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Some Thoughts on the Howarth Shale Gas Paper

by Michael Levi
April 15, 2011

A new paper by Cornell’s Robert Howarth, which claims that shale gas is worse for greenhouse gas emissions than coal, has been getting a lot of attention in the popular press. Howarth’s basic question is an important one: what happens to the claimed emissions benefits of natural gas once you include the methane leaked in its production and transport? Alas, his analysis is based on extremely weak data, and also has a severe methodological flaw (plus some other questionable decisions), all of which means that his bottom line conclusions shouldn’t carry weight. But someone else, with better data and more careful calculations, ought to address this important set of questions that he raises properly.

I won’t catalogue every problem with the study – it’s more useful, I think, to flag the biggest issues. I see four.

First, the data for leakage from well completions and pipelines, which is where he’s finding most of his methane leaks, is really bad. Howarth used what he could get – figures for well completion leakage from a few isolated cases reported in industry magazines, and numbers for pipeline leakage from long-distance pipelines in Russia – but what he could get was very thin. There is simply no way to know (without access to much more data) if the numbers he uses are at all representative of reality.

Second, Howarth’s gas-to-coal comparisons are all done on a per energy unit basis. That means that he compares the amount of emissions involved in producing a gigajoule of coal with the amount involved in producing a gigajoule of gas. (Don’t worry if you don’t know what a gigajoule is – it doesn’t really matter.) Here’s the thing: 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, but Howarth doesn’t do it. This is an unforgivable methodological flaw; correcting for it strongly tilts Howarth’s calculations back toward gas, even if you accept everything else he says.

Third, the problems with gas that Howarth flags have cheap technological fixes (green well completion techniques, better pipeline care), though there may be institutional barriers to implementing them. If we scale up gas and realize we have an emissions problem, there are things we can do. The only technological fix for coal, in contrast, is CCS, which isn’t commercial yet; if we decide we want to fix our coal problem, it’s not clear we have any options.

The fourth question, which has been getting a lot of attention (perhaps most of it), is Howarth’s decision to use 20 year global warming potentials (GWPs) to compare coal with gas, rather than the customary 100 year figures. Basically, the purportedly high lifecycle emissions of gas are due to methane leakage. Methane is a potent greenhouse gas, but decays in the atmosphere on scales of decades, in contrast with carbon dioxide, which decays on the century scale. This means that if you average the impact of GHG emissions over 20 years instead of 100, it boosts the relative influence of methane, and hence the downsides to gas.

Lots of people have been going after Howarth for his unorthodox approach on this front. I have to admit, though, that this is one where I’m not so sure that he’s as wrong as his critics claim. I’ve been a big fan, for example, of efforts to cut near term emissions by targeting black carbon and ozone – but you can’t really justify the value of such measures unless you look at short term GWPs, since these are very short lived species. And given a lot of the rhetoric out there about nearish-term tipping points, it also isn’t entirely clear to me that it’s consistent to turn around and say that we should only look at impacts averaged over a hundred years. Over at NRDC’s blog, Dan Lashof (who I hear wrote his PhD dissertation on GWPs) suggests that a 50-year timeframe is best. This makes as much sense as anything else. [UPDATE: In response to some email feedback, let me clarify: I’m not saying that a 20 year GWP is wise, or that a 50 year one is. All I’m saying is that this is a judgment call, and that one shouldn’t assume that a 100-year time frame is the best way of looking at every problem.]

One last comment: I worry about what this paper says about the peer review process and the way the press treats it. This article was published in a peer-reviewed journal that’s edited by talented academics. It presumably got a couple good reviews, since its time from submission to publication was quite short. These reviewers don’t appear to have been on the ball. Alas, this sort of thing is inevitable in academic publishing. It’s a useful caution, though, against treating peer review as a mark of infallibility, as too many in the climate debate – both media and advocates – have done.

Post a Comment 26 Comments

  • Posted by Erik Schlenker-Goodrich


    Thank you for this critique; it’s helpful. A few thoughts:

    [ML: Thanks for your thoughtful comments. Notes below.]

