The guy I referenced above has some other blogs about how no energy is sustainable at our growth, not even the entire power of the sun. In 2500 years we would need all the energy in the galaxy.
https://dothemath.ucsd.edu/2011/07/g...-scale-energy/
His point is the growth has to stop at some point, just on the physics of it. He then ties that to economic growth in another blog but I'm not convinced the two are 100% tied together.