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Natural gas is mostly methane

By Joe Romm on April 13, 2011 at 10:49 am

"Natural gas is mostly methane"


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In my piece on the Cornell study, my subhed was “Leakage of methane from fracking boosts shale gas global warming impact.” I didn’t note until several paragraphs later that “Natural gas is composed largely of methane,” which comes from the second sentence of the study itself.

But as our bunny friend Eli pointed out yesterday, it seems like not everybody covering the subject is entirely clear on that:

… from Eve Troeh on Marketplace (NPR)

On TV, natural gas gets sold as pristine energy.

Robert Howarth: But that of course is only part of the greenhouse gas footprint.

Cornell University professor Robert Howarth. His new study is the first to quantify the whole carbon footprint for natural gas. He found it’s more Bigfoot than Bambi. Because when you crack shale to get to the clean-burning fuel, out comes “methane” — another greenhouse gas. He says that’s worse than burning coal.

And, of course, not to be caught in the rush, Friend Kloor jumps in at his new day job.

Maybe, but that natural gas bridge might not be as sturdy as previously thought, according to a Cornell University study in the upcoming May issue of Climatic Change Letters. Cornell ecologist Robert Howarth, a lead author of the study, says in a university release that methane (a potent global warming gas) leakage from a controversial drilling method (known as fracking) offsets the lesser carbon emissions that makes makes natural gas more attractive in comparison other fossil fuels:

You know, who would have guessed that natural gas is mostly methane.

I’ve been working in the energy arena for over two decades and sometimes forget to lead with the basics.  Shale gas is “natural gas produced from shale.”  Wikipedia notes “Methane is the major component of natural gas, about 87% by volume” though other sources typically give a range of around 70% to 90%.  Most of the rest of nat gas is ethane, propane and/0r butane.  The stuff that gets to your home “is almost pure methane.”

Methane is CH4 and its combustion produces heat and H2O and CO2.

Methane is a very potent greenhouse gas, though with a much shorter lifetime in the atmosphere than CO2.  Recent studies suggest a very high global warming potential [GWP] for CH4 vs CO2, particularly over a 20-year time frame.  If one is talking about building new natural gas power plants — or vehicles and fueling infrastructure — then I think it is reasonable to look at the 20-year GWP because you are making a commitment to long term natural gas use, which is to say long-term of methane combustion and whatever leakage or fugitive emissions occur along the way.

Hope that clears things up.


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25 Responses to Natural gas is mostly methane

  1. Ben says:

    I’m confused. So they’re losing methane which is similar to the final product that is burned for heat or electricity, and I presume that once the methane is actually burned CO2 is released but this is still in quantities much lower than coal.

    And from the articles I gathered, some of this methane is lost in places where improvements could be made to stop it from leaking. If they were able to capture this leaking methane, then the concern over natural gas would go back to the CO2 emissions, which is still remarkably better than coal?

    [JR: Coal is more carbon intensive than methane, yes. And methane can be burned more efficiently. So new combined cycle natural gas power plants have long been seen as having much lower total life-cycle greenhouse gas emissions than coal plants. If one could (and did) capture all of the leaking methane, then yes, the concerns raised in this study would be addressed to a large degree.]

  2. KAP says:

    The issue is IF. Methane is a gas, and it’s lighter than air, which means it won’t stay put nicely anywhere. Leaks happen, and often you have no idea where the leaks are, or even if they exist.

  3. Mark says:

    Just to continue Joe’s reply to Ben…. what’s needed is gas company cooperation to identify all the ways in which “the good stuff” escapes in the process of extracting, processing, and delivering it to the customer.

  4. Pythagoras says:

    Any discussion of methane (CH4) as a green house gas needs to include the life of methane in the atmosphere. While it is a potent greenhouse gas, it doesn’t have the residency of C02.

