I was under the impression that ultimately none of that voltage change ends up as anything other than heat. (Despite voltage being "electric potential", that's only really meaningful in e.g., capacitors and batteries, not in circuits that keep switching.)
It's harder to imagine how you can reclaim the energy of the computation. Overwriting a bit requires a little energy even in principle, and then you can't get it back. Maybe this is what the commenter I was replying to meant by "all energy generated ends up as heat." Even still, I'm tempted to make the distinction between the energy that is needed to perform the computation and the energy that is lost e.g. to Joule heating.