EROEI Short #4: Bootstrap-EROEI
Posted by jeffvail on September 6, 2007 - 10:00am
One significant issue related to EROEI that must be discussed is the time-lag associated with durable goods and infrastructure. Assume that the aggregate EROEI of our society is declining. Energy was invested 15 years ago in a large piece of coal mining equipment that will last for 15 years. The energy used to build it was, for the sake of example, “100 EROEI” Saudi Crude. As a result, the EROEI of the coal mined by that machine includes an input from the energy required to make that machine—we’ll say this is X. The machine is at the end of its useful life, and a new machine has been ordered. This machine is made with today’s energy, we’ll call it “50 EROEI” Saudi Crude. As a result in this halving of the EROEI of the energy used to make the machine over the past 15 years (just an example), the energy input to the same quantity of coal mined by the new machine is now 2X...
This is an illustration of what I call “Bootstrap EROEI”—the energy that we are producing today is still using, to some extent, machinery and infrastructure that was made in an earlier, higher-EROEI era. Why does this matter? IF we accept that a “first tier” EROEI calculation of coal mining today only accounts for the energy used to operate these coal mining machine and the energy used to produce these machines (i.e. there is no diminishing marginal returns on how easy it is to find and extract the coal), then we will still see a declining EROEI for this operation over the next 15 years as the EROEI of energy used to make each new replacement machine is lower than that of the machine it replaces.
I apologize if that was a laborious explanation, but I think that this is an extremely important concept. Let’s take a current renewable energy favorite: wind. Today’s giant wind turbines are being built with a long-tail of industrial machinery and infrastructure that was largely assembled using higher-EROEI energy. Admittedly, there are brand-new factories being built for wind generation. But there is also an extensive and aging infrastructure upon which this depends. What about the fleet of oversize-load trucks that transport the giant blades? Or the asphalt and concrete to construct, pave, and re-pave the highway (and bridge) infrastructure over which they travel from factory to site? Or the copper wiring for generation and transmission that today costs over $3 a pound (a price representative of the greater energy now required to mine copper). To a significant extent, it seems that today’s “renewable” energy infrastructure is being built on yesterday’s, non-renewable, higher-EROEI energy. Can we build the day-after-tomorrow’s renewable infrastructure on today’s renewable energy and still maintain an EROEI of greater than 1? Maybe if we use the optimistic EROEI figures (with artificial boundaries for considered energy inputs) offered by some.
This is certainly a problematic area for precise calculations—my goal is to spur discussion rather than to definitively answer my own question. My point is this: the problem of “Bootstrap-EROEI” is one that is not being accounted for, and one that (to my knowledge) has no reliable means of calculation. Yet it has a potentially very significant impact on our plans to transition to a renewable energy infrastructure. How can this be addressed?
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jeffvail,
I'm not sure that it can be accounted for in a totally meaningfull way. As a practical matter, maybe we should make the choices such as to use wind over coal for electric generation on the subjective consideration that since wind uses no depleteable fossil fuel for energy and coal has terrible pollution problems from CO2 and various other pollutants, that wind is generally better for the purposes.Bob Ebersole
The EROEI stupidity saga lives on...
Don't take offense, jeffvail, this is not personal. But I kinda hoped for more, since the posts' quality in here is pretty tremendous.
But you make a TREMENDOUS ERROR. And that's calculating energy twice. You can't do that, my friend!
Now, who CARES with which energy was made the truck? That's not how you should math it. You should only calculate how MUCH energy it takes to manufacture the truck. EROEI is a mathematical construct defined to see if you can manage to create more energy than use in its process. Therefore, you should try to know how much energy was spent. You've get x joules. Then, you add up all the joules necessary in the process. Then, you see how many joules you got back. That's it.
No previous saudi arabia is required. That's accounting for twice the same energy, because with that, you can only learn that with previous SA oil you could build more trucks than with now's oil. You won't learn that today's trucks are twice energy expensive. Just that you can only build half as much.
And that's WAY different.
I stopped reading when I saw your error. Correct that. Then I'll read the rest. Gosh, the horror, I've said similar stuff regarding EROEI back in here. PLEASE, please, think before writing?
Please?
luisdias -
I really don't see how you can say that Jeff is counting the energy input twice.
By way of analog, say it is essential for my business that I have a certain size and type of truck, and say I pay $40,000 for it and it gives me 15 years of service before I have to replace it with a new one. And then let's say that when I go to buy a new truck, I discover that the price (in real dollars) has shot up to $60,000, largely due to increased manufacturing costs. If I state that the identical replacement truck now costs me 50 percent more than the original truck, would I be guilty of counting the cost of having a truck for my business twice?
I think what Jeff is getting at is that as the overall EROEI of a modern industrial society starts declining, it gets progressively harder to keep the whole thing going, and that if this EROEI drops fast enough, the system can degenerate into a sort of death spiral. This may or may not happen, but I think this concern is what the whole discussion is all about.
You are absolutely wrong and the original thesis is correct. EROEI is a recursive industrial life-cycle energy accounting that measures the accumulated energy required to produce primary energy. So for instance, early Spindletop petroleum pumped itself out of the ground and into a nearby refinery. Thus the Spindletop petroleum had a high eroei and required very little other energies to extract and process. In contrast today's deep water petroleum must be pumped up from the depths at a cost in additional petroleum. Yes, the fuel is in effect measured twice.
Spindletop preceded refineries closer than Pennsylvania, docks, pipelines ect and spewed out on the ground and was hastily contained by an earth dike. The first 600,000 barrels caught fire and burned up about a week after the Lucas gusher blew in.So the EROEI was negative for quite a while. Reference; "Spindletop" by James Clark & Michael Halbouty, 1953
This is an interesting history book, and could remind people of how difficult it was to start the modern fossil fuel age. The oil business didn't just start by magic, and neither will any alternative that will replace it. It was only when the British and American navies switched from coal to oil around WWI that a steady enough market was assured to make sure oil became the main fuel for the industrialisation of the world. People tend to denigrate the growth of wind and solar as not being fast enough to make a difference in the future, but they are making proportionate progress just like oil did against coal a 100 years ago or so.
Bob Ebersole
No. It is you who is absolutely wrong and the original thesis is junk. See down below.
This is no excuse for lower EROEIs, get me. People tend to think that I'm somehow escusing low EROEIS. I'm not. Of course a good EROEI is better. But you're making WRONG MATHS.
Bear with me while I try out a couple of analogies. Say the joules come in a tin. It's as if each time you open a new tin, you find the supplier has dipped into it themselves in order to bring it to you. And each day there's less. So you need more tins. The energy content has not diminished, it's just that more is being consumed before it gets to you.
Well you'll get back less and less. The truck collects lower-quality coal with a lesser energy payload for the thermal power station down the road, so it has to make 8 trips where 5 used to suffice in the past. And that power station is supplying the electricity to the factory that's making new trucks...
Sorry if I'm being a bit thick, but if Mr. Vail's reasoning is wrong, your argument doesn't make it clear to me as to why. It appears that what you are saying amounts to the same thing.
People just don't understand me. Listen. Less EROEI is as bad as it gets, but please, don't count it twice. A Truck that was built with a EROEI petrol of 100 will use the same energy than a truck built with a EROEI petrol of 50, 30 or 20. That's not the issue with EROEI at all. You're confusing stuff. You're saying that a truck spends the energy it requires PLUS the energy that the pumps and refineries require to function. But those are different things. The problem is how much energy does the production of ENERGY takes out of the system. If you subtract them, there's your real energy output for the society.
