Question

why hydrogen is difficult to store?

Answer 1

Hydrogen is the lightest element and has a low energy density per unit volume. Due to this, it is hard to store a large amount of hydrogen gas in a small space. It can be compressed for storage but still a large space would be required for its storage as compared to other gases such as natural gas. Moreover, hydrogen gas compressed to 800 atmospheres occupies 3 times more volume than gasoline for the same energy. Such high pressures cannot be easily and safely maintained in lightweight tanks normally used. It will be very expensive to store compressed hydrogen gas in high pressure storage tanks.