    1. It strikes me that the uncertainties are less of a problem for the Cornell study and more a problem for proponents of natural gas. It’s hard to justify massive investment in an energy source that is riddled with so many uncertainties relative to climate.

    [ML: Seems to me that the uncertainties are a problem for everyone.]

    2. Using the most modern, efficient gas-fired facilities itself skews the analysis. I don’t know what the right number is, but the reality is that natural gas is proposed for extensive use in both power plants, old and new, as well as transportation. That’s a big swath of combustion sources, not all of which are super efficient.

    [ML: Fair enough. But there’s a decent understanding of the situation here. The administration’s CES proposal, for example, appears to only credit gas if it’s used in highly efficient power plants.]

    3. Although natural gas is touted as a bridge fuel, the end point of that bridge isn’t well defined. And the natural gas industry will certainly not support policies that limit it’s role — they want to take over the market share currently dominated by coal. In so doing, natural gas can supplant investment in efficiency and clean energy from water, wind, and sun. For example, if utilities build new gas-fired electricity plants, that utility is locking in natural gas use for the 30-40 plus years that those plants exist. That investment could be better spent on efficiency measures and clean energy.

    [ML: I can’t say I see the capital constraint you seem to assume. To first order, investment in efficiency (at least beyond the industrial sector) will be dominated by policy, rather than by gas prices, as will investment in solar and tidal. Wind is a bit different — I agree with you that gas will push it out.]

    4. Fundamentally, the Cornell study’s comparison of coal versus gas is useful, but suggests the wrong question for anyone who cares about dealing with climate change. The question isn’t how fast we can get off coal, the question is how fast we can get supplant fossil fuels with efficiency and renewables.

    Natural gas could play a role in that speedy transition, but I surmise it’s a far more limited role than has been, to date, suggested.


  • Posted by Robert Howarth

    Although I do not generally write responses to blogs, Michael Levi has so thoroughly misconstrued our paper that I feel obliged to write at least briefly. I suggest the interested reader take a look at our paper published on April 14 in Climatic Change, rather than rely on Levi’s assessment.

    [ML: Thanks for responding. Some reactions of mine are below. I also encourage readers to look at the actual paper.]

    Some issues:
    1)our analysis is the first comprehensive assessment of the greenhouse gas footprint of shale gas. The data are more sparse and more poorly documented than one would like, a point we make in our paper. BUT, they are the best available data. EPA has established new regulations which would require industry to provide better data, which would be a great step forward. However, industry has sued to stop this.

    [ML: That’s a problem, and industry should take a different approach, but that doesn’t justify the bottom line conclusions in the paper. The paper concludes that “The footprint for shale gas is greater than that for conventional gas or oil when viewed on any time horizon, but particularly so over 20 years. Compared to coal, the footprint of shale gas is at least 20% greater and perhaps more than twice as great on the 20-year horizon and is comparable when compared over 100 years.” There are no caveats, nor an attempt to quantify the uncertainty due to poor data (as opposed to variation among the data that are used, which is looked at). What the analysis in the paper shows is that there are some important open questions about shale gas — but that’s not how it is presented. A lack of good data doesn’t justify making definitive conclusions one way or the other.

    2)Levi is simply wrong that we do not look at the electricity comparison. We do (see section 6 of our paper, and the on-line supporting information; see also draft report by David Hughes on our web site). We do not focus exclusively on electricity, as 70% of natural gas in the US is used for purposes other than generating electricity. We do not use kWh as our unit, since Climatic Change and most other journals do not allow it, instead requiring the standard SI unit of joules instead. Note that 1 GJ = 278 kWh.

    [ML: Here’s the whole discussion in section 6: “Our analysis does not consider the efficiency of final use. If fuels are used to generate electricity, natural gas gains some advantage over coal because of greater efficiencies of generation (see Electronic Supplemental Materials). However, this does not greatly affect our overall conclusion: the GHG footprint of shale gas approaches or exceeds coal even when used to generate electricity (Table in Electronic
    Supplemental Materials). Further, shale-gas is promoted for other uses, including as a heating and transportation fuel, where there is little evidence that efficiencies are superior to diesel oil.”

