And throw a treat snack in every now and then...
In Romain Gary's SF book "The Gasp," a technology was developed that allowed the soul, or some form of energy released at death, to be captured and harnessed as a power source.
It's been years since I read it, but I think part of the drama of the book was that it could not be discerned whether or not the captured force was sentient or not. A lot depended on what you preferred to assume, and how badly you needed the energy.