In a way FR could be thought of as a think-tank. Ideas are often thrown onto the table, sometimes outrageous ideas. It should be noted that a percentage of asteroids and meteors are what they call carbonaceous chondrites:- frozen, mucky, carbon-rich bodies. One might assume that earth itself is made from the same stuff with the exact proportions controlled by its solar environment. Simply burning carbon fuels doesn't remove carbon from the earth, it goes back eventually into the sea and is subducted under the continents, there to be cycled through once more. In the long run, totally renewable. Maybe we can consume the hydrocarbons faster than they are produced, but that is a self-limiting process. When we run low, we will slow down; it's automatic, not a source of concern.