    This is an odd statement: the overall conclusion, as summarized in the abstract, is that gas is invariably worse than coal; that is fundamentally different from “gas approaches or exceeds coal”. This difference doesn’t qualify as “not greatly affect[ing]” the overall conclusion — it pretty much flips it.

    Indeed there is a strong focus in the paper on the claim that natural gas is worse than coal — which is the claim I disputed. But the coal vs gas question is only relevant in the context of electricity; no one is proposing that we start heating our homes with coal. The paper does indeed note in passing that combustion efficiency is an issue, but it buries that point; as far as I can see, it’s pretty central to the coal vs gas comparison. Last: 1GJ does not equal 278 kWh, unless you have perfect combustion efficiency, which you don’t.]

    3)we discuss the technical fixes in our paper. See section 7. Note that fixes are not that cheap however, nor widely used. Stonger governmental regulation will be required to make fixes widely used, and again, industry is resisting this. Also, not all emissions can be stopped.

    [ML: I didn’t say that the paper doesn’t discuss technical fixes. My point was simply that the technical fixes for gas are a heck of a lot cheaper (and politically more feasible) than the technical fixes (ie CCS) for coal.]

    4) I appreciate that Levi is open to considering time frames shorter than 100 years. Note that our paper used both 20-year and 100-year integrations. Note also that of the 3 previous peer-reviewed papers on the greenhouse gas footprint of conventional gas published in the past 15 years, 2 also used the 20-year analysis. Most climate change scientists are in full agreement with us that it is essential to consider the 20-year time frame, if society is to adequately address global warming and avoid tipping points in the climate system.

    [ML: That just isn’t true. There is enormous diversity among climate scientists regarding the appropriate GWP to use in different analyses. I know serious scientists who think it should be 20, and equally serious ones who think it should be 200. Presenting this as a matter of settled consensus is wrong.

    On the peer-review, Climatic Change is a highly respected journal, and we received extensive, thorough reviews. I believe Mr. Levi’s critique of our paper and peer review would have benefited from having some one else take a look at it before he posted it…

    [ML: Best not to make assumptions.]

  • Posted by David Hughes

    As Dr. Howarth mentions, I did carry his analysis through to electricity generation in terms of emissions per kWh. Dr. Howarth certainly does characterize the wide error bars in the data with his minimum and maximum estimates for shale gas and conventional gas.

    [ML: But that’s not a full range, no? He characterizes the range of the data he has, but as best I can tell, there’s no attempt to determine the odds that the data is representative.]

    If you take the mean of his estimates of shale gas emissions, and use the accepted 210 pounds of CO2 per million BTU’s for coal versus 117.8 pounds of CO2 per million BTU’s for natural gas at the burner tip, the existing gas fleet fuelled by shale gas emits 33% more full-cycle emissions than the existing coal fleet. This totally invalidates your assertion in point 2 that this is not the case on a per kWh basis.

    [ML: Not following. What “is not the case”? And this is still not the right comparison. The appropriate conversion factors depend on the efficiency of the generation technology — there is no single one that works. You don’t substitute BTU for BTU in power generation — you substitute kWh for kWh.]

    My report on this and other issues concerning shale gas as a panacea for electricity and transportation will be released in mid-May. An abstract of my report is available here

    [ML: Looking forward to the full thing.]

  • Posted by David Hughes

    Just to add this is on Dr. Howarth’s 20-year timeframe basis.

  • Posted by David Hughes

    Contrary to your comment, I did my comparison on a kWh to kWh basis. According to the EIA, the existing coal generating fleet in the US has an average heat rate of 10414 BTU/kWh, versus 8157 BTU/Kwh for the gas generation fleet. Using Dr. Howarth’s mean estimate of full cycle shale gas emissions, the coal fleet emits 2.41 pounds of CO2 per kWh versus 3.2 pounds of CO2 per kWh for gas. Hence 33% more CO2 per kWh for shale gas than coal.

