Can a Peltier/Seebeck cell transfer energy from a "thermally insulated" system converting (a part of) thermal energy into electrical energy? Suppose you have a closed system, as per the schema attached below, which walls are thermally insulated.
Suppose you want to reduce the temperature of the fluid inside the closed system, without dissipating 100% of the fluid thermal energy into the environment.
Can a Seebeck cell convert (a part of) the thermal energy of the fluid into electrical energy?
Is the Seebeck cell able to convert a part of the thermal energy into electrical energy (with a given efficiency), or the generation of electrical energy is only a cause of the temperature gradient and this thermal energy will eventually entirely return to the environment thorugh the cell (which, differently from the walls of the system, is clearly not insulated)?

 A: *

*Say, we have a stick of some fitting material. It has some temperature, so all electrons in the material bounce around wildly. Some randomly bounce leftwards; others randomly bounce rightwards. There is no net flow of electrons in any direction. There is no current.

*Now, heat up one end. Those now hotter electrons will now bounce around even more wildly. This will make them "fill more space" (more wild random motion means much more pushing on the surrounding particles).

*When the electrons "fill more" in one end, there is less "space" there. They start drifting towards the other and still more "spacious" end. 


Drifting electrons is a current; electrical energy. This is the essence of the thermoelectric Seebeck effect.
The energy that caused them to move more wildly is directly the thermal energy absorbed at the hot end. They still carry this thermal energy, now in the form of a higher amount of kinetic energy at the micro-scale. So, yes, the Seebeck effect converts thermal energy into electric energy so that there is less thermal energy present - although we are talking about tiny, tiny amounts depending on your situation.
