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'''Aviation fuels''' are [[petroleum]]-based [[fuel]]s, or petroleum and synthetic fuel blends, used to power [[aircraft]]. They have more stringent requirements than fuels used for ground use, such as [[heating]] and [[road transport]], and contain additives to enhance or maintain properties important to fuel performance or handling. They are [[kerosene]]-based ([[JP-8]] and [[Jet A-1]]) for gas turbine-powered aircraft. Piston-engined aircraft use [[leaded gasoline]] and those with diesel engines may use [[jet fuel]] (kerosene).<ref name=chevron>{{Cite web|url=https://www.skybrary.aero/bookshelf/books/2478.pdf|title = SKYbrary Aviation Safety}}</ref> By 2012, all aircraft operated by the [[United States Air Force|U.S. Air Force]] had been certified to use a 50-50 blend of kerosene and synthetic fuel derived from coal or natural gas as a way of stabilizing the cost of fuel.<ref>{{Cite web|url=https://www.airforcemag.com/article/0712fuel/|title=The Air Force's Fuel Problem}}</ref>
==Types of aviation fuel==
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[[File:Mig-29 refueling.jpg|thumb|Ground fueling of a [[MIG-29|MiG-29]] from a [[Ural-4320|URAL tanker]] (2011)]]
'''Jet fuel''' is a clear to straw-colored fuel, based on either an [[unleaded]] [[kerosene]] (Jet A-1), or a [[naphtha]]-[[kerosene]] blend (Jet B). Similar to [[diesel fuel]], it can be used in either [[Diesel engine|compression ignition engine]]s or [[Gas turbine|turbine engine]]s.<ref name=chevron/>
Jet-A powers modern commercial airliners and is a mix of extremely refined kerosene and burns at temperatures at or above {{convert|49|C}}. Kerosene-based fuel has a much higher flash point than gasoline-based fuel, meaning that it requires significantly higher temperature to ignite. It is a high-quality fuel; if it fails the purity and other quality tests for use on jet aircraft, it is sold to ground-based users with less demanding requirements, such as railroads.<ref>{{cite web |last=U.S. Centennial of Flight Commission |title=Aviation Fuel |url=http://www.centennialofflight.gov/essay/Evolution_of_Technology/fuel/Tech21.htm |access-date=10 May 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120420064213/http://www.centennialofflight.gov/essay/Evolution_of_Technology/fuel/Tech21.htm |archive-date=20 April 2012 }}</ref>
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==== Biofuels ====
Alternatives to conventional fossil-based aviation fuels, new fuels made via the [[biomass to liquid]] method (like [[sustainable aviation fuel]]) and [[Aviation biofuel|certain straight vegetable oils]] can also be used.<ref>{{cite journal |pmc = 5801801|year = 2018|last1 = Wang|first1 = M.|title = Highly efficient conversion of plant oil to bio-aviation fuel and valuable chemicals by combination of enzymatic transesterification, olefin cross-metathesis, and hydrotreating|journal = Biotechnology for Biofuels|volume = 11|pages = 30|last2 = Chen|first2 = M.|last3 = Fang|first3 = Y.|last4 = Tan|first4 = T.|pmid = 29445419|doi = 10.1186/s13068-018-1020-4 | doi-access=free }}</ref>
Fuels such as sustainable aviation fuel have the advantage that few or no modifications are necessary on the aircraft itself, provided that the fuel characteristics meet specifications for lubricity and density as well as adequately swelling elastomer seals in current aircraft fuel systems.<ref>{{cite journal |last1=Corporan |first1=Edwin |display-authors=et al |title=Chemical, Thermal Stability, Seal Swell, and Emissions Studies of Alternative Jet Fuels|journal=Energy & Fuels |date=2011 |volume=25 |issue=3 |pages=955–966 |doi=10.1021/ef101520v}}</ref> Sustainable aviation fuel and blends of fossil and sustainably-sourced alternative fuels yield lower emissions of particles<ref>{{cite journal |last1=Moore |first1=R. H.