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

Thursday, March 2, 2017

Charlie Hall speaks about EROI (and many other things)

A talk given by professor Charlie Hall in Princeton, last year. More than one hour of presentation to show how rich and interesting is the field of biophysical economics. And here is a comment submitted by Bepi Cima

by Bepi Cima

Waiting for a more affordable digital version of Charles Hall's Energy Return on Investment: A Unifying Principle for Biology, Economics, and Sustainability I watched a seminar on the same subject held by prof Hall less than a year ago at Princeton.

I enjoyed his talk, I believe it summarizes well the main subject of discussion of this blog: the fate of the artificial energy supply. Without it we would go hungry, 2/3 of the fertilizers today are synthetic and much more depends on it.

Many prefer reading a text rather than watching a video but, in this case, it helps to detect the author's emotions directly from his voice. It contains a lot of well-summarized information together with strong, sometimes debatable, statements but I appreciate his spirit and courage.

I feel his frustration for still missing the perfect theoretical context where to locate the issues. As a lightning short summary for the ones who couldn't listen to the whole talk, I propose the following images from his video.

These two images show that we need to make exceptional efforts to afford even basic "luxuries" with the exclusive use of renewables. There is a lot to disagree about quantitatively, for example in this blog look at this Hall-Bardi dialogue.

The last image hints to what's probably the main ingredient to the "problem" solution.

The most flexible, least technologically sophisticated way of satisfying the world energy needs is most likely to reduce energy demand, the product among population density, the quality of its needs and their energy intensity.

Bepi Cima


  1. Thank you for this link and Professor Halls talk and discussion on EROI. I found the tracking the history and refining of the conceptual basis very helpful in improving my understanding of the consideration of energy required for energy used. The lack of dogmatic assertion but presentation of empirically deduced factual heuristics and models was refreshing and even Halls rambling presentation did not detract from the data and views delivered.

    There was little discussion on limits as such but no avoidance of depletion I particularly liked his little diagram illustrating how increasing growth or attempting to increase growth now leads to depressed outcomes contrary to the dogmatic assertions of economists. I am glad he gave econocrats short shrift, they live in hypothetical make believe world.

    More food for thought but as Hall says, we are not having a discussion about this but I guess if you don't understand it and you do not think it is a problem and believe in magic puddings then the now frequent ups and downs of the so called economic cycles will just become more severe in amplitude and duration until they match the biophysical realm. It is one of the reasons why attempting to parse everything through the laws of thermodynamics does not provide solutions only more problems to understanding our current and future predicament.

    I saw the 'Seneca' Curve appeared very early in the talk but not under that description.

  2. Unfortunately, the EROI chart is grossly misleading. It pretends that a doubling of EROI leads to a doubling of useful energy, whereas EROI in reality is subject to diminishing returns.

    EROI itself does not measure useful energy; EROI is merely the ratio of energy output per unit of energy consumed. For example, an EROI of 10:1 means that 10% of energy output is reinvested while 90% is free for other work. Doubling the EROI, say to 20:1, does not double free energy, but increases it by only 6%. Under an EROI of 20:1 5% of energy is consumed, while 95% is free for other work.

    Plotting the data from the graph as percentage of free energy, we get the following:

    As can be seen, solar PV is not five times worse than coal, even though its EROI is five times less. Solar PV, assuming Hall's calculations are correct and that solar PV EROI will remain static, offers only about 10% less free energy than coal. Industrial society is not going to collapse because there is 9% less energy available.

    In general, EROI is one of the most useless metrics I have ever seen. It is misleading in presentation, suffers from massive operationalization problems that render cross-author comparisons wholly meaningless, and can be easily replaced by existing measures. We already know the market price of most energy sources. From there, it is fairly trivial to add back various subsidies and externalities, to calculate the 'true' cost of various energy sources. There is no need to count angels dancing on the tip of a pin by calculating the energy consumed by accountants, the energy value of capital stock, and other such nonsense.

    1. You have a correct point, Homer, but one that's already well known. For instance, look at the "energy cliff"

      It shows that declining EROI starts becoming a serious problem only when it goes under around 4-5. Having an EROEI of 1000 or of 100 makes little difference to the amount of available energy.

      But that doesn't make EROI a "useless metric," not at all. It is deeply embedded in the way ecosystems work and a fundamental parameter in evaluating technological alternatives. Evaluating these alternatives purely on monetary costs suffer of larger problems, just think of how many people are reasoning in terms of prices, today, saying "since oil is cheap, then it must be abundant". You need an EROEI analysis to understand what's going on with the oil market.

  3. I find the logic of ERoEI to be compelling. The real trouble is that I find that the numbers being bandied about are wildly divergent.

    I am attempting to piece together a "peak oil" chart where, instead of the gross amount of oil produced, the actual amount of oil available after all ERoEI is subtracted out is presented.

    I really have to disagree with the "useless metric" propounded above. The "existing measures" are what allowed us to paint ourselves into the corner where we currently reside.

    I think that when (/if I succeed) I complete the task. I have a sneaking hunch that it will only highlight how much we pissed away and how sparse are the pickings ahead.

