But clean energy cannot be the whole solution. What happens in even the best-case scenario when everyone uses clean energy like solar/wind for everything? It will make humanity even more efficient and give us even more space to grow, but the biosphere will still be in trouble and all that clean energy will make people consume even more of earth's resources.
So, it's clear that while clean energy is a start, it is not even close to an end to get people to be in equilibrium with the rest of our planet.