This is just a bad analysis. You have to go to the comments to find relevant terms like "Dyson swarm" and "Kardashev scale". The worst mistake is limiting energ

This is just a bad analysis. You have to go to the comments to find relevant terms like "Dyson swarm" and "Kardashev scale". The worst mistake is limiting energy collection to what hits the Earth. Here is (IMHO) the likely course of humanity, assuming we don't descend into fascism with the upcoming climate-change caused mass migration and starvation or otherwise wipe ourselves out. We will build Dyson swarms. What are Dyson swarms? They are nothing more than a collection of orbitals that orbit the Sun. The most basic form of these is an O'Neil Cylinder, which is about 3 miles in diameter and 10-20 miles long. You put solar power collectors on these things and they're pretty much self-sufficient. Why this size? Because you can build that with a material no stroner than stainless steel. Any larger and the centrifugal force will of rotating for spin gravity will tear it apart. If mass production with graphene ever goes anywhere, it opens the door to building McKendree Cylinder, which could get to ~300 miles in diameter and thousands of miles long. So the question is why. Several reasons: 1. You can effectively collect all the energy the Sun outputs; 2. This is only predicated on solar power, something we can already build. It isn't predicated on nuclear fusion power generation, for example. I'm personaly not convinced fusion will ever be commercially viable. It might and that'd be great but it's not a pre-requisitie for that and that's what's important; 3. It requires no new physics or no magical new materials; and 4. Here's the big one: it's super-efficient in creating living area per unit mass. I think I saw an estimate that you could build a complete Dyson swarm around the Sun with ~1% of the mass of Mercury. Such a Dyson swarm could comfortably house more than 10^15 people with an energy budget per person orders of magnitude than what we have now. So a brief note about the Kardashev scale. This is an approximation but a Kardashev-1 ("K1") civilization is defined as using the entire energy output of a planet. This is estimated as 10^16 Watts. A K2 civilization uses the entire energy output of a star, estimated at 10^26 Watts. A k3 civilization is the entire galaxy at about 10^36 Watts. Humans use about 10^11 Watts (IIRC) of energy. So a K2 civilization might have 10^15 people but have access to 10^26 Watts of power. That's 10^11 Watts of power per person. The scale of a K2 civilization is almost beyond comprehension.