I've made several hydrogen generators via electrolysis, but every time I failed to store the generated hydrogen under (some) pressure. In this-> http://www.youtube.com/watch?v=m9Q6gDKP2R0 video they used an emptied fire extinguiser to store the hydrogen. The only problem with this is that they use a chemical reaction to generate the hydrogen whereas I want to use a renewable source (electricity). I have a compressor so I could use that to generate the pressure. Has anyone got any ideas on how I could store hydrogen under pressure?