While still in their infancy, hydrogen-powered aircraft could be the solution to carbon-free sustainable aviation. Despite considerable advancements in engine designs that produce 25% more efficient engines than the ones they are replacing, they all still burn kerosene.
Aviation fuel or kerosene is a derivative of petroleum and, unlike regular gasoline, has a higher flash point at which it ignites. Kerosene also has a lower freezing point than gasoline and a lower viscosity allowing it to reach the engines without fear of clogging. Kerosene is also significantly cheaper than gasoline, which is an essential consideration for airlines when planes like the Boeing 747 burn around a gallon per minute.
While kerosene might seem like the perfect fuel for aircraft engines, the problem is its emissions when burnt. According to The Air Transport Group, globally, aircraft are responsible for 12% of CO2 emissions from all transport sources. Because of this and the world’s desire to move away from carbon fuels, hydrogen is being seriously considered an alternative energy source for planes.
Combustion of hydrogen
Hydrogen burns in oxygen to form water (hydrogen + oxygen → water = 2H2 + O2 → 2H2O). Many people believe that hydrogen and renewable electricity will replace fossil fuels as a primary energy source because no carbon dioxide is produced when hydrogen is ignited.
The problem with this at the moment, though, is that hydrogen for fuel is currently primarily produced from fossil fuels by steam reforming or partial oxidation of methane and coal gasification. Steam-methane reforming is not the answer as producing hydrogen this way releases carbon dioxide and carbon monoxide into the atmosphere.
Hydrogen needs to be produced using renewable energy
The way forward would be to create hydrogen from water through electrolysis using renewable energy sources like solar or wind power. Once produced, hydrogen can be used in much the same way as natural gas, with the only emissions being water vapor and not the carbons that are harmful to the planet.
Hydrogen internal combustion engines
Many commercial vehicles in the United Kingdom have been converted to run on a mixture of hydrogen and diesel, reducing carbon emissions by 70%. Using hydrogen with diesel allows trucks to only run on diesel when hydrogen is not available.
To power vehicles with hydrogen, minor modifications are needed along with a storage tank with a compression rate suitable for hydrogen.
Using hydrogen to power planes
Hydrogen-powered planes would look very much like aircraft do today except perhaps for a slightly longer fuselage. A recent independent study on using hydrogen in aviation released last June suggests that hydrogen could be powering aircraft by 2035.
“By 2035, it should be possible for a short-range flight plane,” said Dr. Bart Biebuyck, executive director of the Fuel Cells and Hydrogen Joint Undertaking, as reported by Technology Org.
“That means on European soil; you could connect all the big cities in Europe using hydrogen-powered planes. By 2050, the ambitious scenario is that 40% of the (European aviation) fleet would be powered by hydrogen.”
To be able to achieve these goals, several factors need to be overcome:
- Hydrogen storage technologies need to advance
- Aircraft need to be able to carry enough hydrogen for the flight
- New ways to transport hydrogen to airports need to be found
- Trucks to refuel planes at the airport need to be devised
- Aircraft need to be redesigned to accommodate the hydrogen and deliver it to the engines
“With the integration, nothing has been done yet on a big plane,” said Dr. Biebuyck.
“That will be a big challenge. And we still need to prepare a lot of standards, codes, and regulations. For example, what would be the requirement for hydrogen tanks testing for aviation? Still a lot of this research has not been done.”
Boeing flew the world’s first hydrogen-powered plane in 2008, proving that hydrogen-powered aircraft flight was possible. Since then, other people have been busy building hydrogen-powered planes and include Britain’s ZeroAvia.
ZeroAvia flew a Hydrogen-powered plane
ZeroAvia just last month flew the world’s first hydrogen-powered commercial aircraft when a six-seater Piper M-class plane took to the skies above Bedfordshire in England.
When speaking about their achievement and what they would like to do ZeroAvia founder and chief executive Val Miftakhov told Sky News the following:
“What we’re doing is replacing fossil fuel engines with what’s called hydrogen-electric engines, and we also have a fueling infrastructure set up that ensures zero-emission production of hydrogen itself.”
ZeroAvia says the technology is already there for a long, zero-emissions flight by the end of this decade, but existing airport infrastructure would need to be overhauled.
“It’s not just a question of putting hydrogen-based airplanes and getting them to work, we need the infrastructure on the ground to support everything,” said David Gleave, aviation safety investigator, and researcher at Loughborough University.
“We have to work out how to refuel these airplanes because existing infrastructure won’t work, and we have to work out other things such as the fire and rescue requirements for the aircraft, so there’s quite a lot of work to do, but certainly it’s very exciting going forward.”
After the 20-minute flight in the Piper, ZeroAvia is working on a 250-mile flight between the Orkney Isles and Scotland and expects to be carrying fare-paying passengers in the near future.
Too much needs to be done
As you can see, while the science is there, it will involve an awful lot of work to make commercial hydrogen-powered flights an everyday occurrence. While I can see small aircraft like the Piper used by ZeroAvia powered by hydrogen, a colossal effort would need to be undertaken before commercial jets could use hydrogen as a power source.
What do you think about hydrogen-powered commercial planes? Do you think it could become a reality by 2035, or is it just wishful thinking? Please tell us your thoughts in the comments.