Listened to an interview with a shell oil exec. His job was a 30 year planner, where are we going to be in 30 years and how do we get there etc. His comment about future oil supply was all the "easy" oil may be gone. "Hard oil" will be plentiful. Oil from super deep offshore wells, coal shale, politically "hard" to get oil etc. 50 years from now he believes the company will be producing 50% of the oil it is today and will be >50% into other energy sources.