[jwatt]

> Is it practical to have giant nuclear powered facilities that either pump cooled air or artificially cool surface ocean water?

That would be like opening your refrigerator to cool your room - more heat is emitted from the radiator on the back of the refrigerator than is removed and so the room as a whole gets hotter. (Because movement of the heat from the interior to the back cancels out, but the energy used to move it creates additional heat resulting in a nett increase.)