High-pressure tanks weigh much more than the hydrogen they can hold. The hydrogen may be around 5.7% of the total mass https://en.wikipedia.org/wiki/Energy_dens

High-pressure tanks weigh much more than the hydrogen they can hold. The hydrogen may be around 5.7% of the total mass https://en.wikipedia.org/wiki/Energy_density https://en.wikipedia.org/wiki/Energy_density