Metallic storage of hydrogen

[Iago]

As you all know, (at least those who use Interstellar) hydrogen is amazingly useful for a variety of different things. It can be used as propellant, fusion fuel, scram jet fuel and to create a whole lot of organic substances needed for long duration flight.

There is only one problem. Storage. As it stands, you need a giant refrigerated tank to hold only a small amount of hydrogen.

But there is hope! Hydrogen can be stored in a metallic state, naturally found underneath the gassy part of gas giants (kind of like the "surface" of Jool). This allows for storage of a lot of hydrogen for very little volume, which is very useful when building spaceplanes and the like. The thing is, compressing the hydrogen is kind of difficult.

Any thoughts?

[Exploro]

Problem is that to achieve that state Hydrogen gas would have to be subjected to extreme pressures. Doing a quick read the region where Hydrogen would likely become metallic within Jupiter is where pressures are around 200 GPa and further down pressures easily exceed 3000 GPa. Thus the challenges to overcome would be not only finding a means to compress Hydrogen into a metallic state and keeping it in that state but also finding a pressure vessel that can endure extremes of temperature and pressure.

Edited February 15, 2016 by Exploro

[RocketSquid]

We have made metallic hydrogen, but it didn't stick around for long.

https://en.wikipedia.org/wiki/Metallic_hydrogen#Z_machine.2C_2015

[Temstar]

Metallic hydrogen is useless to us. It's only meta-stable metallic hydrogen that would be useful to us and they may or may not exist.

[SomeGuy123]

Yeah if you need a 100k ton tank to hold 1 kilogram of metallic hydrogen, you're not going to space today...

Meta-stable hydrogen could exist but it just kinda seems super unlikely that it's going to be storable at pressures you can achieve in a lightweight tank...

Also, state transitions?  Remember the search for monopropellant in Ignition!?  Everything that is any good as a monopropellant can, by definition, set itself off while it's still in the storage tank (because unstable molecules have higher energy)...

I think the metallic hydrogen for rocket fuel is just a way to siphon off grant money for some chemists who want to study it, even though it is probably useless as a practical substance.

Edited February 16, 2016 by SomeGuy123

[sgt_flyer]

guess any rocket company would ask this first : will using this fuel (or any other exotic fuel) lower the overall launch costs ? (or at least, offer an interesting trade-off for a slightly higher overall cost for the same payload - potential trade-off : extra reliability) - until the launch + exotic fuel costs become lower than classic ones, rocket companies will stick with the cheaper solution. (especially if you need even more careful handling of the fuels - which would drive costs much higher by itself) 

 

most of those exotic fuels will remain scientific material for quite some time i guess

Edited February 16, 2016 by sgt_flyer

[kerbiloid]

When your fuel is stored under such pressure, you don't need an engine, just a valve.

[Hannu2]

As somebody wrote, we do not know if metallic hydrogen is metastable state in normal temperatures and pressures. If it is not, which is very probable, it can not be stored without ridiculous pressure which can only exist deep in giant planets. Releasing the pressure would convert metallic hydrogen back to normal gaseous form.

Even if hydrogen have such metastable state we do not know how stable it is. What is needed to prevent spontaneous conversion from metallic to molecular state. You want to be sure that such a chain reaction can not begin before burning chamber, for example in high speed turbopump. We do not even know if metastable metallic hydrogen (if it even exists) is solid or fluid stuff under normal conditions. We do not know how to fabricate macroscopic amounts of metallic hydrogen. Actually, according to Wikipedia's references, scientists do not even have agreement how reliably whole metallic state have been confirmed. High pressure hydrogen needs probably to be investigated decades before we can answer to questions about its suitability to practical energy storage.

[jf0]

"Hydrogen can be stored in a metallic state" in the same sense that you can supply the worlds electricity by running hamsters in wheels, or that I can make an integrated circuit at home using a microwave oven, or I could get rich recovering gold from seawater as a hobby.

In principle, yes, hydrogen is thought to have a metallic phase ... at several hundred gigapascals of pressure.

[fredinno]

19 hours ago, RocketSquid said:

We have made metallic hydrogen, but it didn't stick around for long.

https://en.wikipedia.org/wiki/Metallic_hydrogen#Z_machine.2C_2015

I'm pretty sure those results were debated and unconfirmed...

20 hours ago, Iago said:

As you all know, (at least those who use Interstellar) hydrogen is amazingly useful for a variety of different things. It can be used as propellant, fusion fuel, scram jet fuel and to create a whole lot of organic substances needed for long duration flight.

There is only one problem. Storage. As it stands, you need a giant refrigerated tank to hold only a small amount of hydrogen.

But there is hope! Hydrogen can be stored in a metallic state, naturally found underneath the gassy part of gas giants (kind of like the "surface" of Jool). This allows for storage of a lot of hydrogen for very little volume, which is very useful when building spaceplanes and the like. The thing is, compressing the hydrogen is kind of difficult.

Any thoughts?