Switzerland dug a hole the size of two soccer fields to install the world’s most powerful underground battery, able to output 1.2 GW within milliseconds.

https://www.ecoticias.com/en/switzerland-dug-a-hole-the-size-of-two-soccer-fields-to-install-the-worlds-most-powerful-underground-battery-able-to-release-1-2-gw-in-milliseconds-and-store-2-1-gwh-at-a-multibillion-dollar/32795/