A short discussion on insulation strategies and design considerations for large-scale storage and transportation of liquid hydrogen

The existing cryogenic hydrogen storage technologies utilize vacuum-based insulation systems, leading to significantly high maintainance cost and potentially huge losses (including safety) upon failure. In this work, we discuss an alternate non-vacuum or soft-vacuum based insulation systems that could be cost effective. However, their development requires an understanding of two key aspects: (i) availability of an accurate effective thermal conductivity model for gas-filled insulation materials in extended pressure and temperature ranges, and (ii) characterization of the natural convection effects in the annular space of the insulation due to density stratification. In this work, we discuss the impact of the insulation material properties on the boil-off rate in commercial scale liquid hydrogen storage tanks and provide some guidelines on design and scale-up.