*UPDATE II* New Study Debunks Cornell GHG Paper. Again.

UPDATE II (9/17/2012, 3:49pm ET): A new report for the European Union examining the potential climate impact from shale gas development further marginalizes the Howarth/Ingraffea thesis, concluding that shale gas has “significantly” lower emissions than coal when burned for electricity.

Some studies, which have received a lot of media attention, have concluded that the lifecycle GHG emissions from shale gas may be larger than conventional natural gas, oil, or coal when used to generate heat and viewed over the time scale of 20 years (Howarth et al, 2011). However the majority of studies suggest that emissions from shale gas are lower than coal, but higher than conventional gas, based on other assumptions.

In our analysis, emissions from shale gas generation are significantly lower (41% to 49%) than emissions from electricity generated from coal. This is on the basis of methane having a 100 year GWP of 25. This finding is consistent [with] most other studies into the GHG emissions arising from shale gas.

The Europeans may drive on the wrong side of the road, but facts are still facts.

UPDATE (11/3/2011, 5:02 pm ET): A new study from the Department of Energy’s National Energy Technology Lab casts even more doubt on the Cornell study. A presentation of the study comes to the following conclusion: “Average natural gas baseload power generation has life cycle GHG emissions 53% lower than average coal baseload power generation” (p. 36). All forms of natural gas scored significantly lower on GHG emissions than coal-powered generation.

And what about the infamous 20-year time for global warming potential (GWP), which Dr. Howarth deemed “critical” for making a proper environmental impact assessment? NETL concludes: “Average natural gas baseload power generation has life cycle GHG emissions 42% lower than average coal baseload power generation on a 20-year time horizon” (p. 37). Once again, all forms of natural gas score lower than coal, even on the 20-year time frame.

—Original post: October 26, 2011—

Maryland joins Carnegie Mellon, Wood Mackenzie, and even U.S. Dept. of Energy in locating gaping holes in Howarth/Ingraffea paper

Earlier this year, researchers from Cornell University — Robert Howarth and Anthony Ingraffea — released a study that found emissions from shale gas production are worse than coal, based chiefly on the global warming potential (GWP) of methane. Of course, the study had more holes in it than big slice of Swiss cheese (read EID’s six-times-updated rebuttal here), with its conclusions resting on such a poor foundation that even a Sierra Club funded study found its premises to be flawed.

Yet the Cornell study continues to be used by ideological opponents of shale gas production, not just in the United States but also in Canada. Which is why we feel it’s imperative to highlight that yet another top-notch study — this one from researchers at the University of Maryland — is pushing the Cornell paper even closer to the ash bin of history.

The new study, entitled “The Greenhouse Impact of Unconventional Gas for Electricity Production,” has many noteworthy conclusions, including:

  • “GHG impacts of shale gas are…only 56% that of coal” {p. 1}
  • “Methane has the ability to trap large amounts of infrared radiation relative to CO2, but it also has a comparatively shorter lifetime in the atmosphere. As a result, methane’s 100 y GWP is much lower than its 20 y GWP.” {p. 5}
  • “Two factors lead to an overall carbon intensity advantage for gas during the combustion stage. First, gas releases more energy per unit of carbon emitted. Second, the technology used for combustion of gas is more thermodynamically efficient than that used for coal, enabling a larger amount of chemical potential energy in the fuel to be converted to electricity.” {p. 5}
  • “[A]rguments that shale gas is more polluting than coal are largely unjustified.” {p. 8}
  • “[W]e have demonstrated that the fugitive emissions from the [shale gas] drilling process are very likely not substantially higher than for conventional gas.” {p. 8}
  • “Evaluated solely on the criterion of GHG emissions from electricity generation, shale gas is not likely to be substantially more polluting than conventional gas.” {p. 8}

And as we said, this most recent study is only the latest to join the party. But don’t just take our word for it…

August 2011, Carnegie Mellon Univ. report on life cycle greenhouse gas (GHG) emissions from Marcellus shale production:

  • “The GHG emission estimates shown here for Marcellus gas are similar to current domestic gas.”
  • “For comparison purposes, Marcellus shale gas adds only 3% more emissions to the average conventional gas, which is likely within the uncertainty bounds of the study. Marcellus shale gas has lower GHG emissions relative to coal when used to generate electricity.”
  • Lead researcher Paula Jaramillo (an ‘energy expert,’ according to ProPublica): “We don’t think they’re using credible data and some of the assumptions they’re making are biased. And the comparison they make at the end, my biggest problem, is wrong.” (as quoted by POLITICO [subs. req’d], Aug. 24, 2011)

