Theory 33/Earth, Climate & Energy /Hydrogen storage
Salt Caverns Creep at Pressure
Capacity is quoted in cubic metres. The usable volume may be set by how fast the walls close.
Hydrogen storage capacity in salt caverns is limited by creep at a threshold pressure rather than by the cavern's geometric volume, so operating pressure sets the deliverable capacity more than the cavity size does.
01The evidence
Salt caverns lose volume over time through creep, and the rate depends strongly on the pressure differential.
02The tension
Capacity is quoted geometrically, which predicts deliverable volume from the cavity and ignores the closure that removes it over decades.
03The mechanism
Salt creeps under differential stress. The closure rate rises sharply as the minimum operating pressure falls, so the pressure window sets how much of the volume survives.
That makes the pressure ratio the determinant, and predicts deliverable capacity should track it rather than geometric volume.
04What this is not
Geometric models count volume. This counts what survives creep.
05Predictions
- P1Capacity should track the pressure window.
- P2Low minimum pressure should reduce deliverable volume.
- P3Creep rate should predict capacity loss.
06Refutation
Deliverable capacity tracking geometric volume would restore the simple model.
07What it changes
It would change cavern operating envelopes.