Chemical hydrides, or chemical hydrogen, refers to hydrogen bonded to a compound in solid or liquid form.
What is it?
Chemical hydrides, or chemical hydrogen, refers to hydrogen bonded to a compound in solid or liquid form. These compounds generally have high hydrogen densities. The hydrogen can be extracted via reaction with water or application of heat. Examples include Ammonia borane, sodium borohydride, and alane compounds.
Why is it important?
Chemical hydrides have high hydrogen densities and can be transported at ambient temperatures.
- Volumetric hydrogen density: 90 to 120 kg/m3
- Gravimetric hydrogen density: 7.5 to 25 wt.% H2
- Storage conditions: Ambient
- Extraction conditions - ~25-200°C if not hydrolysed. Hydrolysis allows release at ambient conditions
- Roundtrip Energy efficiency: N/A – system is irreversible
- Some chemical hydrides offer high volumetric hydrogen density, depending on system configuration
- Typically lighter weight than metal hydrides
- Can transport at ambient temperatures
- Regeneration of the chemical required to be able to use it again for hydrogen storage. This considerably increases the well-to-powerplant fuel cost
- Need to utilise or return carrier chemical if transported
- Some liquids can solidify while hydrogen is not bonded, requiring further handling
- Note: The TRL for 'on-off' utilisation of chemical hydrides that cannot be regenerated is 5-7
- Improve overall ‘wells-to-power plant’ efficiency
- Improve carrier chemical regeneration efficiency
Known active organisations
- Curtin University
- The University of New South Wales
- The University of Sydney