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Why EROEI matters: the role of net energy in the survival of civilization

Why EROEI matters: the role of net energy in the survival of civilization thumbnail


The image above was shown by Charlie Hall in a recent presentation that he gave in Princeton. It seems logic that the more net energy is available for a civilization, the more that civilization can do, say, build cathedrals, create art, explore space, and more. But what’s needed, exactly, for a civilization to exist? Maybe very high values of the EROEI (energy return on energy invested) are not necessary.

A lively debate is ongoing on what should be the minimum energy return for energy invested (EROEI) in order to sustain a civilization. Clearly, one always wants the best returns for one’s investments. And, of course, investing in something that provides a return smaller than the investment is a bad idea. So, a civilization grows and prosper on the net energy it receives, that is the energy produced minus the energy required to sustain production. The question is whether the transition from fossil fuels to renewables could provide enough energy to keep civilization alive in a form not too different from the present one.

It is often said that the prosperity of our society is the result of the high EROEI of crude oil as it was in mid 20th century. Values as high as 100 are often cited, but these are probably widely off the mark. The data reported in a 2014 study by Dave Murphy indicate that the average EROEI of crude oil worldwide could have been around 35 in the past, declining to around 20 at present. Dale et al. estimate (2011) that the average EROEI of crude oil could have been, at most, around 45 in the 1960s Data for the US production indicate an EROEI around 20 in the 1950s; down to about 10 today.

We see that the EROEI of oil is not easy to estimate but we can say at least two things: 1) our civilization was built on an energy source with an EROEI around 30-40. 2) the EROEI of oil has been going down owing to the depletion of the most profitable (high EROEI) wells. Today, we may be producing crude oil at EROEIs between 10 and 20, and it keeps going down.

Let’s move to renewables. Here, the debate often becomes dominated by emotional or political factors that seem to bring people to try to disparage renewables as much as possible. Some evidently wrong assessments, for instance, claim EROEIs smaller than one for the most promising renewable technology, photovoltaics (PV). In other cases, the game consists in enlarging the boundaries of the calculation, adding costs not directly related to the exploitation of the resource. That’s why we should compare what’s comparable; that is, use the same rules for evaluating the EROEI of fossil fuels and of renewable energy. If we do that, we find that, for instance, photovoltaics has an EROEI around 10. Wind energy does better than that, with an average EROEI around 20. Not bad, but not as large as crude oil in the good old days.

Now, for the mother of all questions: on the basis of these data, can renewables replace the increasing energy expensive oil and sustain civilization? Here, we venture into a difficult field: what do we mean exactly as a “civilization”? What kind of civilization? Could it build cathedrals? Would it include driving SUVs? How about plane trips to Hawaii?

Here, some people are very pessimistic and not just about SUVs and plane trips. On the basis of the fact that the EROEI of renewables is smaller than that of crude oil, considering also the expense of the infrastructure needed to adapt our society to the kind of energy produced by renewables, they conclude that “renewables cannot sustain a civilization that can sustain renewables.” (a little like Groucho Marx’s joke “I wouldn’t want to belong to a club that accepts people like me as members.”).

Maybe, but I beg to differ. Let me explain with an example. Suppose, just for the sake of argument, that the energy source that powers society has an EROEI equal to 2. You would think that this is an abysmally low value and that it couldn’t support anything more than a society of mountain shepherds, and probably not even that. But think about what an EROEI of 2 implies: for each energy producing plant in operation there must be a second one of the same size that only produces the energy that will be used to replace both plants after that they have gone through their lifetime. And the energy produced by the first plant is net energy that goes to society for all the needed uses, including cathedrals if needed. Now, consider a power source that has an EROEI= infinity; then you don’t need the second plant or, if you have it, you can make twice as many cathedrals. So, the difference between two and infinity in terms the investments necessary to maintain the energy producing system is only a factor of two.

It is like that: the EROEI is a strongly non-linear measurement. You can see that in the well-known diagram below (here in a simplified version, some people trace a vertical line in the graph indicating the “minimum EROEI needed for civilization”, which I think is unjustified)):

You see that oil, wind, coal, and solar are all in the same range. As long as the EROEI is higher than about 5-10, the energy return is reasonably good, at most you have to re-invest 10% of the production to keep the system going. It is only when the EROEI becomes smaller than ca. 2 that things become awkward. So, it doesn’t seem to be so difficult to support a complex civilization with the technologies we have. Maybe trips to Hawaii and SUVs wouldn’t be included in a PV-based society (note the low EROEI of biofuels) but about art, science, health care, and the like, well, what’s the problem?

