Once upon a time, stormy politics in the Mideast routinely inflicted pain on Americans at the pump. Recently it was storms in the Midwest as infrastructure issues in a region known for corn, not petroleum, made it difficult for some refiners to get the ethanol needed for gasoline. America’s energy renaissance didn’t help one bit. Almost all U.S. gasoline is blended with 10% ethanol thanks to the Renewable Fuel Standard. The mandate at the time was meant to make gasoline cleaner and encourage a shift from dependence on foreign energy sources.The mandate not only has been a boon for farmers, absorbing a big chunk of the world’s largest corn crop, but also a political third rail. When flooding hit the Midwest last month, above-ground shipping was disrupted. The agribusiness company Archer Daniels Midland warned in late March that this could affect earnings.