One widely used method of storing hydrogen is in cylinders.
In gaseous form, hydrogen is 11 times lighter than air. To store 1kg of hydrogen, a tank of 11m3 would be needed. Hence the need to increase the density of this gas in order to contain it in larger quantities.
Thus at 700 bar, hydrogen has a density of 42 kg/m3 against 0.090 kg/m3 at normal pressure and temperature. In a 125L cylinder, we can therefore store 5 kg of hydrogen.
