O emissions are influenced by fuel composition. Figure 7-34 shows the distribution of fuel hydrogen content from the UK survey. O are 3.15 0.01 and 1.25 0.03, respectively, where the variations allow for the range of hydrogen content found in jet fuels. Increasing the hydrogen content of jet fuel has been considered as a way of reducing CO 2 emissions. However, most of the larger values came from two small refineries in southern Europe, whereas larger refineries had much lower values.
Sulfur is removed as a part of hydro-processing.
Reducing the sulfur level would have no direct impact on engine performance or durability. Military fuels use a lubricity additive to guard against the possibility of low-lubricity fuels. Civilian airlines have not found a need to use such additives, except in a few isolated localities where pump failures have occurred and there was little flexibility in fuel selection.