[306bobby]

I must be missing something, why can't it be entirely closed loop like a water radiator in an old car? A simple fan running through large radiator cores would certainly condense within the system, keeping the water in the system

[quickthrowman]

A closed loop system has a COP of 4, adding in cooling towers almost doubles that to 7. You can reject 1.75x more heat for the same amount of electricity by adding evaporative cooling towers.

COP is coefficient of performance.

[pfdietz]

One thing to remember is that much of the waste heat from your car's engine goes out the exhaust, not out the radiator. I think the two are often about equal.