Well it almost would if I wasn't wrong saying what I said. The thing is, a truck spends 10 energy cubes. Imagine. You have 1000 energy cubes produced. You could have built 100 trucks. But to build those energy cubes, you required 10 energy cubes (EROEI = 100), so you can only build 99 trucks with what is left (990 cubes). If EROEI = 50, then a truck won't cost you 20cubes, but still only 10. It's the energy cost that doubled. That means that for producing 1000 energy cubes, you spent 20 cubes. That leaves 980 cubes, which goes to produce 98 trucks. Like someone above said, this doesn't have much influence until it reaches values much closer to 1 (where it reaches infinity).
But get this: the truck ALWAYS costs 10 energy cubes. Not 2X it. That's different. That's WAY different.
Okay?
Not quite so. You've spent X of energy to build the machine, and 1/EROEI * X to gather that energy. For the earlier case, that was X + 0.01 * X = 1.01 * X. For the later case, that was X + 0.02 * X = 1.02 * X. So, you've spent a bit less than 1% more energy, not 100% more.
For highter EROEI, the difference is negligible. But it skyrockets when you approach 1.
...when it reaches infinity. But that's not the point, is it? The point is if wind, solar and the likes are really EROEI positive or negative. That's what it all comes down to, and to which there are people here trying to instill doubt about the rather good EROEI of these machines.
But you cannot count energy twice. You cannot say that the "truck" uses X plus 1/EROEI*X and then sum it back to see if the production of energy is EROEI positive.
You should only do the obvious: sum all the required energy spent. And for that I couldn't care less if it came from EROEI 100 or 1000 or if it was a gift from God himself. Just count it. Divide it from the energy produced. Voilá, there's your EROEI.
Why do people keep inventing what's been already invented? Move on people, don't stray in the primary school.
You are probably one of those who absolutely can not abide a negative eroei.
It's a grammar error I usually make. By "negative" EROEI, I wasn't meaning a value of <0, but a value <1. I added to the confusion. Sorry about that.
Actualy, I had two points. One is to evidence an error of the post, that does not take away all its meaning, but can lead to wrong interpretations sometimes.
My second point it that it doesn't really matter if our energy source has EROEI if 50, 100, 1000 or 10^9. But it really does matter if its EROEI is 1.3.
It is of limited value to talk about EROEI in isolation.
What if the EROEI was 1.3 but it had a 1 sec turnover rate.
Every second you would have 30% more energy that you had the second before. Or what if the the EROEI was only 1.3 but required almost no equipment or labor. Would it really matter then?
You are correct in one sense that eroei only becomes an issue as the net energy (see clifman's analysis) approaches 1 or zero. Then the externalities of the effort (labor devoted to energy acquisition 'stolen' from other social goods, negative environmental damage,et) become very important issues.
If as you said the primary energy source requires no equipment or labor to harvest and process then it would have an infinite energy return.
If the primary energy source requires lots and lots of equipment and labor to extract (for instance a fossil fuel from the ground or wind from the air) then it could have negative eroei.
... which is an assumption without real study. If the energy used would be more mechanized and without human input (a perfect machine that would function without human intervention for centuries, for example - and yes, I know it sounds like sci-fi, but we are getting into that), it wouldn't really mean a thing if the EROEI was 1.3. It would only be of importance if the energy output was not enough for our needs. Machines would be restless.
Of course, I'm not endorsing it. The problem with EROEI = 1.3 or smth like it is that it is more risky. If the production line explodes, or major malfunctions, or whatever, you may easily get EROEI < 1. And that's very bad.
It is precisely these type of picayune arguments that obfuscate and trivialize the entire problem we face. These accounting procedure arguments ignore the basic fundamental question, TO WIT:
Could a wind turbine produce in its lifetime all the energy that was used in every aspect of its own manufacture? From mining, to transit infrastructure, to manufacture, to feeding and housing the people who do that work.
See. Pretty damned simple.
NO need to worry about how coal mining is going or if old trucks are depreciated energy-wise. Just a simple question.
Hi Cherenkov,
I confess I'm having a hard time getting my head wrapped around this topic, so bear with me as I try to muddle my way through this. I guess my question is really this: When we assign a value to a particular energy source, do we do so solely on the basis of the energy inputs that went into its development/production (e.g., steel, concrete, etc.), or would it be more appropriate to assign a value based on the energy inputs it displaces?
Wind power might be a case in point... here in Nova Scotia, each kWh of wind could, in theory, displace up to 10,000 BTUs of thermal coal. Which would be a more appropriate measure of its true value? How about investments in energy conservation? When I add loft insulation to my home, would I assign a value based on the resources that were consumed in its production and transportation, or should I my accounting be based on the energy it saves?
Cheers,
Paul
You are raising a question that is slightly off the EROEI issue, but no less important in a world choked by our excesses.
I think EROEI ratios are important too though, unlike some posters above. And here is why:
If you have a total production of xGJ with a total EROEI of 4:1, then you have 0.8xGJ available for use.
If you have a total production of xGJ with a total EROEI of 2:1, then you have 0.33xGJ available for use.
A stricking difference, even before you get to values close to 1:1. Why not just build more capacity at lower EROEI? Simple - waste and materials. The whole "just build more/bigger" meme is part of the problem that got us to where we are today...
"You can never solve a problem on the level on which it was created."
Albert Einstein
This is a problem with biofuels. A major one.
But not with solar and wind and the likes, which have EROEIS in the order of 6-20.
Thing is, there's no other stuff that so easily substitutes oil as biofuels do. That's why such a bad investment is being done. We should question though its wide implications. Ecological, social, etc.
Thanks for sharing your insight; much appreciated. In the words of Stephen Leacock, my thoughts often go "madly off in all directions", but one more tangential question, if I may. Is any credit given to the recovery of energy inputs at the end of a product's service life, assuming some or all of the hardware can be recycled or reused? In the case of a solar panel, say, I take it the aluminium frame can be salvaged and perhaps some of the other components as well, in which case, at least some of the embodied energy is recoverable. On the other hand, I'm assuming much of the concrete and steel used in the construction of a hydroelectric dam or nuclear reactor cannot. Do these types of calculations normally take into consideration residual value when comparing one option to another?
Cheers,
Paul
I think that you want 0.66xGJ for EROEI 2:1. For EROEI 1:1 it is still 0.5xGJ. I think the way you want to look at this is the way you put it terms of scale of the operation. So, start by asking how much energy you want, then pick some quantity like land surface area that has a definite limit, and ask what EROEI is feasable to produce the amount of energy you want from the resource available. That way you know what your minimum target EROEI is. You'll have to put in other details like raw productivity or, for oil, the amount of surface area that has oil under it. In terms of raw productivity, you can accept a lower EROEI for higher productivity since you need less land all other things being equal.
So, lets take, for example, 35 billion gallons of ethanol per year by 2017 set by the president. The raw productivity is about 400 gallons/acre/year for corn so we need about 86 million acres or 137,000 sq mi or 2.4 Iowas. You can do this with any EROEI that you like, but if you want be sure that you get the whole 35 billion gallons for use other than say growing corn, you need to give a limit on how much land you are willing to devote, say 4 Iowas, and look for a target EROEI that lets you do this. In this case you would be using 1.6 Iowas to support net energy production from 4 Iowas so your target EROEI is 2.5. Now you have said something helpful. You are not going to use more than 2.4 Iowas to meet your production target but you know where the self-sustaining EROEI is. Then you are fine using natural gas and oil to grow corn because you are not putting a greater burden on those resources that is not compensated for elsewhere by the ethanol. As it turns out, getting to an EROEI of 2.5 does not appear to be feasable using natural gas and oil, so you need to think of something else. One thing you might do is ask how many Nevadas it would take to produce nitrogen fertilizer using solar power and a low pressure aluminum nitride process instead of Haber-Bosch because then you effectively increase the usable land area to non-arable land. If you innovate in various way, you might get to the target EROEI. The usefulness of EROEI is to be able to ask and answer what if questions of this type.
