Arlanda airport outside of Stockholm uses a similar system: https://www.swedavia.com/about-swedavia/the-aquifer/ https://www.swedavia.com/about-swedavia/the-aqu

Arlanda airport outside of Stockholm uses a similar system: https://www.swedavia.com/about-swedavia/the-aquifer/ https://www.swedavia.com/about-swedavia/the-aquifer/ But in this case, the aquifer is naturally occurring and not man-made. Constructing underground aquifers requires a lot of energy so I wonder how many charge-and-drain cycles are needed before more energy is saved than spent.