Methods of hydrogen storage on the blackboard?

[Topher925]

I was just curious if anyone knows of any new and upcoming methods of hydrogen storage to be used for fuel. The only three methods I know about are hydrides, liquid hydrogen, and compressed tank storage. Does anyone know of any new methods that are in development? I know there's a lot of money being spent in order to solve this problem.

 

[Q_Goest]

I saw Guido Pez present this at a symposium a few years ago.
http://www.hydrogen.energy.gov/pdfs/review05/pd34_pez.pdf

Basically, you have a 'liquid carrier' which hydrogen can be bonded to. That liquid gives up the hydrogen when heated. The hydrogen is then sent to a fuel cell and the spent liquid placed in a second storage tank. The spent liquid is then removed at the next refueling and replaced by liquid which has already had hydrogen bonded to it. In that way, the liquid is continuously recycled.

 

[Topher925]

Very interesting, I never even knew liquid hydrides even existed. But what advantage does a liquid hydride provide over a conventional solid hydride besides the form of the fuel tank? Mn if I remember correctly can store up to 11 wt.% while the liquid hydride in that proposal can only store 6 wt.%. Is it easier or more efficient to extract the H2?

 

[Q_Goest]

Good question. The primary advantage is safety and secondarily is the ease of handling. Liquid is both safer and easier to handle. Solid hydrides require some amount of pressure and require gasseous storage at the point of delivery. Liquids don't require any pressure and allow liquid delivery. H2 gas can leak easily and without being noticed and can even burn without producing a visible flame. Liquid leakage is less likely because of the lower pressure and higher molecular weight. Also, liquid won't burn without producing a visible flame. Note also the percentage of H2 mass is all still in development, so the 6% might be increased in the near future.

 

[Topher925]

That makes a lot of sense. If there was a leak at STP at about what rate would the H2 dissipate from the liquid? Your link has data for extraction at 190C+ under pressure but would the H2 sort of "extract" if there was a liquid leak from the storage tank?

If someone were to get develop a safe, cheap, and readily available liquid hydride with a ~50 wt% that would change everything. Although I would imagine there would still be a lot of issues with cold start up which is an issue that compressed H2 does not have.

 

[mheslep]

Chemisttree started this thread last year, referencing a Chemistry World article on a discovery that an ethylene substance would hold 14% H by weight, or about double what hydrides will do.
https://www.physicsforums.com/showpost.php?p=1540473&postcount=1"

If if works out, then by this http://www.rsc.org/chemistryworld/Issues/2007/October/HydrogenStorageTargetsOutOfReach.asp" ethylene becomes gravimetrically and volumetrically comparable with liquid hydrogren storage (10% H by weight), a big win. No results yet on absorption/release cycling, nor any mention of energy required in cycle, which is the problem with liquid H.

 

[Q_Goest]

If there was a leak at STP at about what rate would the H2 dissipate from the liquid? Your link has data for extraction at 190C+ under pressure but would the H2 sort of "extract" if there was a liquid leak from the storage tank?

The page in the presentation regarding 190 C temperature and "hydrogenation" at 1000 psi regards the process of taking the 'empty' liquid and putting hydrogen into it. That process is done at the plant. So under elevated temperature and pressure, the liquid is hydrogenated. Once the hydrogen has been 'put in' and the temperature brought back down to ambient, the hydrogen can't come back out. You could have it sitting in an open cup and no hydrogen would break free from the carrier. In order to have the hydrogen separate from the carrier liquid, heat must be applied. Note also that a catalyst is used for both hydrogenation and dehydrogenation as indicated on sheet 4 of the presentation. Sheet 12 of the presentation shows rates of dehydrogenation given various temperatures and the overall conversion rate. Conversion rate is the percent of hydrogen removed from the liquid carrier.