LE BOURGET—Former Bombardier products are emerging as favored targets as startups seek to retrofit regional airliners with zero-emission hydrogen propulsion later this decade.

Propulsion developer ZeroAvia and Mitsubishi Heavy Industries Regional Jet (MHIRJ) Aviation—type-certificate holder for the Bombardier CRJ—have completed a technical study that has identified an initial entry point for a CRJ700 retrofit.

The year-long study has confirmed maximum takeoff weight, center of gravity and structural allowances for the CRJ700 modification and validated the retrofit approach for other in-service CRJ-series regional jets, such as the CRJ550 and CRJ900, ZeroAvia says.

Netherlands-based Conscious Aerospace, meanwhile, is appearing at Paris Air Show having signed a first-phase agreement with De Havilland Canada (DHC) to collaborate on the application of a hydrogen fuel-cell propulsion system to the Dash 8-300 regional turboprop, formerly produced by Bombardier.

The collaboration with Dash 8 type-certificate holder DHC will involve an assessment of retrofitting the 8-300 with Conscious Aerospace’s 2-megawatt HAPSS 2100 hydrogen powertrain and storage system. The Dutch startup is aiming for service entry in 2028.

UK/U.S. startup ZeroAvia is already working with investor Alaska Airlines to retrofit a 76-seat Dash 8-400 to a demonstrator for its 2-megawatt-class ZA2000 fuel-cell powertrain. The company has established an engineering partnership with DHC to exchange data on the airframe, aiming for certification in 2027.

The hydrogen-electric CRJ would be fitted with two derivatives of the ZA2000 and could fly 60 passengers 560 nm, covering more than 80% of current CRJ flights. The engines would have increased-diameter geared ducted fans or open rotors to overcome the loss of turbine core thrust, ZeroAvia says.

The Phase 1 study with MHIRJ Aviation included a high-temperature proton exchange membrane fuel cell system with a specific power of 2.4 kW/kg. ZeroAvia has already demonstrated 2.5 kW/kg at the cell level and plans to deliver 3 kW/kg system-level specific power within two years.

Conscious Aerospace was established in September 2021 by consultancy Unified International. The HAPSS program is a public-private partnership involving 17 companies, Delft University of Technology and Netherlands aerospace center Royal NLR. The program is being supported by €100 million ($109 million) in government funding from the €383 million LIT (Aviation in Transition) program, company founder Michel van Ierland says.