The aviation industry is being pressured to cut aircraft emissions and create a more sustainable future for air transport, with both governments and the general public demanding action. While a fully electric aircraft seems technologically out of reach in the foreseeable future, several voices see in hydrogen a mid-term solution toward zero-emission propulsion. 

In its ‘Performance Analysis of Evolutionary Hydrogen-Powered Aircraft’ study published in January 2022, the International Council on Clean Transportation (ICCT) estimated that if the technology progresses as planned, liquid hydrogen could potentially dominate the small and medium-haul aircraft market by 2050.  

The first zero-emission, hydrogen-powered commercial aircraft is not expected to take to the skies before 2035. While this estimate may seem far away, the industry does not have a second to waste. 

So, how is the industry trying to harvest hydrogen power and ensure a cleaner future for aviation? AeroTime investigates.   

ZEROe 

In September 2020, Airbus unveiled three hydrogen-powered concepts it was working on. The program, codenamed ZEROe, includes:  

  • A jet airliner, similar in size to an A320 that can transport up to 200 passengers with a range of more than 3,500 kilometers (2,000 nautical miles). The liquid hydrogen tank, which powers the modified gas-turbine engine running on hydrogen, is fitted in the rear of the fuselage. 

  • A regional propeller plane capable of carrying around 100 passengers, for shorter journeys. The aircraft is powered by hydrogen combustion in modified gas-turbine engines. 

  •  A ‘blended-wing body’ design, with similar performances to the A320, but a completely different hydrogen storage and propulsion system. 

The European manufacturer considers hydrogen power as a “priority strategic axis” in its research and development on sustainable aviation. But the CEO estimates that the development would require "several tens of billions of euros”, hinting at the need for governmental support. 

This may come in the form of financial support from France. Shortly before ZEROe was unveiled, the country where Airbus Commercial Aircraft is headquartered pledged to dedicate €1.5 billion in public aid over three years to participate in “the decarbonization of world air traffic”. 

In February 2022, Airbus and the engine maker CFM International, a joint venture between Safran and General Electric, announced they were working together to study propulsion technology for hydrogen aircraft using an A380 superjumbo as a testbed. 

In June 2022, the Hungarian ultra-low-cost carrier Wizz Air signed an agreement with Airbus to jointly study the “operational and infrastructure opportunities and challenges” of a hydrogen ecosystem. 

H2FLY 

Another potential application of hydrogen power for aviation could come from the use of fuel cells. This is the approach taken by H2FLY.  

The HY4 prototype of the Stuttgart-based company is a double-fuselage aircraft capable of transporting four people. It is powered by a low-temperature hydrogen fuel cell system developed by DLR, the German space agency. 

In April 2022, the HY4 set a world record for hydrogen passenger aircraft with a flight at an altitude of 7,230 feet (2,203 meters).  

H2FLY hopes to demonstrate the use of hydrogen fuel cells as a viable solution for aviation by flying a 40-seat, hydrogen-electric powered Dornier 328 by 2025. 

ZeroAvia 

The US-British start-up ZeroAvia is another pioneer in the area of hydrogen fuel cells. It set the ambitious goal of operating the first hydrogen-powered commercial flights by 2024. 

After successfully testing its electric-hydrogen propulsion system in a Piper M-series aircraft, the company hopes to test its ZA-600 hydrogen aircraft engine on Dornier 228 aircraft as part of the HyFlyer II program. 

"We're doing ground commissioning now. The first flight will be in a matter of weeks," James McMicking, vice-president of strategy at ZeroAvia, told AeroTime at the Berlin ILA Airshow on June 22, 2022. The aircraft will initially be flown with one aircraft using ZeroAvia's powertrain, with the other powered conventionally. McMicking said ZeroAvia would not rush into flight testing if it didn't feel ready, with safety taking priority.  

He said: "It will take as long as it takes." The company, which was only founded four years ago, has what McMicking admitted was a "very ambitious" timeline, hoping to bring the product to market by the end of 2024. 

In June 2022, ZeroAvia also signed a partnership with the US-based manufacturer Otto Aviation to develop a new long autonomy hydrogen aircraft using the latter’s Celera 500L airframe. 

Universal Hydrogen 

California-based Universal Hydrogen plans to fly regional hydrogen planes from 2025, ten years ahead of Airbus’s ZEROe turboprop. To do so, the company is developing a “plug-and-play” solution using existing aircraft. Currently, it is working on conversion kits for two popular regional turboprops, namely the Dash 8 and the ATR-72. 

The kit is composed of an electric powertrain and a fuel cell that replace the original turboprops. The hydrogen is stored at the rear of the fuselage in compact tanks developed especially for the system. 

In March 2022, Universal Hydrogen opened an engineering center in Toulouse, France, close to ATR assembly lines. In June 2022, the company received a large order from the US-based Connect Airlines to convert 75 ATR 72-600 regional aircraft to hydrogen. 

What about Boeing? 

Back in 2008, the Fuel Cell Demonstrator, a two-seat Diamond DA20 light aircraft converted to run on a fuel cell by Boeing Research & Technology Europe, took off for a successful maiden test flight. 

Lately, however, the US giant does not communicate as much as its European rival on hydrogen technology. In January 2021, Boeing chief executive David Calhoun dismissed hydrogen as a short-term solution.  

Though it does not necessarily mean that no work is being done in this area, Boeing has so far been betting on sustainable jet fuel. The effects of the latter are less significant in terms of reducing emissions, but they do not require a technological breakthrough like hydrogen does. “This is the only answer between now and 2050,” Calhoun said.  

Will it be enough?

While these advancements seem to bring a greener future for aviation within reach, technological advancements alone might not be sufficient. According to David Ziegler, Vice President, Aerospace & Defense Industry at Dassault Systèmes, the ecosystem around hydrogen power might play an important role in reaching zero-emissions targets.

“Decarbonizing aviation is now on the agenda of every executive in the aerospace industry,” Ziegler told AeroTime. “While there are many possible technological levers today such as sustainable aviation fuels (SAFs), hydrogen fuel and electrical aviation, the winners of this race will be parties that can build the right ecosystem around the use of these levers.”