What Technology Is Required for Airlines to Turn to Hydrogen?
People are continually interested in making flying a more eco-friendly activity. It’s not currently among the “greener” options due to the associated high carbon emissions. However, that could change if airlines switch to planes that run on hydrogen.
That’s not a widespread option yet. However, a recent study indicates hydrogen planes could account for one-third of passenger air traffic by 2050. Let’s look at the technology necessary for these aircraft to run.
A Modified Engine or Fuel Cell
Today’s aircraft engines cannot use hydrogen without people making some changes first. The most straightforward option is to adapt the existing engine for hydrogen compatibility. Mike McCurdy, a managing director with aviation consulting firm ICF, confirmed doing that would allow burning hydrogen like petroleum-based fuel to power the plane.
The other option is to load hydrogen onto the plane and put it through a fuel cell to cause a chemical reaction. Doing that creates the electricity necessary to power the craft. In 2020, a startup called Universal Hydrogen announced plans to take that approach with regional airliners. It has modules approximately 7 feet long and 3 feet in diameter. They carry the hydrogen in compressed gas or liquid form.
A fuel cell is similar to a battery and has an anode and a cathode. The hydrogen comes into the cell via the anode. The hydrogen atoms then react with a catalyst, splitting into electrons and protons. Oxygen from the ambient air comes into the other side of the fuel cell and through the cathode.
Positively charged protons then pass through an electrolyte membrane. The negatively charged electrons move out of the cell and generate electricity for a plane’s electric or hybrid-powered propulsion system. The protons and oxygen combine in the cathode, producing water.
A Different Design to Accommodate the Hydrogen Tank
Airplanes currently have kerosene fuel tanks in their wings. However, hydrogen planes will need a different option.
Barnaby Law is an airplane fuel cell expert at MTU Aero Engines. He said, “There has to be a compromise somewhere if you want aircraft to be powered by hydrogen.” That’s because the hydrogen’s volume is four times that of kerosene with the same energy content. Besides being larger, hydrogen tanks must also have spherical or cylindrical shapes to tolerate the higher pressures than kerosene.
Law commented, “If you don’t want to mount the tank on the outside of the aircraft — not advisable, as it would have a major impact on the aerodynamics — the fuselage is your only option.” If hydrogen planes will someday transport a similar number of passengers to those using gas, they must either have a wider-diameter fuselage or an overall longer length.
Statistics show a more than 50% drop in per-passenger airplane emissions since 1990. That progress has not stopped airlines from investigating hydrogen options to make further gains. These planes will also need electric motors to rotate their propellers.
Some companies are also looking at electrical propulsion systems that would enable electric vertical take-off and landing (eVTOL) for hydrogen-powered aircraft. HyPoint has eVTOL technology that tests indicated could provide up to 2,000 watts per kilogram of specific power.
If that holds in real-world applications, it would be more than three times the power-to-weight ratio of conventional liquid-cooled hydrogen fuel cell systems. Work is underway to make the world’s first hydrogen-powered helicopter.
However, eVTOL is not only an option for helicopters. A company called Lilium uses the technology on a commercial jet. It plans to start passenger flights in 2024. If it succeeds, we might see airports adapting to the new technology by redesigning current runway space. Those facilities will also need to make infrastructure changes related to fueling the planes with hydrogen.
Will Customers Want to Travel on Hydrogen Planes?
It’s still too early to say whether people will feel ready to travel on hydrogen planes. Many of the options tested or in development can only achieve relatively short flights, which could limit early adoption.
Plus, flying on a hydrogen plane is not the only way to choose a greener form of travel. A plane cut emissions by 7% when it flew from California to Australia using 10% mustard seed oil and 90% standard jet fuel.
A study also suggested people might pay from 10%-50% more per ticket for a hydrogen-powered flight, depending on its length. Many people already consider air travel expensive enough.
A Fascinating Future for Hydrogen-Powered Flight
It could take decades for hydrogen-powered planes to become mainstream. Nevertheless, it’s a great sign that people are working on high-tech options to reduce aircraft emissions. As they make more discoveries and learn what’s best, those advancements bode well for hydrogen flights and all other types.
Author bio: Jane works as an environmental and energy writer. She is also the founder and editor-in-chief of
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