The Fog Condenser is a world object in the Fallout 4 add-on Far Harbor.
Background
The fog condenser technology was invented and developed by the synths at Acadia, particularly DiMA, who provided the condensers to the citizens of Far Harbor to protect them from the radioactive Fog. It is for this reason that the Children of Atom residing on the Island resent DiMA, since, to the Children of Atom the Fog is holy. DiMA states only he and Acadia can properly maintain them and without their assistance, the condensers would eventually fail and the fog would consume the island.
Gameplay
Fog condensers are constructed with wooden beams, a blue light affixed to the top. Under that is a tube that drips a clear liquid into a small canister at the bottom of the structure. Condensed Fog can be collected from this canister.
It is a device used on the Island and Far Harbor to remove the Fog from a small area proximate to the condenser. This keeps not only the fog at bay, but also the creatures of the Island. Without the condensers, the humans of Far Harbor would already have perished.