|display-authors=et al|title=Biofuel blending reduces particle emissions from aircraft engines at cruise conditions|journal=Nature|date=2017|volume=543|issue=7645|pages=411–415|doi=10.1038/nature21420|pmid=28300096|pmc=8025803|bibcode=2017Natur.543..411M|url=https://elib.dlr.de/112943/1/Moore_et_al_Nature_2017.pdf}}</ref> and GHGs. They are, however, not being used heavily, because they still face political, technological, and economic barriers, such as currently being more expensive than conventionally produced aviation fuels by a wide margin.<ref>{{cite web|url=http://www.kic-innoenergy.com/wp-content/uploads/2016/03/RREB_Biofuels_in_Aviation_Draft_Final.pdf|title=RREB report|website=kic-innoenergy.com|access-date=7 May 2018|url-status=live|archive-url=https://web.archive.org/web/20160914130724/http://www.kic-innoenergy.com/wp-content/uploads/2016/03/RREB_Biofuels_in_Aviation_Draft_Final.pdf|archive-date=14 September 2016}}</ref><ref>IATA 2014 Report on Alternative Fuels</ref><ref>{{cite web|url=http://www.sqconsult.com/content/newsletter_html/mrt_14_SQ_Consult_Bringing_biojet_fuels_to_the_market.html|title=Bringing biojet fuels to the market|access-date=2016-12-27|url-status=dead|archive-url=https://web.archive.org/web/20161105204547/http://www.sqconsult.com/content/newsletter_html/mrt_14_SQ_Consult_Bringing_biojet_fuels_to_the_market.html|archive-date=2016-11-05}}</ref>
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==== Compressed natural gas and liquified natural gas ====
{{Main|Natural_gas#Transportation}}
[[Compressed natural gas]] (CNG) and [[Liquefied natural gas#Transportation|liquified natural gas]] (LNG) are fuel feedstocks that aircraft may use in the future. Studies have been done on the feasibility of using natural gas<ref>{{cite web|url=http://lae.mit.edu/aircraft-design/|title=Aircraft Design - MIT Laboratory for Aviation and the Environment|access-date=27 December 2016|url-status=dead|archive-url=https://web.archive.org/web/20161230163921/http://lae.mit.edu/aircraft-design/|archive-date=2016-12-30}}</ref> and include the "SUGAR Freeze" aircraft under NASA's N+4 Advanced Concept Development program (made by Boeing's Subsonic Ultra Green Aircraft Research (SUGAR) team). The [[Tupolev Tu-155]] was an alternative fuel testbed which was fuelled on LNG.<ref>{{cite web|url=http://midwestenergynews.com/2013/08/26/could-natural-gas-fuel-commercial-flights-of-the-future/|title=Could natural gas fuel commercial flights of the future?|last=EnergyWire|access-date=2016-12-27|url-status=live|archive-url=https://web.archive.org/web/20161105204049/http://midwestenergynews.com/2013/08/26/could-natural-gas-fuel-commercial-flights-of-the-future/|archive-date=2016-11-05}}</ref> The low [[specific energy]] of natural gas even in liquid form compared to conventional fuels gives it a distinct disadvantage for flight applications.{{citation needed|date=March 2018}}
==== Liquid hydrogen ====
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|doi-access=free}}</ref> With materials available in the 2020s, the mass of tanks strong enough to withstand this kind of high pressure will greatly outweigh the hydrogen fuel itself, largely negating the weight to energy advantage of hydrogen fuel over hydrocarbon fuels. Hydrogen has a severe volumetric disadvantage relative to hydrocarbon fuels, but future [[blended wing body]] aircraft designs might be able to accommodate this extra volume without greatly expanding the [[wetted area]].
Even if finally practical, the industry timeline for adopting hydrogen is fairly lengthy. Alternatives to conventional aviation fuel available in the near term include [[aviation biofuel]] and synthetically created fuel (aka "e-jet").<ref>{{Cite web|last=Trakimavicius|first=Lukas|date=December 2023|title=Mission Net-Zero: Charting the Path for E-fuels in the Military|url=https://www.enseccoe.org/data/public/uploads/2023/11/d5_mission-net-zero-charting-the-path-for-e-fuels-in-the-military-by-lukas-trakimavicius.pdf |publisher=NATO Energy Security Centre of Excellence}}</ref> These fuels are collectively referred to as "Sustainable Aviation Fuel" (SAF).
