Based on what? For now. But they are being depleted rapidly. We have to move on anyway. Why not now. Gas is cleaner than coal, why not burn it instead? Why not invest in wind farms . . . essentially power from nothing. Most importantly we need to invest in research into the next energy sources, be it zero-point energy, gravity/magnetics, cold fusion, or antimatter. The big breakthrough is coming and it need to be an American breakthrough, not a Chinese or Russian one. Then you have not been paying attention.