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Comment by jackmott42 | Hacker News Reader

How would a hydrogen powered passenger plane work? How big and or heavy would the fuel tanks need to be? As I understand it you either need very big tanks to store it as gas, or very heavy insulated tanks to store it liquefied. Would a passenger plane still work?

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Hydrogen planes have been tested. The physics works out provided you have more room for the tanks.

Ah yes, it works if only it weren’t for those pesky economic considerations.

Making more room for the tanks means either less cabin/storage and/or bigger cross-section and increased drag.

The alternative is SAF, which has to be a synthetic fuel if the goal is to be honestly green. However, that requires enormous green hydrogen production anyways.

The alternative is electric and biofuels.

There will never be a long-distance battery powered plane. Not with any kind of battery we can conceive of today at any rate. And again, biofuels are not green.

> There will never be a long-distance battery powered plane.

"Long-distance" is a subjective term. There is an ever-increasing distance for which batteries are doable. Everything else is will be liquid biofuels, rather than efuels.

Biofuels are as green as the process making them. Electrify the equipment being used (something that's being done for reasons orthogonal to this) and you're already made the process more green.

Airplanes are not cars. Weight actually matters, even for short trips. There are not an “ever-increasing” number of routes that can be powered by batteries. You can’t even legally send passengers using batteries, because you can’t even get to reserve range minimums. It is basically zero today. And people have noted that even with miracle battery advancements, we would still not have a battery good enough to build a 737 or a320 equivalent. As a result, most of the aviation community has abandoned the idea altogether.

Again, biofuels are not green. The process that makes them involve vast quantities of land and resources. It is in fact a very inefficient and resource intensive idea. It is actually much worse than what it takes to make e-fuels.

Wing tanks won't work for hydrogen, and wing tanks are essential for weight distribution and reducing load on the wing roots. A hydrogen cylinder in the central fuselage will require a complete rework of the aircraft design and a new type designation, it's not something that can be retrofitted into current aircraft, even if converting the engines to hydrogen would be otherwise feasible.

Aircraft will remain liquid-hydrocarbon-fueled for the foreseeable future, even if the fuel production transitions to a synthetic process vs. refined crude oil.

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