    By the way I am comparing shale gas to surface mined coal on a 20 year basis. The updated link to the abstract of my forthcoming paper is

    [ML: Sorry if I misunderstood — there’s no way to know what your calculations look like given that they haven’t been published. (The abstract doesn’t shed additional light.) I appreciate that you can get this result if you pick numbers this way. But there’s no reason to believe that the mid-point of Howarth’s range is anywhere close to correct, to only compare to surface mined coal, or to only look at a 20 year time frame. Nor is there a reason to focus exclusively on the average heat rate, given that gas-substitution policies being considered generally restrict themselves to gas used in high-efficiency plants, and that the coal plants they’re likely to replace are the least efficient ones. None of this says that gas is universally better than coal — but it strikes me as being very unwise to claim the opposite without caveat, as the Howarth paper does (in contrast with your more hedged abstract, which I haven’t commented on). I look forward to having a chance to look at the actual paper.]

  • Posted by Marlowe Johnson

    Great post Michael.

    Having spent far more time than I’d like poring over lifecycle assessments, it’s nice to see someone highlight the importance of true apples to apples (i.e. kwhr) comparisons.

    Like you, I think that the study would also have benefitted from more caveats and cautious language. But at the same time I think that Erik makes a good point above about the onus being on NG proponents to provide more data. One need only look at experience with ethanol to see why. Interstingly, another Cornell alumni, David Pimentel, rose to mainstream media fame with his LCA work on ethanol. Time will tell if Howarth’s analysis turns out to be the outlier that Pimentel’s was.

  • Posted by Jack Young

    In this paper, the authors acknowledge that “the uncertainty in the magnitude of fugitive emissions is large”. After a quick review of their sources for their claimed methane emissions during well completion, I believe that this uncertainty effect may be far outweighed by the magnitude of the unstated assumptions made by the authors in arriving at their numbers.

    Take, for instance, the most controversial and powerful number given by the authors, the reported emission of 6,800,00 cubic meters of methane during the flow-back period by an average Haynesville Shale gas well. This would amount to roughly $1,000,000 of gas (wholesale) being vented to the atmosphere in 10 days, or 3.2% of each well’s lifetime production. The source given for this figure was Eckhardt M, Knowles B, Maker E, Stork P (2009) IHS Industry Highlights. (IHS) Houston TX Feb-Mar 2009.

    When I went to the cited publication to substantiate the reported methane emissions, I found a summary of initial production figures for newly completed gas wells around the country (which are generally taken after the flow-back period), but no data whatsoever regarding gas production during the flow-back period, what percentage of the gas was actually methane, or whether this production was sold, flared (burned) or vented to the atmosphere. In short, there was no support whatsoever in this reference for the methane emissions figure stated in the paper.

    I agree with the authors that “given the importance of methane in global warming, these emissions deserve far greater study than has occurred in the past.” I also would suggest that more attention be devoted by researchers in this field to understanding and reporting the data that exists already.

  • Posted by David Hughes

    I actually looked at the CO2 emissions per kWh of the average coal fleet, the average gas fleet, combined cycle gas, combustion turbine gas, subcritical coal, fluidized bed coal, supercritical coal, ultrasupercritical coal and IGCC coal. But for the sake of argument in this comments section and to be brief I compared the average of both the existing gas and coal fleets in my previous comment.

    If you compare the most efficient coal technology – ultrasupercritical coal – to the most efficient gas technology – combined cycle gas, gas has 47% more GHG emissions using Howarth’s mean estimates. It is just as true Mr. Levi that an old inefficient coal plant can be replaced with best-in-class efficiency coal technology, as opposed to best-in-class gas.

    [ML: I’m not going to bite. If you want to share your actual calculations, I’d be happy to provide a forum for debate. I have no interest, though, in debating conclusions absent the underlying analysis.]

    Of course, Mr. Levi, you can argue until you are blue in the face that Howarth’s mean emission estimates may not be correct – Howarth admits to the issues with the data. But he has generally been conservative in his overall estimates if you read the text of the published Climatic Change Letters paper. If you have any better estimates to offer they would be most appreciated.

    [ML: Like I’ve said before, a lack of data doesn’t give one license to make unequivocal claims one way or the other (as the paper does). End of story. I would also dispute the “conservative” characterization: including things like local distribution and long distance pipeline losses when neither exists in the relevant situation is not “conservative”. Nor is assuming that all gas that isn’t delivered to customers is leaked.]