  5. catman306 says:

    “Most of the rest of nat gas is ethane, propane and/or butane.” These three, and methane are also greenhouse gases and all break down to CO2 over different time periods. And, I think, all become tropospheric ozone along the way to becoming CO2.

  6. tst says:

    A question for any gas experts out there. I’ve wandered around some of the natural gas fields in Wyoming, where the methane is typically both deep and stable. (In other words, it’s stays put unless we drill for it.) At the same time, vast stores of shallow gas are destabilizing and venting in the arctic. Since it seems likely that a high percentage of the arctic gas will eventually escape into the atmosphere, and since that leads to a potentially devastating feedback loop, why, if we’re going to use natural gas anyway, aren’t we focusing our efforts on capturing arctic methane?

  7. Joan Savage says:


    Thanks a ton for a Back to Basics!
    As long as we are momentarily at the 8th grade level, I’d add a couple of items.

    The other 30-20% of the unprocessed natural gas, largely “ethane, propane and/or butane” are greenhouse gases, too.

    “Fugitive release” is regulatory language for substances that escape confinement under regulated conditions, like methane escape from a landfill, or gases from a pipe or well. The broader plain language term “leaking” can include both the fugitive releases and movement of gas that is not regulated, like the bubbles of methane from clathrates.

  8. catman306 says:

    @tst: I’ve wondered the same thing and thought:

    Why not put great sheets of white, reflective plastic over the leaking permafrost to capture the escaping methane and at the same time lower the albedo to that of frozen snow? Sounds like a two for to me: Free methane for fuel and a chance to keep the permafrost frozen for everyone’s benefit.

  9. tst says:


    I’m not saying your idea wouldn’t work, but you’d have to look at the nuts & bolts of it first. It wouldn’t be easy, or cheap, to cover hundreds of thousands of square miles in plastic. And I suspect it would have a huge impact on the ecosystem. I’ve spent a little time on the tundra in ANWR and there’s an incredibly diverse biotic community up there. We’d need to know that the benefits outweigh the negative impacts, and that there’s not a more sensible way to accomplish the same thing.

    It’s food for thought, though.

  10. M says:

    “then I think it is reasonable to look at the 20-year GWP because you are making a commitment to long term natural gas use”

    I’m not sure about the reasoning here: remember that the GWP is just a way of comparing different gases to each other. A 20-year GWP means ignoring all climate impacts that happen more than 20 years after emissions in this comparison. That means that a 20-year GWP gives more weight to methane, and therefore less to CO2. If I’m choosing between building a gas plant and a coal plant, or choosing between a methane-leak-reduction project and a increased-efficiency-car project, I don’t see why a 20-year GWP is a more accurate measure of relative, relevant climate impacts.

    (yes, it better captures the relative climate impacts in the next 20 years… at the cost of not capturing at all the relative climate impacts in 50 or 100 years, which is, IMO, where things have to potential to get really bad. And increased CH4 concentrations are more reversible than increased CO2 concentrations).


  11. Dickensian American says:

    Catman306, that honestly sounds as foolhardy and flawed a plan as booming oil in the gulf. Too many places for failure. And likely too much potential devastation of what ecosystems are there.

  12. catman306 says:

    Obviously only areas where methane is actively coming out of the permafrost would need to be covered in plastic sheeting. Those areas could easily be located with infrared detectors. So it need not be as environmentally damaging as you imagine.

    Maybe it could be tried on a small scale basis around communities where the methane could be used immediately as fuel. Or to run electric generators that might power some vital piece of equipment.

  13. tst says:


    If it pencils out from a greenhouse gas perspective, your small scale trial makes sense to me. It could also potentially alleviate high fuel costs & scarcity in many of the small northern communities.

    Regardless, though, the basic idea of capturing and using as much arctic methane as possible seems like a no brainer. I’d be curious to know if anyone is currently capturing arctic methane on a commercial scale, or if there are any plans in the works. If we’re going to lose a certain percentage of methane to fugitive release, we should probably focus on gas that would vent anyway.

