The world’s largest demonstration plant for a new kind of renewable energy storage is up and running in the west of the China. Called liquid-air energy storage (LAES) the plant uses renewable electricity to compress air to extreme densities until it turns to liquid. It can then be rapidly released to power a turbine and discharge that green energy back into the grid.
Is not compressed, when it becomes liquid it can be unpressurized and just needs thermal insulation to stay cold. That’s how gas works. Not about pressure at all. You can pump the liquid or let it drain into an unpressurized thermos.