Exactly a century ago, in 1923, the eminent biologist J. B. S. Haldane wrote an essay entitled “Science and the Future.”
He predicted that in four hundred years England would run on hydrogen. A network of windmills will generate energy that will split oxygen from hydrogen into water; hydrogen will be liquefied and stored as fuel. This fuel can be used for industry, heating, lighting and transport. He specifically mentioned “its use in aircraft”.
Haldane No predict just 14 years later, in 1937, an event that dealt a near death blow to the possibility of using hydrogen for aviation. The swastika adorned the German airship LZ-129 Hindenburg — the largest vehicle ever built, filled with 140,000 cubic meters of flammable hydrogen — exploded violently while trying to dock in New Jersey, killing 36 people.
Certainly Hindenburg uses all the hydrogen, which is lighter than air, to keep it afloat, not as jet fuel; diesel engines). But the infamous photograph of the explosion served as a major deterrent to the idea of fueling aircraft with the infamous volatile gas.
But are we finally seeing a new addition to hydrogen flight? This week, the American company Universal Hydrogen announced video on twitter his new passenger plane fueled with “green hydrogen” successfully took off and landed at Washington State Airport. Other companies, including some from the UK, have recently shown off their hydrogen-powered aircraft, and in February the UK government announced £113m for “hydrogen and all-electric flight technology”.
Hydrogen is usually obtained from reactions such as burning coal or methane, which produce carbon dioxide and other pollutants. But the “green” species is so named because it is formed from the breakdown of water molecules, as Haldane suggested in his vision of windmills in 1923. The production of hydrogen using renewable energy sources is not so harmful to the environment and does not burn in the aircraft engine: this is where water is mainly produced.
Pavel Eremenko, CEO of Universal Hydrogen, is optimistic about hydrogen aircraft. In a video that his company quickly went viral, he explained that passengers can take a “guilt-free”, environmentally friendly “hydrogen-powered regional flight” “as early as 2025.” And in his accompanying tweet, he added, “No, it’s not Hindenburg.”
From a technical standpoint, these recent advances are not the first examples of hydrogen-fueled flight: in the late 1980s, an experimental aircraft was flown in the USSR – larger than that of Universal Hydrogen or any of the new companies – called the Tupolev Tu-155 which uses hydrogen as fuel. But he made several test flights to try different types of fuel (later he flew on natural gas), and the collapse of the Soviet Union put an end to further development.
Can we really get to the point where planes use completely clean fuel so we can go on vacations on hydrogen? The first part of the answer will probably not be for a while. What was not mentioned in Universal Hydrogen’s video is that their plane only took 15 minutes to fly – time to make a few circuits around the airport, but barely enough time to get to Mallorca.
The main reason for this lies in the physics of hydrogen. Compared to kerosene, the standard jet fuel, hydrogen contains much more mass energy. Thus, with the same weight of hydrogen, you will get much more energy than using kerosene. But here’s the problem: he has a lot below energy through volume – about a quarter of the energy you would get for the same amount of kerosene. This means that you need a lot of hydrogen on your plane to get anywhere, which in turn means you need a lot of fuel storage space.
And to add another difficulty, hydrogen fuel must be stored as a liquid, and in order to turn it into a liquid, it must be cooled to -253 degrees Celsius. All this cooling equipment is heavy, adds weight to your aircraft, and—in addition to the space taken up by the hydrogen itself—can carry fewer passengers.
Michael Liebreich, a clean energy expert and UK government adviser, calculated in a skeptical essay that enough hydrogen for a long-haul flight would take up as much space as the entire fuselage of a passenger plane. He believes this makes the idea “unfortunate”. On short-haul flights, he estimates that hydrogen will take up about a third of the fuselage, and since that means fewer passengers, “prices could double or triple.” This is in stark contrast to Universal Hydrogen’s Paul Eremenko, who called hydrogen flying “more affordable,” though he didn’t explain why.
To make matters worse, getting enough hydrogen to the airport is also a logistical nightmare. There is no technology to cool pipelines to the required temperature, says Liebreich, which means we have to use a very large number of tanks and trucks carrying liquid hydrogen on our roads, which increases the risk of accidents. To quote a NASA statement: “Even small amounts of liquid hydrogen can be explosive in contact with air, and only a small amount of energy is required to ignite it.” We might as well not talk about them Hindenburgbut the same security issues apply.
“In the end,” writes Liebreich, “liquid hydrogen could power a few business jets…but not aviation as we know it.”
Even “green hydrogen” loses its luster on closer inspection. The electrolysis process to produce hydrogen from water is currently expensive, which may explain why only 1 percent of the world’s hydrogen is produced this way. financial times reported in 2021 that when it comes to green hydrogen, “there is skepticism about its efficiency and whether enough electricity can be produced from renewable sources at an economically justified cost.”
JBS Haldane believed that we would not have viable hydrogen-powered aircraft by 2323. If companies like Universal Hydrogen are to be believed, we could beat his forecast by about three centuries. But the hydrogen skeptics’ arguments are hard to ignore: they are based on the basic science of how hydrogen works and the inevitable fact that you so many hydrogen to get your aircraft a considerable distance. We may not have to wait three hundred years for hydrogen release, but it could last much longer.
Jet fuel of the future
Apart from hydrogen, here are the main candidates:
- Biofuel: They can be obtained from crops such as soybeans or canola oil, from used cooking oil, or even from wastewater. They are less carbon intensive than fossil fuels, but when produced from crops they take up a lot of farmland and water.
- Synthetic e-fuel: Hydrocarbons can come from a steady process that begins with the reaction of carbon dioxide with water. But right now, it’s a complex process: synthetic e-fuels require more energy to produce than to burn.
- Ammonia: Ammonia can be made from renewable hydrogen, but it’s much less flammable than hydrogen itself, but that also means it contains far less energy. This also leads to more pollution. Ammonia can be stored as a liquid at -33°C, so it requires much less refrigeration than hydrogen.
Sources: Royal Society; Irish Aviation Authority
Source: I News
With a background in journalism and a passion for technology, I am an experienced writer and editor. As an author at 24 News Reporter, I specialize in writing about the latest news and developments within the tech industry. My work has been featured on various publications including Wired Magazine and Engadget.