[TheForge] Hydrogen storage

[Demon Buddha]

James Binnion wrote:
> 
> On May 8, 2006, at 7:36 PM, Demon Buddha wrote:
> 
>> Can it not be safely kept in liquified form?
>>
> 
> Depends on your definition of safely. To my knowledge all  refrigerated 
> liquid gases are stored in dewars that continuously vent  the gas as it 
> boils off. If I understand it correctly this is due to  the imperfect 
> nature of the insulation of the dewar. If one did not  allow this 
> constant venting then the dewar would rupture from the  pressure of the 
> expanding gas. Dewars for gases like liquid hydrogen  cannot stand much 
> in the way of pressure due to the brittle nature of  the tank materials 
> at these low temperatures (just about any material  is brittle at these 
> temperatures). So I would not want to step into  my garage and flick on 
> the light switch after my cars tank full of  liquid hydrogen was venting 
> in it over night. I am also less than  eager to be in an accident with a 
> tank full of liquid hydrogen in my  vehicle.

	So you are saying that liquefication of H is inherently different from 
LPG, propane, butane, etc.  Even in those cases the propsect of a 
collision isn't very appealing.
> 
> But with a lot of engineering ways can probably be found to safely  
> store the hydrogen. Bruce mentioned metal hydrides as a possible  
> storage method. I am a little dubious about the practicality of  
> hydrides as they can store at most  5-7% by weight hydrogen (by  heating 
> the hydride to 250C or greater to release the H2) and more  reasonably 
> 1-2% by weight at room temperature. So you will need a  hell of a lot of 
> metal hydride mass to store a reasonable amount of  hydrogen.  That 1 lb 
> of hydrogen would need 50-100 lbs of metal  hydride mass to  store it. 
> Twenty six pounds of hydrogen is about  equivalent to 15 gallons of gas 
> so you would need somewhere between  1000-3000 lbs of metal hydrides to 
> store it. I think a lead acid  battery electric would probably be more 
> practical, it certainly is a  more mature technology.

	Well this is all looking very positive.