ResearchBlogging.orgProponents of shale gas extraction are not particularly pleased with the attention drawn this week to a new study in Climatic Change that found widespread development of Marcellus natural gas may actually accelerate climate change rather than slow it down. Unfortunately for them, their primary argument rests on a lack of hard data on 1) the actual greenhouse-warming potential of methane; and 2) how much methane finds its way into the atmosphere during drilling and transmission of natural gas. You can find a good summary of the defense’s case at something called the Marcellus Shale Coalition. And it is unfortunate for them, because most opponents of the industry, and the author of new study, use exactly the same argument.

Let’s face it: this is pretty critical. The potential reserves of natural gas in the Marcellus Shale, which underlies a good portion of the U.S., mean that they could, in theory, replace much of the conventional fossil-fuel industry in the country. Vast amounts of money are at stake. But more importantly, so is the future of America’s contribution to global warming. We need to know answers to both questions.

Industry has been loathe to supply answers. Money is being made now, political inertia is largely in its favor (although the threat posed from perceived or real problems of water contamination is growing) and so the risk to the industry if the answers do not come out in their favor is enormous.

So in absence of better numbers, it would be useful to take a look at the implications if industry is right, if the Howarth approach grossly exaggerates the greenhouse warming potential, and if industry is actually much better at minimizing fugutive emissions, what can we conclude?

I wrote about some of the basic science here. The take-home message is that burning natural gas, as a replacement for coal, has only half the effect on the atmosphere. It has about 70% the effect compared with oil and its transportation fuel products. But the effects of methane itself, not burning it, are more tricky. When vented directly in the atmosphere it has at least 20 times the effect of CO2, which the problematic product of combustion. Those are numbers about which there is general agreement, assuming we’re talking about the effects averaged over 100 years.

Given the need to reduce carbon emissions to at least 20% of current values — and probably more like 0 — within the next 30 years, does switching to natural gas make sense? Yes, the proponents argue, if you assume it is only a “bridge” fuel that buys us time to development genuinely clean alternatives (wind, solar, fusion, etc.).

But, goes the argument for the people, the real greenhouse warming potential (GWP) should be measured over a shorter time span because if it’s significantly higher, then the induced warming could trigger more greenhouse-gas release (from the permafrost, for example) and push the planet’s ecosystem over a tipping point, after which it doesn’t really matter what methane’s effect is. And again, there is widespread agreement that most of methane’s effects on the atmosphere are felt in the first few decades.

Over 20 years, when interactions with aerosols are considered, the effect may be as high as 105 times that CO2. Let us assume, for the sake our best-case argument, that things aren’t as bad as generally thought, and we have more time to act before triggering positive feedbacks in the permafrost. Add a couple more decades to our horizon and the GWP methane falls to just 50 or thereabout.

So then the question becomes, how much methane can we afford to vent directly into the air before the benefits of burning nature gas are no longer significant?

If the end GWP is close to half that of burning coal, then it might make sense as a bridge fuel. But 50% is only possible if fugitives emissions are close to zero, which they’re not. I would argue that anything over 67% makes the benefits marginal, given the timeframe at our disposal. In other words, if switching to natural gas only gets us no more than 33% reduction in emissions, it’s not worth the many billions of dollars the transition will cost. We can argue about that number, but I doubt anyone would say it’s worth it if the savings are anything lower than 25%. So let’s be as generous as possible and say total natural gas emissions can be as high as 75%

So how high can the figure for fugitive emissions be? The math is simple:

CO2 emissions of burning methane + (relative GWP of methane over 50 years x fugitive emissions) = Emissions relative to burning coal

Turning that around

(Target emissions – emissions relative to coal)/relative GWP of methane over 50 years
= Max fugitive emissions

(75-50)/50 = 0.5%

If industry can keep its fugitive emissions (or “lost and unaccounted gas”) down to one half of one percent of what is delivered and burned, then maybe, just maybe, we can afford to drill for the Marcellus Shale gas. If you think that’s even remotely likely, well, be prepared for a lot of debate.

Or, we could exercise reasonable caution, and assume that fugitive emissions will probably be 2 or 3 times that much, at best. Probably a lot more. We could also not count on an extra couple of decades of breathing room, because, well, the science doesn’t support that. Again, we’re back to the uncertainty of the science. Does it really make sense to assume that all the unknowns are going to work out in industry’s favor? I, for one, don’t like the odds.

Howarth, R., Santoro, R., & Ingraffea, A. (2011). Methane and the greenhouse-gas footprint of natural gas from shale formations Climatic Change DOI: 10.1007/s10584-011-0061-5

Comments

  1. #1 Pierce R. Butler
    April 15, 2011

    Does it really make sense to assume that all the unknowns are going to work out in industry’s favor?

    Isn’t that the default formula found in the fine print of all regulatory paperwork?

  2. #2 Mike
    April 15, 2011

    It’s good to see a rational discussion on this, particularly as most governments and large energy companies:

    [Here is a Shell Climate Change Advisor David Hone http://blogs.shell.com/climatechange/category/low-carbon-economy/

    are taking the view that moving to gas as a replacement for oil and coal is the primary way to decrease climtae changing emissions, and/or maintain them at current levels in the next 5 to 20 years, aka the Low Carbon Economy. So I see this discussion as being more general than shale gas.

    Calculating what an acceptable level of fugitive gas emissions would be seems to be a good way of setting some standards or regulation for thes sorts of developments and I think there are a couple of things to add to the calculation.

