Don: My understanding is that the BTU's dropped when ethanol was added to our gasoline available in most places in the US?

I'm not a chemist and I'm trying to understand why you can have 2 gasoline's, one with out ethanol at 91 Octane and another with ethanol at 91 Octane yet from what I was told the non ethanol gasoline has higher BTU's. I've read and I beleive it's common knowledge that cars running ethanol gasoline get lower MPG than with non ethanol gasoline of the same octane.

Regarding over winter gas storage, I'm done with that. Red drains the tank completely for me now for the past two years