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Super cool stuff! There are some greatly quotable sentences in the paper: > Moreover, SMH (solid metal hydrogen) is predicted to be metastable so that it may

by toufka 10y ago

Super cool stuff! There are some greatly quotable sentences in the paper: > Moreover, SMH (solid metal hydrogen) is predicted to be metastable so that it may exist at room temperature when the pressure is released. If so, and superconducting, it could have an important impact on mankind’s energy problems and would revolutionize rocketry as a powerful rocket propellant. > The principal limitation for achieving the required pressures to observe SMH in a DAC (diamond anvil cell) has been failure of the diamonds. > The sample was cryogenically loaded at 15 K and included a grain of ruby for pressure determination. > As of the writing of this article we are maintaining the first sample of the first element in the form of solid metallic hydrogen at liquid nitrogen temperature in a cryostat.

mrfusion 10y ago
If it's stable at room temperature wouldn't it make a really high density fuel too?
- dogma1138 10y ago
  Metallic Hydrogen can also be a liquid and even a gas, the metallic part indicates it's an electric conductor, not a solid. The "idea" behind metallic hydrogen is that since hydrogen is above the alkali metals in the periodic tables there should be a phase where it behaves like a metal, the state of the phase is not defined as a solid/gas/liquid in fact in all honesty it would exist as all 3 and more. The first production of metallic oxygen was a liquid, this is the first solid one, tho at these pressures it's really unlikely that it would effective as fuel store. One of the more interesting parts about metallic hydrogen is the information we learn also applies to hydrides (hydrogen alloys) especially things like Lithium-Hydrogen since basically you can stabilize a large amount of hydrogen atoms (6 or more) around a single atom of Lithium, this might actually be very interesting for a lot of applications including energy storage. Hydrides should be considerably more stable and more importantly at considerably lower pressures which would mean that they can actually be used for various applications since you are not going to find something that only can exist at 400 gPA levels of pressure or higher very useful for high stress applications.
  - DenisM 10y ago
    Metallic hydrogen is atomic, recombining two atoms into an h2 molecule releases huge amount of energy. Iirc 4x as much as burning h2 in oxygen.
    - dogma1138 10y ago
      Technically it's degenerate matter since the atoms do not interact due to the pressure and other conditions, this happens because the electrons would have to follow the exclusion principle under those pressures/densities the electrons basically separate from the hydrogen proton as they cannot occupy the same space and the hydrogen becomes a degenerate matter; a sea of electrons flowing freely through a lattice of protons, because of this none of the "atoms" can combine into molecules, but they aren't technically atoms at that point either. The problem with hydrogen as fuel storage (mainly for space travel) is the pressure, operating a fuel tank at 400 gPA or higher is going to be tricky, I've edited my previous post and added the bit about Hydrides which might actually considerably more viable for both terrestrial and space applications. If we can actually make LiH6 alloys and can find an easy way to break them apart it can be a great fuel source, yes we might have to carry some "dead weight" but Li has an atomic number of 3 Oxygen has an atomic number of 8, considering that Hydrogen-Oxygen reaction is pretty much 1 to 1 (well "2") we have to carry considerably more Oxygen now than we would have to carry Lithium. If a Hydrogen-Hydrogen