Engineering Carbon for Impressive Hydrogen Storage

[kristopher]

Engineering Carbon for Impressive Hydrogen Storage
May 22nd, 2009 by Laura Mgrdichian

(PhysOrg.com) -- University of Missouri researchers recently showed how carbon nanostructures can be engineered to become excellent media for hydrogen storage, work that may be important for the advancement of hydrogen-energy technologies for vehicles and other applications, which have been slow to develop due to the lack of suitable storage materials.

Using a combination of experiement and computer modeling, the group investigated the storage potential of various “nanoporous” carbon materials - carbon that contains tiny vacant spaces with diameters ranging from less than one nanometer to several nanometers.

Nanoporous carbon is a member of a class of materials being targeted as promising storage candidates because they can reversibly store hydrogen, are easy to load with hydrogen, and don't have heat-management issues. Carbon has an edge over other materials because it is both cheap and lightweight, but the low interaction energies between hydrogen molecules and carbon atoms lead to storage capacities that are inadequate at room temperature.

But no material, carbon or otherwise, presently comes close to the 2010 targets that the U.S. Department of Energy (DOE) has set for hydrogen storage at low-pressure, room-temperature conditions, namely 45 grams (g) of hydrogen per kilogram (H2/kg) material for rigid storage materials and 28 g per liter for liquid storage.

“Our work makes the case that it is possible to significantly increase hydrogen storage capacities in carbon materials by engineering the nanopores,” said University of Missouri physicist Carlos Wexler, the study's corresponding researcher, to PhysOrg.com....

http://www.physorg.com/news162195986.html

[NNadir]

1. The "hydrogen breakthrough" nonsense is almost as old as the "solar breakthrough" meme.

Both have been ridiculous crap foisted up by old fossil fuel apologists like Amory Lovins for close to 4 decades now.

In the last half a century, while dunderheads have been betting the future of all humanity on this dumb ass "breakthroughs" almost 1 trillion tons of dangerous fossil fuel waste has been dumped into the atmosphere while little babbling simpletons make big and worthless promises.

In fact, since 1980 alone, just 29 years ago, the figure is 603 billion tons.

http://www.eia.doe.gov/pub/international/iealf/tableh1co2.xls

Worse is the fact that none of the fundies advancing this "hydrogen is great" scheme seem to have grasped that hydrogen is not now, and never has been, a primary form of energy, although they continuously display scientific ignorance by pretending it is.

[vincna]

2. Problem with hydrogen?

Hydrogen does not occur naturally, but is always bonded to some other atom, e.g. oxygen in the case of water or carbon in the case of methane. I've always been under the impression that it takes energy to separate the hydrogen from whatever it's bonded to, so you wind up with little or no net energy. Am I wrong?

[kristopher]

3. No, you are correct.

However you are mis-categorizing the function of H. It should be viewed as a storage medium and compared to batteries.

In that comparison it scores lower, so the trend is for adoption of battery storage and not H. However, one of the factors involved in the evaluation is the energy costs of compressing the H for storage, and technologies that stand to substantially change the equation should be observed with interest, IMO.

[vincna]

4. I haven't studied the thermodynamics,...

but my gut tells me it's not a very practical approach. Compressing it does take a considerable amount of energy so the net would be reduced. You have to be careful handling it because it is so explosive when mixed with air.

We use hydrogen as a cooling medium in large generators. It has lower windage losses and does a better cooling job than air, but special procedures are followed to insure safety. A hydrogen fire can be really nasty - the flames are invisible.

I think there are better ways - batteries, compressed air, pumped storage, etc.

[kristopher]

5. In the early days H looked most promising...

because of the ability to manufacture H from water, the efficiency of the fuel cell over the ICE and its potential energy density in compressed form; but with the development of lithium batteries all that changed.

There are a lot of parts to the analysis, but it boils down to batteries are better. Large scale is a different discussion. Google "energy storage gravel heat pump" for a very promising development.

[vincna]

6. I saw that, but...

it wasn't clear (to me at least) how such a system would work. I didn't see any articles that explained it in any detail. I assume that there is a motor that drives the heat pump and it becomes a generator when the process reverses. The article claims 99% isentropic efficiency but that seems high to me considering that pumped storage is only about 70 - 80 % efficient.

Speaking of energy storage, if you are ever in Wales, you should check out this place:

http://www.fhc.co.uk/dinorwig.htm

It was for sale in 1996 and I got to do the evaluation for a possible bid, so I got the grand tour. Fully charged, it can deliver almost 2,000 MW for 5 hours. It has 6 motor/generator units and each can go from synch-idle (0 MW) to about 300 MW in 16 seconds. It's built inside a mountain in the Snowdonia National Park in northern Wales and you could drive past it an not even know it's there.

[kristopher]

7. Pumped hydro is limited by geography.

It has potential for expansion, bu not much in comparison to the amount of storage that is needed. The gravel/heat pump system is reporting a round trip efficiency of somewhere around 70% (competitive with pumped hydro) and it is geographically neutral. It is hard to imagine a simpler, more scalable system that approaches such efficiency. I've been studying this sector pretty closely and when considering the total picture it is, by far, the most promising technology out there for a renewable grid, so, I'm cautiously very optimistic on this one.

Take a look at this photo:


The *claimed* capabilities are at this page: http://isentropic.co.uk/index.php?page=storage

I'd like to take a tour of a facility like Dinowirg, it looks impressive. I know some people from Mitsui pretty well, maybe they can get a peon like me a grand tour also.

I'm under the impression that the old coal mines in the Appalachians are being surveyed now, do you know anything about that?

Added on edit: The HEAT PUMP portion of the energy journey is what they claim to be getting 99%+ efficiency on. It appears to be an increase of 5-8% on other claims.

[Nihil]

8. FWIW

Dinorwig does public tours ("Electric Mountain") and these are
quite interesting too - did one about seven years ago as I was
in the area.

I'd still like to see a full-size gravel pumped system though
as that would open up a *lot* more sites for storage.