Earlier quoted context omitted.
That will be a problem in a few hundred years of our energy consumption continues growing at this rate; I've done the math on this website a year or two ago.
At the rate our energy consumption is growing, even if we avoid climate change wrecking our society today, the heat waste of our energy production will start to eclipse the effects of climate change in only a few centuries, at most a millenium. Which isn’t that long of a time.
You can get pretty far by being extremely efficient. We keep making better and better superconductors and even have some above room temperature. Vac-trains with superconducting maglev is more efficient, in principle, than anything short of orbiting. Better materials can make dry mass near nothing.
Reversible computing requires no fundamental energy input.
Space based solar power could make sure the waste heat from electricity production is almost zero and only useful energy is pumped to the ground.
You can shade the Sun at the limit. And you can shade only the portions of the spectrum that are not biologically active, i.e. shade infrared. That's tens of Petawatts.
You can also literally build radiators at high altitudes to dump waste heat into space before it gets conducted into the atmosphere.
You can also just do more work in space instead of on the ground.
I think also we won't grow exponentially but instead linearly or quadratically. That's actually sustainable for as long as the universe would've lasted anyway.