August 2011, Worldwatch Institute study points out how Howarth and Ingraffea are the exception, not the rule:

  • “Despite differences in methodology and coverage, all of the recent studies except Howarth et al. estimate that life-cycle emissions from natural gas-fired generation are significantly less than those from coal-fired generation on a per MMBtu basis.” (p. 9)

June 2011, Cornell Univ. professor Lawrence M. Cathles [report submitted for publication]:

  • “[Ingraffea’s and Howarth’s] analysis is seriously flawed in that they significantly overestimate the fugitive emissions associated with unconventional gas extraction…”
  • “[T]he assumptions used by Howarth et al. are inappropriate and…their data, which the authors themselves characterize as ‘limited’, do not support their conclusions.”

May 2011, U.S. Dept. of Energy report: Emissions from natural gas are low compared to other fuels.

  • “Howarth [and Ingraffea] found a large fraction of produced gas from unconventional wells never made it to end users, assumed that all of that gas was vented as methane, and thus concluded that the global warming impacts were huge. As the [Dept. of Energy] work explains, though, 62% of that gas isn’t lost at all – it’s ‘used to power equipment.'” (CFR blog, May 20, 2011)

May 2011, Wood Mackenzie study “Methane Emissions from Unconventional Well Completions”

  • “Our analysis indicates that the Cornell study overestimated the average volume of natural gas vented during the completion and flowback stages by 60-65%. We conclude that the Cornell study overestimated the impact of emissions during well completions by up to 90%.”
  • Howarth “used obsolete data and considerably overestimated Haynesville emissions that contributed to the overestimation of vented methane.”

May 2011, Navigant Energy Practice, “How does the Howarth team’s report affect natural gas development?”

  • “[T]he report concludes that the average well [in the Haynesville Shale] spits 250 million cubic feet of methane into the sky. That’s about a million and a half dollars’ worth of gas at today’s prices. … I have to wonder whether the authors have ever seen a working drilling / fracturing operation.”

May 2011, Global Warming Policy Foundation, “The Shale Gas Shock

  • “[Howarth’s conclusion] requires unrealistic assumptions about: the quantity of methane that leaks during fracking, production and transport; the lack of methane leaks from coal mines; the residence time of methane in the atmosphere; and the greenhouse warming potential of methane compared with carbon dioxide. … And Howarth gets his numbers on high gas leakage from shale gas wells from unreliable sources, his numbers on gas leakage from pipelines from long Russian pipelines, and assumes that ‘lost and unaccounted for gas‘ is actual leakage rather than partly an accounting measure. He also fails to take into account the greater generating efficiency of gas than coal.” (p. 30)

John Hanger, former head of the Pennsylvania Dept of Env. Protection:

  • “Professor Horwath’s conclusion that gas emits more heat trapping gas than carbon flies in the face of numerous life cycle studies done around the world.” (April 12, 2011)
  • “Professor Horwath just adopted an extreme and false assumption of no flaring that conveniently moved the result of his life cycle analysis in the direction that he wanted.” (April 12, 2011)
  • “Bit by bit the Howarth study is being consigned to the junk heap.” (Aug. 25, 2011)

Natural Resources Defense Council’s Dan Lashof rejects the Cornell study’s use of a 20-year time frame:

  • “Moreover, while I can see an argument for using a time horizon shorter than 100 years, I personally believe that the 20-year GWP is too short a period to be appropriate for policy analysis because it discounts the future too heavily. I calculate that over a 50 year period, the GWP of methane would be in the range of 42-56, based on the IPCC and the Shindell et al. analyses.”

And, just as a refresher, here are Howarth and Ingraffea discussing the flaws of their own paper:

  • Howarth: “They are limited data. These are not published data. These are things teased apart out of PowerPoint presentations here and there. So rather than try to extrapolate based on any complicated formula, we’ve ended up simply taking the mean of those values.” (Howath presentation to colleagues, 22:30, March 15, 2011)
  • Howarth: “A lot of the data we used are really low quality, but I’m confident that they are the best available data.” (38:50)
  • Howarth: “Let me just as an aside say that, again, the quality of the data behind that number [methane emissions during well completion] are pretty lousy. You know, they’re these weird PowerPoint sort of things.” (44:15)
  • Ingraffea: “We are basing this study on in some cases questionable data.” (38:20)
  • Ingraffea: “I hope you don’t gather from this presentation that we think we’re right.” (57:15)
  • Howarth: “We did not look as carefully at coal. … We didn’t put anywhere near the amount of effort into them [coal numbers], but I’m sure they are lower than natural gas.” (39:10 – 40:08)



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