Hydrogen tank

Low-pressure tanks

Type I

• Metal tank

  Type II

• Metal tank with filament windings like glass fiber/aramid or carbon fiber around the metal cylinder. See composite overwrapped pressure vessel.
• Approximate maximum pressure, aluminum/glass, steel/carbon or aramide.

  Type III

• Tanks made from composite material, fiberglass/aramid or carbon fiber with a metal liner. See metal matrix composite.
• Approximate maximum pressure, aluminum/glass, aluminum/aramide, aluminium/ carbon.

  Type IV

• Composite tanks such of carbon fiber with a polymer liner. See rotational molding and fibre-reinforced plastic.
• Approximate maximum pressure.

  Type V

• All-composite, linerless Type V tank. CTD has built the first prototype tank for testing January 1, 2014. 1000 psi

  Tank testing and safety considerations

• Burst test: the pressure at which the tank bursts, typically more than 2x the working pressure.
• Proof pressure: the pressure at which the test will be executed, typically above the working pressure.
• Leak test or permeation test, in NmL/hr/L (Normal liter of H2/time in hr/volume of the tank.
• Fatigue test, typically several thousand cycles of charging/emptying.
• Bonfire test where the tank is exposed to an open fire.
• Bullet test where live ammunition is fired at the tank.

• U.S Department of Energy maintains a hydrogen safety best practices site with a lot of information about tanks and piping. They dryly observe "Hydrogen is a very small molecule with low viscosity, and therefore prone to leakage.".

  Metal hydride storage tank

Magnesium hydride

Other hydrides

Research

• 2008 - Japan, a clay-based film sandwiched between prepregs of CFRP.