Physical storage of H2 •Compressed •Cryogenically liquified
Chemical storage of hydrogen •Sodium borohydride • Ammonia
•Metal Hydride (“sponge”) •Carbon nanofibers
•Methanol • Alkali metal hydrides
New emerging methods • Amminex tablets
•Solar Zinc production
•DADB (predicted)
• Alkali metal hydride slurry
Compressed
•Volumetrically and Gravimetrically inefficient, but the technology is simple, so by far the most common in small to medium sized applications. •3500, 5000, 10,000 psi variants.
Liquid (Cryogenic)
•Compressed, chilled, filtered, condensed •Boils at 22K (-251 C). •Gravimetrically and volumetrically efficient •Slow “waste” evaporation but very costly to compress •Kept at 1 atm or just slightly over.
Metal Hydrides (sponge) •Sold by “Interpower” in Germany •Filled with “HYDRALLOY” E60/0 (TiFeH2) •Technically a chemical reaction, but acts like a physical storage method •Hydrogen is absorbed like in a sponge. •Operates at 3-30 atm, much lower than 200-700 for compressed gas tanks •Comparatively very heavy, but with good volumetric efficiency, good for small storage, or where weight doesn’t matter
Carbon Nanofibers
Complex structure presents a large surface area for hydrogen to “dissolve” into Early claim set the standard of 65 kgH2/m2 and 6.5 % by weight as a “goal to beat” The claim turned out not to be repeatable Research continues…
Early Adoption of inefficient system
Compressed Hydrogen is one of the least efficient both volumetrically and gravimetrically, but is currently the most common (because it’s a simple solution).
Credits
http://psych.ucsc.edu/faculty/kg/H2Spirit/images2.htm http://www.photos.gov.ca.gov/essay20.html http://www.amminex.com/index_files/Page344.htm http://www.h2interpower.de/deutsch/produkte/zubehoer.html#mhs20 http://www.pnl.gov/news/notes/transportation05.stm http://www.safehydrogen.com/technology.html http://www.isracast.com/tech_news/090905_tech.htm http://www.h2fc.com/industry/infra/storage.shtml Fuel Cell Systems Explained, by James Larminie and Andrew Dicks