  14. Alteredstory says:

    I gotta say, this is another one of those things that I assumed everybody knew.

    I need to stop doing that.

  15. Aaron Lewis says:

    Fracking by its nature fractures rock. Sometimes those fractures provide pathways from the methane bearing formations to the surface. While there should be competent rock over the fracking, lateral drilling allows fracking in places where the cap rock has not been studied.

    Sometimes there are fractures, “windows”, and perforations (old wells) in the rock over the methane bearing formations subject to fracking. Under current operations, such releases are not predictable or monitored. What we know is that fracking does affect near surface ground water, and thus the layers of rock between the deeper methane bearing formations and the shallow formations are frequently compromised.

    I do not think anybody has a good estimate of the long term (500 year) methane releases to the atmosphere that can be expected as a result of fracking industry. I do not think that anybody has a good estimate of the long term methane releases that can be expected as a result of any particular fracking project. No wonder the industry spends so much money on PR.

    My guess is that under current operating practice, the life-cycle green house gas cost of fracked natural gas is no better than the life-cycle green house gas cost of — coal.

    However, I am not opposed to fracking. I just want the frackers to monitor (for a very long time) for methane releases and take full responsibility for remediation of their projects if such releases occur.

    This would not raise the price of fracked natural gas. It would merely force the costs of fracked gas to be paid by those who derived the benefits.

  16. Michael Tucker says:

    I just love this statement:
    “…when you crack shale to get to the clean-burning fuel, out comes “methane””

    Oh that magical ‘clean-burning fuel’ if it wasn’t for that evil methane we would be able to solve all our energy security problems and global warming too!

    This is proof that Orwell was right about language but wrong about government surveillance and mind control. Government does not need to monitor information. Have all the libraries you like, put all that information online for all to read, but also make sure you have TV.

  17. Richard Brenne says:

    Simplifying explanations to the public and even experts is a huge part of the immense value of Climate Progress, so here’s a primitive primer:

    Earth’s atmosphere is about 78% nitrogen and 21% oxygen, but the greenhouse gases comprising less than 1 per cent effectively act like the planet’s thermostat.

    The most important of these is CO2, comprising about 72% of annual human greenhouse gas emissions, with methane comprising about 18% (or ¼) and nitrous oxide 9% (or 1/8).

    The synergy of all greenhouses gasses is complex and not absolute, but roughly speaking methane comprises about a third of the total greenhouse gasses of CO2. That means that just adding methane to CO2 would give a CO2 equivalency of 520 ppm in the atmosphere. Nitrous oxide and CFCs would add even more.

    I’d love to hear your best estimates of total CO2 equivalency from all greenhouses gasses, though unfortunately there is no quantifiable figure as there is for CO2, since all the gasses overlap and synthesize in complex and constantly changing ways.

    Despite this added complexity, ideally among sophisticated audiences this concept of CO2 equivalency would become a standard frame of reference, otherwise the additional dangers of methane, nitrous oxide and CFCs will be systematically understated, as land use issues also are (giving a nod to our friend Mike Roddy and throwing a bone to or at Roger Pielke, Sr).

    Water vapor comprises about 1% of Earth’s atmosphere and for every 1 degree F increase in global average temperature, water vapor increases by about 4%, or about the equivalent to 1.5 Lake Superiors in the atmosphere.

    With 10 degrees F increase possible by 2100 even in conservative IPCC Report Projections, that would mean a 40% increase in water vapor or 15 Lake Superiors with additional amplifying factors such as the total energy added to the system is the equivalent to the output of almost 2 million nuclear power plants operating 24/7/365 (please note that I am not suggesting nor recommending that we build 2 million nuclear power plants).

    Water vapor is the most plentiful of all the greenhouse gasses and it is also the most powerful positive feedback of all, according to Kevin Trenberth. ( I’d listed all the positive feedbacks except Kevin’s beloved water vapor on a panel I was moderating and Kevin said “You’re missing the most important one of all.” Nothing jogs the memory quite like public humiliation, the one subject I’ve researched most thoroughly.)

