 9, 2008.
  20. Afton Chemical, History of mmt®. Retrieved September 9, 2008.
  21. EPA, Removal of Reformulated Gasoline Oxygen Content Requirement (national) and Revision of Commingling Prohibition to Address Non-0xygenated Reformulated Gasoline (national), U.S. Environmental Protection Agency. Retrieved September 9, 2008.
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References
ISBN links support NWE through referral fees

  • Blume, David, R., Buckminster (FWS) Fuller, and Michael Winks. 2007. Alcohol Can Be a Gas!: Fueling an Ethanol Revolution for the 21st Century. Santa Cruz, CA: International Institute for Ecological Agriculture. ISBN 0979043772.
  • Conaway, Charles F. The Petroleum Industry: A Nontechnical Guide. Tulsa, OK: PennWell, 1999. ISBN 978-0878147632
  • Hyne, Norman J. Nontechnical Guide to Petroleum Geology, Exploration, Drilling, and Production, 2nd ed. Tulsa, OK: PennWell, 2001. ISBN 087814823X.
  • McCain, William D. The Properties of Petroleum Fluids. Tulsa, OK: PennWell, 1989. ISBN 0878143351.
  • McKetta, John J. Jr. (ed.). Encyclopedia of Chemical Processing and Design: Volume 31—Natural Gas Liquids and Natural Gasoline to Offshore Process Piping: High Performance Alloys ... of Chemical Processing and Design. CR Press, 1989. ISBN 082472481X.
  • Meyers, Robert A. Handbook of Petroleum Refining Processes, 3rd ed. McGraw-Hill Handbooks. New York: McGraw-Hill, 2004. ISBN 0071391092.
  • Wendel, C.H. American Gasoline Engines Since 1872. Osceola, WI: Motorbooks International, 1999. ISBN 0760307849.

External links

All links retrieved May 23, 2017.

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