United Flight Using 100% Sustainable Aviation Fuel Sets Precedent

The first commercial flight using 100% sustainable aviation fuel (SAF) took place on December 1. United flight 2701 from Chicago to Ronald Reagan Washington National Airport (DCA) served as an important milestone as the aviation industry tries to combat its contributions to climate change.

The approximately 100 passengers on United 2701 didn’t notice any difference, but the Boeing 737-8 flew the 612 miles with one engine burning 100% SAF. The flight used 500 gallons of SAF in one engine, while the other engine used 500 gallons of jet fuel. It proved that there are no operational differences between the two.

“Today’s SAF flight is not only a significant milestone for efforts to decarbonize our industry,” United CEO Scott Kirby said in a statement, “but when combined with the surge in commitments to produce and purchase alternative fuels, we’re demonstrating the scalable and impactful way companies can join together and play a role in addressing the biggest challenge of our lifetimes.”

Both SAF and conventional jet fuel emit carbon dioxide when burned in a plane’s engine. However, SAF is refined from material that already exist in the environment like cooking fats and plant oils rather than fossil fuels. This means that SAF can have a smaller carbon footprint than crude oil based fuel.

Some airlines currently use a blend of SAF into the fuel they use, but standards for jet fuel limit blending to 50%. It would be challenging for airlines to use 100% SAF on a consistent basis because it is unlikely that enough could be produced due to a limited supply of raw materials. In addition, the limited availability of SAF on the market makes it three to four times more expensive than conventional fuel.

According to International Air Transport Association, about 26 million gallons of SAF will be produced this year. That’s far less than 0.1% of our total fuel supply in a given year.

United Airlines has set a goal of being 100% green by reducing its greenhouse gas emissions 100% by 2050, without relying on traditional carbon offsets. To work towards this goal the company says it plans to buy 1.5 billion gallons of SAF. So far this year, they've purchased more than 7 million gallons.