This summer, starting on its Los Angeles to San Francisco route, United Airlines will fly commercial jets using a biofuel made out of plant oil and animal fat. In 2013, United agreed to buy 15 million gallons of the fuel, produced in California by AltAir Fuels, over three years, with the option to buy more. AltAir uses discarded farm waste like tallow (rendered animal fat) plus non-edible natural oils to make biofuel that works in existing jet engines.
The AltAir fuel will be blended with traditional jet fuel, starting with a 30/70 mix. But United isn't placing all its bets on AltAir. On Tuesday, The New York Times says, United will announce a $30 million investment in Fulcrum BioEnergy — a small amount compared with the $11.6 billion United spent on fuel last year, but the largest such investment by a U.S. carrier to date. Fulcrum turns municipal garbage into aviation fuel, promising cheap green fuel from a plentiful source of raw material.
Airlines are trying to reduce their carbon emissions but alternative, sustainable sources of jet fuel aren't yet available in dependable quantities. The industry hopes to cut its greenhouse gas emissions to half their 2005 levels by 2050.