==Production of aviation fuel==
The production of aviation fuel falls into two categories: fuel suitable for [[Gas turbine|turbine engine]]s and fuel suitable for spark-ignition piston engines. There are international specifications for each.
[[Jet fuel]] is a gas turbine fuel used in propeller and jet aircraft and helicopters. It has a low [[viscosity]] at low temperature, has limited ranges of density and [[calorific value]], burns cleanly, and remains chemically stable when heated to high temperature.<ref>{{cite web|author=Air BP |title=Avgas vs Jet Fuel |url=http://www.bp.com/sectiongenericarticle.do?categoryId=4503818&contentId=57639 |access-date=10 May 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120425054146/http://www.bp.com/sectiongenericarticle.do?categoryId=4503818&contentId=57639 |archive-date=25 April 2012 }}</ref>
[[Aviation gasoline]], often referred to as "avgas" or 100-LL (low-lead), is a highly refined form of [[gasoline]] for aircraft, with an emphasis on purity, [[engine knock|anti-knock]] characteristics and minimization of [[spark plug]] fouling. Avgas must meet performance guidelines for both the rich mixture condition required for take-off power settings and the leaner mixtures used during cruise to reduce fuel consumption. Aviation fuel can be used as CNG fuel.
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The [[net energy content]] for aviation fuels depends on their composition. Some typical values are:<ref>[[Air BP]]. [http://www.bp.com/liveassets/bp_internet/aviation/air_bp/STAGING/local_assets/downloads_pdfs/a/air_bp_products_handbook_04004_1.pdf BP Products handbook] {{webarchive|url=https://web.archive.org/web/20110608075828/http://www.bp.com/liveassets/bp_internet/aviation/air_bp/STAGING/local_assets/downloads_pdfs/a/air_bp_products_handbook_04004_1.pdf |date=2011-06-08 }}. Retrieved 2008-09-13</ref>
*BP Avgas 80, [[Orders of magnitude (energy)#1E6|44.65]]{{Broken anchor|date=2024-05-26|bot=User:Cewbot/log/20201008/configuration|target_link=Orders of magnitude (energy)#1E6|reason= The anchor (1E6) [[Special:Diff/383867230|has been deleted]].}} [[Joule|MJ]]/kg, density at 15 °C is 690 kg/[[cubic metre|m<sup>3</sup>]] ({{Round|44.65*690/1000|2}} MJ/litre).
*Kerosene type BP Jet A-1, 43.15 MJ/kg, density at 15 °C is 804 kg/m<sup>3</sup> ({{Round|43.15*804/1000|2}} MJ/litre).
*Kerosene type BP Jet TS-1 (for lower temperatures), 43.2 MJ/kg, density at 15 °C is 787 kg/m<sup>3</sup> ({{Round|43.2*787/1000|2}} MJ/litre).
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===Forecasting demand===
In recent years, fuel markets have become increasingly volatile. This, along with rapidly changing airline schedules and the desire to not carry excess fuel on board aircraft, has increased the importance of demand forecasting. In March 2022, Austin's Austin-Bergstrom International Airport came close to running out of fuel, potentially stranding aircraft.<ref>{{Cite web |last=Best |first=Paul |date=March 28, 2022 |title=Austin airport sends out fuel shortage alert amid 'increased flight activity' |website=[[Fox Business]] |url=https://www.foxbusiness.com/economy/austin-texas-airport-fuel-shortage-alert-increased-flight-activity
== Safety precautions ==
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* [https://web.archive.org/web/20121018042938/http://www.bp.com/sectiongenericarticle.do?categoryId=4503664&contentId=57733 History of jet fuels] (by [[BP|AirBP]])
* [https://web.archive.org/web/20090704014521/http://www.chevron.com/products/ourfuels/prodserv/fuels/documents/aviation_fuels.pdf Aviation Fuels Technical Review] (by [[Chevron Corporation|Chevron Global Aviation]])
{{DEFAULTSORT:Aviation Fuel}}
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