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Storage is a vital factor in the commercialisation of fuel cells as a safe, efficient and energy dense way of storing hydrogen will greatly improve the viability of fuel cell technology, particularly for automotive applications. Hydrogen can be stored in any state; as a solid, a liquid or a gas.
More information about hydrogen storage can be found at the International Energy Agency website.
| State | Storage Mechanism and Supply Mechanism | Advantages | Disadvantages |
|---|---|---|---|
| Gas | Pressurised Carbon Fibre composite gas tank up to 700 bar. | Commercially available. | Energy required for compression. Energy from fossil fuels usually used to produce hydrogen. Tanks are bulky and must be cylindrical. Safety concerns. Costly tanks.
|
| Liquid | Cryogenic tank at -253 degrees centigrade. | Commercially available. Excellent gravimetric and volumetric hydrogen capacity at low pressures.
| 30-40% energy loss to cool to cryogenic temperatures. 1%/day losses from boil-off. Safety concerns. Costly tanks. |
| Solid | Chemical hydrides heated to <100 degrees centigrade to decompose and release hydrogen. | Excellent gravimetric and volumetric hydrogen capacity. Safe, easy to handle. | In the early development stages. Energy required for off-board regeneration. Harmful by-products must be removed from the impure hydrogen gas stream. |