Hydrogen once produced is able to be stored to be used to produce energy later when needed. Hydrogen is considered to be one of the best routes to obtain high capacity, long duration energy storage systems . Batteries are for shorter duration and grid stability purposes and are subject to self-discharge and cyclic degradation.
There are physical and material-based mechanisms to store the Hydrogen.
Two good methods used for hybrid microgrid Hydrogen storage are (1) compressed gas and (2) interstitial metal hydrides. Other methods like cold/cryogenic compressed storage or liquified nitrogen are more CAPEX and OPEX intensive and therefore may not be appropriate for remote microgrid applications.
For the compressed gas method of storage, a wide range of storage pressures are possible, associated with the type of storage tanks and type of withdrawal (i.e. use in fuel cell, use in generator, or injection into natural gas pipeline).
Higher pressure (~300-500+ bar) storage methods and tanks are also able to be used with additional compression facilities. A different risk profile and this storage solution may not needed except for transportation refuelling.
For the interstitial metal hydride method of storage, produced Hydrogen is introduced into metal storage containers where compacted powdered elemental hydrides (consisting of various compounds such as lanthanum, nickel, aluminium, boron (borohydrides), and/or magnesium hydride) were packed ready to store Hydrogen through adsorption. Subsequent Hydrogen desorption requires heat input which can often be recovered from the production process. A major benefit of this storage method is its efficient storage of Hydrogen at relatively low pressures and volumes. Two equal sized containers can contain the same volume of Hydrogen – high pressure (182 bar) compressed Hydrogen in one and low pressure (10-20 bar) adsorbed Hydrogen in the other. Hydrogen is released from storage through desorption using thermal heat (45-65°C) with outlet pressure down to <5 bar. Storage capacity of this kind of system is 1.5 kg (~50 kWh) Hydrogen per 100 kg of the metal hydride compound material.