There absolutely is, but of course it's nonzero cost to capture.

Also, the temperature is not high enough (compared to the steam coming out of a gas/oil/nuclear plant) to obtain much work from the waste heat.

That is 100% the issue. This is really low quality heat. Making it better would require even more energy input (e.g. a heat pump) because we can’t safely run electronics hot enough to generate high quality process heat.

Rockdale is a small town of ~5000 residents. Even if it were practical to install district heating - which I don't think it is - there certainly isn't demand for hundreds of megawatts of it.