Aviation fuel is a specialized type of petroleum-based fuel used to power aircraft. It is generally of a higher quality than fuels used in less critical applications, such as heating or road transport, and often contains additives to reduce the risk of icing or explosion due to high temperatures, among other properties.
Most aviation fuels available for aircraft are kinds of petroleum spirit used in engines with spark plugs, i.e. piston and Wankel rotary engines, or fuel for jet turbine engines, which is also used in diesel aircraft engines. Alcohol, alcohol mixtures and other alternative fuels may be used experimentally, but alcohol is not permitted in any certified aviation fuel specification.
Avgas is sold in much lower volumes, but to many more individual aircraft, whereas jet fuel is sold in high volumes to large aircraft operated typically by airlines, military and large corporate aircraft.
The Convention on International Civil Aviation, which came into effect in 1947, exempted air fuels from tax. Australia and the USA oppose a worldwide levy on aviation fuel, but a number of other countries have expressed interest.
Jet fuel is a mixture of a large number of different hydrocarbons. The range of their sizes (molecular weights or carbon numbers) is restricted by the requirements for the product, for example, the freezing point or smoke point. Kerosene-type jet fuel (including Jet A and Jet A-1) has a carbon number distribution between about 8 and 16 carbon numbers; wide-cut or naphtha-type jet fuel (including Jet B), between about 5 and 15 carbon numbers.
The primary differences between Jet A and Jet A-1 are the higher freezing point of Jet A (−40 °C vs −47 °C for Jet A-1), and the mandatory requirement for the addition of an anti-static additive to Jet A-1.
Like Jet A-1, Jet A can be identified in trucks and storage facilities by the UN number 1863 Hazardous Material placards. Jet A trucks, storage tanks, and pipes that carry Jet A are marked with a black sticker with a white "Jet A" written over it, next to another black stripe.
The annual U.S. usage of jet fuel was 20.2 billion US gallons (7.6×1010 L) in 2009.
Jet A Fuel must reach ASTM specification D1655 (Jet A)
Typical physical properties for Jet A / Jet A-1 fuel:
There are several methods for detecting water in jet fuel. A visual check may detect high concentrations of suspended water, as this will cause the fuel to become hazy in appearance. An industry standard chemical test for the detection of free water in jet fuel uses a water-sensitive filter pad that turns green if the fuel exceeds the specification limit of 30ppm (parts per million) free water.
Synthetic jet fuels show a reduction in pollutants such as SOx, NOx, particulate matter, and hydrocarbon emissions. It is envisaged that usage of synthetic jet fuels will increase air quality around airports which will be particularly advantageous at inner city airports.
Green Flight International became the first airline to fly jet aircraft on 100% biofuel. The flight from Stead airport in Stead, Nevada was in an Aero L-29 Delfín piloted by Carol Sugars and Douglas Rodante.
Most aviation fuels available for aircraft are kinds of petroleum spirit used in engines with spark plugs, i.e. piston and Wankel rotary engines, or fuel for jet turbine engines, which is also used in diesel aircraft engines. Alcohol, alcohol mixtures and other alternative fuels may be used experimentally, but alcohol is not permitted in any certified aviation fuel specification.
Avgas is sold in much lower volumes, but to many more individual aircraft, whereas jet fuel is sold in high volumes to large aircraft operated typically by airlines, military and large corporate aircraft.
The Convention on International Civil Aviation, which came into effect in 1947, exempted air fuels from tax. Australia and the USA oppose a worldwide levy on aviation fuel, but a number of other countries have expressed interest.
Energy content
The net energy content for aviation fuels depends on their composition. Some typical values are:- BP Avgas 80, 44.65 MJ/kg, density at 15 C is 690 kg/m3
- Kerosene type BP Jet A-1, 43.15 MJ/kg, density at 15 C is 804 kg/m3
- Kerosene type BP Jet TS-1, (for lower temperatures) 43.2 MJ/kg, density at 15 C is 787 kg/m3
Chemical composition
Aviation fuels consist of blends of over a thousand chemicals, primarily hydrocarbons (paraffins, olefins, naphthenes, and aromatics), as well as additives, such as antioxidants and metal deactivators, and impurities. Principal components include n-heptane and isooctane. Like other fuels, blends of aviation fuel used in spark-ignited piston-engined aircraft are often described by their octane rating.Jet fuel
Jet fuel is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines. It is clear to straw-colored in appearance. The most commonly used fuels for commercial aviation are Jet A and Jet A-1 which are produced to a standardized international specification. The only other jet fuel commonly used in civilian turbine-engine powered aviation is Jet B which is used for its enhanced cold-weather performance.Jet fuel is a mixture of a large number of different hydrocarbons. The range of their sizes (molecular weights or carbon numbers) is restricted by the requirements for the product, for example, the freezing point or smoke point. Kerosene-type jet fuel (including Jet A and Jet A-1) has a carbon number distribution between about 8 and 16 carbon numbers; wide-cut or naphtha-type jet fuel (including Jet B), between about 5 and 15 carbon numbers.
Differences between Jet A and Jet A-1
Jet A specification fuel has been used in the United States since the 1950s and is only available in the United States, whereas Jet A-1 is the standard specification fuel used in the rest of the world. Both Jet A and Jet A-1 have a flash point higher than 38 °C (100 °F), with an autoignition temperature of 210 °C (410 °F). This means that the fuel is safer to handle than traditional avgas.The primary differences between Jet A and Jet A-1 are the higher freezing point of Jet A (−40 °C vs −47 °C for Jet A-1), and the mandatory requirement for the addition of an anti-static additive to Jet A-1.