    As for Mr. Young, if he cared to read Table 2 in Howarth’s paper he would see that the “Emissions during well completion” for shale gas used by Howarth was 1.9%, not the 3.2% Mr. Young states.

    [ML: I don’t want to speak for the commenter, but he is talking (correctly) about a specific figure in Table 1.]

  • Posted by David Hughes

    You win Mr. Levi. Guess we’d best pack up and go home. Just stick our heads in the sand and wait until data that meets your ideals emerges. Howarth has presented the best data that is available, taken a conservative stance, and presented the implications. You obviously don’t like them, but that doesn’t mean they should not be considered. By the way, the calculations you don’t want to bite on are trivial – the heat rates of the various coal and gas generation technologies are well documented, as are the emissions of gas and coal in terms of CO2 per unit of heat (which I mentioned in an earlier comment).

  • Posted by Jack Young

    As noted above, Mr. Hughes might want to check Table 1 in the Howarth paper – that’s the one that cites the emissions figure for the Haynesville Shale well I referred to. The figure given in Table 2 was an average which included, and was influenced by, the mistaken emissions figure I highlighted. I’m not sure how he made this mistake, but I apologize if my post was in any way unclear.

  • Posted by Miguelito

    Howarth et al. did not provide conservative estimates, certainly not in their low case because they vastly overestimate vented gas during completions.

    He assumed flowback rates would be over 20 million cubic feet per day for the Haynesville Shale and almost 1.5 million cubic feet per day for the Barnett. However, these are typical peak rates for each shale, not flowback rates. Flowback rates are far, far less as the shale cleans up (the shale is busy pushing out the frack water and not producing so much gas) and occur many weeks after production has started and long after they’re hooked into a pipeline.

    Plus, they assume the gas is vented, not flared. Frankly, if you’re venting 20 million cubic feet of gas per day near your rig, you might as well drop a bomb on it. Flowback gas is flared, even at lower rates, for safety reasons. Same with gas when drilling out plugs.

    Frankly, this aspect of the paper was completely botched and I have no idea how this paper got through peer review in the state it’s in.

  • Posted by Erik Schlenker-Goodrich

    Dear Michael-

    Thanks for the dialogue. Some quick thoughts in reply to your responses.

    First, the uncertainties are certainly a problem for all of us, but that’s a bit too rhetorical for my blood. The NG industry has framed NG as a “gamechanger” that is far cleaner than coal without actually backing up their conclusion with good data. They compound the error by now fighting attempts by government to get a better handle on NG carbon emissions. In a carbon constrained world, the proponents of intensified fossil fuel use, here NG, bear a heavy burden to demonstrate that their solution is actually grounded in verified, ground-truthed fact.

    Second, to suggest that the Administration’s CES proposal only credits gas if in highly efficient power plants doesn’t mean the dirty power plants suddenly disappear. Moreover, it is problematic that any CES would include a fossil fuel. NG may have advantages that provide for its limited use as a bridge fuel, but that doesn’t mean it’s actually a clean fuel. The CES standard strikes me as a political gimmick, not good policy.

    Moreover, we have proponents of NG for not just the limited role of efficient power plants, but all manner of uses. To ignore these dynamics by using an ideal scenario is problematic.

    Third, I think the capital constraint is actually quite clear. Utilities — who play powerful roles in terms of *both* demand and supply side management — have choices, e.g., to invest in demand side efficiency or supply side new power, whether fossil fuels or renewables. If gas prices are cheap, and encouraged by policy, this will operate to advantage NG relative to demand side efficiency and supply side renewables. Thus, I do not understand (and I’m saying this genuinely, not rhetorically) your point about ‘policy,’ as ‘policy’ begs the question what that policy actually is and that policy’s efficacy in light of other policies (e.g., those that deal with NG) and fuel prices (NG, renewables, etc.).


  • Posted by Hans Nicolaisen

    After reading Jack Young’s first comment on Howarth’s reference source for Haynesville I decided to look at all Howarth’s references for his Table 1. Briefly, this is what I found.