Chris
"Could a wind turbine produce in its lifetime all the energy that was used in every aspect of its own manufacture? From mining, to transit infrastructure, to manufacture, to feeding and housing the people who do that work."
Yes.
"For highter EROEI, the difference is negligible. But it skyrockets when you approach 1."
I think this is a critical issue that is being grossly overlooked. Here's a little table I built to illustrate the basic concept:
EROEI % net Representative Source
100:1 99 Early oil
50:1 98 Mid 20th century
33:1 97 Late 20th century
25:1 96 Turn of 21st
20:1 95 Century oil
15:1 93 Oil now?
10:1 90
9:1 89 Deep water oil?
8:1 88
7:1 86 Tar sands?
6:1 83
5:1 80 Polar oil?
4:1 75
3:1 67 Biodiesel
2:1 50
1.5:1 33 Oil shale?
1.33:1 25 Ethanol best
1.25:1 20
1.1:1 9
1:1 0
1:.7 -43 Ethanol worst
The next steps are to consider increasing population and declining extraction in concert with declining EROEI. Together, those three trends cut useful per capita energy in half before 2030, which is only a college student's lifetime away, and which places us where we were before the green revolution, which raises the issue of feeding ourselves - seen grain prices lately? Another student's lifetime and we're back where we were before the Great Depression. But I think by then we may think of that "Great" in a whole different vein, as in that was the Great Depression, and this is the Terrible One.
(sorry I don't know how to insert a table nor align these columns 'freehand')
Words, words and more words.
But some neat words too.
Perhaps we all should think how to translate these words into ACTION.
Hey, do something. Then POST. Start a PROJECT.
Just don't write words which are sure to be lost aka the bit bucket.
regards from senior techie.
We're just learning maths here with each others.
Easy on us :).
Each thing on its time and place.
Greets
"For highter EROEI, the difference is negligible. But it skyrockets when you approach 1."
It may skyrocket when it approaches 1:1, but I think it becomes extremely important well before that - at least in ratios under 10:1. See my reasoning in my post above...
"You can never solve a problem on the level on which it was created."
Albert Einstein
"For the later case"
What case are you refering to? The importance to EROEI and any percentage will depend on how much energy the machine processes over its lifetime.
What you say is correct: the factor is not 2X but 1.0099X. In order to get 2X you would need the second input EROEI to be less than 1.
Chris
Mr. Vail,
I think I see your point. As an analogy, the 3 foot log I burn in a (make-believe) fireplace puts out the same number of BTUs regardless where it comes from... you point out that the EROI difference is between a log from the backyard and a log that comes from 100 miles away (so to speak).
The Hidden EROI costs are those that happen between tree-stump & fireplace. To me the BTUs from the log appear the same, but the EROI costs are hidden in the transport.
The same applies to the coal. It now take MORE energy INVESTMENT to build the truck (because today's coal is deeper); even though the ABSOLUTE energy needed to build the truck STAYS THE SAME. (We get less truck per same amount of energy invested).
"As a result in this halving of the EROEI of the energy used to make the machine over the past 15 years (just an example), the energy input to the same quantity of coal mined by the new machine is now 2X..."
Why is this so important? The energy required to make the machine is only a small part of the energy required to mine the coal. Most of the energy will be in the form of the fuel used. The energy required to make the machine is spread over the 15 years. What is the ratio of the energy used to make the machine to the energy processed over its 15 year life?
The general form of the equation for EROEI would be something like
x/ax+b)
where:
x is the energy of the processed coal
a is the ratio of fuel energy to coal energy
b is the energy required to make the machine
As the amount of coal processed rises, the constant (b) becomes less important. The extra energy required, might easily be offset by increased quality, giving the machine a longer life.
I think there is something more important than just the cost of making the machinery here. You have to fuel the machinery, you have to maintain the machinery, you have to move/feed/cloth the people who are involved with the machinery. In short, the price of that machine is costantly adding up over the years. It's almost like asking whether I should spend $15,000 for a new car that will be maintenace free for 10 years?.. or $2,000 for an almost antique that will cost me $1,300 in maintenace/per year over 10 years. Both will "cost" $15,000 over that 10 year period, but the newer car will have less downtime, thus be more productive.
Also, if hypothetical space-aliens came down and suddenly exchanged all our planet's oil for an energy equivalent amount of coal, we'd be hard pressed to use it. The diesel-powered mining trucks and mechanical shovels would stop, the gas-powered cars the miners used to get to the mine wouldn't work, the food trucks wouldn't feed the miners, the diesel powered trains couldn't deliver the coal, etc.
So the source of where this energy comes from is also important.
In short, I see jeffvail's point that we need to discuss this problem more so that we can define it better.
'Why is it important?'
Because we are not interested in a snapshot of time, but the changes which are underway when you live on a permanent upward slope of costs/downward slope of eroei. The point is that a production cost today is actually at a discount to its true total because of lower overheads in the past. So we are constantly underestimating costs and overestimating eroei etc. There are many parallels:
If I say 'oil at $80bbl is high and you say - yes but it was higher inflation adjusted 30 years back, both facts are only partly true. Part of inflation is due to rising costs including oil, so once oil prices begin to climb at a higher rate than 'other' inflation, it becomes an important factor...
I would ramble on, but I'm going for a curry
cheers
"when you live on a permanent upward slope of costs/downward slope of eroei"
This is the fundamental mistake you and the author make. You see some new energy systems have a lower EROEI than oil, although this is debatable, and subsequently conclude that it will continue to go down. A permanent downward slope? How about calculating an actual EROEI for wind or solar and tell us why it is not high enough.
Jeff:
You consider energy cost of first generation 'renewable', and then of second generation 'renewable' for which the cost of infrastructure renewal will surely be higher than for first generation. This is a real complication that should not be ignored.
But perhaps the problem should be restated in a way that makes handling the complication easier:
Think about the 'Nth' generation, somewhere well beyond the first and second. There will be a time when each generation of renewable infrasturcture will have a cost structure that is pretty much the same as the cost structure of the '(N-1)th' generation. If we had a vision of what the economy and technology will be at that future time, we could think about various ways to get from here to there. Call these alternative paths. For each of these paths, we could estimate costs and uncertainties as to whether the path is doable.
Can we make useful guesses about future renewable technology? I think yes. For example, it will involve various forms of solar: ie photovoltaic, wind, biofuels, hydroelectric. But not nuclear, which is not renewable because of its own finite resource issues that have nothing to do with fossil fuels. OTOH, nuclear can be a component of an intermediate step along a path. And, it may be useful to planning to use nuclear waste as a heat and sterilizing resource. There must be much more that can be said about this future, but I can't say much more here.
The idea is that the problem of choosing a path into the future can be discussed and analyzed in great detail. Fixating on the first step is probably not useful.
I see your discussion of the complexity of EROEI as a useful demonstration of the need for a different approach. This is my tentative suggestion for such.
In other words, if and when we reach a steady-state economy, the EROEI in the broadest possible sense will be 1:1 (no growth possible), but that would be OK. Getting from here to there is the problem, and it's a problem of social organization, not technology.
