h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I've been doing a bit of studying on hydrogen economies lately, and noticed that H2 gas has a loss rate of 3-4% a day when sent through pipes. I think there are losses from canisters as well, maybe 1-2%.

I know it's something to do with H2 being small and light, but why exactly? I wouldn't have thought the molecule was smaller than gaps between metal ions or plastic molecules.

Anyone know what the reason is?

in advance.

cylinder valves and pipework joints?

H2 is indeed small enough to be contained between metal interstitials (gaps between atoms). In fact that forms a large basis for the proposed hydrogen economy, and it would certainly be where hydrogen atoms are lost in transit, thanks to diffusion. In plastic piping, the problem would be even worse.

My degree thesis was about determining the saturation point of certain alloys. The results were much larger than anyone expected, which is proving a little obstructive to hydrogen transportation at present.

B

>I wouldn't have thought the molecule was smaller than gaps between metal ions or plastic molecules.<

Sadly you would've thought wrongly - as said above. Hydrogen is the tiniest of molecules.

Can't liquid hydrogen drip through metals?

Yeah, it can at about 3-4% per day I think.