Cassandra has moved. Ugo Bardi publishes now on a new site called "The Seneca Effect."

Sunday, April 17, 2011

Shale gas: the problem with EROEI

Carcinogenic chemicals associated with the extraction of shale gas have raised great concern. But perhaps there are worse problems as recent results indicate that gas losses during extraction by "fracking"  may generate great damage in terms if global warming.

The idea that fossil fuel depletion might be a cure for global warming has been around for quite a while. With time, the interaction of climate change and depletion has become a small field of study that I tried to review in a post on TOD titled "Fire or Ice?" Some recent entries in the field are a paper by Chiari and Zecca (in Italian) and one by Ward et al. on "Hydrology and Earth System Science."

In general, one would expect that depletion would ease the climate problem and this is, indeed, the opinion of several (possibly most) of the authors who have studied the question. Of course, depletion doesn't mean "running out" of a resource. Rather, the effect of depletion on production is best understood in terms of energy return on energy invested (EROEI). As a resource is progressively depleted, extraction must move to more expensive (lower EROEI) sources. That increases the price of the resource, lowers the demand and, eventually, causes production to decline. So, lower production means less greenhouse gases emitted and that is good for the atmosphere.

However, there is a problem: EROEI does not measure how "dirty" a fuel is, in particular in terms of greenhouse gas emissions. Hence, even depletion may not be a solution to the climate problem (this point was made, among others, by Zecca and Chiari.) A recent paper by Howarth et al. to be published in "Climatic Change" (see also a review on the BBC site) is adding - almost literally - fuel to the fire by examining the emission of shale gas extracted by the fracking process.

As well known, "shale gas" is the new resource that is promising to bring us nothing less than "a new era of abundance" ("unless politicians and environmentalists get their way.") Unfortunately, even if this new era were real (and there are serious doubts about this point) it comes with strings attached; and what strings! The study by Howarth and his coauthors arrives to the conclusion that shale gas might be a true disaster for the environment.

Natural gas is composed mainly of methane (CH4) which is a potent greenhouse gas. Because of the higher ratio of hydrogen to carbon, it is true that natural gas produces less CO2 than other fuels when burned. But the extraction, processing, and transportation of gas is never perfectly tight and a certain amount of gas always is lost into the atmosphere. In time, atmospheric CH4 is transformed into CO2 and its warming effect is reduced; but it never disappears.

After an examination of various sources of losses, Howarth and coauthors conclude that:

Summing all estimated losses, we calculate that during the life cycle of an average shale-gas well, 3.6 to 7.9% of the total production of the well is emitted to the atmosphere as methane (Table 2). This is at least 30% more and perhaps more than twice as great as the life-cycle methane emissions we estimate for conventional gas, 1.7% to 6%.

Here are the results in graphic form for a 20 year time horizon. For a 100 year case, emissions from shale gas look less dramatically higher than the others, but are still very important.
(Note that the scale of the figure says "Grams Carbon per MJ", but it seems clear from the text that the authors are not simply reporting the mass but the warming potential of the gases).

Of course, the data and the assumptions of the study can be criticized; as done in a recent paper on Scientific American.  On the whole, however, its conclusions make sense: the complex operation of "fracking"is much more prone to gas losses than the simpler extraction of conventional gas. This is bound to generate more global warming.

What is striking in the paper by Howarth and the others is that shale gas does not seem to be so expensive in EROEI terms; that is in terms of the higher amount of energy needed for extraction. So, we are facing a fundamental shortcoming in the way we account for costs and benefits of what we are doing. In monetary terms, shale gas seems to be a good deal. In EROEI (energy) terms it is probably less good but it may still provide a positive return. It is in environmental terms - in the so called "external costs" that shale gas is a disaster. We don't have enough data to show that this is a general case - that is, if what is happening with natural gas is happening with all energy resources. But, if this is the case, our problem is not that the EROEIs of fossil fuels are too low; they might be too high!

So, it may be that society is reacting to scarcity in the wrong way by following a path that is perhaps easing the situation in the short term (getting more energy) but horribly worsening the problem in the medium/long term (global warming). If it were true that shale gas will bring a "new era of abundance" in terms of energy, then we risk to move toward a climate disaster: runaway global warming. But we just can't see it coming; we lack the necessary accounting tools, we don't have the appropriate decisional structures. So, we are blithely moving onwards (anyone said "lemmings?")

