United Airlines made new history Wednesday with the successful flight of the world's first passenger flight using 100 percent sustainable aviation fuel (SAF).


The flight, which departed from Chicago's O'Hare International Airport and headed to Reagan National Airport in Washington, D.C., had more than 100 passengers on board, according to a company press release.


United wrote on Twitter that "aviation history has been allowed to take off," along with a video of the takeoff. Passengers included United CEO Scott Kirby, business leaders, government officials, members of the media, NGOs, and companies including Boeing and World Energy (which produces SAF, or Commercial Sustainable Aviation Fuel) in the executives of partner companies.


The flight was a new United 737 Max 8. "Currently, airlines are only permitted to use up to 50 percent of SAF on aircraft, and the SAF used in today's flights is out-of-the-box and compatible with existing aircraft fleets," United said.


United is licensed to operate one engine with 100 percent SAF. The other uses conventional jet fuel to further demonstrate that there is no operational difference between the two and to create the conditions for more scalable future use of SAF by all airlines.


United said the plane had flown 612 miles, and the SAF's engines emitted an estimated 75 percent less carbon dioxide than flying on conventional jet fuel.


Aviation is a tough topic for sustainability. Land transport options may be making progress away from fossil fuels. But the technical challenges that must be overcome are enormous if the commercial flight is to achieve the same transformation. Historically, the aviation industry contributes about 2% of global carbon emissions—a small but significant share.


Replacing regular kerosene with sustainable fuels can reduce carbon emissions by 80%. Previous flights have used a mix of conventional and sustainable fuels, but the most recent flight is the first to use only sustainable fuels - a major testament to its reliability.


We found several innovations aimed at purifying the aviation industry. These include synthetic e-kerosene and electric planes designed to transform regional travel.