Buckyballs Can Store Concentrated Hydrogen

Pickens brings news that researchers from Rice University have discovered that it's possible to store hydrogen inside buckyballs. Hydrogen can be an excellent power source, but it is notoriously difficult to store. The buckyballs can contain up to 8% of their weight in hydrogen, and they are strong enough to hold it at a density that rivals the center of Jupiter. "Using a computer model, Yakobson's research team has tracked the strength of each atomic bond in a buckyball and simulated what happened to the bonds as more hydrogen atoms were packed inside. Yakobson said the model promises to be particularly useful because it is scalable, that is it can calculate exactly how much hydrogen a buckyball of any given size can hold, and it can also tell scientists how overstuffed buckyballs burst open and release their cargo."

Re:A point worth making-

[oni]

as much hydrogen as the centre Jupiter,

So what you're saying is that you don't understand the difference between density and volume.

Re:That's nice and all...

[Alwin Henseler]

No prob. The issue here is finding an (energy-)efficient / easy way to make the buckyballs store and release hydrogen. But once the hydrogen is released, I can't imagine it would be hard to separate 2-atom hydrogen molecules from 60-atom buckyball molecules. Or find a way to do so.

Some hints: at room temperature, buckyball molecules may behave as solid or liquid-like material, or be dissolved in other liquids, while hydrogen is a thin gas. And buckyball molecules come in different sizes (number of C-atoms).

Summarized: the carbon here should be regarded as a carrier, not part of the fuel.

Re:Clearly I'm missing something

[oxidiser]

You're comparing apples and oranges here. The buckyballs DO contain carbon, but that fact alone does not make them dangerous to the environment. Carbon as fuel is bad because it gives off CO2 as a byproduct of burning. In this case the carbon is just the container, the hydrogen is the fuel. Unless of course I'm missing something, which is entirely possible.

Don't you mean "could" store hydrogen?

[Fysiks Wurks]

Let's RTFA a bit: "'Based on our calculations, it appears that some buckyballs are capable of holding volumes of hydrogen so dense as to be almost metallic,' said lead researcher Boris Yakobson"..." If a feasible way to produce hydrogen-filled buckyballs is developed, Yakobson said, it might be possible to store them as a powder."

What a difference one word can make in a summary. News flash, "Miss Universe can have sex with Slashdot users! According to simulations conducted with fold-out pictures in Randy's basement..um...research center"

The simulation work is pretty cool, the headline and summary can and does mislead the reader.

Here's How They Work (Informative!)

[Colonel Korn]

Okay, no one in a modded-up post on this story understands the concept. Buckyballs look like soot. You have a tank filled with this soot in your car. Then you flow very high pressure hydrogen gas over them for awhile (this has been done for years with carbon nanotubes, which offer more storage but because they only confine in 2 dimensions, unlike the balls, they don't provide the capillary forces necessary to make this easy). Hydrogen then adsorbs (notice ADsorbs, not ABsorbs) onto the inner surfaces of the Buckyballs. Capillary forces, like those that cause liquid to be drawn into a straw, allow the hydrogens to live essentially as liquids inside the balls, meaning that when you remove the high pressure hydrogen flow, the hydrogren in the buckyballs doesn't all immediately fly out. Hydrogen leaks out of the balls slowly, becoming a gas and maintaining a roughly constant pressure in the tank, and you then siphon off the hydrogen that you want to power your car. You can control the leakage rate by changing the temperature.

You then reuse the Buckyballs by flowing hydrogen gas over them when they're empty. They're 100% reusable storage, not tiny gas tanks. Someone mod this up so that the dozens of "oh nos, Buckyballs hurt teh environments" posts go away.

Re:Not true! They will be VERY convenient for a bi

[ukemike]

If this is practical and it's energy potential can be tapped, we'll have at our fingertips, an unlimited power source that won't kill you with radiation.

It astonishes me how often /.ers forget the first and second law of thermodynamics. You'll only have the unlimited source of energy after you expended the same amount of energy (and more) generating and compressing the hydrogen to get it into the buckyballs in the first place.

Wake up world. Hydrogen isn't a source of energy any more than capacitors are. It's a way to store energy.

Re:Here's How They Work (Informative!)

[mapsjanhere]

You will reach an equilibrium pressure in your tank at which adsorption and desorption occur at the same speed. The big question here is kinetics anyway. How fast does the hydrogen adsorb, and how fast can it be released? The whole idea only becomes practical if you can "fill your tank" in a reasonable time and with decent equipment requirements, lets say 5 min at 2000 psi. And the release has to be fast enough to allow an engine to generate 100 kW or so without depleting the hydrogen flow (or needing a m^3 of tank).

