Also I don't think you realize what "excess of energy" means - it specifically means there is no one to sell the energy to,
I think most bitcoiners don't realize that when heat waves or subzero temps arrive, their is NO EXCESS ENERGY!
When there is a source of power far enough away that there are no people ... and no easy way to deliver that energy to the rest of the people ... I think that's what they mean. If you are talking about cities, then of course, there are people there and energy requirements and all the energy is used by that city and the price of energy will be too high for any miner so the miner will move their equipment away from the higher priced energy and go to a lower priced energy.
expect bitcoin PoW mining to be permabanned around the world.
I actually don't see that happening ever. Or maybe I am just blind and can't see it. What I see is more renewable sources of energy appear around the world whereever they are. And how does one ban mining? Oh, you mean, like China maybe? When you have a bunch of people with 1 device in their home mining ... it's going to be difficult to ban that.