So, what do we do? Right now, with a wave of rampant climate denialism engulfing about everything in the debate, the idea that we can stop fracking by traditional method of international climate treaties seems to be unthinkable (and that should be clear also from this article on the Weekly Standard). Even more unthinkable is that we could do it by telling people to install high efficiency light bulbs. So, the only hope we have to avoid a climate disaster is to beat shale gas in its own terms: economic ones. Don't forget that shale gas may well be abundant, but it is also expensive in monetary and energy terms. So, if we can deploy renewable technologies that produce electricity at a lower price than gas, then there is a chance that shale gas will stay where it is: underground.


  1. Hello prf. Bardi ; first of all let me wish you an happy Easter and say thanks for your great instructive work ; referring to above chart, is it correct to speculate that a coal based economy could be as impacting on greenhouse effect as a conventional gas based one ?

    Second point : I read that modern factories could not persist having a fossil fuel based economy with an EROI less than 5 : assuming this as correct, even if EROI does not tell much on carbon emitted in atmosphere,could not be shale gas a mere chimaera uncapable to run per se current (light)oil based economy and could not it be historically revisited as one of the last efforts to run business as usual ?

  2. Really the "EROEI of Shale gas"?


    It seems a little silly to try have a intelligent open discussion on the EROEI of Shale gas when we live in a environment of leaders telling us that using 5 barrels worth of energy to recovery 1 barrel is nothing to worry about... Really.

    So comparing model of energy efficiency to this one makes all arguments invalid.(But hey, at least it makes our math easier ;-)

    And remember when you decide to argue with any idiot, there are now two idiots arguing.

    But I applaud you for your attempt to add a glimpse of intelligence in the void of reason ;-)

  3. Francesco, I think that an economy based on ANY fossil fuel will be lethal for humankind - eventually. After rethinking the natural gas story, I tend now to believe that gas is worse than coal. At least, coal stays where it is when not used. Gas, instead, leaks all the time.

    About the "minimum EROEI" needed for civilization; I think that Charles Hall, the creator of the concept, has done a good work in calculating a value of about 5. But what is the EROEI of shale gas? Very, very difficult to say. As a guesstimate, it might be somewhat higher than 5, perhaps around 8-10 which would be extremely bad for us - actually lethal, as i said.

  4. Well, EHS director, the question of shale gas could be the crucial test of our civilization. That is, it could tell whether we are able to forsake a short term gain for a long term one.

    And, unfortunately, it is very likely that we will fail it, utterly.

  5. ...So lets keep fingers crossed and hope that on large scale ( planetary ), shale gas' EROEI will show up not far from 5 and fracking will cease at once.

  6. Ugo,

    "And, unfortunately, it is very likely that we will fail it, utterly."

    - maybe we will (unintentionally) double fail and it will turn out as a success - oil prices are soon going to crash (as a result of deflation) so there are possibly no money (and energy) left for shale gas - that is our only chance...

    that will of course leaf to population crash, which will of course be good for people after us...



  7. Prof. Bardi,

    a very-well written and instructive post.
    I would simply add two enviromental issues, to complete the terrifying picture.

    a) the potential for contamination of ground water as a result of chemicals used in hydraulic fracturing;
    b) the huge amounts of water required:it has been estimated that 4-5 million are needed to fracture one well (IEA, 2009).

    Personally, taking into consideration the current economics, the structure of the gas industry and the legislation framewok, I think that the rapid growth of shale gas in the US, in the medium term, is unstoppable. And some European countries (e.g. Poland) are likely to to start commercial development.


    Arnaldo Orlandini

  8. Amendment:

    b)... 4-5 million gallons


  9. Professor Bardi,
    wouldn't the concept of the EROEI of shale gas be treated similarly by the shale gas company as other externalities of extracting shale gas?
    The lower the EROEI, the larger the externality, or cost passed on to the commons or to other parties. So a profit-seeking firm would prefer high-externality low EROEI fuels. Which would cause the fuel production mix to change over time to lower EROEI and higher carbon-intensity, other things being equal?

    1. Well, if I understand your point, you mean that companies are "blind" to externalities. Which is, of course, correct.

      But I am not sure about the proportionality you propose. Normally the EROEI analysis doesn't measure externalities. Other things being equal, companies would normally prefer high EROEI resources; of course.

  10. I can shorten my idea a bit.
    "A company generally prefers high EROEI resources to low EROEI, and is generally blind to externalities, but would be happy with low EROEI resources "if the price was right" and would still be blind to what may or may not be larger externalities from the lower EROEI resources".



Ugo Bardi is a member of the Club of Rome, faculty member of the University of Florence, and the author of "Extracted" (Chelsea Green 2014), "The Seneca Effect" (Springer 2017), and Before the Collapse (Springer 2019)