The Future of Commercial Flight, or an Unrealistic Alternative?
Written By: Shelby Deegan
Edited By: Justin Weir
The aviation industry is currently responsible for about 2.4% of global emissions, a massive proportion.[1] Aviation also creates contrails — combustion-produced water vapor that condenses onto soot from a plane’s exhaust.[2] Contrails can then trap heat that would otherwise leave earth’s atmosphere, generating a sort of greenhouse effect. These impacts, coupled with the rising cost of kerosene, have led to a push among companies and governments to figure out an alternative fuel source for aircrafts.
Among possible alternative fuels, hydrogen shows the most promise to be an effective and efficient replacement. Hydrogen is significantly lighter than kerosene, and has three times the energy, per unit of mass. Its potential to contribute to decarbonization has led many engineers to pursue it as a fuel source in aviation, as well as other sectors.[1]
In the aviation industry, hydrogen can be used in two ways. In both processes, the only waste product is clean water. Rather than pressurized hydrogen gas, current research focuses on liquid hydrogen, due to its higher energy density. Current technology generates electricity by using liquid hydrogen to power a fuel cell, combust in an engine, or a combination of the two.
The main complications with hydrogen power arise from temperature sensitivity. For hydrogen to be liquified, it must be cooled down to cryogenic temperatures of -253 ° C. Though hydrogen is much lighter and mass-efficient than kerosene, it takes up more space — requiring four times the volume of kerosene to achieve the same power output potential. Therefore, hydrogen aircraft designs must incorporate heavy, insulated tanks which can store very large quantities. As a result, hydrogen storage is particularly troublesome for longer flights. Kerosene, on the other hand, is able to be stored in the wings of planes.[1]
Infrastructure is another key issue for hydrogen airplanes. Though possible to produce liquid hydrogen in the large quantities needed, its transportation remains difficult. Liquid hydrogen is volatile, and it would need to be transported to airports on a global scale. Once transported, the storage demands would also be higher than they currently are with kerosene.
Despite significant challenges to hydrogen-powered flight, many companies and governments are investing heavily in the possibility — betting that the benefits could outweigh the costs. One example is ZeroAvia, a start-up geared entirely towards zero-emissions aviation.[3] The UK government is supporting ZeroAvia’s 2020 hydrogen-powered flight, dubbed ‘HyFlyer I’. Currently, the company is developing a hydrogen plane that can carry 20 passengers about 350 nautical miles. They expect to offer commercial flights as soon as 2023, while increasing range to 500 nautical miles and passenger count to 80 by 2026.[4]
Meanwhile, Airbus — the world’s largest aircraft manufacturer — announced in 2020 plans for a “new generation of zero-emissions commercial aircraft”. Under the project name ZeroE, Airbus has published plans for three concept planes which aim to be completed by 2035. Two of the designs look similar to current models; however, the planes would need to carry less passengers in order to accommodate for hydrogen storage. This would mean a decrease in ticket revenues for airlines using the aircraft. The third model is more innovative, with a blended-wing design. This makes the plane able to carry more passengers — but it’s much larger, increasing drag.[4] So, while these designs offer opportunities to transition to hydrogen-powered aviation, they are yet to be as commercially appealing to airlines as conventional planes.
Production of hydrogen itself presents another problem for zero-emissions goals. The majority of hydrogen produced today is done so using fossil fuel methane, which releases carbon dioxide — this is known as blue hydrogen. Instead, hydrogen can be produced using renewable energy through a process called electrolysis — this is known as green hydrogen. However, with current technology, this remains expensive; only about 1% of hydrogen is currently produced this way. For hydrogen-powered flights to be truly green, production of green hydrogen needs to become more viable on a large scale.[4]
The cost of hydrogen is also a major barrier to adoption. For now, liquid hydrogen is roughly four times as expensive as jet fuel. As production capacity increases, this price is expected to drop — but it could be decades before parity with kerosene is achieved. To balance this, conventionally-fueled flights could be priced to reflect their environmental impacts, such that hydrogen becomes comparably priced.[4] As more international agreements are signed and worldwide environmental goals are set, the likelihood of governments taxing fossil fuel use will increase, and it could become a reality.
Although the reality of hydrogen-powered flight being both scientifically and economically feasible may still seem daunting, the actors working towards it are making significant strides to lessen the barriers in the way. To upscale production infrastructure and lower costs ZeroAvia announced a partnership with ZEV station to develop green hydrogen refueling infrastructure at airports. Similarly, Airbus signed a memorandum of understanding to work with industrial gasses company Linde to work on the development of hydrogen infrastructure at airports.[4]
With costs being the biggest barrier to widespread implementation of hydrogen-powered flights, things could change rapidly in the next few decades, making them much more of a reality. As the price of kerosene goes up, the price of hydrogen will hopefully be driven down, making it a viable alternative. ATI expects that as soon as the mid-2030s, efficient hydrogen planes may be a better economic choice than current planes, because hydrogen supply costs will be reduced as other sectors facing the same issues will shift towards hydrogen.[3] With the rapidly changing energy climate, many of us may see ourselves stepping onto futuristic looking flights powered by hydrogen much sooner than we might think.
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Works Cited:
[1] Mark, Piesing. “The Epic Attempts to Power Planes with Hydrogen.” BBC . BBC Future, March 21, 2022. https://www.bbc.com/future/article/20220316-the-epic-attempts-to-power-planes-with-hydrogen.
[2] The Editors of Encyclopedia Britannica . “Contrail.” Encyclopædia Britannica. Encyclopædia Britannica, inc. Accessed November 1, 2022. https://www.britannica.com/science/vapor-trail.
[3] Hampel, Author: Carrie, William Tahil, Ajay Goyal, and Name *. “Hydrogen Fuel Cell Aircraft – What for and When?” electrive.com, August 26, 2022. https://www.electrive.com/2022/08/26/hydrogen-fuel-cell-aircraft-what-for-and-when/.
[4] Henderson, Caspar. “The Hydrogen Revolution in the Skies.” BBC . BBC Future, April 7, 2021. https://www.bbc.com/future/article/20210401-the-worlds-first-commercial-hydrogen-plane.