Fuel currently used for turbine jet engines is refined from crude oil and is kero­sene-based with selected additives to provide the desired properties. Jet fuel is an energy-dense hydrocarbon fuel. The international jet fuel, called Jet A-1, has a specific energy of 43.15 MJ/kg and an energy density of 34.7 MJ/L, has low freezing and high flash points, and relatively low viscosity, making it ideal for long­distance flight. At least four standards exist for jet fuel:

1. Jet-A is the standard fuel for commercial and private US aviation and has a freezing point below —■40°C.

2. Jet A-l is the standard fuel for commercial and private European aviation and has a freezing point below —47°C.

3. Jet propellant 8 (JP-8) is the US military and NATO standard for jet fuel used in military aircraft, and has the same freezing point as Jet A-1.

4. Synthetic paraffinic kerosene (Bio-SPK). ASTM D7566 synthetic jet fuel: aviation turbine fuel containing synthesized hydrocarbons.

The Bio-SPK fuel used in test flights by airlines like Continental, KLM, Japan Airlines, TAM, and Air New Zealand either met or exceeded all of the performance specifications for jet fuel. In addition, the Bio-SPK jet fuel demonstrated a higher energy density per unit mass than typical jet fuel, so airplanes could fly a longer distance using less fuel. Carbon dioxide emissions were reduced substantially as well. For all of the test flights, the blended biofuel displayed no adverse effects on any of the aircraft systems (see Chapter ).

17.7