Like Jet A-1, Jet A can be identified in trucks and storage facilities by the UN number 1863 Hazardous Material placards. Jet A trucks, storage tanks, and pipes that carry Jet A are marked with a black sticker with a white "Jet A" written over it, next to another black stripe.
The annual U.S. usage of jet fuel was 20.2 billion US gallons (7.6×1010 L) in 2009.
ypical physical properties for Jet A and Jet A-1
Jet A-1 Fuel must meet the specification for DEF STAN 91-91 (Jet A-1), ASTM specification D1655 (Jet A-1) and IATA Guidance Material (Kerosine Type), NATO Code F-35.Jet A Fuel must reach ASTM specification D1655 (Jet A)
Typical physical properties for Jet A / Jet A-1 fuel:
| Jet A-1 | Jet A | |
| Flash point | 42 °C | 51.1 °C |
| Autoignition temperature | 210 °C (410 °F) | |
| Freezing point | −47 °C (−52.6 °F) | −40 °C (−40 °F) |
| Open air burning temperatures | 260-315 °C (500-599 °F) | |
| Density at 15 °C (59 °F) | .804 kg/L | .820 kg/L |
| Specific energy | 43.15 MJ/kg | 43.02 MJ/kg |
| energy density | 34.7 MJ/L | 35.3 MJ/L |
Jet B
Jet B is a fuel in the naphtha-kerosene region that is used for its enhanced cold-weather performance. However, Jet B's lighter composition makes it more dangerous to handle. For this reason it is rarely used, except in very cold climates.Additives
The DEF STAN 91-91 (UK) and ASTM D1655 (international) specifications allow for certain additives to be added to jet fuel, including:- Antioxidants to prevent gumming, usually based on alkylated phenols, e.g., AO-30, AO-31, or AO-37;
- Antistatic agents, to dissipate static electricity and prevent sparking; Stadis 450, with dinonylnaphthylsulfonic acid (DINNSA) as the active ingredient, is an example
- Corrosion inhibitors, e.g., DCI-4A used for civilian and military fuels, and DCI-6A used for military fuels;
- Fuel System Icing Inhibitor (FSII) agents, e.g., Di-EGME; FSII is often mixed at the point-of-sale so that users with heated fuel lines do not have to pay the extra expense.
- Biocides are to remediate microbial (i.e., bacterial and fungal) growth present in aircraft fuel systems. Currently, two biocides are approved for use by most aircraft and turbine engine original equipment manufacturers (OEMs); Kathon FP1.5 Microbiocide and Biobor JF.
- Metal deactivator can be added to remediate the deleterious effects of trace metals on the thermal stability of the fuel. The one allowable additive is N,N’-disalicylidene 1,2-propanediamine.
Water in jet fuel
It is very important that jet fuel be free from water contamination. During flight, the temperature of the fuel in the tanks decreases, due to the low temperatures in the upper atmosphere. This causes precipitation of the dissolved water from the fuel. The separated water then drops to the bottom of the tank, because it is denser than the fuel. From this time on, as the water is no longer in solution, it can freeze, blocking fuel inlet pipes. Removing all water from fuel is impractical, therefore fuel heaters are usually used on commercial aircraft to prevent water in fuel from freezing.There are several methods for detecting water in jet fuel. A visual check may detect high concentrations of suspended water, as this will cause the fuel to become hazy in appearance. An industry standard chemical test for the detection of free water in jet fuel uses a water-sensitive filter pad that turns green if the fuel exceeds the specification limit of 30ppm (parts per million) free water.
Synthetic jet fuel
A significant effort is under way to certify Fischer–Tropsch (FT) synthetic fuels for use in U.S. and international aviation fleets. In this effort is being led by an industry coalition known as the Commercial Aviation Alternative Fuels Initiative (CAAFI), also supported by a parallel initiative under way in the U.S. Air Force, to certify FT fuel for use in all aviation platforms. The U.S. Air Force has a stated goal of certifying its entire fleet for use with FT synthetic fuel blends by 2011. The CAAFI initiative aims to certify the civilian aviation fleet for FT synthetic fuels blends by 2010, and has programs under way to certify HRJ hydrogenated biofuels as early as 2013.Synthetic jet fuels show a reduction in pollutants such as SOx, NOx, particulate matter, and hydrocarbon emissions. It is envisaged that usage of synthetic jet fuels will increase air quality around airports which will be particularly advantageous at inner city airports.
- Qatar Airways became the first airline to operate a commercial flight on a 50:50 blend of synthetic GTL jet fuel and conventional jet fuel. The natural gas derived synthetic kerosene for the six-hour flight from London to Doha came from Shell’s GTL plant in Bintulu, Malaysia.
Jet biofuels
The air transport industry is responsible for 2 percent of man-made carbon dioxide emitted . Boeing estimates that biofuels could reduce flight-related greenhouse-gas emissions by 60 to 80 percent. One possible solution which has received more media coverage than others would be blending synthetic fuel derived from algae with existing jet fuel:Green Flight International became the first airline to fly jet aircraft on 100% biofuel. The flight from Stead airport in Stead, Nevada was in an Aero L-29 Delfín piloted by Carol Sugars and Douglas Rodante.
- Boeing and Air New Zealand are collaborating with Tecbio Aquaflow Bionomic and other jet biofuel developers around the world.
- Virgin Atlantic successfully tested a biofuel blend consisting of 20% babassu nuts and coconut and 80% conventional jet fuel, which was fed to a single engine on a 747 flight from London to Amsterdam.
- A consortium consisting of Boeing, NASA's Glenn Research Center, MTU Aero Engines (Germany), and the U.S. Air Force Research Laboratory is working on development of jet fuel blends containing a substantial percentage of biofuel.
