Right, but what do we do when we’ve covered every surface of the earth with solar panels and wind turbines?

We’ll need to move into space sooner or later if we want to continue exponential growth.

We'll just have to clear some area, I suggest the quickest way would be with the giant orbital heat beam! :D

(100% agree that getting into space is important, and that if we want to continue exponential growth we'll need more than one planet. In fact, we'll need more than all the planets and we fairly rapidly (in cosmic terms) hit the point where the available volume of our light cone isn't enough. Maybe indefinite exponential growth isn't something we should feel entitled to...)

We're nowhere close to that. Covering all land in solar would be ~100x our current energy needs, and then we still have ocean (most of the surface) available.