The number of flights performed per year increased steadily throughout the 2000s and 2010s. In 2019, the number of flights performed annually peaked at 38.9 million. Flying is an essential part of how the world functions, with people holidaying and taking business trips, and freight being transported from country to country. But have you ever thought about the fuel that aeroplanes rely on? Aviation kerosene is the fuel of choice for aircraft across the globe. But why do planes use kerosene over other types of fuel? Let’s find out…
One of the primary reasons as to why jets rely on kerosene is due to its low freezing point. Aviation kerosene has a freezing point of -47 °C.
Planes fly at extremely high altitudes, which means they spend a lot of airtime in sub-zero temperatures. As a result, planes need to use fuel with a low freezing point – like kerosene - so the fuel functions properly without solidifying during the flight.
Highly Flammable
Kerosene is highly flammable, more so than diesel, which gives it the explosive burning qualities required for take-off. In fact, diesel’s lack of flammability would not generate enough initial power to get the plane off the ground, ruling it out as an option.
Gasoline is also highly flammable, but its energy pay back is poor and fuel consumption too rapid, which is more inefficient. This means a plane would have to carry a greater volume of fuel for the same journey duration.
Low Viscosity
Aviation kerosene is less viscous than gasoline when used during flight, making it the preferred choice for jet crafts. Liquids with a high viscosity are thick, sticky and gluey – this is not an ideal property for jet fuel!
Kerosene maintains a low viscosity during flights thanks to its low freezing point. This means it will keep the plane running as it should and won’t clog up the engine.
Affordable
Kerosene is much cheaper than gasoline, making it a more affordable option for airlines. Flights are an expensive operation, so its important for airlines to use a cheaper source of fuel without compromising safety.
Safe
Safety is a crucial factor for all airlines, and aviation kerosene is an extremely safe source of fuel.
Firstly, kerosene has a higher flash point than gasoline, meaning its unlikely to cause unplanned combustion.
Secondly, kerosene has a lower freezing point, so it won't thicken up and clog the engine when the plane is moving through extremely low temperatures.
Thirdly, aviation kerosene has additives to enhance its safety and reduce the risk of unplanned hazards. These additives include anticorrosive agents, anti-static chemicals and de-icing agents.
Is Aviation Kerosene and Jet Fuel the Same Thing?
Jet Fuel is most commonly referred to as Jet A1, but its technical name is actually Avtur (Aviation Turbine Fuel). Avtur is designed for use in both turbo-jet and turbo-prop aircraft, which basically accounts for all modern planes of any real size. Avtur can rightfully be mixed up with is standard grade kerosene, because that is what it is, and, in the UK at least, this is the grade of fuel that is also used for heating oil in boilers and home-range cooking stoves!
Aviation Fuel Facts
A “standard” 747 in mid-flight will burn approximately 4 litres of fuel every second which, based on a cruising speed of 565 mph, means consumption of 25 litres per mile (giving a fuel economy range of 0.18 miles per gallon!).
A 747 has the capacity to carry a staggering 220,000 litres and this only gives it a distance range of around 8,500 miles - not enough to get to Australia from London non-stop.
A 747 with a full tank of fuel, adds an incredible 175 tonnes to the plane’s payload.
Total consumption of jet fuel in the UK is an impressive 15bn litres per annum, but an incredible 55% of this volume goes through Heathrow – that’s over 22m litres per day.
All of Heathrow’s jet fuel comes in by pipeline - either direct from refineries (Immingham, Fawley and Stanlow can all pump product directly into Heathrow’s fuel farm) or via import pipelines from the Thames estuary (over 60% of UK jet fuel is now imported).
Once it arrives at Heathrow, the Avtur is stored in the airport tank before being further distributed via its 80 miles of pipelines. This incredible underground “hydrant” system runs the length and breadth of the airport and has multiple fuelling points to allow the airport’s mobile bowsers to connect up and fuel planes across the whole Heathrow complex.
It’s hard to believe that all this is going on at the airport!
Hopefully you now understand why planes use kerosene over other popular fuels, like gasoline and diesel. Kerosene offers airlines so many benefits including safe flights, lower costs and lighter aircrafts.
