Jet fuel smells like itself: oil, chemicals, potential. In a glass, it resembles vodka, or sometimes a pale tequila. It is less heavy than water, cheaper by weight than milk, and harder to set alight with a flaming match than ethanol. Where kerosene is more refined than diesel, so jet fuel is more refined than kerosene. For chemists, it is a jumble of Cs and Hs, and the occasional sulfurous S; for mechanics, it is something to avoid splashing on your skin. For the aviation industry, it is a puzzle.
That’s because this unglamorous substance is the best thing we’ve yet found to power the planes that allow us to cross the earth. It’s not the only thing—planes will run on many different kinds of fuel—but it is, for now, the best balance between cost and energy density.
For the planet, jet fuel is not the best option. The process of first extracting it from the earth and then refining it is exceptionally bad for the environment—burning it, meanwhile, pumps thousands of tons of carbon dioxide into the air every year.