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UnCommonSense99 t1_iya9o1e wrote

Reply to comment by Muchablat in World’s first test run of a hydrogen jet engine a success by BlitzOrion

Lol it's almost impossible to store enough hydrogen on a jet plane to fly a long way unless you get rid of the passengers.

This stuff about hydrogen planes is basically green washing

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Deranox t1_iyanz9c wrote

Yes, all manner of highly intelligent people work on this for years only to green wash us. Mobile phones were huge bricks, look at them now. When there's will, there's improvement and results.

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Kelmon80 t1_iycy2w0 wrote

Improvement is neither automatic nor always possible.

There is a limit to which you can compress hydrogen, and there are limits to how strong a pressure vessel needs to be (read: How heavy it will be).

Cars need about 100kg of tank to store 5kg of hydrogen.

A 737 can carry about 25.000l of fuel, with fuel tank weight more or less negligible, which is around 20 tons. Let's say 22 to account for the tanks as well.

Let's assume a sort of "worst case" - for safety reasons, car-sized hydrogen tanks are used for planes. A full tank being 105kg, this gives you 210 tanks on the plane, for a total of around 1050kg of hydrogen. So about 1/20th the weight in jet fuel. As Hydrogen has three times the energy density as jet fuel, that still leaves you with range reduction of 1/6th, at same load for the plane. And you probably lose quite a bit of space in the plane to accomodate all those small tanks.

Now the best case: You somehow fit two huge pressure vessel into the plane that carry all the hydrogen, and they are of the same shape and weight as the original fuel tanks, but (magically) are at a pressure high enough to get the hydrogen close to its boiling point - 25.000l of it will still be just around 1800kg, or 1/11 the weight of jet fuel, or a 4-fold reduction in flight range - but with the added bonus of also having a much lighter plane, buying you more range. Still, I doubt even in this magically ideal case, you get more than half the original range out of it.

The bottom line is that physics can't be cheated. A hydrogen plane *will* have a far lower range unless you're willing to allocate a considerable amount of additional space for hydrogen storage.

Mind you, that would still make them an interesting alternative on short-range flights, just not an universal replacement.

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UnCommonSense99 t1_iyernee wrote

All sorts of intelligent people worked on the Microsoft Zune lol

If you want to know why hydrogen wont- work as an aircraft fuel you should Google volumetric energy density

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r448191 t1_iybv6ge wrote

Right because there are no dead ends in science... /s

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