Slashdot Mirror
New Hydrogen Storage Technique
pwp writes to mention that researchers at the University of New Brunswick are reporting they have found a new method of storing hydrogen gas. The new method is able to condense hydrogen gas into a usable solid under mild conditions. "Hydrogen gas is typically stored under pressure in large metal cylinders, approximately four feet high. These cylinders are heavy and expensive to transport. Since they are under pressure, they also pose a safety hazard. 'We've reached a milestone with our ability to condense hydrogen into a usable solid,' said Dr. McGrady. 'The next step is to produce a safe, compact storage system for the compound that is both lightweight and affordable.' The research is expected to produce reversible hydrogen storage materials that can be processed into a powder for use in limitless commercial applications."
They bind it with aluminum to create a stable hydrogen/aluminum powder.
At least, that's what a local news report mentioned a few days back.
M
There's very little actual information in the article, so I did some digging - here is the recipe:
- - - - - - - - - -
Brunswick Stew
In a 2 gallon pot, over low heat melt ¼ lb of butter then add:
3 cups small diced potatoes
1 cup small diced onion
2 14½ oz. cans of chicken broth
1 lb baked chicken (white and dark)
8-10 oz. smoked pork
Bring to a rolling boil, stirring until potatoes are near done, then add:
1 8½ oz. can early peas
2 14½ oz. cans stewed tomatoes - (chop tomatoes, add liquid to the stew pot)
3 cups prepared onion barbecue sauce
1 16 oz. can of baby lima beans
¼ cup Liquid Smoke
1 14½ oz. can creamed corn
Slow simmer for 2 hours
- - - - - - - - - -
The exciting revelation is that this recipe actually contains more than twice the percentage of hydrogen by weight that is stated in the article. Real progress.
You can't talk about Wikipedia's flaws on Wikipedia
Danm I love this joint!
May the Maths Be with you!
Whoah, seriously? They're making alane (stabilized aluminum hydride, AlH3)? Yep, a quick search revealed this to be the case. This would interest the rocketry industry as well, since alane offers great Isp. Let me check those weight numbers. Aluminum's atomic mass is about 27, while hydrogen's is about 1. AlH3 would thus be about 10% hydrogen by weight, so 9% would be essentially saturated, and 6% over half saturated. If correct, this would be incredible.
HOWEVER...
As many people seem to forget on energy and rocketry threads, breakthroughs like this are sadly a dime a dozen. The vast majority never reach the market or reach it in a greatly diminished form. Thus, take press-release style reports of breakthroughs with a heavy grain of salt.
Assuming ethanol comes from murdered children and the hydrogen from magic, hydrogen saves 132% more lives than ethanol.
I agree that it would appear they could be talking about Alane (AlH3), which has a theoretical weight-density of about 10% hydrogen. Yes, 10% is good...but as folks in the hydrogen storage community would be quick to tell you, it's not unusual. For example, Lithium Borohydride (LiBH4) has a theoretical weight-density of almost 18.5% hydrogen! The key is simply to bind hydrogen with light elements in a stable configuration, right?
Wrong. That's not even the tip of the iceberg.
The real problem, as any hydride person would correctly point out, is not "theoretical storage fraction"; rather, it's REVERSIBLE storage fraction. It doesn't really matter, in the long run, if you can store 18%, or even 25% hydrogen by weight in a substance if the following are true:
1. it takes a LOT of energy to put it in (theormodynamically unfavorable hydrogenation reaction)
2. you can only get out a small fraction of what you put in under favorable conditions (non-reversibility)
3. the reaction doesn't move very quickly (unfavorable kinetics)
With these limitations, you face a severe energy penalty for trying to use the material as a hydrogen carrier, mostly because it's one-way. The keys to an inexpensive, efficient solid-state hydrogen storage material combine high storage fraction with a high level of reversibility: why bother using a material if you have to ship it back to the "refinery" when the hydrogen has been depleted? As an example, let me use the typical automotvie application to illustrate. (I know that TFA - which doesn't really say ANYthing, natch - doesn't explicitly state that their "revolutionary" material is for automotive applications, but that's where all the money is coming from these days.)
What I want to do is expose the dehydrogenated powder (it's usually a powder) to hydrogen gas at about 1 atmosphere (~15 psi), remove some heat of reaction (for later use, naturally) and go on with my business. Preferably at a "hydrogen filling station", whatever that ends up looking like. Oh, and refueling shouldn't take more than about 5 minutes. And once the tank is full, I should be able to drive 300 miles without filling up again.
Right now, there is NO material known on Earth that can fulfill these requirements and still be designed into a car.
The astute reader will notice immediately that I'm leaving out what might be the single-most crucial design driver: SAFETY. I don't know if everyone's been keeping up, but alane (and the alanate hydrides in general) are ROCKET FUELS. Personally, I don't want to drive around with 20kg of solid rocket fuel in my car's gas tank. In this case, safety will absolutely drive eventual adoption, even trumping reversible storage fraction.
For example, sodium alanate (NaAlH4) has a theoretical storage fraction of 5.6%, and the reversible fraction is starting to approach 4-5%, which is a very, very good track record. However, when it sees water (which it might, in a car accident) it EXPLODES. Well, deflagrates, but you get the point.
(rant on)
Don't get me wrong. I'm all about solid-state H2 storage, and the "H2 economy" in general, whatever that happens to be. I'm even a "real" materials engineer, working with hydrides. But I'm also all about reality, and hopefully trying to "drop the veil" of proprietary information wherever possible. We're working as a team, people. So, to the press folks at UNB: write better articles, publish some papers, or both.
(rant off)
-joe.