If E15 is bad in the Summer, why is E10 also not banned?
Gas blended with more ethanol has a lower vapor point so it evaporates quicker in the summer heat. E15 evaporates quicker than E10 which puts more organic vapors in the air. That's why summer blends contain less ethanol.
In any case, it's a dumb idea. They're going to allow more ethanol so it'll lower the price of a gallon of fuel, but the extra ethanol also lowers fuel mileage. It'll cost less to fill up but the tank of gas won't take you as far so it won't lower the cost of driving. The price on the pump will be less so they reason that consumers will cheer Biden for lowering fuel prices when in reality it won't do a thing other than damage more engines because of the extra ethanol.