Biofuel

Almost all commercial aircraft burn kerosene derived from oil. It is possible to produce kerosene-type alternative fuels from coal or gas using the Fischer-Tropsch process (developed by German scientists during World War II) though the conversion process is both costly and carbon-intensive.

There is therefore increasing interest in trying to find a fuel from a renewable, plant-based source that can be used in aircraft. Currently, both technical and social problems lie in the way. Biofuels freeze at high altitudes except when blended with kerosene, and concerns about displacement of food sources have cast doubt on the environmental and social benefit of biofuels in general.