Actually, there is a problem. It has to do with growth. Let me go back to the example I made before, that of a hypothetical energy technology that has an EROEI = 2. If this energy return is calculated over a lifetime of 25 years, it means that the best that can be done in terms of growth is to double the number of plants over 25 years, a yearly growth rate of less than 3%. And that in the hypothesis that all the energy produced by the plants would go to make more plants which, of course, makes no sense. If we assume that, say, 10% of the energy produced is invested in new plants then, with EROEI=2, growth can be at most of the order of 0.3%. Even with an EROEI =10, we can’t reasonably expect renewables to push their own growth at rates higher than 1%-2%(*). Things were different in the good old days, up to about 1970, when, with an EROEI around 40, crude oil production grew at a yearly rate of 7%. It seemed normal, at that time, but it was the result of very special conditions.

Our society is fixated on growth and people seem to be unable to conceive that it could be otherwise. But renewables, with the present values of the EROEI, can’t support a fast growing society. But is that a bad thing? I wouldn’t say so. We have grown enough with crude oil, actually way too much. Slowing down, and even going back a little, can only improve the situation.

(*) The present problem is not to keep the unsustainable growth rates that society is accustomed to. It is how to grow renewable energy fast enough to replace fossil fuels before depletion or climate change (or both) destroy us. This is a difficult but not impossible task. The current fraction of energy produced by wind and solar combined is less than 2% of the final consumption (see p. 28 of the REN21 report), so we need a yearly growth of more than 10% to replace fossils by 2050. Right now, both solar and wind are growing at more than a 20% yearly rate, but this high rate is obtained using energy from fossil fuels. The calculations indicate that it is possible to keep these growth rates while gradually phasing out fossil fuels by 2050, as described here


10 Comments on "Why EROEI matters: the role of net energy in the survival of civilization"

  1. makati1 on Mon, 13th Mar 2017 6:21 pm 

    Another “feel good” ending…

    “Slowing down, and even going back a little, can only improve the situation.”

    Slowing down is NOT possible if you want to keep the 1st world, well, 1st world.

    Another “for the money” article.

  2. Cloggie on Mon, 13th Mar 2017 7:31 pm 

    Disciplining Charles Hall was long overdue.

  3. shortonoil on Mon, 13th Mar 2017 8:00 pm 

    New Gas and Oil would be ahead of legacy fields (the legacy fields are already depleting out). Coal would be ahead of wind. He has got his graphs backwards.

    That is not a good way to start a hypothesis; it confuses the readers!

  4. penury on Mon, 13th Mar 2017 8:14 pm 

    Whether we want it or not the world and the humans are slowing down. But like most things and bankruptcy it starts slowly at first and then suddenly all at once. To change the world will take a long while.

  5. makati1 on Mon, 13th Mar 2017 8:29 pm 

    Penury, or it could happen tomorrow. An ‘accident’ in the S.China Sea or an Ooops! in North Korea could change everything in a heartbeat. EVERYTHING.

    ‘Washington Considers Military Action against North Korea to Force “Regime Change””
    “North Korea and the THAAD Missile System: Potential Gateway to Military Escalation and Global Warfare”
    “US Delta Force, SEAL Team 6 Prepare To Take Out Kim Jong-Un, Practice Tactical North Korea “Infiltration””
    “No One Is Taking The North Korean Nuclear Threat Seriously: “Could Easily Drag A Half Dozen Nations Into The Conflict””
    “The Biggest Show Of Force Since World War II”: Japan To Send Its Largest Warship To South China Sea”

    How many fuses does it take to explode a growing time bomb? N.Korea w/Russia and China? Iran w/Russia and China? Syria w/Russia and maybe China? Etc…

  6. Davy on Tue, 14th Mar 2017 1:40 am 

    The problem with civilization is deeper than eroi. If it were only an eroi issue we could adapt. Our problem is our attitudes and behaviors which points to our wisdom then combine that with population overshoot and the resulting planetary decline. Our arrangements that have resulted in our current global civilization is beyond adaptation and transition. We know fossil fuels will end soon. Renewables are not going to substitute for a system that is broken for more reasons than just energy. In a different arrangement with much smaller populations and the possibility of quality renewables applied to a society without all the entropic waste activities of consumerism, leisure industry, and military activities maybe society could transition. Those three activities are a significant amount of what we are and they have no future. This is also a matter of economies of scale and what it takes to produce renewables. It takes this entropic waste of unneeded activities to realize renewables through economies of scale. We have to produce so much with so many to realize a narrow technology like renewables. This puts us in a predicament that is a trap of progress and our systematic existential arrangement.