reaction could be harvested as a propellant it would still be more effective than what we have even if we don't find any clever ways of catalyzing the lithium we already carry to push the reaction even further, we might be able to carry a smaller amount of oxygen also to catalyze the lithium tho I'm not sure if the energy from that reaction would be worth the added weight of the oxygen and the parts of the fuel and propulsion systems that would support it and the O-Li process. P.S. Metallic hydrogen is also of "interest" to those who still study cold fusion, even tho you can't call it cold fusion any more due to the stigma, at certain conditions there is a high likelihood of Inertial Confinement Fusion and Pycno Nuclear Fusion occurring, this often brought up as "superconductor fusion" simply because you can't call anything cold fusion and get it published. That might also be a quite interesting fuel source, especially if you simply need to push it to a certain limit and once the fusion kicks in it would transition to other fusion stages. And lastly this might be especially interesting if we can make Li-Deuterium alloys since D-Li fusion produces Helium 4 and over 20 MeV of energy :) This (last) type of fusion is extremely interesting because not only it's highly energetic but it's aneutronic, which means that less than 1% of the energy is released via neutrons vs 80-90% in other forums of fusion, aneutronic fusion produces tons of energy an pretty much no ionizing radiation which means if you can make it work it would be in theory a safe enough battery to power a cellphone without frying your brain.
- ArkyBeagle 10y ago
  I'm no chemist, but I'd expect it to be more of an explosive than a fuel.
  - JackFr 10y ago
    To-may-to, to-mah-to....
  - adrianratnapala 10y ago
    Whether or not MH is metastable in the real universe, it -- or at least some form of it -- is metastable in Alastair Reynolds "Revalation Space" universe, and there ohh boy is it explosive.
- inimino 10y ago
  From the paper: "Moreover, SMH is predicted to be metastable so that it may exist at room temperature when the pressure is released (10). If so, and superconducting, it could have an important impact on mankind’s energy problems and would revolutionize rocketry as a powerful rocket propellant (11)."
- oscrr 10y ago
  I wonder what the specific impulse of the stuff would be.
  - Symmetry 10y ago
    The exhaust velocity would be 17 km/s according to: http://www.projectrho.com/public_html/rocket/enginelist.php#metallichydrogen http://www.projectrho.com/public_html/rocket/enginelist.php#...
- deleted 10y ago
  [deleted]
wfunction 10y ago
> Super cool stuff! Literally!
Shivetya 10y ago
hell with rocket fuel, if the stuff isn't horribly expensive to produce it could be a good portable source period
- amelius 10y ago
  This makes me wonder, what is the energy density of this stuff? And how easily does it release its energy? (Is it hazardous?)
  - adrianratnapala 10y ago
    TL;DR: Theres lots of energy (but less than I thought), it's probably (too) easy to release, so yep it's dangerous. If I understand it correctly most of the energy (apart form E=mc^2 energy that can't be tapped easily) is what comes from the mechanical work squishing the hydrogen down to size. That means the energy density should be in the order of the pressure, which is 495 GPa. So a cubic metre of the stuff would have half a terajoule of energy. Wikipedia says the Nagasaki bomb was about 90 terajoules. If the stuff behaves in a simple way, you can release the energy by just releasing the pressure. If it is "metastable" that means it can somehow remain compressed when the pressure is released -- but will be "trying" to explode to its uncompressed state. We don't know if the metastable state even exists, let alone how easy it is to get out of.

