Storage in Caves
Natural caves and lava tubes are possible locations for compressed air storage. If the walls are lined with an impermeable membrane, the structure of the surrounding rock may be sufficient to contain the pressure. The entrances to the cave or tube are the only areas that need to be strengthened. Compressed air storage can be about 35-40% efficient in the best conditions.
Some forms of adiabatic compressed air storage might reach about 70%. This would require extensive heat exchangers and tanks. These would probably need to be produced in-situ to be cost effective.
Methods to manage condensation must be included in any design, and may even be integrated into ISRU plans. the most common form of condensation control is gravity separation, with valves controlled to drain the condensate as it accumulates, but without wasting the compressed air