    If we would have started this process years before in earnest and focus maybe this transition could occur. We are out of time and out of that quality that civilizations have of systematic adaptability. We are beyond adapting out of fossil fuels because we went all in with fossil fuels. We left behind much of what humans were very good at pre-fossil fuels and we will have to leave fossil fuels quickly. We denied they were so finite and we assumed we would transition and substitute for them as we went all in. That was a critical deadly error of lack of civilizational wisdom. Our civilization is now built out based on global and regional transportation instead of localism. Our food arrangements are not seasonal and now are a manufacturing activity instead of small scale local and home preservations and preparations. Our culture is highly complex electronic interchange instead of personal and close. Few of us can play musical instruments which was once sound leisure activity now we hope in a car to joy ride. We don’t read books anymore and the ones we do are pulp fiction. Our health care is overly sophisticated instead of holistic, personal, and local. We need more personal home visits. We eat wrong and too much. Most of all we blame and complain and point fingers when we need to ask ourselves individually how are we contributing to this mess.

    We also have to contend with paying for our mistakes. You can’t just throw a huge party of modernism and avoid the cleanup costs. If civilization did not have the opportunity cost of what we did to ourselves and our planet then things could be different. We cannot bring back extinct species and a stable climate. We cannot repair a disturbed ocean. We cannot put radiation back into the planet like we took it out. Most of all we can’t live with ourselves with 10,000 NUK weapons at the ready and a civilizations unravelling.

    So what is the real situation and eroi? We still have time in this process with current eroi but very little. Life does not have to end as we know it immediately. We can spiritually advance and choose proper wisdom even in a decline and a die off paradigm. We can embrace a hospice and lifeboat mentality not because we all must die immediately but because our civilization as-is must end. It must end necessarily per natural selection. Nature is showing us we are an evolutionary dead end. Our populations and complexity will plummet because of this natural selection. We can make arrangements to adapt to this paradigm shift to a new and different arrangement both at the level of civilization and as a species. We don’t know if we will survive this journey we do know that our populations must drop by an order of magnitude. We can spiritually embrace that fairly and with strength in wisdom.

    That solution above my friends is another problem. The reason for this problem is a trap of our social narrative and social focus of denial. This denial is both active and passive. We have billions of people making decisions based on progress and status quo. We also have a global leadership fully committed to a status quo with no future. This is a corrupted moral hazard of wealth transfer and extend and pretend. This leave a hospice and lifeboat mentality and resulting wisdom to the individual and small community. We can create monasteries of sapience and storehouses of vital knowledge and preserve some of the better accomplishments of humans that do lend themselves to the preservation of the species. We can do this at the grass roots level and dispersed globally per the individualism of so many different locals. Some will survive the collapse of modernism some wont which is little different from what nature does with seeds.

    It is possible at some point in a dramatic existential crisis that will likely happen in the near future of the next few years to few decades that we may then be able to turn to these monasteries for guidance. All our leadership and social capital now is corrupted by a failed liberal democracy and market based capitalism paradigm of individualism and free choice centered on globalism and technological progress. We must embrace a nature based system that is a humanistic arrangement much more akin to seminomadic hunter gatherers than modern global people. This can be a mixture and a new human type. Modernism is a dead man walking but all of it need not end.

    What are these transformative arrangements? This is not something complex it is elementary and simple which paradoxically makes it complex. These arrangements are much more in harmony with nature and with much lower eroi of natural energy sources. We will need to be much smaller populations because the habitability of the earth will be greatly reduced. Plant and animal communities are and many more will be destroyed to such an extent that renewable sources of support will not be there as they once were for premodern humans. Modernism cannot replicate in decline so much of our physical legacy will deteriorate quickly. In this stair step down we can salvage and cannibalize this infrastructure to help us transition. This is a step down physically and a step up spiritually. It is a return to what we once were and something new. It is not clear if we can do this but it is our only hope.

