The current fleet of aircraft consumes 2.4 billion gallons of jet fuel per year. The A-10 test flight went well with “no problems whatsoever” according to the pilot. Biofuel used in the A-10 flight is referred to as hydrotreated renewable jet, or HRJ. The biomass-derived fuel is created from animal fats and plant oils. This summer, the Air Force plans to expand the biofuel testing to the F-15 as well. Later in the year the biofuel blend will be used in both the four-engined C-17 Globemaster as well as in the F-22 Raptor, the Air Force’s high-end stealth fighter.