Whereas not many years ago, it was thought impossible to fly an airplane on biofuels, United flew a jet light from SFO to LAX using biofuels.  This March 11,2016 San Francisco Chronicle article talks about how biofuels are a way the airlines can deal with climate change and are a potential hedge against high oil prices .

United Airlines reportedly signed a three-year agreement with AltAir Paramount, which makes fuels out of animal fats and nonedible plant oils at a refinery near the airport. United has moved aggressively to test and develop biofuels, last year investing $30 million in an East Bay startup, Fulcrum, that makes fuel out of organic trash. ——-Compared with cars, airlines account for a small fraction of the world’s greenhouse gas emissions — about 2 percent. ,,,,,,,,,United will blend AltAir’s biofuel into standard jet fuel for planes flying from LAX to San Francisco International Airport, with biofuel comprising 30 percent of the fuel in the planes’ tanks. The greenhouse-gas emissions associated with making and burning AltAir’s fuel are at least 60 percent lower than those of petroleum-based jet fuel, said Bryan Sherbacow, the company’s president.

Source: United flies LAX to SFO on biofuel – SFGate