    Piceance: EPA (2007) – For years 2002-2006 there were 1064 well completions with flowback. Average 91.1% of flowback recovered.

    Barnett: EPA (2004) – One slide with data for 30 wells by Devon in Fort Worth Basin. Not clear how Howarth came up with his figures from this. The slide notes: “ Expects emission reduction of 1.5 to 2 Bcf in year 2005.”

    Uinta: Samuels (2010) – Table on page 3 shows 847 well completions for years 2005-2010. Historical flowback time of 5 days per well at an average flow rate of 1,625 mcf/day. For 847 wells that would indicate a total flow of about 6.9 bcf. But, the table shows an “Estimated Gas Captured” of 8.8 bcf. ??

    Denver-Julesberg: Bracken (2008) – For the period 1998-2005, an average of 421 wells/year frac’d with “Estimated Gas Lost” of about 2.1 bcf. For the period 2006-2007, an average of 613 wells/year frac’d with estimated loss of 20.5 mmcf. A considerable reduction – to say the least.

    All in all, I don’t see how Howarth came up with his figures for Table 1 from material available in his references. If anything, his references indicate that whatever gas was lost in earlier years during flowback is being increasingly captured through “green completion” measures. While the earliest wells may have lost a high amount of gas during flowback, it appears that very significant gains are being made to reduce this.

    In addition, Howarth has been noted to be strongly opposed to fracking and it seems to me that this may have affected his research. I came across a short YouTube video in which he is addressing an anti-fracking rally in September, 2010 and, in this, he mentions working on the “study” that has resulted in his paper. Here is the link.

    Overall, my personal feeling is that Howarth has tried to manipulate the data in ways that lead to the outcome he desires. It’s good that he has drawn attention to the issue, but it’s unfortunate that he has done so in a manner that fits his apparent agenda.

  • Posted by Jack Young

    I actually contacted the author of one of the powerpoints used as a reference for the methane emissions figures by Howarth etal, and he said that they had badly misused his work. The true emissions number he gave me for that producing area was 1/148th of the figure used in the paper.

    This reminds me of Andrew Wakefield, the doctor in the UK who started the whole “M.M.R. vaccination causes autism” scare. Funded by a biased source, built around unsupported (and eventually proven to be bogus) claims, that paper did more harm (thanks to excessive publicity) than anything he’ll ever be able to compensate society for.

    One hopes that won’t be the legacy of these claims when people look back on them in 20 years, but who knows.

  • Posted by Kojiro Vance

    Comparing energy on a heating value basis rather than its end use (electricity) is a major flaw. I would agree that newer coal plants are a lot more efficient. It is disengenous of environmentalists who support Howarth to claim that a supercritical PC plant is nearly as efficient as NGCC, while they protest every new SC PC proposed.

    The flowback losses are a couple of order of magnitudes too high. We are to believe that in 5-12 days gas flowing back through the well along with frac water amounts to over 3% of the gas produced during the decades of production??? This claim doesn’t pass the laugh test.

    Don’t get me started on LUG. Dr. Howarth seems clueless that gas doesn’t balance on a volumetric basis, but WOULD on a mass basis when accounting for removing liquids, water, and gas used during processing. If I have to explain it to you Dr. Howarth, then you are not qualified to be writing on this subject.

    Try talking so someone and quoting sources OTHER than envirnomental scientists!

  • Posted by Jack Young

    One other small point I should make – natural gas is typically only 70 to 90% methane, the rest being other hydrocarbons that I understand have no unfavorable global warming potential. So whatever emissions of natural gas eventually are accepted by the scientific community, the impacts on global warming will be substantually smaller than what the Howarth paper suggests. I assume they didn’t realize that natural gas before processing isn’t all methane, although that does seem to be a pretty basic point to have missed.

  • Posted by Hans Nicolaisen

    At the risk of continuing going on too long in this discussion….

    After I made my earlier post above I found a video presentation from March 15 by Howarth and Tony Ingraffea, a co-author of the paper. It’s quite good. Especially the Q&A. It’s about an hour long. What struck me was how many times the co-authors mentioned the sparseness and poor quality of their data sources. Yet they seem content, if not encourage, reporting of the paper to center on GHG emissions of shale gas being as much as twice that of coal. They also make it seem like this is about Marcellus, when what data they have has nothing to do with Marcellus. The questions from the audience during the Q&A sometimes put the authors in a difficult position. Here’s the link.

