yes we know exactly what you want to do, but we all so know from experiance it ain't going to happen in a uselfull way.
So there are your options.
Rankin cycle using R-290, Peltier, or PV and battery
I use the heat directly for comfert, then use the pv for power personaly.
and as I say from certain water coolers you can harvest a 50watt peltier, 2 NTC 10K thermisters, and if lucky a really nice toleroid transformer 110v to 24 volt center tapped, some rectifiers a 741 op amp, and a few other goodies.