Inside the Resolution Copper Mine, 1.3 Miles Underground
Story in the WSJ prompted me to look into this. The temperature at the bottom of the mine shaft is 180 degrees Fahrenheit, too hot for people to survive, much less work, but they've got people down there, so I want to see what their air conditioners look like, and I want to see their electric bill.
Didn't find much about the A/C used here, but Carrier air conditioned the nearby Magma mine back in 1937:
|Dr. Willlis H. Carrier, whose invention of air conditioning dates back to July 17, 1902, is shown (at center) with the machine which made large-scale air conditioning feasible - the centrifugal refrigerating machine.|