US-UK zero carbon emissions aviation company ZeroAvia and US hydrogen storage and refuelling technology startup company Verne have signed a memorandum of understanding to collaborate in the evaluation of opportunities to employ cryo-compressed hydrogen as an aircraft fuel, and for refuelling aircraft with it using both gaseous hydrogen (GH₂) and liquid hydrogen sources. Cryo-compressed hydrogen is gaseous hydrogen stored at cold temperatures, an approach that increases its energy density and so would allow an aircraft to achieve a greater range than it could using standard GH₂ as fuel.

ZeroAvia is developing hydrogen-electric powertrains (engines) for propellor-driven commuter and regional airliners, which would replace conventional, fossil-fuel burning, turboprop engines. The company’s powertrains employ hydrogen, in fuel cells, to generate electricity, which then powers electric motors, which drive the aircraft’s propellors. Its ZA600 powertrain is currently undergoing a series of flight test programmes, fitted to a 19-seat Dornier 228 aircraft, in the UK. The prototype of its larger ZA2000 powertrain is being retrofitted into a 76-seat De Havilland Canada Dash 8-400 regional airliner, in the US.

“With our engines just a few years from flying passengers and cargo, it is important for us that we find the optimal solutions to support airport hydrogen ecosystems,” explained ZeroAvia chief business officer Sergey Kiselev. “Increasing storage capacity and refuelling speed using novel technologies is an important avenue for scaling up hydrogen aviation, and we’re delighted to work with Verne on assessing the role of cryo-compressed hydrogen.”

Verne has received grants from US government agencies, including the Department of Energy, to support its work. The company is also backed by investors such as Amazon’s Climate Pledge Fund, Caterpillar Venture Capital, and the Collaborative Fund. It has developed cryo-compressed hydrogen storage systems, hitherto focused on surface transport, which it has been demonstrating in cooperation with the Lawrence Livermore National Laboratory (LLNL), located in the US State of California.

In December, Verne and LLNL announced that they had successfully demonstrated a 29-kg capacity cryo-compressed hydrogen fuel system, which was three-times larger than the previous largest known such system. Two of these 29-kg systems would, Verne analysis indicates, give a Class 8 lorry (that is, with a gross vehicle weight rating of more than 14 969 kg) a range of more than 800 km.

“Aviation is a massive potential market for Verne, as it becomes clear that hydrogen is critical to tackling the industry’s climate impact,” highlighted Verne co-founder and CEO Ted McKlveen. “Airports can be centres of hydrogen activity, with co-located hydrogen demand for aircraft, aircraft ground operations, and on-road commercial transportation. Cryo-compressed hydrogen has a key role in optimising this ecosystem.”