I'm convinced that the studio forced the change to 'human batteries' out of concern over a conflict with Hyperion.

I saw a YouTube video where they said this was more-or-less the original backstory but then they changed it. I think it said that the People In Charge thought the 'living power source' would be easier for the audience to understand?

I don't have the link handy, and don't trust everything I read on the Internet, etc, etc.

But yeah - this makes so much more sense than breeding, raising, and feeding humans just to harvest their body heat.

I like how the other story that has this premise is Hitchhiker's Guide to the Galaxy.

I'm sure that one Star trek episode had the same premise, together with something from Lem. The connection human/machine brain is rather old and human brains being used for computation is so reused, it is practically public domain.