[Geee]

Just run your closed loop cooling through a heat exchanger in sea water. They probably do something like this already.

[itintheory]

Yes, pouring more heat into the already warming oceans is surely a safe plan.

[Geee]

The added heat is so minuscule that it doesn't have any effect on the temperature of the ocean.

[sanex]

I think they prefer to use evaporative cooling though.