    This would create a climate with weather we can’t now begin to imagine, although Pakistan, Australia, Tennessee and many other places in the last year are the smallest previews of these coming attractions.

    In 2008 the world derived a third of its energy from oil, over a quarter from coal and a fifth from natural gas (81.2% of all energy coming from these fossil fuels, if I haven’t depressed you enough).

    Since natural gas emits 30% less CO2 to create the same amount of heat as oil and 45% less than coal, it was considered the cleanest of the three fossil fuels.

    Calculating all the leaks of methane into the atmosphere at every stage of natural gas production, delivery and consumption alters this equation so that when there are sufficient leaks as in hydraulic fracking of natural gas, gas might emit more greenhouse gasses in total than even coal does.

    Gas is cleaner than coal in many other areas, but taking our eye off the ball of greenhouse gasses might mean getting hit by countless firehoses of flash floods from behind home plate, to mix as many metaphors as possible.

    And just for the record, while all agriculture especially rice paddies and including livestock and especially cows emit up to 20% of all human-caused methane (it’s likely Earth wouldn’t have almost 2 billion cows without us), 90-95% of their emissions come from burping and breathing, not farting.

    Also human farts are mostly nitrogen because air is mostly nitrogen and typically contains little or no methane, although lighting them can occasionally work (I’m told by the scholars investigating this).

    And speaking of human farts, please see my comments about Bjorn Lomborg in the natural gas fracking story four posts below (at #26).

  18. Green Hornet says:

    In reading and rereading the Howarth et al paper, I remain unconvinced by the data presented that nat gas derived from shale poses as great or greater threat to GHG release than coal. Look carefully at Figure 1, where the 20 year and 100 year overall effects of conventional nat gas and shale-fractured gas are compared to deep-mined coal and surface coal. The Figure assumes that the release of methane from deep coal mines is negligible. But are there really data on the amount of CH4 released by the venting of coal mines (to keep the methane concentration low enough in the mine to prevent explosions)?

    Howarth et al cite no source for their estimate of CH4 release from deep-mined coal, other than referral to Supplemental Electronic Materials, which aren’t accessible to the reader (at least I couldn’t find them). My question is, if measurements of the amount of CH4 released to the atmosphere over the life span of a coal mine are accurately known, why are there no publication citations by the authors? While the report raises important questions regarding inadvertant release of CH4 from shale drilling, I don’t see that their conclusion that shale gas is worse than coal is scientifically well grounded.

    On another aspect of the report and discussion of same, there is mention that natural gas may be no better than diesel as a truck fuel. That position fails to take into account the fact that diesel particulates released from busses, garbage trucks and heavy trucks are a leading cause of asthma. If filtering the exhaust could really remove 90% of the particulates as claimed, what is the evidence that is true, and why have many cities switched to CNG for their bus fuel?

    I’m concerned that this report, on the basis of meager evidence, will provide propaganda to the coal-fired power plant advocates. Its wide publicity in the NYT and other media outlets insures it will simply confuse an already befuddled public and their representatives in Congress.

  19. GFW says:

    The reason we’re not capturing arctic methane, either on land or at sea is it’s vastly harder than conventional drilling or fracking, and might not even achieve positive EROEI.

    Collecting the clathrates would be like deep sea mining – they’re solids. As soon as they’re not solids, they start bubbling straight up. I’m thinking *maybe* a vacuum dredging system with a wide fugitive emission capture funnel might work, but I’m not sure how to pull all the gas off at the surface while dumping the water and mud back into the sea. Disturbing that much silt might cause other environmental problems too. And of course the system has to work in arctic conditions.

