If cows could fly: What’s in United Airlines’ biofuel?


We recently covered the announcement that United Airlines was powering scheduled flights with biofuels made by AltAir Paramount, “a California-based refinery that converts sustainable feedstocks, like non-edible natural oils and agricultural wastes, into low-carbon, renewable jet fuel, according to United.”

The first comment on the post asked “what is the source of this bio-fuel?” On TreeHugger we don’t like to leave those kinds of questions hanging, and found that the AltAir plant makes its fuel from beef tallow and pig fat, which are not considered edible oils.

The US Navy made a big deal of an order from AltAir, noting that fuel made from tallow is “drop-in”- chemically identical to the petroleum based fuel it replaces. It was rather proud of the fact that it was using beef tallow as a feedstock, with Secretary of Agriculture Tom Vilsack announcing:

Today’s deployment proves that America is on its way to a secure, clean energy future, where both defense and commercial transportation can be fueled by our own hardworking farmers and ranchers, reduce landfill waste and bring manufacturing jobs back to rural America.

Steve Csonka, executive director of the Commercial Aviation Alternative Fuels Initiative (CAAFI) tells food website Munchies why beef fat is used: “The process is pretty robust, and there are different manufacturers who are playing in this space. We are primarily talking about product that’s coming out of slaughterhouses, from the first processing that occurs prior to finished meat.”

An AltAir Fuels spokesperson said “that beef tallow fuel is a “drop-in diesel,” meaning it can be directly substituted, gallon-for-gallon, for traditional petroleum-based diesel.”

Csonka explains why biofuel is better for the environment:

From the carbon dioxide perspective, these fuels are identical. So if I burn a gallon of jet fuel and I burn a gallon of HEFA (hydro processed esters and fatty acids) fuel, the carbon dioxide that comes out of the tailpipe of the airplane is identical,” he said. “The difference comes from the fact that I’ve produced the synthetic or renewable jet fuel without actually pulling additional carbon molecules out of the ground, or I did it at a substantially reduced level versus what I would have had to pull out of the ground if I just wanted to make petroleum-based jet fuel.

honeywell jet fuel© Honeywell doesn’t mention beef tallow much either.

On the United site, they do not mention beef tallow. They only say:

Whereas conventional jet fuel is derived from crude oil, sustainable aviation biofuels can be derived from sources like non-edible natural oils and agricultural wastes. The AltAir facility converts this feedstock into sustainably produced jet fuel that is expected to provide a greater than 60 percent reduction in greenhouse gas emissions on a lifecycle basis compared to fuel produced from crude oil.

But does that lifecycle analysis take into account the carbon footprint of raising cows, which are responsible for seven percent of the world’s carbon emissions? When it comes to chemistry, it’s perfectly good jet fuel. The beef tallow is a waste product so one can make a case for ignoring the carbon footprint of making it.

Given the impact that raising cattle has, from its use of land and water to the carbon emitted raising it, I suspect that a lot of people would look less favorably at United’s initiative if they knew they were flying on beef tallow. And I am sure a lot of flying vegetarians wouldn’t be too happy either.

It turns out that it’s probably beef fat.

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