    On last Thursday, 4/21, there was a “Webinar” by EnergyBiz, entitled “The Future of Coal Generation”, which, of course, includes the future of natural gas.

    After the three presentations, the “Cornell paper” was brought up. It was the consensus among the panelists that flowback losses are manageable and will be controlled. One panelist (Mark Griffith from Black and Veatch) suggested that this, and transport losses for all gas, are quantifiable and loss control will be built into price – which he thought would be less than $1/mmbtu added.

  • Posted by Jack Young

    I’ve heard that the Park Foundation gets the press rights to all research they fund. So the enormous publicity this paper got, and the misplaced focus on the Marcellus shale, may not actually be something the authors are directly responsible for. I think that the Park Foundation has a clear agenda here, and they aren’t bound by any code of ethics in their efforts to influence the public policy debate.

  • Posted by Raindog

    Another important point is this:

    Coal and gas were compared on the amount of energy produced. When they are both used to generate electricity, it seems that the greater average efficiency of gas plants should be accounted for and this was addressed in the original post above. Howarth’s lack of understanding of the industry also led to several fairly elementary mistakes (gas is flared vs vented, LUG is mostly not methane lost to the atmosphere). I get the impression that from all of the mistakes made in the paper that emissions from gas probably have GW potential of about half the GWP per unit of electricity that coal does or perhaps even less than that.

    But what about the 70% of gas that is used directly for heat, hot water or for industrial purposes? About 50% of home heat comes direcly from burning gas (not electricity produced from gas). If one were to compare direct heating from gas to electric heat that comes from burning coal, the numbers are even more strongly in favor of gas. From what I understand, more than half the electricity generated at coal plants is lost in transmission. So even if gas emits the same amount of GHGs that coal does, gas fired heat emits half the GHGs of electric heat from coal. If gas emits half the GHGs of coal per unit of energy on a life-cycle basis (which is the conclusion of many other studies), gas heat emits about 1/4 the GHGs of electricity from coal.

    This is relevant because about 90% of our domestic gas wells today are hydraulically fractured. If those who would like to ban hydraulic fracturing have their way, gas will become so expensive and then so scarce that there will be a major shift over to the remaining cheapest source of energy which would be coal.

  • Posted by Hans Nicolaisen

    I thought this discussion had probably come to a well deserved end but, in checking in just now, I see it hasn’t. Raindog’s comments above are a bit hard to follow, but I noticed two glaring errors.

    The first is, “From what I understand, more than half the electricity generated at coal plants is lost in transmission.”

    In general, transmission losses from coal plants are no different from other sources of base load generation. I don’t have current US transmission loss figures but it’s far less than 50%.

    The second error is, “This is relevant because about 90% of our domestic gas wells today are hydraulically fractured.”

    I believe the figure for fracked wells is about 20% of the total. The EIA currently forecasts that to rise to 45% by 2030.

    Sorry to prolong the discussion, but I couldn’t let those figures go uncorrected. And hope I haven’t forgotten how to use html tags…

  • Posted by Raindog


    You are right – I was confused. Only about 6.5% is lost in transmission. The higher number was for energy lost at the plant itself. I just saw some references that said that the least efficient coal plants lose about 65% of the energy produced while the most efficient lose about 45-50%.

    But I think the broader point is still correct. Less than 50% of the energy produced by burning coal ends up with the end user in the form of electricity. Almost all of the energy from burning gas at the site in a heater goes to making heat. So heating with gas has a far smaller greenhouse gas footprint than using coal-fired electricity to run an electric heater. In fact any gas that is used on site for hot water or cooking is probably going to have a much smaller footprint than electricity produced from coal (or gas for that matter). The option for on-site burning just isn’t there with coal anymore (thankfully!).

    A ban on hydraulic fracturing of gas wells would almost certainly lead to a great decrease in supply and a great increase in price making it unaffordable to most Americans. The best alternative price wise would be to switch to electricity produced by burning coal.

