[Dylan16807]

Somewhere on the fridge is a bunch of metal that heats up when it's working. If that gets particularly hot, then you have the potential to save power. You could add more surface area or have low-power fans blow air across it. That would make the actual fridge unit be more efficient. The amount of electricity you would save is much more than the amount you could harvest. Any device that harvests power would also impede the efficiency more and make it work even harder.

But either one would be a pretty small amount.

It's fun as a toy, but not much more.

If you want to save power, buy a more efficient fridge. Maybe also get one where the hot part can go outside.

If you want free power, get solar panels.