I don't think so. With an EROI of 1:1 you'd be burning all the fuel you got simply to get the same amount of fuel to burn in order to get just enough to keep the cycle going. It would be an unproductive ritual. You'd be burning 100 gals of oil to get only 100 gallons of oil (which you'd use to get another 100 gallons of oil to- oh, whatever).
:-0
That's why I said "in the broadest possible sense". This is the "bootstrap EROEI" thread. In a steady-state economy there is no growth possible. Whatever energy is not used directly to generate new energy, is used indirectly in the societal functions necessary to keep everything, including the energy systems, going.
I don't think you can equate a steady-state economy with an EROEI of 1.0.
An energy-producing system (the 'system' not necessarily being a single physical entity) with an EROEI of 1.0 internally consumes 100% of the energy it produces, with zero energy left over for 'societal functions' or anything else. . It is the thermodynamic equivalent of paying someone to dig a hole and then fill it back up again. Or maybe more accurately, it could be thought of as an engine which has just barely enough power to run itself but has zero ability to do any external useful work.
A steady-state economy, i.e., one with zero growth, need not be steady-state with regard to energy production and consumption. A zero-growth economy can be very energy-efficient or very energy wasteful. But perhaps you are using the term 'steady-state' interchangeably with 'sustainable'.
This is not aimed at you, but while we're on the subject, I also think it misleading and not very useful to talk of the EROEI of society as a whole. The purpose of a society, per se, is not to produce energy. Rather it consumes energy in carrying out its various functions. Almost by definition, a society will (eventually) consume 100% of the net energy it produces. Otherwise there would be no point in producing excess energy.
EROEI 1:1 (all the society) with all the waste counted, theoretically, is possible, not only possible, but what happens.
Of course, its meaningless.
EROEI 1:1 in the energy production line, possible for its own sake. A never ending machine in its own. Completely useless for society.
Just a thought.
1:1 is only if we capture all the sunlight incident on the Earth. I don't expect that to ever happen. But maybe it will.
" But not nuclear, which is not renewable because of its own finite resource issues that have nothing to do with fossil fuels."
The sun is finite too. It will only last 5 billion years or so. Nuclear power can last just as long.
http://www-formal.stanford.edu/jmc/progress/nuclear-faq.html
"There will be a time when each generation of renewable infrasturcture will have a cost structure that is pretty much the same as the cost structure of the '(N-1)th' generation."
Really? When will that be? This may be useful for a conservative approach, but it discounts technology improvements.
"If we had a vision of what the economy and technology will be at that future time, we could think about various ways to get from here to there."
We could also get very rich. Let us know how that goes for you.
When the Sun quits, we die. The issue is to figure out how to last that long.
Nuclear power can last as long as there is available nuclear fuel. John McCarthy believes in nuclear power. I am unpersuaded. It seems to require very special conditions of social stability to succeeded - conditions that I have no confidence will be continuously available from now until the Sun quits.
The Earth operated on a steady state solar economy for many hundreds of millions of years before the advent of mankind. Because of continental drift, etc., there were slow changes to the steady state condition. I think such a steady state is what people envision when they talk about 'sustainable' technology. I'm not aware of a detailed argument that forces sustainable technology to necessarily have EROEI of precisely 1:1. If there is, that should be folded into consideration of what paths to investigate. It might prune the tree of possibilities quite substantially.
There is actually a lot of room for technological improvement in this view. I think, for example, that our first cut at a plastics technology based only on biologically generated feed stocks will likely be rather crude when compared with the tenth or twentieth generation.
(We need plastics for the throw-away plumbing that is used in hospitals.)
"It seems to require very special conditions of social stability to succeeded - conditions that I have no confidence will be continuously available from now until the Sun quits."
But making wind turbines and solar cells doesn't require social stability?
What are those special conditions? Do they exist now?
"What are those special conditions? Do they exist now?"
Think about Three Mile Island or Chernobyl. Malfunction of a nuclear reactor results in forced moving of millions of people 'as a precaution'. Broken wind mill doesn't even get mentioned on the evening news. I think the social organization might exist now in some places. I used to think it existed in USA until Katrina hit New Orleans. Now I don't know. It certainly doesn't exist in Iraq, for example.
It troubles me that you had to ask what I was talking about. Surely you are aware of the safety issues of nuclear power.
I am. I've been doing it for 17 years. But my question was: What are the "very special conditions of social stability"?
No energy source is infinite. We just can't imagine ever fulling utilizing it. That's why we're in the situation we are with regards to oil; it's why the Easter Islanders used up all of their trees. I think that it is very possible people would try to cover the landscape with solor power facilities of whatever kind and wind turbines and tidal generators. Then we would have "Peak Land."
I'm pretty happy with the world I live in. I do not want to see it go away. However, I do not see how it is sustainable in any possible way.
- Scott
"Try sour grapes; you might like them."
I would suggest you look at the NREL solar maps, then do a calculation as to how much land it would require to supply all of our energy needs. I think you will be surprised.
We could probably do it with only solar, but we also have wind, biomass, geothermal, ocean and nuclear. We have a lot of fossil energy left, so we have time to do it.
Perhaps not as much time as we think (from a simple analysis I did a couple of years back):
There are several convergent factors that I never see discussed together that should be. First is decline rate, and what it really means. Most are familiar with compound interest. Decline rates work the same in reverse, so for Hirsch’s range, a 13% decline rate would cut supply in half in just 4 years, 7% would cut it in half in less than 9 years, even the rosiest 3% cuts supply in half in 22 years. Using this mildest decline rate, and assuming 2005 was the peak, at 31Gby, by 2027 production will be only 15.5 Gby. Yikes. That’s the same as it was in about 1945, when the population was only 3.4 billion. But in 2027, the median UN projection is for population to be about 8 billion. So whereas in 1945, there were 4.56 barrels per capita, in 2027 there will only be 1.94 b/c. Double yikes. Then there’s EROEI. Whatever it is today, it was more in 1945, and will be less in 2027. Let’s just say in 1945 it was 50:1, today it’s 25:1 and in 2027 will be 10:1. I like to use easy math to make the point. That means in 1945, there was actually 15.19 Gb net, or 4.47 b/c. Today, we have 4.58 b/c ((31*.96)/6.5), and in 2027 there will be only 13.95 Gb net, or 1.74 b/c. Triple yikes. It’s this confluence of declining production, increasing population and declining EROEI that seems generally overlooked. I know my assumptions are simplistic, but I don’t think wildly out of line, and I hope they make the point. And I did use the mildest decline rate that Hirsch found per region. If the world declines at anything greater… well, you do the math.
So is declining energy per capita a good thing or a bad thing? Well it is good because that means that systems are becoming more efficient and people are making better choices. But wait! It is bad becuase energy prices went up, and people HAD TO do these things. Very few people are going to change their lifestyle just to reduce the worlds energy use. They will only do it when they have to, or it makes financial sense. So is the decline rate going to happen becuase the oil and gas companies can't fulfill their contracts or will it happen because people stop buying the stuff. What is the peak oil price?
Jeff,
The concept you are conveying explains why I believe wind power is merely equivalent to purchasing a large amount of oil at today's prices on the premise of a higher price later. We are using infrastructure given to us by our oil endowment to create renewables, and will never see the day where renewables create renewables. Instead of constructing PV cells, governments should be purchasing fuel, unfortunately. Perhaps when oil prices spike, this point will speak for itself, as the replacement infrastructure for constructing renewables will no longer make it economical.
