Jet fuel

Jet fuel is a type of aviation fuel designed for use in jet-engined aircraft.

Description
Jet fuel is clear to straw colored. The most common fuel is an unleaded/paraffin (kerosene) oil-based fuel classified as Jet A-1 (otherwise known as AVTUR), which is produced to an internationally standardized set of specifications. (see below).

The only other jet fuel that is commonly used in civilian turbine engine-powered aviation is called Jet B, 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, and it is thus restricted only to areas where its cold-weather characteristics are absolutely necessary.

Jet fuel is a mixture of a large number of different hydrocarbons, possibly as many as a thousand or more. The range of their sizes (molecular weights or carbon numbers) is restricted by the requirements for the product, for example, 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.

Both standard jet fuels (Jet A and Jet B) may contain a number of additives:
 * Antioxidants to prevent gumming, usually based on alkylated phenols, eg. 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.
 * Biocide can be added if evidence of bacterial colonies inside the fuel system exists.

Militaries around the world use a different classification system of JP numbers. Some are almost identical to their civilian counterparts and differ only by the amounts of a few additives; Jet A-1 is similar to JP-8, Jet B is similar to JP-4. Other military fuels are highly specialized products and are developed for very specific applications. JP-5 fuel is fairly common, and was introduced to reduce the risk of fire on aircraft carriers (has a higher flash point - a minimum of 60 °C). Other fuels were specific to one type of aircraft. JP-6 was developed specifically for the XB-70 Valkyrie and JP-7 for the SR-71 Blackbird. Both these fuels were engineered to have a high flash point to better cope with the heat and stresses of high speed supersonic flight. One aircraft-specific jet fuel still in use by the United States Air Force is JPTS, which was developed in 1956 for the Lockheed U-2 spy plane.

Jet fuels are sometimes classified as kerosene or naphtha-type. Kerosene-type fuels include Jet A, Jet A1, JP-5 and JP-8. Naphtha-type jet fuels, sometimes referred to as "wide-cut" jet fuel, include Jet B and JP-4.

Jet A
Jet A is the standard jet fuel type in the U.S. since the 1950s and is only available there. Jet A is similar to Jet-A1, except for its higher freezing point of −40 °C (vs −47 ° Jet A-1). Like Jet A-1, Jet A has a fairly high flash point of 38 °C, with an autoignition temperature of 410 °F (210 °C). 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 will be marked with a black sticker with a white "Jet A" written over it, next to another black stripe. Jet A will have a clear to straw color if it is clean and free of contamination. Water is denser than Jet A, and will collect on the bottom of a tank. Jet A storage tanks must be sumped on a regular basis to check for water contamination. It is possible for water particles to become suspended in Jet A, which can be found by performing a "Clear and Bright" test. A hazy appearance can indicate water contamination beyond the acceptable limit of 30ppm (parts per million).

The U.S. commercial fuels are not required by law to contain antistatic additives, and generally do not.

The annual U.S. usage of jet fuel was 21 billion gallons (80 billion liters) in 2006.

A consortium consisting of Boeing, NASA Glenn Research Center, MTU Aero Engines (Germany), and the US Air Force Research Laboratory is investigating development of jet fuel blends containing a substantial percentage of bio-fuel. 

History of jet fuel
Fuel for a piston-engine powered aircraft (usually a high-octane gasoline known as Avgas) has a low flash point to improve its ignition characteristics. Turbine engines can operate with a wide range of fuels, and jet-aircraft engines typically use fuels with higher flash points, which are less flammable and therefore safer to transport and handle. The first jet fuels were based on kerosene or a gasoline-kerosene mix, and most jet fuels are still kerosene-based.

Piston engine use
Jet fuel is very similar to diesel fuel, and a few aircraft engine manufacturers, most notably Thielert, have begun offering piston engines which run on jet fuel. The technology promises to be a way to provide light, powerful, and environmentally-friendly engines for the general aviation market while simplifying airport logistics and phasing out leaded avgas.

Jet fuel is often used in ground support vehicles at airports, instead of diesel. The United States military makes heavy use of JP-8, for instance. However, jet fuel tends to have poor lubricating ability in comparison to diesel, thereby increasing wear on fuel pumps and other related engine parts. Civilian vehicles tend to disallow its use, or require that an additive be mixed with the jet fuel in order to restore its lubricity.

Jet biofuels
The airline industry is responsible for about 11 percent of greenhouse gases emitted by the U.S. transportation sector. Boeing estimates that biofuels could reduce flight-related greenhouse-gas emissions by 60 to 80 percent. The solution would be blending algae fuels with existing jet fuel:

Green Flight International flew the World's first jet aircraft on 100% biodiesel. The flight was in a single engine L-29 Jet piloted by Douglas Rodante and Carol Sugars.
 * Boeing and Air New Zealand are collaborating with leading Brazilian biofuels maker Tecbio and Aquaflow Bionomic of New Zealand and other jet biofuel developers around the world.
 * Virgin Atlantic successfully tested a biofuel made from babassu nuts and coconut on a single engine on a 747 flight from London to Amsterdam.

Oil prices increased about fivefold from 2003-2008, raising fears that world petroleum production is becoming unable to keep up with demand. The near-total dependency on petroleum for aviation fuel adds extra urgency to the search for alternatives.