Water electrolysis and air powered dive gas booster pump. That's it. Same ones used for all gasses, including methane and hydrogen are used for dive gas boosters.

http://pressuretestpumps.com/media/html/gas_pumps.htm

http://www.divegearexpress.com/rebreathers/booster.shtml

That is brand new.

http://cgi.ebay.com/HASKEL-AIR-AMPLIFIER-AIR-PUMP-AIR-BOOSTER-MAA-2-5-NEW_W0QQitemZ110448511070QQcmdZViewItemQQptZBI_Pumps?hash=item19b73e885e

The link to the manufacturer is just to show that air powered booster pumps do the job, and are the right thing for that job. And the air powered part is the important, non hindenburg thing. You can run one of these with an airline from a tank or air compressor, whatever.

Now the "just go buy a tank" hydrogen black market action... This is to permanently avoid that.

The Pt cats, platinum oxide or the Pt black are do able at home. Hydrogen is the hard part. I hope not anymore.

Oh yeah, nobody die doing this.

The H2 required in most procedures nowadays is fairly low (1-10 atmospheres) - generate your hydrogen and pass it through a condenser so it is COLD (talking -78C - dry ice/acetone slurry) and store it in whatever container you intend to store it in at that same cold temp. Going via the ideal gas law, simply allowing the stored hydrogen to come up to RT from there will give some serious pressure. Shit, even salt water/ice slurry (about -10C IIRC) and RT of about 25C is going to generate some pressure... Whereas standing the hydrogen tank in a pot of boiling water (ie.100'C) is going to add to that pressure significantly.

I'll attempt to demonstrate - in this we use the temperature as being on the Kelvin Scale, so 0'C = 273'K, thus -78C = 195'K, -10'C = 263'K, 100'C = 373'K and the idealized room temperature of 25'C = 298'K... OK?

For the purpose of working this shit out - let's just say that we generate our hydrogen successfully (and relatively cleanly) using an acid on a metal, and have managed to successfully remove any remaining halides/water/oxygen/etc. from the gas stream.

Ideal Gas Law: pV=nRT

Going from Wikipedia ('cos I really don't want the brain damage that I suspect would be associated with carrying around a head full of this shit)

I've got some serious burns and am on serious med's as a result so I'm not even going to try this whilst medicated to the gills - if you look around I'm sure there will be an ideal gas law calculator/hydrogen pressure diagram/graph online somewhere to help you out.

Suffice to say, if you generate the hydrogen (reaction of a metal with an acid), dry it, remove the contaminants, etc. at RT/STP and then pass the generated H2 through a coiled condenser in an acetone/dry ice bath and then store it in a cylinder @ that temperature (-78'C/195'K) and then allow that container to come to RT (ideally 25'C/298'K) then you'll have some serious pressure (an increase in temperature of 103'C/K will do that). If you put that container in a pot of boiling water/steam (100'C/373'K) then you'll have even more (temperature increase of 178'C/K).

That should be more than anyone here should ever need at any rate I'm guessing.

PS Electrolysis of water should be fucking useful in terms of the purity of the end product, just remember you'll need to cool the piss out of it in order to take advantage of the Ideal Gas Law to pressurize it sufficiently

I recently saw a youtube video of hydrogen production by mixing NaOH with silicon, then adding a little water. It generates H2 like crazy in a runaway reaction. It doesn't self-ignite, though, unless performed in a flammable container. I thought it was an interesting technique.

PP