I would like to point out that in your article's example, there is a flaw in your explanation's diction. Assuming that the methodology of producing the machinery then is the same in terms of energy expenditure as today's, the energy cost of the machinery is still X today. I think what you meant is that if the energy supplier got X:Y and now gets (2X:Y == X:.5Y), then the energy supplier needs twice as much input to supply the energy required for the machinery, not twice as much output. However, if this energy supplier wants to have the same net energy production as before (in terms of quantity), they would need to double the magnitude of their operation - do twice as much oil extraction. Thus, the machinery required to maintain uniform output has doubled in energy cost, even though the energy cost per machinery unit has not changed. I think this is what you meant to say. Correct me if I'm wrong.
A.J.Wald
" ... and will never see the day where renewables create renewables."
I don't see that this is true, and don't think Jeff was saying it's true. Maybe it's true for wind in particular, but I doubt even that. I have great confidence in human ingenuity.
But I wonder - will there every be a time when the world is so full of windmills that they modify weather patterns? ;-)
http://science.reddit.com/info/2milf/comments
if you are so inclined...
I'm trying to understand..
We booted into coal using wood
We booted into oil using coal
We booted into natural gas using coal and oil
Now we are booting into solar, wind, biomass, geothermal, ocean and nuclear using oil and coal and natural gas.
The EROEI of these can only get better.
What is the problem again?
Oh, yeah: "Can we build the day-after-tomorrow’s renewable infrastructure on today’s renewable energy and still maintain an EROEI of greater than 1?"
Well, lets look at the percentage of our energy use that goes into maintaining the energy infrastructure.
According to Energy Flow 2002 https://eed.llnl.gov/flow/02flow.php
The entire industrial sector only used about one fifth of our total energy use. So, to be ultra conservative; as long as the energy systems we make have a net EROEI of greater than 5, I'd say we'll be OK.
The industrial infrastructure is supplied with products whose transportation energy costs are accounted for elsewhere.
And futhermore staffed by humans whose use of transportation energy is often dominated by the need to get to such industrial infrastructure every working day.
The problem is that until now preceding primary energy sources contained less embodied energy those subsequent ones bootstrapped. So wood contained less btu's then coal which has less than petroleum. From now on all subsequent energy sources will have less embodied energy.
I'd be surprised if a wind generator can in its lifetime generate enough electricity to mine and process the steel and plastic it is made from.
I think you are in for a surprise then.
For a modern large wind turbine it can be readily shown that the sum of the i) energy content of the materials of construction, ii) energy consumed in manufacture, and iii) energy expended in construction and life-cycle operation and maintenance is way far less then the amount of energy produced by the wind turbine over the course of its operating life.
I don't have any recent figures handy, but I believe that various analyses have estimated the energy payback period as being only a few years.
You are of course entirely correct in that switching to renewables such as wind and solar amounts to a reversal of the trend to go toward more and more concentrated forms of energy. But that is the whole trick: efficiently and economically extracting energy from relatively dilute natural energy fluxes, such as direct sunlight and wind (indirect sunlight).
See if this "back of the envelope" calculation appeals to you:
Step 1: Determine how much energy the wind turbine will produce in it's lifetime
If we assume that:
- A 1 MWatt "namplate" capacity windmill
- Actual continious output in a decent location is 20% of nameplate, or 200 KW
- service life is 30 years
then liftime power production is something like
30 X 365 X 24 X 200 ~= 52 million kwh
Step 2: Determine an upper bound for energy embedded in the windmill using cost of production.
If we assume that:
- The windmill cost $1.5 million to build
- ALL of that cost was due to energy costs (remember this is an upper bound calculation only)
- ALL of the energy came from the cheapest conventional source, which will give us the highest value for embeded energy in the mill (i.e. the very pessimistic case)
- That source is coal at a current cost of say $0.04 per kwh
Then we get an upper bound on the embedded energy in the mill of 1500000 / 0.04 = 37.5 million kwh giving a net surplus of 14.5 million kwh in the mills favour
Any assumptions here you don't like?
Even with your calculations the EROEI is only 1.4:1. That implies that the windmill would have to be dedicated to building its replacement for the first 21 years of its useful life. If you include the cost of maintennance during its life, it would take even longer.
- Scott
"Try sour grapes; you might like them."
No you have misunderstood, this was not intended to be an accurate calculation of the actual EROEI
Rather it was an intentionally pessimistic estimate intended only to semi-guess at the question of if the EROEI was greater than 1, which was the implied question in the original post of the subthread.
Did you read the post before making these sentences?
He was making a very good example: even if all of the money involved in building the windmill was 100% about energy and such money was the most well spent (buying the least expensive energy, or the most energy possible), even still, it is more than 1:1.
But you cannot say that this is the case. The money involved in the building and maintenance of these things involve much much much more than energy (in terms of money), and it probably doesn't involve such an inexpensive energy.
Thus EROEI will be much much bigger than 1,4:1. In fact, it will be closer to 20:1.
luisdias:
Thanks, that was the point I was trying to make.
I've thought about this some more, and I realize that an EROEI of 5 would not be conservative. I really don't know what it would be, but in general I think the EROEI of oil is way over estimated. We should be calculating UEROEI. Useful energy return on energy invested. What is this ratio for oil? Most oil is used for transportation, which is currently 20-25% efficient. It takes about 10% of the oils energy to refine it into gasoline. So the ratio of the energy that went into making the fuel to the useful energy output is only about 2:1.
Reminds me of discussion in Accounting 101. Try to match expenses with revenues. That's how complicated it is.
Alright boys and girls. You've managed to make this way more complicated than it needs to be. Likely because you are too focused on the specific technicalities that you understand.
Energy is a function of the level of infrastructure a culture must maintain to continue its behaviours. Thus energy use can be simply charted on a log table, the more advanced a culture is the more energy is required to maintain it.
It simply doesn't matter where the energy comes from.
If you wish to maintain a US level of sophistication and waste you must expend a very predictable amount of energy. If you wish to reduce the amount of energy used then you have to give up something.
No wind turbines are not going to use less energy than that of a coal fired generator. They will consume precisely the same amount of energy if they are meant to deliver the same amount of electricity.
"Thus energy use can be simply charted on a log table, the more advanced a culture is the more energy is required to maintain it."
It depends on what you mean by advanced.
"If you wish to reduce the amount of energy used then you have to give up something."
What would I be giving up when I am driving a PHEV powered by solar panels? The energy used would be less, unless you follow the EIA practice of multiplying renewable energy by the fossil fuel heat rate, but I have would not have given anything up.
"No wind turbines are not going to use less energy than that of a coal fired generator. "
I thought wind turbines generated energy. When you replace heat engines with renewable electricity, the energy used goes down.
You are mistaken when you compare wind and coal I think. Wind is a directional flow so whatever inefficiency there may be, you can catch more of it down stream. You can, in principle, use all of wind until you cause it to no longer blow. With coal, you are making a heat engine (omnidirectional jiggling) so you are fundementally limited in the fraction of energy you can extract. So, wind will use just about exactly the energy it generates, but coal will use twice as much or more of the energy it generates.
Chris
I think that is basically what I said. I am, however, confused by your use of the phrase:
"So, wind will use just about exactly the energy it generates,"
What do you mean...wind will use?
