Storing gaseous hydrogen safely and economically at 35 to 70 MPa pressures is one of the few viable options for long-duration energy storage. The service duty cycles endured by the pressure vessels result in high fatigue stresses that determine their design life or inspection intervals. Hydrogen-assisted fatigue crack growth rate (HA-FCGR) due to hydrogen embrittlement exacerbates this and causes increases in the fatigue crack growth rates in pressure vessel steels by as much as 20 times. A phenomenological model that predicts the crack growth rate behavior as a function of ∆K, load ratio, R, and hydrogen pressure, P_(H_2 ), is used to assess the designs of all steel, Type 1, and wire-wrapped, Type 2 vessels. Digital twins of Type 1 and Type 2 vessels are proposed for comparing the two design concepts over a broad pressure range using simulated service loading conditions in actual vessel sizes. Wire-wrapped Type 2 cylinders show significant advantages over Type 1 cylinders. At a storage pressure of 500 bar, the wire-wrapped pressure vessels save 33% in storage space, and 33% in materials' cost, and can store 155% more hydrogen compared to Type 1 vessels of similar exterior dimensions. These advantages increase further with a storage pressure of 700 bar, compared to lower pressures.