NAT GAS STUDY CHALLENGED

Cornell Gas Study Stirs Heated Debate
Tom Zeller Jr., April 18, 2011 (NY Times)

"…Many of the reactions [from researchers and policy analysts] echo earlier complaints [about the study of natural gas emissions] that some of the methane leak data on which the study’s conclusions were based are thin (a fact that the authors, including the lead author, Robert Howarth of Cornell University, conceded).

"Others critics continue to suggest that the authors unduly amplified the greenhouse gas footprint of unconventional gas development by measuring the global warming potential of leaked methane over a 20-year time frame, rather than the 100 years more commonly used by the Intergovernmental Panel on Climate Change…[That ups] methane’s global warming footprint unnecessarily, allowing the authors to…[conclude] unconventional natural gas development is worse than coal."

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"Indeed, Melanie Kenderdine, the executive director of the M.I.T. Energy Initiative…[has said the hundred-year period should be lengthened, not shortened]…Dan Lashof, the director of the Climate Center at the Natural Resources Defense Council…suggested…values for 20, 100 and 500 years [should be considered]…

"Mr. Howarth, [the paper’s lead author,] said that the majority of peer-reviewed papers on the greenhouse gas footprint of conventional gas have tended to consider both the long- and short-term time scales…[but] major scientific organizations [do not support extending it]…"

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"…Michael A. Levi, the David M. Rubenstein Senior Fellow for Energy and Environment at the Council on Foreign Relations [said]…Howarth’s gas-to-coal comparisons are all done on a per energy unit basis…[but] modern gas power generation technology is a lot more efficient than modern coal generation, so a gigajoule of gas produces a lot more electricity than a gigajoule of coal. The per kWh comparison is the correct one…[C]orrecting for [this] strongly tilts Howarth’s calculations back toward gas…

"…[Howarth replied that] per kWh is the ‘correct’ analysis only if the question is simply one of generating electricity from natural gas vs. coal…70 percent of natural gas in the U.S. is used for purposes other than for generating electricity, such as home and commercial heating, hot water heating, transportation, and industrial energy uses…For these purposes, natural gas has no efficiency advantage…For the 30 percent of natural gas used to generate electricity, there is indeed an efficiency advantage for natural gas over coal which is stated] explicitly in the paper…[M]ore points and counterpoints [are expected]..."