Here is what I mean: Lets say you use 1kwh of electricity. If it came from coal, your energy use would be about 3kwh of thermal energy. If the 1kwh came from wind, would you count the wind not captured as energy use? When the EIA reports total energy they multiply wind, solar, hydro and geothermal by approximately 3 ( fossil fuel or geothermal heat rate) to accurately compare their worth to fossil fuels, but does it make sense to say we used 3kwh of wind energy? Thats why I say the energy use would be less. We are generating a higher quality energy directly, so we need less total energy.
"With coal, you are making a heat engine (omnidirectional jiggling) so you are fundementally limited in the fraction of energy you can extract."
Yes, as long as you are making electricity. If it were burned in a cogeneration plant or used directly for heat, you could use nearly all the energy.
It is always difficult with renewables to use the same kind of language. This is why I take some departures at my blog. What I am saying is that if you were worried about using up wind, the energy you extract is something you'd miss further on down the flow, then wind behaves like hydro in the sense that the energy delta of the wind is pretty close to the energy you get out. Conversion of kinetic energy is more complete than conversion of thermal energy because it is more organized (lower entropy).
The thing is, you don't care about the wind or sunshine you are not using. You didn't do anything to make them available, they just are. You can't really waste them. With coal, aside from your example of just wanting heat, it is frustrating that so much energy is lost because it took so much effort, blood and destruction to obtain it. It is precious because people die to bring it to us. As such, it excites lust, as the old song goes, and the idea of waste has a lot of traction.
Chris
Jeff are you saying anything that isn't going to be incorporated in the economic price? If all markets are perfect (OK big if) then your old equipment and infrastructure, which has probably paid for itself, can be used to make cheap wind turbines. However once that equipment breaks down you will have to buy new machinery, whose price will embody everything that has gone into its manufacture: at some level, EROEI will be reflected in that price. So then you will only build your wind turbines if the price of electricity is high enough to pay for their manufacture. Prices might fluctuate, and other factors might predominate, but overall if EROEI is less than one then it will never be economic to build your wind turbine using that equipment. We will either have to find a cheaper way of making them, or a cheaper way of harnessing the power of wind, or abandon it. If EROEI is >1, it might be economic to do so, but the price will tell you.
Andy
Mission: improve the soil
Jeff seems to be mixing apples and oranges and I am not sure why.
First, as Cherenkov and others note, EROEI is simply counting the energy in versus the energy out. There is zero concern directly with quality there.
Second though, when he drags in the different EROEI oil what actually occurs is fewer trucks get built for the same total energy (because more energy went into the extraction of the oil so less is available for downstream processes).
Someone up above asked if wind turbines can be EROEI positive (can wind turbines build their replacements and still produce a surplus of energy for human usage)? And the answer to that question is yes though it's not by some huge margin. What a society based on wind turbines would have to be is far more conservative about growth, far more concerned with maximizing efficiency, etc.
You can build a civilization around any positive EROEI source but how fast you can extend and expand that civilization is directly related to how high the EROEI ration actually is. The extremely fast expansion of modern civilization is directly due to the high EROEI of our energy sources.
And this brings us clear back around to our hypergrowth economy and exponentially growing population. If we move towards sustainable energy sources we cannot do this anymore. We need to find another way to organize our lives other than the caveman superstition called economics and money, and further, that new way must take into account the physical boundaries of our planet.
"The greatest shortcoming of the human race is our inability to understand the exponential function." -- Dr. Albert Bartlett
Into the Grey Zone
I understand your point, but you're wrong. Let's make some maths about it.
Even taking for granted an EROEI of 6:1 which is totally pessimistic for renewables (like a lot), let's make an example of what you are saying.
Basically, let's say that you have a windmill based economy. This windmill creates 600 units of power in 20 years - Remember, this is a pessimistic case - We could say that a particular windmill percentage inside an economy is scheduled to make enough power to create more windmills. Each of these windmills create 6 more windmills within 20 years. But then you have to discount the windmill itself that will have to be substituted (This is very pessimistic). That's 5 windmills per 20 years for this "task group". That's one windmill per 4 years, or a 25% growth each year.
Now if you allocate 10% of windmills to create enough power to the next generation of windmills, you'll have a 2.5% growth in power each year. That doesn't seem too different from our present situation.
And this is like, worst case scenario. So, while I know what you're talking about, you're wrong.
This is yet another issue, and I fully agree with you on that.
I feel the answer lies in multiplying the age of infrastructure by the proportion of "energy in" contained in that infrastructure... then considering the rate of global EROEI decline. I expect, in fact I'm pretty sure that "old energy" i.e. energy that was input into the infrastructure sufficiently long ago that the subsequent decline of global EROEI is significant, is small. I'm led to this belief since the vast majority of energy used in the world flows to thermal noise pretty quickly and does not get embodied. Not enough energy gets embodied for this "old energy" from a high global EROEI era to be significant.
That make sense?
I believe that understanding energy economics (EROEI is one way) is critical to making good investment decisions, and this kind of discussion helps even if we don't have "the answer." I'm posting this partially to help me frame my own thinking.
First, I'll set some boundaries conditions. I'll limit my time horizon to the next 500 years. Sustainable sources of energy (solar, wind, tidal, hydro, etc.) will not be considered as energy invested. Non-renewable resources (oil, coal, etc.) will be considered as stocks, and counted as enegy invested when used. In this sense, the non-renewables are considered "energy in the bank", and renewable energy as "energy flow."
Using my boundary conditions, Jeff's mining machinery example doesn't really work. Mining machinery doesn't capture energy, it just takes it out of the bank faster. Lets pretend that we are building a windmill instead. Assume the windmill has a lifetime generation capacity of 400 units (present value). Lets also assume that the embodied energy is 100 units. This is equivalent to an EROEI(windmill) = 5 if the investment energy was free. Lets call this the EROEI(windmill, ideal).
EROEI = 1 + (Net energy gain / Energy expended)The energy expended to make the windmill is
= 100 + (100 / (EROEI(source)-1))
So for various quality energy inputs ....
The bootstrap EROEI occurs when the EROEI(windmill) equals the EROEI(source). The results of this calculation show in this example that the EROEI(windmill, bootstrap) is only 20% lower than the free energy EROEI(windmill, ideal). If I did the derivation right ...
EROEI(windmill, bootstrap) = EROEI(windmill, ideal) - 1So, the bootstrap EROEI is only 1 less than the ideal. This is no big deal if the ideal return is high, but is signficant as the ideal approaches 2. As the EROEI(ideal) approaches 2, EROEI(bootstrap) approaches 1. Game over.
However, ROI is not a favored metric for managerial accounting. What we should really be looking at is the energy NPV of a project. Then we can apply some of the managerial accounting techniques for choosing among multiple positive NPV projects when we have limited investment resources.
Another one bites the dust.
I can't stress this enough: YOU ARE COUNTING THE ENERGY TWICE!
Or, can't you see that your EROEI calculations make any EROEI like 50:1 equals to 50:2 and 25:1 equals 25:2 and so on?
This should have opened your eyes.
Basically what you are saying is: okay. I've got this windmill. It took me 100 energy units. But I have to spend another 100 energy units to build yet another windmill to substitute this one. That is 200 units. If my windmill gives me 600 units, then I'll only get 400 out of the equation.
This is insane. Please. Spare me your mathematics! Get this: from the point of being built, the windmill makes 600 energy points. That's it. If you want to build another one (and thus creating a full circle), this will cost you 100. That means you get 500 for your own, not 400.
The only way you would get 400 would be if you were accounting for the production of two windmills with the energy of one, which would mean growth, not bootstrap.
Okay?
Let's repeat this sentence like 100 times on the board:
"Bootstrap" EROEI IS EQUAL TO EROEI!!!
