[jacquesm]

You're edging on the laws of thermodynamics there: on a long enough time scale all energy is non-renewable, every little bit of consumption gets you that much closer to the heat death of the universe. But given the vast reserve in that system for once humans won't be able to meaningfully affect it unless we start consuming far more than we do today. Interesting aside: that momentum is a giant energy reserve and conceivably you could rob some of it to create a means of escaping the gravity well even if there had not been any other.