The genesis of the CMU life cycle gas study remains mysterious, and the study itself has yet to get much attention, though that is changing a bit.
But the Sierra Club to its great credit provided some financial support for the study. See the acknowledgements section of the study, where the researchers thank the Sierra Club for financing it and also make very clear that the findings, opinions, conclusions, recommendations in the study are those of the 6 CMU researchers and not the Sierra Club. I too am making that distinction clear.
You can link to the study at http://iopscience.iop.org/1748-9326/6/3/034014/fulltext.
If you want to read the best article available so far on the CMU study, go to http://www.eenews.net/climatewire/print/2011/08/19/2. The reporter of the piece is Joel Kirkland.