"Bootstrap" EROEI IS EQUAL TO EROEI!!!
"Bootstrap" EROEI IS EQUAL TO EROEI!!!
Thanks.
I do agree that EROEIbootstrap = EROEI - 1
Starting from the post of Marcos Dumay (thanks), that the energy invested has an EROEI "overhead" as well of X/EROEI and that this overhead has its overhead of its own, etc adinfinitum, and using the geometric series for 1/EROEI,which is convergent for EROEI > 1, I found
EROEIbootstrap = EROEI - 1
I could not understand the meaning of this mathematics for real life, until I read the comment of Luisdias (sincere thanks). The central problem is indeed: do we want to eat it all now, or do we want to reserve for replacement (not growth, but replacement)?
One consequence of EROEIbootstrap = EROEI - 1 is that all technologies with EROEI < 2 are just parasitic on technologies with EROEI > 2. However this parasitism can go on for a long period, because the higher EROEI is sunken in durable goods, infrastructure etc.
Someone slap me. I'm starting to go insane. Please, tell me I'm not insane. Or else tell me where did I go wrong in my reasoning.
Please tell me, where does this "-1" comes from. I cannot see it. I can't really. Can't you see you are counting it twice? I'm starting to feel unnerved, may I be completely wrong? I cannot see where.
Ok. Hmm. What?
Now, let me tell you this. EROEI is a measure that already accounts for a new REPLACEMENT of power generators. Get this: I build a windmill which gives 600 power. EROEI 6:1 tells me that if you want to guarantee a substitute for it, you should save at least 100 from its production so you can make another windmill. So, EROEI already accounts for its own substitute.
If you subtract to it another 100, you are doubling the energy cost of the windmill, and somehow you get to the I-don't-know-where-it-came-from EROEI-1 "Bootstrap".
Forget "Bootstrap". EROEI bootstrap is, abstractically speaking, theoretically, EQUAL to EROEI, not EROEI-1. This is a HUGE mistake from your part. Please, get this.
Okay? Please gentleman. This is BASIC mathematics.
Else, please tell me where I am wrong. 'Cause I can't see it.
The difference between EROEI(original) and EROEI(bootstrap) is caused by where I set my boundary conditions. Remember that I chose to include the embodied energy of fossil fuels, as well as the cost of extraction in the energy invested. Let us assume that the EROEI(source), where we get the energy to build the windmill, is infinte. In this case the energy invested is just the cost to build (100 units).
EROEI(original) = (600/(100 + 0)) - 1 = 5
Now at some later time, we have used up all of our infinite EROEI source. Now we have to build another windmill, and use the energy from the one we have running. The energy in will be 100 + the energy invested in the running windmill to generate that 100 units. It turns out that
EROEI(booststrap) = (600 / (100 + 20)) - 1 = 4
pd is on to something with this
What you are saying is that the windmill has to produce the energy to invest in the new windmill and pay back the energy required for it to be built in the first place. Get this: you _ are _ counting _ energy _ twice.
I'll make another story for you. Correct me if I'm wrong, because to me this is clear as 2+2=4, but after reading so many intelligent people claiming 2+2=5, I'm beginning to have doubts!
Now in my story, you only need one windmill to run a society. But in this society, which never grows, windmills have to be substituted every 20 years. So. Windmill one is built with coal energy. But that's it. No more coal from now on. Windmill is all there is. Ok, now windmill produces 600 energy units. It has to give power to the society and ensure society's future, meaning it must pay 100 energy units to build it's "descendant". So windmill no 2 is built with those 100 energy units. With the windmill no 2, 600 units are produced in its entire age. Etc. Question. How much energy was spent, per windmill, in building windmills (plus maintenance, given that in 100 units all things are considered)?
Exactly 100 energy units per windmill.
That leaves 500 to society.
Now, if I'm like some geek that likes maths, I could say that any energy unit spent in society is actually one unit plus one fifth, given that it was required that power to build the windmill that is giving for us that one unit of power. But, really, that's only trivia for me. I can only "taste" one energy unit. Or put it another way, I can divide things and let it be that way, much simpler: I spent one energy unit and windmill spent 100. Simple. Pure.
No "bootstrap".
There is no "bootstrap". That element is already inside EROEI concept.
How can you not see this?
Please tell me that 2+2=4 or else teach me maths, 'cause I'm going to pop.
Hmmm.
I concede. EROEI = EROEI and 2+2 = 4 UNLESS you do not count the non-renewable energy spent as part of the embodied energy. I did, so for my example you are corret.
Wouldn't want you to pop anyway. Thank you for our persistence. I am reminded again why I am not a fan of ROI.
I think we need to NOT use ROI, but rather look at free energy flow or something. I'll think about it.
luisdias,
Excuse me for having been to concise due to lack of time.
Ofcourse 2 + 2 = 4.
And ofcourse you're right, that EROEIboostrapped = EROEI,
depending on your definition of EROEI. It is not so much a matter of boundaries but of definition.
So let me give the definition of EROEIbootstrapped for wich, EROEIbootstrapped = EROEI -1, i.e. the EROEI that takes into account all the energy invested (within the choosen boundaries of the system) to grow to the present production level, so you are right that growth is included in this way. But that is the meaning of bootstrapping: starting from a very small entity en building on its own strength.
EROEIbootstrapped defined in this way is relevant when colonizing a far away planet, with only a one time supply of technology. So far for SF.
But it is also meaningfull on planet Earth. Shit happens, e.g. Katrina. Is building to the old level growth or is it maintance/replacement? That depends on the value you attach to a human life. Lifeboats for anyone or just enough for the lucky and the elite (who happens often to be the same), just enough to start society all over again?
In a perfect stable world, any EROEI > 1 is fine, although the larger the EROEI the bigger the party.
But the real world is not stable, and sometimes you have to start from scratch and if you don't have the spare capacity for that, well you just can't bootstrap. In ecosystems this is called resilience. And the difference in EROEI is only one, so only relevant at EROEI close to 2.
But again, if you are so wise to incorporate all the contingicies and the basic need for resilience, than ofcourse the resulting EROEI is bootstrapable.
Or to keep it short: it is the old story of the chicken and the egg.
"Let us assume that the EROEI(source), where we get the energy to build the windmill, is infinte. "..."Now at some later time, we have used up all of our infinite EROEI source."
These are contradictions in terms. How could you have an infinite EROEI, and if you did, how could you "use it up"? There are two ways to generate infinity. Divide by zero, in which case there would be no energy invested, or invest a speck of energy and then let the energy roll in forever. Either way, your statements are nonsense.
I see your point but I was trying to define a bounding case. Assume that I divided by zero, but it only worked for a finite quantity of energy.
In any case I concede the point to Luis on the project level.
One thing to note is the different time-scales for embodied energy. The tower on which the turbine is mounted can likely be reused once the turbine has failed in some way and needs to be replaced. For solar, recycling requires only about one third the energy needed to make the first instance of a panel, so EROEI is an increasing function of time converging at a factor 3 higher than the initial EROEI for the whole system. Similarly for wind, the refurbishment of the turbine likely requires less energy than building the original. I doubt that many accounting systems other than those used to manage endowments for universities can easily include these aspects.
Chris
I agree with Cherenkov, luisdias, and GreyZone.
