[nine_k]

The system actually sort of uses the atmosphere as an ambient heat sink (when compressing) or heat source (when expanding).

I wonder if that heat could be stored in a more sensible way, e.g. as heated water in a tank near the bubble. This could improve the efficiency figures at short repeating patterns (charding at high noon, discharging through the night).

[anotherpaul]

As far as I understand they do try to keep the heat around for the next decompression. As of course they need it. But I could not find what type of heat storage they use. Ultimately they "only" seem to need to store it for 12h, right?