With or without e-15, one of the brewing clashes is the one coming between corn and advanced ethanol. There are only so many gallons of transportation fuel that will be needed in any given year.The U.S. Senate Committee on Environment & Public Works held a hearing last week on the oversight of domestic renewable fuels. It was one more look at the 2014 required volume obligations (RVOs) issued by the EPA and the broader issue of renewable fuel standard (RFS) reform that is likely to be debated in 2014 or 2015.Wesley Clark, co-chairman of Growth Energy, testified and cited his years in the military. He is a retired Army general who underscored the energy independence argument:I spent almost 40 years in our nation's armed forces and have s...