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Hydrogen Storage

Hydrogen Storage. An application-specific issue. Hydrogen Storage Overview. Physical storage of H2 Chemical storage of hydrogen New emerging methods . Compressed Cryogenically liquified. Metal Hydride (“sponge”) Carbon nanofibers. Sodium borohydride Ammonia. Methanol

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Hydrogen Storage

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  1. Hydrogen Storage An application-specific issue.

  2. Hydrogen Storage Overview • Physical storage of H2 • Chemical storage of hydrogen • New emerging methods • Compressed • Cryogenically liquified • Metal Hydride (“sponge”) • Carbon nanofibers • Sodium borohydride • Ammonia • Methanol • Alkali metal hydrides • Amminex tablets • DADB (predicted) • Solar Zinc production • Alkali metal hydride slurry

  3. 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.

  4. Liquid (Cryogenic) • Compressed, chilled, filtered, condensed • Boils at 22K (-251 C). • Slow “waste” evaporation • Kept at 1 atm or just slightly over. • Gravimetrically and volumetrically efficient • but very costly to compress

  5. 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

  6. 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…

  7. Methanol • Broken down by reformer, yields CO, CO2, and H2 gas. • Very common hydrogen transport method • Distribution infrastructure exists – same as gasoline

  8. Ammonia • Slightly higher volumetric efficiency than methanol • Must be catalyzed at 800-900 deg. C for hydrogen release • Toxic • Usually transported as a liquid, at 8 atm. • Some Ammonia remains in the catalyzed hydrogen stream, forming salts in PEM cells that destroy the cells • Many drawbacks, thus Methanol considered to be a better solution

  9. Alkali Metal Hydrides • “Powerball” company, makes small (3 mm) coated NaH spheres. • “Spheres cut and exposed to water as needed” • H2 gas released • Produces hydroxide solution waste

  10. Sodium Borohydrate • Sodium Borohydrate is the most popular of many hydrate solutions • Solution passed through a catalyst to release H2 • Commonly a one-way process (sodium metaborate must be returned if recycling is desired.) • Some alternative hydrates are too expensive or toxic • The “Millennium Cell” company uses Sodium Borohydrate technology

  11. Amminex • Essentially an Ammonia storage method • Ammonia stored in a salt matrix, very stable • Ammonia separated & catalyzed for use • Likely to have non-catalyzed ammonia in hydrogen stream • Ammonia poisoning contraindicates use with PEM fuel cells, • but compatible with alkaline fuel cells.

  12. Amminex • High density, but relies on ammonia production for fuel. • Represents an improvement on ammonia storage, • which still must be catalyzed. • Ammonia process still problematic.

  13. Diammoniate of Diborane (DADB) • So far, just a computer simulation. • Compound discovered via exploration of Nitrogen/Boron/Hydrogen compounds (i.e. similar to Ammonia Borane) • Thermodynamic properties point towards spontaneous hydrogen re-uptake – would make DADB reusable (vs. other borohydrates)

  14. Solar Zinc production • Isreli research effort utilizes solar furnace to produce pure Zinc • Zinc powder can be easily transported • Zinc can be combined with water to produce H2 • Alternatively could be made into Zinc-Air batteries (at higher energy efficiency)

  15. Alkaline metal hydride slurry • SafeHydrogen, LLC • Concept proven with Lithium Hydride, now working on magnesium hydride slurry • Like a “PowerBall” slurry • Hydroxide slurry to be re-collected to be “recycled” • Competitive efficiency to Liquid H2

  16. Storage Method Comparison

  17. 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).

  18. 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.h2-interpower.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

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