We have bookoo acres in this country.

Something on the order of 2,428 million acres.

http://en.wikipedia.org/wiki/List_of_U.S._states_and_territories_by_area

even at 90 mln acres of corn that is only 3.71% you are saying that we don't have room to expand ethanol production over time...???

Currently there are just under 31 million acres in the CRP.

http://content.fsa.usda.gov/crpstorpt/rmepegg/MEPEGGR1.HTM

In my neck of the woods.. this is a significant amount of the land base.. in some area's like 20 to 25%

Now I DO NOT support taking ALL land out of the CRP.. we need to KEEP the sensitive land in conservation... However some of this ground is very good productive land that was placed in the CRP because the farmer wanted to retire.  We needed production in 08.. those acres are coming out... we probably need to ease off the retire side and keep sensitive acres for conservation in place.. waterways.. erosion.. buffer strips.. etc.. continue GOOD Land Stewardship practices... the Hunters like CRP also.. and there's room and a need for that also.

Furthermore, I would think that a better use of most of it would be haying/grazing.. freeing up better ground for crop production.

Also I believe over time we will convert ethanol production to cellulosic.  It's taken Crude Oil refining almost a Century to get to this point... Ethanol almost 30 years.. and Cellulosic is still in its (currently investment starved..) infancy.

Consider this chart... what will things look like at the next peak?

http://futures.tradingcharts.com/chart/CO/M

as you can see the trend is upward sloping. 

Does policy need to be adjusted as we go along?  No doubt.. evidently we are dumping a lot of sawdust or something into the BCAP which wasn't anticipated..  However, the growth in fuel useage must be met from somewhere.  The US Corn ethanol conversion is probably going to top out somewhere around...????   Hmmm... currently 14 bil gallons of capacity in various stages of completion... maybe in ten years... 18 bil gallons.  Over the next two decades the growth will come from Cellulosic.. and yes it probably will take the next spike in crude before that takes off...  But we need to keep working on the problem.

Cellulosic is growing fastest in Municipal waste, forestry and areas outside the heart of the US Cornbelt.. which in a way is good as it diversify's the fuel's land base and lowers delivery costs to the market.

Again ethanol isn't a total solution.. there are still problems to solve.. but what else has been this successful?  Afterall it is working.

The efficiencies of the ethanol plants continue to improve over time...

http://www.ethanolrfa.org/objects/documents/1916/usethanolefficiencyimprovements08.pdf

as we add things like Corn oil recovery to the conversion process.. we will gain more value and efficiencies.  Crop yields are trending higher..

http://www.agmanager.info/livestock/marketing/graphs/Crops/Corn/USCornYields.htm

Maybe we won't need as much additional Crop land as first expected..?

I won't deny the "bumpy weather.."  But you have to go back and look at the source which is rising energy prices over time.. and our response to it.  Sure we can drill for more oil..

http://tonto.eia.doe.gov/dnav/pet/hist/LeafHandler.ashx?n=PET&s=MCRFPUS1&f=M

However, domestically you are sliding down hill... and as older fields mature and dry up.. they must be replaced..  Each year you can grow a new corn crop from the same land.. and probably realize an uptrending yield in the process.

That's why over time the economics of Ethanol is only going to get better.