    Here is but one reference that says that 90% of wells today are hydraulically fractured

    Here is the quote from that article in the NYT:

    “Fracking has been around for decades, and it is an increasingly prominent tool in the effort to unlock previously unreachable gas reserves. The oil and gas industry estimates that 90 percent of the more than 450,000 operating gas wells in the United States rely on hydraulic fracturing.”

    Here is Schlumberger saying the same thing

    The 90% number seems to be pretty well accepted.

  • Posted by Hans Nicolaisen

    Quick follow-up for anyone still checking in.

    US electric transmission and distribution losses in 2007 were 6.5%. Probably distribution losses exceed transmission losses, so maybe around 3% for transmission.

    In 2009 shale gas production was about 21% of production from all gas wells.

  • Posted by Jack Rivkin

    Michael, I posted this comment on your earlier blog on Howarth’s work. I think it belongs here as well.The CMU PHD Thesis published in 2007, which you referred to in the earlier post was based on emission data from 1993 for the most part and really doesn’t address specifically fracked shale gas. Even this thesis says the following: “Looking at the life cycle also allowed us to identify that in a future where emissions from the power plant are reduced, the benefits of natural gas over coal are not very significant…” It would be useful if the industry would provide data to make the case for shale gas, using research as opposed to attacking the researcher. The industry has this data. They should provide it. Of course, this doesnt address the local impacts as you imply. The industry runs the risk of killing a big step toward energy independence if they frack without considering the consequences of not addressing the local issues,the politics, spending more time understanding the geology, chemistry of these shale formations, and making sure that the GHG footprint is in fact better than competing carbon sources. Gas will be fracked in the rest of the world. If it is not fracked here because of short-sightedness on the part of the industry, we lose a real opportunity to move toward energy independence, much less toward reduced GHG emissions. Looking forward to your comments on the “local” issues.

    [ML: Jack: Agree. Search for my recentish Houston Chronicle piece arguing that industry needs to be more proactive to avoid creating a backlash in which everyone loses.]

  • Posted by Hans Nicolaisen

    Jack Rivkin makes a good point when he writes, “Gas will be fracked in the rest of the world. If it is not fracked here because of short-sightedness on the part of the industry, we lose a real opportunity to move toward energy independence, much less toward reduced GHG emissions.”

    A somewhat similar point about coal was made in the webinar, “The Future of Coal Generation”, which I linked to in an earlier post. There the observation was made that the US has a great deal of wealth in our coal resources and, if this coal is not mined for use in the US, it will be mined for use elsewhere – perhaps India and China. Whether it’s shale gas, or coal, we need to find more efficient ways to utilize these resources in order to both reduce GHG emissions and extend the useful life of the remaining reserves.

    To move on to an area that’s beyond my understanding. Quite a lot has been made of Howarth et al using a 20 year time frame for GHG as opposed to the more commonly used 100 years. But, since calculations of US gas reserves (including shale gas) now estimate we have reserves sufficient for 100 years of consumption at current rates, what effect does that have on the calculations of GWP?

  • Posted by Raindog

    Hans Said

    In 2009 shale gas production was about 21% of production from all gas wells.

    An amazingly high percentage for a resource that was 90% of gas wells drilled in the US are currently hydraulically fractured. There just isn’t much natural gas left in conventional reservoirs here.

    The US has also seen an uptick in oil production recently, largely from the Bakken and Eagle Ford Shales which only works if produced from hydraulically fractured horizontal wells. More than 50% of US oil wells drilled last year were hydraulically fractured. This number will only go up with time.

    I still think it is important to point out that gas burned at the site of use is far more efficient than using coal-fired electricity for the same job! Probably at least twice as efficient and maybe 3 times as efficient, even if we take Howarth’s unrealistic assumptions as facts!

  • Posted by gas thermocouples

    Shale gas has become an increasingly important source of natural gas in the United States over the past decade, and interest has spread to potential gas shales in Canada, Europe, Asia, and Australia. One analyst expects shale gas to supply as much as half the natural gas production in North America by 2020.

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