This falls squarely into the "Your scientists were so preoccupied with whether or not they could, they never stopped to consider whether they should" category.

There are so many unknowns with potentially horrifying answers.

We don't know what generates human consciousness. But we know the brain is a key part of it. At what point does a bunch of lab grown human neurons become conscious? Can it become conscious outside of a body? What would that experience be like if a lab grown brain used as a computer developed consciousness? And what would happen to that consciousness?

The potential energy savings aren't worth risking the potential horror.