Is it just a matter of not being worth it? I see cooling towers releasing what appears to be a ton of steam, pretty high up. If that steam were captured at the top and allowed to condense, wouldn’t that result in a ton of water with a lot of gravitational potential energy? That water could then be released and used to power water turbines. Maybe I’m overestimating the amount of water being released as steam, or underestimating how much is needed to spin a water turbine to get a meaningful result, but it seems like wasted energy to me.
Even assuming you had 100% efficient, and totally free energy capture systems for the evaporative clouds you see coming off the cooling towers… You probably wouldn’t use them because of the need of the primary system for time based cooling.
Any capture and recycling system will slow down the cooling rate of the primary system, if your goal is to use the primary system to maximum efficiency then that cooling rate can not be slowed down. .