Well, I read up a bit today before it was time for work, here's what I have.
Important things to note:
Sensitivity analyses with EBAMM and elsewhere show that net energy calculations are most sensitive to assumptions about coproduct allocation (17). Coproducts of ethanol have positive economic value and displace competing
products that require energy to make. Therefore, increases in corn ethanol production to meet the requirements of EPACT 2005 will lead to more coproducts that displace whole corn and soybean meal in animal feed, and the energy thereby saved will partly offset the energy required for ethanol production.
This should be self explainatory. Coproducts haven't been addressed in most of the conversations about ethanol that I have found.
It also appears that switchgrass requires much less of a petrochemical input than does corn, this also changes the ERoEI assumptions that have been made about using a feedstock corn as an ethanol source. From a google search:
Because it is native, switchgrass is resistant to many pests and plant diseases, and it is capable of producing high yields with very low applications of fertilizer. This means that the need for agricultural chemicals to grow switchgrass is relatively low. Switchgrass is also very tolerant of poor soils, flooding and drought, which are widespread agricultural problems in the southeast.
We will disregard the corn ethanol discussion, since really that's not going to help, ERoEI of 1.2, it's food, and still has emission issues. I am mainly concerned with this report and the switchgrass, as it really does bring some new items to the table. Scale is something that we all know about. Oil will not be replaced by ethanol, but since it can work in an existing infrastructure, unlike hydrogen, and has a respectable ERoEI, it can help offset declines in oil production worldwide. Will help China grow at 15% annually? No. Is America still in trouble? Of course, but humor me in my anti-doomerism for a minute.
For all three cases, producing one MJ of ethanol requires far less petroleum than is required to produce one MJ of gasoline (Fig. 2). However, the GHG metric illustrates that the environmental performance of ethanol varies greatly depending on production processes.
GHG emissions from ethanol made from conventionally grown corn can be slightly more or slightly less than from gasoline per unit of energy, but ethanol requires much less petroleum inputs. Ethanol produced from cellulosic material (switchgrass) reduces both GHGs and petroleum inputs substantially.
Cellulosic ethanol is expected to have an extremely low intensity for all fossil fuels and a very slightly negative coal intensity due to electricity sales that would displace coal.
Now, this report has an issue with the report by Pimentel and Patzek, they state that ethanol production using switchgrass required 50% more fossil energy than the ethanol fuel produced. So I registered at the website to gain the article and see how they arrived at such disparate numbers from the EBAMM models. They mentioned in the beginning of the paper that it was due to not calculating the coproduct allocation (for the corn numbers)
Here's the data sets that Pimental and Patzek give. I haven't tried to verifiy the numbers given in either report, just offering this up for comparison purposes. I also note that the report here has much less data than the EBAMM stuff, they at least have numerous spreadsheets backing up how the numbers were arrived at.
I may be wrong here, but there's inputs calced in those tables that should be a one time, or once in every X years investment. You need steel and cement for infrastructure, but surely not every time you produce ethanol. They also have only dedicated a couple of paragraphs to the switchgrass production. Both reports agree that more electrical energy would be gained by simply burning the pellets, however that doesn't do anything for the liquid fuel crisis. We can as well all agree that corn ethanol is a bad idea, for numerous reasons cited in the reports.