It's a spring. You put in mechanical energy, you get back mechanical energy and heat. The engineering challenge, I think, is making something that can compress a useful quantity of the stuff.
> The engineering challenge, I think, is making something that can compress a useful quantity of the stuff.
That's spot on.
To me the whole concept sounds like a mechanical ratchet and a spring, the pressure pushes the chemicals in to a configuration they would not normally achieve because of repulsive forces, the pressure helps to overcome those forces and then the new dominant force locks in the configuration so the pressure can be removed.
After that if you weaken the force that holds everything together the molecule expands to its original size and will release a bunch of energy as heat in the process.
I don't think the pressure _can_ be removed. Nothing in the article says this "material" is stable at ordinary pressures. They're just saying that the chemical structure changes as it is squeezed into a smaller and smaller space. If you let go, it presumably expands immediately.
To be clear, I also think the energies they are storing in their experiment are a small fraction of a joule. The "energy density" is high because the sample is very small.
It is the case. It's not a ratchet and a spring, it's just a spring which can be compressed further than any spring before. (The phase changes along the way are interesting, but will reverse themselves as you release the pressure).
Now, if you could get a giant diamond anvil cell (with house-sized near-flawless diamonds), you could use it to compress a macroscopic quantity of this down, and then get the energy back. The problem is that while the substance in its compressed form may have more energy per cubic foot than, say, a tank of gasoline, in releasing that energy it would expand to something much larger, so your entire apparatus would be very space-inefficient for energy storage (not to mention the difficulties of obtaining those giant diamonds).
My rough guess is this noble gas + fluorine combination = crazy ultra-reactive material at room temperature and standard pressure.
I'd say this is not something one wants to release into the wild. There might be a clever way to contain it. But it would a bit hard to make laptop batteries of out of it.
Edit: You're right, Alfred only organized other chemical things...
I suspect the bigger challenge is making it so that releasing the energy happens in a controlled, preferably non-explosive manner.
There's lots of materials with super-high energy density that have little more than curiosity value due to their tendency to release said energy spontaneously before you're even done making them.
As I said below (or possibly above) this material is only energy-dense when it's in its most compressed state. To get the energy out you have to expand it again, at which point you find that you need a vast apparatus to store your energy.
Remember, the state of the art in energy storage is a metal tank filled with liquid hydrocarbons. It's pretty damn hard to beat for price, reliability, safety [ * ] and energy density. What we really want is a more efficient way of producing those hydrocarbons out of water, CO2 and energy.
[ * ] Relative to most ways of storing large quantities of energy, that is.
Also as long as you don't care about energy leakage -- no matter how good your bearings are, they're imperfect. Flywheels store energy for minutes or hours, batteries for days or weeks, non-volatile hydrocarbons for millions of years.
Obviously weak on details but it would be pretty interesting to think that energy stored in crystals (as so many sci-fi worlds use) is actually a reality.
On the topic of details, any ballpark conceptual idea on how efficient it would be storing and retrieving the energy from a source like this?
Creating such pressures requires very tricky engineering in order to do it on a scale that you can actually use so I would wager that it would not be very efficient.
Diamond anvils are not exactly high volume devices. There may be a way around that but we don't currently have one that I'm aware of.
