Somewhere between the second and fourth bullet you need to significantly limit the process' energy overhead (almost certainly, heat) to something manageable at

Somewhere between the second and fourth bullet you need to significantly limit the process' energy overhead (almost certainly, heat) to something manageable at scale. If you can't do that, then a net gain is not good enough: If you can power a town but boil a lake's worth of water with the excess heat, that's not much of a viable process.