  7. tita on Tue, 14th Mar 2017 3:02 am 

    Maslow pyramid applied to the EROEI? But the Maslow pyramid of needs is wrong, and this one is even more wrong. Extracting energy is not a need… It becomes a need when it is related to other real needs. And arts are always been there, whatever all the other parameters.

  8. Alice Friedemann on Tue, 14th Mar 2017 4:07 pm

    Solar EROI advocates have cheated on their calculations:
    The biggest difference Hall has found so far is due to solar advocates multiplying solar electricity generation by a factor of 2.6 (BP) or 3 (IEA) because advocates claim that solar power is worth 3 times as much as fossil electricity since two-thirds of fossil generation is lost as heat.

    According to Gail Tverberg, in her post “The Wind and Solar Will Save Us Delusion“, this is done by BP to account for the loss of energy when fossil fuels or biomass are burned and transformed into electricity. BP corrects for this by showing the amount of fuel that would need to be burned to produce this amount of electricity, assuming a conversion efficiency of 38%. Thus, the energy amounts shown by BP for nuclear, hydro, wind and solar don’t represent the amount of heat that they could make, if used to heat apartments or to cook food. Instead, they reflect an amount 2.6 times as much (=1/38%), which is the amount of fossil fuels that would need to be burned in order to produce this electricity.

    But wait! Fossil fuels used for heat are several times more effective than heat generated with electricity, and burning natural gas at home in a 98% efficient furnace is far cheaper than burning it at a natural gas power plant and losing two-thirds of it to create electricity.

    EROI simply must include all of the energy inputs required to build a solar plant as in Prieto & Hall’s study at a minimum, so we can see if it is worth subsidizing solar (or wind) in the first place. If solar and wind can’t replace fossil fuels, because they depend on them too much, then the money/energy would be better spent building passive solar homes that would last for hundreds of years, preparing to go back to muscle power, expanding organic agriculture and departments at high schools and universities, and so on.

    I didn’t see any justification to through out Prieto and Hall’s solar PV study. In fact, they left out the EROI of the energy storage and transmission and labor energy solar would need to have to keep civilization running. Most solar advocates only looked at the panels themselves. Well hello, there is a lot more to a solar facility than that. See

    How can anyone argue that ALL of the energy that makes a solar facility possible not be counted? And those who say that oil refining has not had this level of scrutiny are simply incorrect according to Hall

  9. BobInget on Wed, 15th Mar 2017 9:56 am 

    “Artificial Intelligence” yet to be fully understood by
    casual analysts.
    Self-driving monster trucks. Automated rigs.
    3/D look down radar. Supercomputers themselves have already lowered labor costs, thereby lifting costs.
    Deeper, steerable, multi Horizontal Wells on a single pad halved drilling costs.

    Oil drilling labor, a highly paid, (free spending) bunch.
    Who will get the highly paid jobs that buy everything from multi ton pick-ups to four-bedroom homes?

    Gone are the days when robotics replaced only low paid dangerous jobs. First went the telephone operator, I wasn’t a telephone operator, then, almost overnight, gone are elevator men and women. Gas station attendants, cash machines appeared……

    Today, drones are commonplace, land sea and air. How much longer before you won’t know if you are talking to a ‘real’ doctor or lawyer?

  10. BobInget on Wed, 15th Mar 2017 10:26 am 

    There’s a certain great feeling when a person is not dependent on even a finely tuned grid for electric power. I know, I know it’s impossible to calculate

    Seven years ago when I installed our first seven KW
    solar array my neighbor, a progressive BTW, said I was foolish to pay years of utilities in advance. Even though today I’m able to double those seven KW with
    the same money and still haven’t paid down my first
    expenditure, I never regretted any of the project.

    Last year I bought a e-Golf. Again, I overpaid for years
    of diesel or gasoline fill-ups. 6,300 miles, not a drop
    of oil used, since I charge during daylight hours there’s no discernible cost for ‘fuel’.
    No more oil changes, radiators or transmissions, brake repairs (regeneration), tune-ups,
    pollution inspections even road taxes.

    Yes, solar and electric land transport are indeed disruptive technology.

    We are only getting started. Solar will play a huge part in desalination, irrigation and water pipeline power.

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