The hydrogen-electric aircraft developer ZeroAvia has raised an additional $30 million from new investors, the company announced this week at the Farnborough International Airshow.

Its new investors include Barclays Sustainable Impact Capital, the Saudi zero-carbon city project Neom, and the Berlin-based technology fund AENU. International Airline Groups, which has previously invested in ZeroAvia, has also increased its holdings. ZeroAvia says it has now raised a total of $68 million in its Series B funding round, following investments made by United Airlines and Alaska Airlines in December. 

ZeroAvia is based in Hollister, California, and also has test facilities in the UK. The company is working to develop two zero-emissions commercial airplanes with hydrogen-electric propulsion systems. 

Its first project will be a nine- to 19-seat aircraft with a 300-mile (480 km) range and a 600-kilowatt hydrogen-electric powertrain called ZA600. The company claims it is on track to have this aircraft enter service by 2024. It also aims to have a 40- to 80-seat hydrogen-electric aircraft with a range of 700 miles (1,100 km) ready by 2026. The larger aircraft will utilize a two- to five-megawatt ZA2000 powertrain and will run on liquid hydrogen, while the smaller one will use hydrogen gas.

ZeroAvia has already secured experimental flight certificates from the FAA and CAA for its two prototype aircraft. The company is in the midst of ground testing its ZA600 powertrain at its research and development facility at Cotswold Airport in western England, where it is preparing to retrofit a 19-seat Dornier 228 twin-turboprop regional airliner that will serve as a testbed for the new hydrogen-electric propulsion system.