Cryogenic means low temperature. The word itself refers to the technology of sub-zero temperatures. 

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We very well know that Air (Gas molecules) cannot be stored. So, to enhance the Storage of Gas Like Oxygen, Argon, Nitrogen etc. which are pressurized 

at high pressure and cooled at a stage where gas forms are converted into Liquid form where the gas are stored in Liquid form so, whenever there is requirement this liquified gas can be converted to gaseous form for the further usage. 

The thermal energy (heating - cooling) at the required temperature plays a vital role for the storage of gas in the tank and for further process usage