American Airlines has signed a conditional agreement with ZeroAvia, a British-American developer, to purchase 100 hydrogen-electric engines to power regional jets. These engines are designed to enable zero in-flight emissions, apart from emitting water vapor. The agreement follows American Airlines' earlier purchase option on the engines. The terms of the agreement, such as opt-out conditions, have not been disclosed by the companies. ZeroAvia is currently in the testing phase of a hydrogen-electric prototype for a 10- to 20-seat aircraft and is also working on developing engines for larger planes like the Bombardier CRJ700, which American Airlines uses on certain regional routes with 65 seats. ZeroAvia aims to achieve certification for the 20-seat plane by the end of the next year, offering a range of up to 300 nautical miles. Furthermore, the company plans to develop a powertrain capable of powering 40- to 80-seat planes for distances of up to 700 nautical miles by 2027. In addition to the engine purchase agreement, American Airlines has expanded its investment in ZeroAvia, building on its initial investment made in 2022. While specific details of this increased investment were not disclosed, ZeroAvia states that it has secured more than 2,000 pre-orders for its hydrogen-electric engines, amounting to over $10 billion. Notable potential customers for ZeroAvia include United and Alaska Airlines. Hydrogen-electric engines operate by utilizing electricity generated through a chemical reaction in a fuel cell to drive an electric motor. This technology is seen as a promising solution to address the aviation industry's impact on the environment by significantly reducing emissions during flight.