Re:Here's How They Work (Informative!)

[Gryphia]

Oops. Wasn't logged in. So no one will see the previous comment, I'm sure. Wrong. What you are describing is how you load hydrogen into the pores between buckyballs in a C60 crystal. What this article describes is theory based on hydrogen loaded inside a single buckyball cage. Due to the pore size (basically it's a C6/C5 ring, depending on where you are on the buckyball), you can't load hydrogen into the cage of a buckyball. To get hydrogen inside a buckyball, you actually have to synthesize the buckyball with hydrogen in there (at least, at this point. No one has a better way to do it). This has been done for a single hydrogen molecule. Being able to do it for the pressures they are talking about . . . is nowhere on the horizon. The gas adsorption method that you describe is typical, but it's not what we're talking about in the case. It was shown a while back (FitzGerald et al, Phys. Rev. B, 65, 2002) that the kinetics of the situation are just absurd. It takes hours to reach an equilibrium loading situation at room temperature, and even that is only about 1 H2 per C60 (I'll let you do the math, but 1 C is ~ 6 times as massive as an H2, so the loading by volume . . . is very low). C60 through traditional gas adsorption has no potential to store hydrogen for commercial purposes. These days, much attention is being focused on metal organic frameworks (MOFs), which operate by similar methods, but hold much more C60 by weight (~10% for the best) . . . the problem is the binding energies are still so low that they don't hold hydrogen at room temperature very well at all.

Re:Here's How They Work (Informative!)

[cupofjoe]

I'd like to second Colonel Korn on this one (I've certainly never written THAT before); the concept of reusable hydrogen storage materials is not a new one. It's devilishly difficult, of course, but not new. Check out http://hydrogen.energy.gov/ [energy.gov] to see what's been done so far.

Buckyballs, like carbon nanotubes (CNTs) before them, store hydrogen by physisorption, whereby hydrogen molecules (not atoms, usually) "stick" to the near-surface via van der Waals forces (or equivalent). The issue with CNTs, of course, is that they really didn't do it as well as folks had hoped (or originally thought; there was some controversy over this). Overall, physisorption systems (the AD- vs. AB-sorption that the parent was referring to) don't do as well as chemisorption systems like metallic hydrides, though. The peak capacities are something like 3-6% vs. 12-15%, respectively.

But let's not mince words here; the real key issue in this case is that the nice folks at Rice have RUN A MODEL. They haven't done any empirical work to determine whether this actually works. If you've been keeping score here, that's where the rubber meets the road. Personally, I'm not holding my breath on the claimed 8% number.

After working in this field for a while, I've noticed that these kinds of claims appear at regular intervals (usually from universities with good media departments) regarding "miracle materials" that store tons of hydrogen. Don't get me wrong; any active thinking is progress - but let's be productively skeptical, eh?

To Rice's PR department: good show, but I don't buy it. Sorry for the cynicism.

Cheers,
--joe.

Comparing to pyrene

[vuo]

Pyrene is a hydrogen transfer catalyst that can contain 0.99% hydrogen if hydrogenated to 4,5-dihydropyrene. I did the same H2 content calculation for C60 and found that the current state of the art, one H2 in one fullerene or C60@H2, is 0.28% hydrogen. To be better than pyrene, you need to put in eight hydrogen atoms as four H2 molecules, or C60@4H2. To give that 8% storage capacity you need not less than 62 hydrogens, or C60@31H2. That's slightly more than one hydrogen per one carbon, which is a lot. (Gasoline is 16% hydrogen, btw.)

The major problem with this "discovery" (it's just a calculation, I'd say) is that you'll need to design a chemical synthesis that forces metallic hydrogen into a buckyball, without inducing hydrogenolysis (spontaneous production of hydrocarbons from hydrogen and carbon). Then you should be able to design molecular "hatch" that you can open and close while being under this enormous hydrogen pressure. A small obstacle to this being that I suspect nearly any heteroatom you'd need for the hatch would be immediately torn off by hydrogenolysis. My guesstimate would in fact be that the fullerenes themselves would be hydrogenolyzed on contact with metallic hydrogen. As you can see, it's the physicists and their phyucher flying cars again. It's interesting but no real problem has been solved.

And also, the problem of producing the hydrogen is still unsolved, no matter the hype. The problem that we want a reducing agent (H2), which unavoidably requires energy to produce. The major options are fossil and nuclear; the world runs out of arable land area if we try to produce it by agriculture. Actually the situation can be summarized like this:

1. Invent technologies to transport or spend existing hydrogen (fuel cells, hydrogen storage, etc.)
2. ???
3. Hydrogen economy!