As you may recall, the shift from coal to oil, which occurred in the late 19th and early 20th centuries, did not occur because the world ran out of coal. It occurred because oil proved to be the superior energy resource.
Eventually, technological advances will usher in a new energy resource to replace oil. Oil will not cede its position as the preeminent fuel because the world runs dry, but because technology has rendered it less desirable. We in Saudi Arabia believe that there are sufficient quantities of oil left to make the transition to the next great energy source a smooth one."