Boeing 737 MAX 8 made its first passenger flight with one of its engines fully fueled with eco-friendly fuel.

United Airlines conducted the first flight of a Boeing 737 MAX 8 powered by a renewable fuel engine derived from biological and other waste, carbon dioxide and other organic components.

Its first demonstration flight took place from Chicago to Washington, with 115 passengers on board. Among them was the head of United Airlines, Scott Kirby.

The company said the LEAP-1B engines can run on both fossil fuels and Sustainable aviation fuel (SAF). It is an advanced aviation fuel used in jet aircraft and is certified environmentally friendly. SAF has a much lower carbon footprint than conventional jet fuel due to the raw materials from which it is produced.

According to the standards set by the American Society for Testing and Materials (ASTM), under normal conditions, the use of such fuels is still allowed only in a mixture with classic fuels with a 50/50 ratio. But the organizers said they used fuel that is almost 100% identical to the regular fuel used by the airliners.

The ultimate goal is to develop a fuel that can be used without modifying existing engines. So far, this configuration has not been certified.