  4. Having paid rapt attention to Prof Hall's presentation, and having read many of the linked documents, it seems to me that ERoEI is a bag that cannot hold all the different meanings different people want to cram into it.

    Hence, I agree with Prof Bardi (et alia) who plead for standardized definitions. My preference would be for a very simple definition of ERoEI (let’s drop the lower case “o” for starts!) and specifically call out the other energy-consuming leeches under their own names, acronyms or whatnot and see the forest and the trees one at a time or however interests us.

    Separately, I am glad the linking led me to the song “La Montagnola”(posted by Prof Bardi) which I enjoyed, even tho the lyrics were a mystery to me.

  5. Homer2101, I think you misunderstand the very basis of EROI, it measures energy used for energy produced. The original application was to biological organisms (hence the calorific unit of measurement) and biological lifeforms activity but it can usefully be expanded to look at all systems that require energy to function.

    I would agree the energy source for activity can be varied and multidimensional and hence seeking a one size fits all explanation is not a practical endeavour. I would like to disagree with your position that the monetarised value of a thing, in the case energy can be used as a measure of the energy required and energy used, your confusing what is value. The value of energy is that it allows a complex system, biological or mechanical to operate and we now know enough biology and engineering and physics to confidently measure that value, it is quantitative and will have different sums according to the energy type. A monetarised value ascription merely provides a tally of demand measured in a commonly accepted transfer mechanism by which energy can be obtained, providing it is available to be obtained at the price demanded by the supplier.

    So if you go back to the first example used by Hall, of a fish, its energy demands are met by the ingestion of other creatures, who in turn have also consumed molecules capable of being converted into energy to be used. The fish consumes a certain food or energy source which can be sufficient to give it more energy (stored in fat in the tissues) than it expends catching and eating the organism. Because there are more of the organisms than fish at certain places, the fish does well, if there are not, it eventually expends its stored energy and over time will die. All energy to be useful has to have a means by which it can be stored and that is a physical constraint, what happens to all energy when it is used is adequately described by the laws of thermodynamics.

  6. Continuaing - During the epochal cycle of human existence we have developed and found different energy sources, first there was simple combustion (using wood), then animals, then mineral oils. Any clear examination of our history shows we have exploited and used various sources of energy to a point where we so depleted the resource that it became unviable, either because we could not expend any more available stored energy to obtain it or process it or because there was none to be had in the quantities required. None of these problems had anything to do with money they are all dependent upon physical limits. Oil has proved to provide a remarkable bonanza to us as a species because it contains so much energy in a simple stored form (hydrocarbons) that we were able to do things that were never possible before because of that form of energy, we needed only small quantities of it, we could store it easily and it did not spoil or lose its energy over time. We are in fact merely using ancient energy provided by the sun and derived from geological and biological processes of organisms who used that energy, entropy in this case worked in our favour because entropic energy was recombined by geological processes into wells of stored energy. We are sufficiently intelligent to have worked out that there is only so much of this stored energy available, how much we have used, and how much we continue to use but few can understand that there is a cliff approaching and the cliff is the quantitative amounts of this energy that will be available or left to us to use will be insufficient to provide energy to all and sundry. That cliff relates to all energy or energy derived systems or machines, I prefer to call it the entropy wave and it will carry us all to infinity where it finally stops. That is our dilemna, we cannot recognise the limits, we cannot recognise the nature of energy and we cannot understand the need to respond to less, when like the sun it always seemed to be plentiful and available. Counting as far as time is concerned is useful but counting in terms of a monetarised value is deceptively dangerous, if we think price will guide us. Lets return to the example of the fish, it is well and good being in a big school of fish chasing a stream of amoebic creatures is no help to determining if there are enough creatures or how many fish will get to eat.

  7. I was wondering about the hierarchy of needs chart.

    Probably "the Arts" requires definition: if it means building a Zaha Hadid fantasy or paying exorbitant sums for Ai Wei Wei's self portrait in Lego, I would agree, but actually I think forms of art have always been one of the nearly primary needs of mankind, as is art's close cousin "religion", which does not even appear on the list.

    Think of the shaman healing ("health care") by singing ("art") an invocation to the bear spirit ("religion")...

  8. "Environment, Power, and Society" Howard T. Odum Columbia University Press, 2007
    "Power Density" Vaclav Smil MIT Press 2015
    "Radical Simplicity small footprints on a finite Earth" Jim Merkel New Society Publishers 2003
    "Grass, Soil, Hope A Journey through Carbon Country" Courtney White Chelsea Green 2014

  9. Comment received by Professor Hall, pasted here on his behalf.

    We in the field are cognizant of the seeming (but exaggerated) discrepancies in values of EROI for particular technologies and have worked hard to try to decrease them or understand the philosophical reasons for any divergence. These are summarized in Murphy et al 2011 my new book from Springer Energy Return on Investment: A unifying Principle for Biology, Economics and Sustainability and we will be having a workshop on that issue this June in Montana.

    Murphy, D., Hall, C.A.S., Cleveland, C., P. O’Conner. 2011. Order from chaos: A Preliminary Protocol for Determining EROI for Fuels. Sustainability: Special Issue on EROI. 2011. Pages 1888-1907.



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)