Renewable Identification Number.. (??)  I believe I got that right.. EPA's way of enforcing compliance with the RFS..  Scott Irwin (who posts on NAT..) has done some very good work on the subject.. I can't find his update on RIN's supply/carry forward into this Crop year.. there was a surplus from past years.. like 2.5 billion gallons.. worth..

Here's some on the topic from last spring..

http://www.ethanolproducer.com/articles/8656/stockpiled-rins-hold-potential-to-reduce-corn-demand

looks like Nick Paulson's work.. U of Ill.  This was done before the drought really hit so.. at the time didn't probably realize just how important the carry in was going to become.

and here's a little more recent work.. with Scott's work.. along with Darrel Good.

http://www.farmdocdaily.illinois.edu/2012/08/ethanoldoes_the_rfs_matter.html

VERY good stuff.. thanks guys.  Wally Tyner at Purdue as well as Bruce Babcock at Iowa State have done work recently in this area also.  Wally is linked above.

later.