    On land, the permafrost is even more widely distributed, and produces methane relatively slowly – a passive collection system over thousands of square miles would cost more than the gas collected would be worth, and would shade the ground, killing the ecosystem, etc. Non-passive approaches (e.g. strip-mining) would only get the current methane content, and leave behind vast piles of organic matter that would emit methane slightly faster than the existing permafrost. Not to mention everything else that would be wrong with strip-mining the tundra.

  20. Ken says:

    Please note the NYT Article also referenced a study at GISS of NASA
    “The researchers include a recent study from the Goddard Institute for Space Studies at NASA suggesting that an interaction of methane with certain aerosol particles significantly amplifies methane’s already potent greenhouse gas effects, particularly over a 20-year time horizon.”
    This is not really so recent. See “Interactions with Aerosols Boost Warming Potential of Some Gases Oct. 29, 2009″ at http://www.giss.nasa.gov/research/news/20091029/

    The ongoing wotk work by Schindell et. al. dates back to 2005 See for example Shindell, D.T., G. Faluvegi, N. Bell, and G.A. Schmidt, 2005: An emissions-based view of climate forcing by methane and tropospheric ozone. Geophys. Res. Lett., 32, L04803, doi:10.1029/2004GL021900. at Methane’s Impacts on Climate Change May Be Twice Previous Estimates
    July 18, 2005

  21. Jeremy says:

    I like how the article you quoted puts “methane” in quotation marks. I imagine they’re making some kind of euphemism that is too adult for somebody as innocent as myself.

  22. David B. Benson says:

    What is sold to you as natural gas is not natural; it has been highly refined to be mostly methane with the distinct smell agent added for leak detection. I call the result of refining (and oder addition) natgas.

    Most of my natgas is mined in Alberta. Out of the drilled hole comes a mixture of a little water, lots of carbon dioxide, some hydrogen sulfide (H2S, hihgly toxic), lots of methane with some butane and propane. All that goes to the refinery nearest to the well. The refinery vents just the CO2 (I don’t know where the water and hydrogen ends up) and produces separate product streams of elemental sulfur, butane, propane and lots of almost pure methane which goes into the trunk pipeline. When it reaches my utility’s site, it is depressurized down to distribution pressure and the oder agent is added. The resulting natgas then flows through the utilty’s distribution network to customers.

  23. Prokaryotes says:

    ‘Fracking’ Mobilizes Uranium in Marcellus Shale, UB Research Finds

    Scientific and political disputes over drilling Marcellus shale for natural gas have focused primarily on the environmental effects of pumping millions of gallons of water and chemicals deep underground to blast through rocks to release the natural gas.

    But University at Buffalo researchers have now found that that process — called hydraulic fracturing or “fracking”– also causes uranium that is naturally trapped inside Marcellus shale to be released, raising additional environmental concerns. http://www.buffalo.edu/news/11885

  24. Villabolo says:

    @7 Tst:

    “Since it seems likely that a high percentage of the arctic gas will eventually escape into the atmosphere, and since that leads to a potentially devastating feedback loop, why, if we’re going to use natural gas anyway, aren’t we focusing our efforts on capturing arctic methane?”

    As a non-expert I can sum it up with these words. No way. Someone could figure out the nuts and bolts for the joy of it but basic intuition tells me that the Methane activity is too diffuse for collection and long distance distribution for commercial purposes.

    For small local villages, tapping the accumulated and somewhat pressurized gas from frozen lakes may be feasible (see video link below).

    @13: Catman:

    “Obviously, the only areas where methane is actively coming out of the permafrost would need to be covered in plastic sheeting. Those areas could easily be located with infrared detectors. So it need not be as environmentally damaging as you imagine.”

    Catman; the Methane is mostly coming out of lakes and does not require an infrared detector to locate. Take a look at the following dramatic video:


    The ice covering over the lake actually makes it more convenient to collect the Methane than tarps during the summer. However, this as I just mentioned to Tst, would be of use only to small villages in proximity to those lakes.

    Now take a look at this portion of the (former) tundra.


    Would it be practical to set up equipment and lay out pipes in that muck?