[asdfadsfgfdda]

They likely use air as the refrigerant, like most air liquefaction plants.

[ncmncm]

THIS. Nobody uses freon for industrial-scale refrigerant.

Even at intermediate scale, ammonia is preferred.

[boringg]

Fair enough - I am unfamiliar with refrigeration at scale. As long as none of the HFC, PFCs, HFE, CFC etc compounds are used seems like a low risk.