Not sure where to post this question, but it struck me the other day that the major driving force behind our modern industrial society is owed nearly entirely to the harnessing of petroleum power in the form of coal and primarily oil products.
As I understand it, the current explanation for these deposits' existence is the carboniferous period when plants basically evolved woody structures that allowed them to grow trunks and grow tall. Nothing at the time could digest these structures so they piled up when the trees died and eventually were buried in large amounts and became the various petroleum reserves we find under the surface of the earth.
Well, how likely is it that this specific path of evolution (or lack thereof on the part of organisms that would consume the dead plants) happens on many other planets, resulting in essentially a gigantic reserve of "free" energy buried and waiting to be exploited by a society of intelligent organisms?
Is this almost a necessary occurrence for industrial civilization? Couldn't this explain the apparent lack of interstellar civilizations? That it's such a rare thing to have all this free easy access energy already stored up for a civilization to access?