American Airlines is investing big in a new sustainable kind of flying: The Fort Worth-based airline has entered into a conditional agreement with ZeroAvia, a "clean aviation" company, to buy 100 hydrogen-electric engines they'll use to power regional jet aircraft.

A hydrogen-powered aircraft uses hydrogen fuel as a power source, and is said to result in zero emissions, other than water vapor.

American has also increased its investment in ZeroAvia. The airline made its first investment in ZeroAvia in 2022 and has now participated in the company’s Series C financing round. The engine agreement follows a Memorandum of Understanding the companies announced in 2022.

ZeroAvia is developing hydrogen-electric (fuel cell-powered) engines for commercial aircraft, which offer the potential for close to zero inflight emissions. The company is testing a prototype for a 20-seat plane and designing an engine for larger aircraft such as the Bombardier CRJ700, which American operates on certain regional routes.

“Advancing the transition of commercial aviation to a low-carbon future requires investments in promising technologies, including alternate forms of propulsion,” says American’s CEO Robert Isom in a statement. “This announcement will help accelerate the development of technologies needed to power our industry and uphold our commitment to make American a sustainable airline so we can continue to deliver for customers for decades to come.”

American’s goal is to achieve net-zero greenhouse gas emissions by 2050, and they've undertaken an extensive fleet renewal effort to move more aggressively into improving fuel efficiency, including finalizing an offtake agreement with Infinium, a producer of next-generation low-carbon sustainable aviation fuel, as well as Graphyte, which has created a permanent carbon removal process.

“In signing this purchase agreement and furthering its investment, American is supporting our mission of innovation for clean aircraft propulsion and it is a good signal that ZeroAvia is delivering on our technology roadmap,” said ZeroAvia Founder and CEO Val Miftakhov. “The solutions that can serve the largest airlines are within reach, and the clean future of flight is coming.”

ZeroAvia’s hydrogen-electric engines use hydrogen in fuel cells to generate electricity, which is then used to power electric motors to turn the aircraft’s propellers.

Initially, the hydrogen-powered flights are expected to be restricted to short-haul, turboprop airliners seating 50 to 60 passengers such as short flights between New York and Washington, D.C.

Other companies such as AirBus and Universal Hydrogen are also developing hydrogen-powered planes.