I see nobody here has mentioned shale.
Thee is a geopolitical analyst named Peter Zeihan. His two books are THE ACCIDENTAL SUPERPOWER and THE ABSENT SUPERPOWER - The Coming Shale Revolution.
He also has a number of YouTube videos of his public speaking appearances. Very interesting to watch. Here's one mostly on shale:
https://www.youtube.com/watch?v=du7jG1aDkdMSome of the takeaways:
The US and Canada are already functionally energy independent. By 2020, we won't need the Canadians anymore. The Saudis, the Iranians, and the rest of OPEC can go to Hell.
The price of shale oil is already below the price of conventional oil, and it's still dropping.
Iowa's going to have to figure out something else to grow. We simply won't need Ethanol anymore.