by toufka 10y ago

mrfusion 10y ago

If it's stable at room temperature wouldn't it make a really high density fuel too?

dogma1138 10y ago
Metallic Hydrogen can also be a liquid and even a gas, the metallic part indicates it's an electric conductor, not a solid. The "idea" behind metallic hydrogen is that since hydrogen is above the alkali metals in the periodic tables there should be a phase where it behaves like a metal, the state of the phase is not defined as a solid/gas/liquid in fact in all honesty it would exist as all 3 and more. The first production of metallic oxygen was a liquid, this is the first solid one, tho at these pressures it's really unlikely that it would effective as fuel store. One of the more interesting parts about metallic hydrogen is the information we learn also applies to hydrides (hydrogen alloys) especially things like Lithium-Hydrogen since basically you can stabilize a large amount of hydrogen atoms (6 or more) around a single atom of Lithium, this might actually be very interesting for a lot of applications including energy storage. Hydrides should be considerably more stable and more importantly at considerably lower pressures which would mean that they can actually be used for various applications since you are not going to find something that only can exist at 400 gPA levels of pressure or higher very useful for high stress applications.
- DenisM 10y ago
  Metallic hydrogen is atomic, recombining two atoms into an h2 molecule releases huge amount of energy. Iirc 4x as much as burning h2 in oxygen.
  - dogma1138 10y ago
    Technically it's degenerate matter since the atoms do not interact due to the pressure and other conditions, this happens because the electrons would have to follow the exclusion principle under those pressures/densities the electrons basically separate from the hydrogen proton as they cannot occupy the same space and the hydrogen becomes a degenerate matter; a sea of electrons flowing freely through a lattice of protons, because of this none of the "atoms" can combine into molecules, but they aren't technically atoms at that point either. The problem with hydrogen as fuel storage (mainly for space travel) is the pressure, operating a fuel tank at 400 gPA or higher is going to be tricky, I've edited my previous post and added the bit about Hydrides which might actually considerably more viable for both terrestrial and space applications. If we can actually make LiH6 alloys and can find an easy way to break them apart it can be a great fuel source, yes we might have to carry some "dead weight" but Li has an atomic number of 3 Oxygen has an atomic number of 8, considering that Hydrogen-Oxygen reaction is pretty much 1 to 1 (well "2") we have to carry considerably more Oxygen now than we would have to carry Lithium. If a Hydrogen-Hydrogen reaction could be harvested as a propellant it would still be more effective than what we have even if we don't find any clever ways of catalyzing the lithium we already carry to push the reaction even further, we might be able to carry a smaller amount of oxygen also to catalyze the lithium tho I'm not sure if the energy from that reaction would be worth the added weight of the oxygen and the parts of the fuel and propulsion systems that would support it and the O-Li process. P.S. Metallic hydrogen is also of "interest" to those who still study cold fusion, even tho you can't call it cold fusion any more due to the stigma, at certain conditions there is a high likelihood of Inertial Confinement Fusion and Pycno Nuclear Fusion occurring, this often brought up as "superconductor fusion" simply because you can't call anything cold fusion and get it published. That might also be a quite interesting fuel source, especially if you simply need to push it to a certain limit and once the fusion kicks in it would transition to other fusion stages. And lastly this might be especially interesting if we can make Li-Deuterium alloys since D-Li fusion produces Helium 4 and over 20 MeV of energy :) This (last) type of fusion is extremely interesting because not only it's highly energetic but it's aneutronic, which means that less than 1% of the energy is released via neutrons vs 80-90% in other forums of fusion, aneutronic fusion produces tons of energy an pretty much no ionizing radiation which means if you can make it work it would be in theory a safe enough battery to power a cellphone without frying your brain.
ArkyBeagle 10y ago
I'm no chemist, but I'd expect it to be more of an explosive than a fuel.
- JackFr 10y ago
  To-may-to, to-mah-to....
- adrianratnapala 10y ago
  Whether or not MH is metastable in the real universe, it -- or at least some form of it -- is metastable in Alastair Reynolds "Revalation Space" universe, and there ohh boy is it explosive.
inimino 10y ago
From the paper: "Moreover, SMH is predicted to be metastable so that it may exist at room temperature when the pressure is released (10). If so, and superconducting, it could have an important impact on mankind’s energy problems and would revolutionize rocketry as a powerful rocket propellant (11)."
oscrr 10y ago
I wonder what the specific impulse of the stuff would be.
- Symmetry 10y ago
  The exhaust velocity would be 17 km/s according to: http://www.projectrho.com/public_html/rocket/enginelist.php#metallichydrogen http://www.projectrho.com/public_html/rocket/enginelist.php#...
deleted 10y ago
[deleted]

wfunction 10y ago

> Super cool stuff! Literally!

Shivetya 10y ago

hell with rocket fuel, if the stuff isn't horribly expensive to produce it could be a good portable source period

amelius 10y ago
This makes me wonder, what is the energy density of this stuff? And how easily does it release its energy? (Is it hazardous?)
- adrianratnapala 10y ago
  TL;DR: Theres lots of energy (but less than I thought), it's probably (too) easy to release, so yep it's dangerous. If I understand it correctly most of the energy (apart form E=mc^2 energy that can't be tapped easily) is what comes from the mechanical work squishing the hydrogen down to size. That means the energy density should be in the order of the pressure, which is 495 GPa. So a cubic metre of the stuff would have half a terajoule of energy. Wikipedia says the Nagasaki bomb was about 90 terajoules. If the stuff behaves in a simple way, you can release the energy by just releasing the pressure. If it is "metastable" that means it can somehow remain compressed when the pressure is released -- but will be "trying" to explode to its uncompressed state. We don't know if the metastable state even exists, let alone how easy it is to get out of.