Here is a concept I came up with when I was experimenting with Peltier devices.
The idea is that inside a bee hive it is 33 degrees C / 91 degrees F and that is pretty much fairly reliable when the bees are present.
What if we harnessed the power of that heat with Peltier devices?? Could we have peltier plates inside the hive converting that heat into reusable energy.
I am not claiming you could run a house or anything but I think you could realistically get enough energy to store in a battery to power some LED lights here and there.