    1. So-called fugitive losses are lost revenue, and gas producers do not like to do this if it can be avoided. The industry site referenced above is correct in the section discussing fugitive gas. The difference between produced and sold is a combination; that used for fuelling the production systems such as pumps and compressors, that burnt directly as a safety system flare, and that lost by venting directly to the atmosphere. In the places I’ve worked, (which doesn’t include the Marcellus Shale,) the total for these categories is typically less than 2% and the direct losses are 0.1-0.2% at worst. Of course it may be worse in the Marcellus shale.

    2. Most shallow shale type fields, including the Marcellus shale, have a slow leakage of gas(including methane) to the atmosphere via the ground-water sytem as gas is dissolved in the water as it percolates through the ground. I don’t know what the scale of these gas volumes is in the Marcellus shale area, but it efectively means that fugitive gas emissions take place even if you don’t produce the gas. Producing it would actually reduce these loses, although that may not be significant in the scale of things.

    Sorry to be so verbose:)

  3. #3 Mike
    April 15, 2011
  4. #4 NJ
    April 15, 2011

    Mike @ 2:

    Most shallow shale type fields, including the Marcellus shale, have a slow leakage of gas(including methane) to the atmosphere

    Funny you should mention that:

    http://blogs.agu.org/magmacumlaude/2010/11/12/gas-seeps-in-western-ny/

  5. #5 Miguelito
    April 15, 2011

    Like I said in the last thread, the Howarth estimate is probably significantly inflated.

    Flowback gas is flared, not vented, and, while the CO2 has its footprint, it’s not nearly as high as the methane’s. Further, Howarth’s estimates for venting during drilling out plugs originates from tight gas wells, not shale gas, and they treat tight-gas wells very differently from shale-gas wells as to when they drill out plugs (in shale wells, plugs get drilled out before flowback begins and there’s very little gas in the well at that point).

    This probably more than doubles the direct emissions of methane during flowback in their low case and shrinks their high case down by 20% and maybe more. I can’t begin to imagine how this error was made other than to say they have no background in oil and gas operations (at first, I thought Ingraffea was an ex oil and gas man, but it turns out he has no experience with operations). Given this lack of experience, it’s not a surprise this mistake was made and it’s a big parallel to flawed analyses made by climate-change deniers.

    As for the high case, the estimate of leaked gas from pipelines and compressor stations is probably unrealistic given that more gas is being produced and then consumed within the local region rather than imported over long distances (a shorter distance of pipeline travel means fewer places for it to leak — for example, less gas has to flow 1500 km from Canada and only needs to flow a few hundred km from Pennsylvania to NY State).

    Now, I do agree that there needs to be a better demonstration of the risks (although, there are many, many studies on conventional gas, just not much in the way that’s included unconventional). I’m onside with using a higher GWP for methane than in IPCC (2007). But I’d prefer it get done by somebody like Paulina Jaramillo, who has a good background in this kind of stuff or somebody else with experience. Hopefully, a study like this gets more going in the pipeline (yuk yuk) if only to refute it. Further, hopefully it gets companies to release some real data, a real constraint on doing a proper analysis (I really sympathize with Howarth and how scant the data is to use on something like this). Until then, the EPA a number is a decent, even if it might be a bit low, start.

    Finally, in your math above, you’re excluding the higher efficiencies of combined-cycle power plants for gas over coal-fired power plants. Please don’t take this as an insult, but it’s another example of a non-expert making a sub-par analysis.

    It’s not that I have great love for the oil and gas industry, I don’t. They create most of their own messes and then deny until the lawyers pay up in lawsuits or buy politicians. I just like good analyses, and I doubt this is one of them.

  6. #6 Miguelito
    April 15, 2011

    “I don’t know what the scale of these gas volumes is in the Marcellus shale area, but it efectively means that fugitive gas emissions take place even if you don’t produce the gas. Producing it would actually reduce these loses, although that may not be significant in the scale of things.”

    Probably not, because they’re unlikely to drill the shallow shales. The deep stuff won’t be leaking any time soon, so any fugitive gases from them wouldn’t occur unless the shale was drilled.

  7. #7 williamsmith114
    April 16, 2011

    A switch from propane to natural gas will likely be taking place across parts of Worcester within the next five years. However, a representative of Eastern Shore Gas Co. (ESG) warned the County Commissioners that the change would be both expensive and complex.

    “This is a multi-year, multi-million dollar project,” said Steve Ashcraft, the Vice President and General Manager of ESG.

    Ashcraft explained that recent interest in natural gas and the fact that the resource is just now becoming available in the area via a pipeline in Millsboro, Del., has led his company to take the first steps towards a conversion. He said that ESG hopes to provide natural gas to a large percentage of the county by 2016.

  8. #8 Samantha Vimes
    April 18, 2011

    I’ve always thought we should capture currently leaking sources of natural gas– sewage treatment plants, landfills, dairy/farm waste, etc and utilize that gas both for energy and to keep the methane out of the atmosphere. Tearing up a lot of rock to extract locked fossil fuels, however, has a lot of environmental drawbacks.

  9. #9 altın çilek
    April 21, 2011

    As for the high case, the estimate of leaked gas from pipelines and compressor stations is probably unrealistic given that more gas is being produced and then consumed within the local region rather than imported over long distances (a shorter distance of pipeline travel means fewer places for it to leak — for example, less gas has to flow 1500 km from Canada and only needs to flow a few hundred km from Pennsylvania to NY State).

  10. #10 Cora R.
    April 26, 2011

    I found this post really helpful, because I never really understood the reality of how big problem fossil fuels are. I think that we should gradually decrease the amount of fossil fuels we use and increase the amount of natural gases we use, but not all at once, because that wouldn’t do anyone any good. After reading this post I will definitely make my life a whole lot “Greener”!