The Storage of Hydrogen as a Compressed Gas

The reason for Ihe low mass of hydrogen stored, even at such very high pressures, is of course its low density. The density of hydrogen gas at NTP is 0.084 kg m, compared to air, which is about 1.2kgm. Usually less than 2% of the storage system mass is actually hydrogen itself. 

It is most widely used in places where the demand for hydrogen is variable and not so high. It is also used for buses, both for fuel cells and internal combustion engines. It 

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