Hydrogen tank and method for operating a hydrogen tank

A hydrogen tank, comprising:

• a tank vessel configured with an enclosed interior space for storing an admixture of carbon dioxide and gaseous hydrogen;
• and
• a tank port configured to fluidly contact the interior space of the tank vessel, the tank port comprising a semipermeable membrane configured permeable for the gaseous hydrogen and impermeable for the carbon dioxide, the semipermeable membrane being arranged to seal the tank vessel against the outside such that the gaseous hydrogen can enter and leave the tank vessel through the tank port via the semipermeable membrane but the carbon dioxide is kept in the tank vessel;
• wherein the interior space of the tank vessel is filled with the admixture including at least partially solid and/or liquid form of the carbon dioxide and the gaseous hydrogen under a first inner pressure in a filled condition of the hydrogen tank such that the carbon dioxide starts to transit into its gaseous phase when the gaseous hydrogen leaves the tank vessel under a working temperature of the hydrogen tank.