Comment Technically nothing is really renewable (Score 2) 626
Stars and supernovas aren't quite a renewable resource, except possibly through initiating a new "big bang" and rebooting the universe. The universe ultimately uses energy and moves to increased entropy. New stars are formed, but the pool of matter and energy to form them from is limited; some is lost over time (think of loss to black holes, for example... no real way to recover matter once it reaches that state.)
If renewable energy doesn't exist, then the whole premise that any civilization--human or otherwise--could be powered entirely by renewable energy is moot.
If renewable energy doesn't exist, then the whole premise that any civilization--human or otherwise--could be powered entirely by renewable energy is moot.