I was kind of waiting to see if anyone else wanted to weigh in on this...

Ethanol competes as an oxygenate with other gasoline components.  Right now ethanol is the cheapest but other components made from fossil fuels are sometimes used because the formulator of the gasoline wants to use it..  MTBE is made mostly from Natural Gas.. it's usage as an oxygenate is on the decline within the US but still used in other countries as I mentioned last week..  Some states have banned it's use.. and since it is carcinogenic.. with good reason.

Butane can be mixed with gasoline but adds to the vapor pressure more so than ethanol.  When we switch to winter blends EPA relaxes the vapor pressure due to cooler temperatures and Butane use can increase..  It's one of the reasons winter blend is cheaper than summer blend..

Flip side some of the winter blends are more stringent as far as an oxygenate goes thus that could be part of the reason for an increased usage overall of ethanol as a percentage of the mix.

My last guess (not that it's correct.. either..??) but I would assume that blenders have storage and would accumulate ethanol during perceived off peak prices (assumed not during the summer driving season) and would rebuild stocks during the off peak season... given this the accounting may (incorrectly ??) show it as "inputted" when in actually it's just been transferred from one tank.. (say at an ethanol plant..) to another (say at the storage farm of the blender..) ???

I would mainly just guess that as the refiners are cranking out the gasoline.. like this week at 9.7 myn bbls per day.. they also are cranking out a lot of the by products.. off peak for Natty.. and some how some of those lessor (even though they might be more expensive..) components get added to the mix.. and sold at the peak summer price...???  According to the "business plan" of the blender.. selling the wares they have for the most $$$ possible..

... but those are just my "guesses."

I'm sure the market is a lot more complex then I understand it to be... which is one of the reasons why I track it.  I still believe we have a wonderful opportunity to market ethanol overseas and replace carcinogenic MTBE.. especially at today's cheaper values... but..

"I could be wrong."

However ethanol exports have firmed in recent years.. on an upslope since coming off the droughts of 2011/12..

http://www.eia.gov/dnav/pet/hist/LeafHandler.ashx?n=PET&s=M_EPOOXE_EEX_NUS-Z00_MBBL&f=M

How much business can we buy at these now lower values?

6 byn gallons of MTBE are still used throughout the world.. and some places (Mexico for instance) are right next door.. Latin America.. Asia.. etc.. with a little work.. we can gain access to these markets..

imho.