Isn't a large part of ethanol it's use as a fuel additive that it boosts octane and is relatively cheap? Compared to leaded gasoline it seems very "green".
Turning solar power into something we use to destroy the environment doesn't strike me as very "green" at all. Quite the opposite. I can't imagine it's a very efficient use of money, either.
Granted, we will likely always need to do this, but where was the need at this absurd scale? Most of our heavy industry runs on diesel anyway.
It goes full circle: where does the carbon in the biofuel come from? The plant. Where does the carbon in the plant come from? The air. This is why biofuels are carbon neutral in theory at least. There is of course loss in process like in most things.
In terms of a use of money it is a good way to subsidize the american corn farmer. Whether you believe that is worthwhile depends on your views of WWIII.
The devil is in the details. Where did the land used to plant it came from? What was there before? Deforestation emits a lot of CO2. Fertilizer needs fossil fuels to be manufactured, tractors and harvesters burn diesel, et cetera.