Howarth, Ingraffea Shale Gas Study on Global Warming Discredited by U.S. Department of Energy | Marcellus Drilling News

Howarth, Ingraffea Shale Gas Study on Global Warming Discredited by U.S. Department of Energy | Marcellus Drilling News.

Comment from Howarth:

We are working on a more detailed response, but in the meanwhile, I have
sent the following message out to some folks.  Feel free to share,
 “We are working hard to try to understand what the DOE/NETL analysis  is based upon.  This is not easy, as their data are not well documented in the PowerPoint from their talk.  Apparently, NETL is working towards publication of a technical report, which one would hope would have far better documentation.  But that is not yet available to us.  To date, the PowerPoint available to us and to the public has not seen any rigorous, independent peer review.
We have ascertained that the NETL analysis has an estimate for methane  emissions from coal  that is similar to ours.  Therefore, the reasons for the differences between their estimates and ours lie elsewhere.  At this point, we believe there are 4 major differences:
1) we believe they have underestimated the fugitive emissions of methane.  They apparently assume no emissions from storage and from distribution systems, and their estimate for >transmission losses are far lower than the estimates we developed for losses from transmission, storage, and distribution.  Their estimates are also far lower than those from the US EPA, which we also feel are too low (as is discussed in our paper).
2) they have a very high, optimistic estimate for the total amount of gas produced over the life of a well.  This has the effect of giving a low estimate for percentage losses from venting and leaks, particularly during the initial well completion period.  Only time will tell what the actual production of these wells will be, as the technology is too new to know.  However, we used the best available information on estimates of life-time production, thoroughly documented in our paper.  The NETL estimates are far higher.
3) they used a global warming potential for methane of 25, based on a 100-year time integral and the old data from the Intergovernmental Panel on Climate Change.  We used values of 33 for a 100-year time integral and 105 for a 20-year time integral, based on more recent science (Shindell et al. 2009).  Their use of the older science results in significantly down-playing the importance of methane venting and leakage on the climate system.
4) they focused solely on generation of electricity.  We included generation of electricity in our study, and the analysis by David Hughes for the Post Carbon Institute took that even further.  HOWEVER, only 30% of the natural gas in the US is used for electricity.  The other 70% is used in home and commercial heating and for industrial processes.  To focus on just electricity provides the most optimistic view of natural gas, as that is the only use where natural gas has an efficiency advantage over other fossil fuels.
This focus on electricity generation by the NETL group is curious, as in their own talk, they emphasized that it was not likely that natural gas from shales would replace coal for electricity generation over coming decades.  Rather, they predict a DECREASE in the amount of natural gas used to generate electricity in the US.  The development of shale gas is expected largely to replace conventional gas in its current uses, and they predict some increase in the use of gas for industrial purposes.  Both the replacement of conventional gas by shale gas and the increased use of gas for industrial purposes will significantly increase the overall methane emissions from the US, and the overall greenhouse gas footprint of our nation.  The NETL study chose to ignore these aspects.”
Robert W. Howarth, Ph.D.
David R. Atkinson Professor of Ecology and
        Environmental Biology, Cornell University
Telephone:  1-607-255-6175

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