I dont think that this is a distinguishable effect. I think your discussion is essentially another way of pointing out that most EROEI measures undertaken today are too optimistic because they dont include all of the necessary inputs. It doesnt seem to really have anything to do with the higher EROEI sources in the past; except for the fact that your "bootstrap" effect will make it obvious that many people did hugely flawed EROEI studies. Yes it is important that society will be increasingly hard to run as the average EROEI from our energy sources gets closer to 1, but that is a separate issue from how to measure EROEI.
Theoretically EROEI should be able to ignore the EROEI of the sources used to make the inputs assuming that EROEI is just energy out/energy in. All that should matter in an EROEI study is how much input energy is needed to utilize the energy source vs how much energy it produces. It is the strong tendency to underestimate the required input energy that needs to be guarded against.
So if I havent made it clear already, your "problem" of bootstrap EROEI doesnt need to be accounted for at all. We just need to make sure that we actually include all of the necessary inputs.
Also, someone said that we will "will never see the day where renewables create renewables."
Well if we don't then our society is finished. This issue is precisely why the EROEI study is so important. If done correctly, an EROEI analysis should be able to answer whether a putatively renewable energy source really is one(before we find out the hard way that it isn't).
Dear all.
Wind generator EROEI is >20
In Denmark the environmental and energy costs of Wind generation has been calculated numerous times. The energy, emissions etc has been evaluated by Life Cycle assessment "cradle to grave" for the last 10 years.
Many of the points raised in todays discussion has been raised and are included, and the effect included.
At present the EROEI of a 2 MW wind generator in favorable wind speed area is 20-30 times during the 20-25 years lifetime.
That is: all energy spent for raw material, for construction of the mill, erecting, infrastructure, use and maintenance- and disposal has been included. Still the wind generator has an energy payback time of less than a year.
One example of an LCA on a 2 MW generator here:
http://www.vestas.com/NR/rdonlyres/99148F67-F421-4131-B018-88BF0A8E7344/...
kind regards/And1
Well, forget it, people will always come to you and say that windmills are not EROEI possible, that they are "negative" and bullshit like that,
...because the world's gonna crumble you know? and there's a thing called receding horizons you know? and because I'm a friggin genius despite the fact that I flunked maths a lot, I'm gonna make some weird EROEI calculations in my knee and tell you that your EROEI = 20 is bullshit, because I've invented this stuff, you know, its "bootstrap", great name, uh? It manages to give that shilling tone to the thing, which is good because we're gonna die and people should be scared shit. And 20 is bullshit, you know? 'cause it's been calculated by greed people, and it shou'd be more like 6, but then again, its not 6, its 3 because bootstrap. Brilliant, hu? See how you've been duped?
Yes, I see it alright. I see it through.
People. Please. Stop. Think a little. Jeffvail. Everyone. You're not making any sense at all.
FWIW to be viable an energy producing technology must return 10X or more of the energy cost of producing a "generator".
From the papers I have looked at the return is from 10X to 20X. Which makes it viable.
In addition wind is still coming down the learning curve. Which means the total cost of the energy used in production is declining.
To have renewables create renewables, we would need some large magnitude multipliers on wind and tidal technology. These really are the only two technologies I see being successful. However, the EROEI of these technologies decreases as we ramp up production. This is because the material inputs require more energy to synthesize as they become even more scarce (oil is the principle ingredient and to produce composites and polymers with other materials, we go through a very energy-intensive process in the lab). Until I am shown a full method/specification of producing tidal and wind technology components using the output of these technologies, I shall remain skeptical. The only solution I see is using electricity to produce thermal energy or pressurized gas which may be used in the reaction processes for the required materials, or in mining the materials, or for powering the machines that make these components. These energy "form conversion" processes are not even 75% efficient (as far as I've seen), so there's a strong drop in your EROEI right there. I've always thought how fun it would be to see a pilot project where renewables create renewables. Thus far it's only a dream.
A.J.Wald
Underlying this issue IMO are some nasty net present value problems involving more than the usual assumptions.
For example, many western farmers outside of federal irrigation projects irrigate crop ground by individually pumping water up out of a river or the river underground water table onto the river flood plain. These pumps have been powered by industrial gasoline engines then diesel and more and more by electric motors, the shifts being due to changes in the relative prices of diesel and rural electricity. Because rivers have a vertical fall down their courses, as long as the fall of the irrigation ditches is less than that of the river they could be extended miles up river to (eventually) meet the river bed, decreasing the lift considerably and thus the operational energy requirement. But building these ditches requires a major up front investment because right of ways have to be obtained, a lot of dirt has to be moved and if they are not lined, they loose a considerable amount of water to seepage over their length. So, do we locate these current circumstances, make the big investment now, essentially in diesel fuel to move the dirt, to reduce long term operational energy investment in lifting the water and producing crops? ASFAIK, the US government is not doing these major irrigation projects now but should it do so now to support future crop production for the expanding population? Or let the market take its course?
I'm reading the posts here and I must say here that I think this is a very important area. True, the question is (can be made to be) very simple, but to find the answer requires some very complex equations (BTW, M. King Hubbert's 1956 paper predicting the US's 1970's oil production peak was over 50 pages long and full of equations. Thanks to Ken Deffeyes we get the HL curves).
In short, today's energy producing industry is very intertwined. We use oil to dig out coal, coal to power the electric pumps that move natural gas, natural gas to turn tar into asphalt, etc. None of the refineries today fully resemble the structures that they were originally built to be, refinery "creep" has changed the face of the industry. The processes used in these energy industries have changed due to technological innovations, and as a consequence so have the EROEI numbers. I've heard some suggestions that a lot of the oil pumped in the US wouldn't be coming up if not for the IMPORTED low-EROEI petroleum-based products used to power the pumps. I don't know if this is true, but it would be interesting if it is.
The energy industry is motivated by profit; when the profit is gone so is the flow. As such, I believe oil (and other energy sources) will stop flowing LONG BEFORE we ever get close to an EROEI of 1:1. When it's 1:1 there will DEFINITELY no longer be a profit in it... BUT WILL THERE be a motivating profit in it at 2:1?.. 3:1?.. 4:1?
I don't know.
Well put, gentleman. It's a hard pressing issue.
Meaning that, if coal heavily depends on oil (to move trucks and so on), and oil would be suddenly "out" (not likely, but still), then coal wouldn't be produced at all, and this doesn't even take consideration at EROEI.
I like the idea of being able to measure EROEI, and this series (and the lively discussions it has provoked) has been interesting to read.
I think that markets might be a useful way to maximise EROEI, but only if they are rigged. Rigged using tax structure and legislation, all of which have to be flexible enough to transmit efficiency gains into the markets' mechanisms. How do you keep the lobby groups out, distorting markets and diverting resources to their personal troughs?
I'm not sure about the price proxy idea though. The basic problem is that economics thinks its basic unit is money, whereas in reality, economies depend on energy. If the economists could work out how to base their fundamenal equations on energy it would be a significant advance. Even worthy of the label "paradigm shift".
One thing that occurred to me is that, given the difficulty in calcualting total EROEI, would not measuring the delta in EROEIs be of use? For example, consider the energy to grow the food and take it to the supermarket and then to the home of the guy whho eats it and goes to work in the oil fired power plant. This energy will be the same, whether he works in an oil fired plant, or if he works on a wind farm. So the delta is zero. You only need to look at the differences between the oil fired plant and the wind farm.
Then you can look at things like the difference in commuting distance for the same vehicle, or consider the delta if he uses an SUV or a Toyota Prius.
The difficulty with your suggestion is that energy is not just energy. It comes at different prices depending on the energy required to extract it from the environment. Or maintain the machinery (think humans).
The dollar - to a certain extent encapsulates the sum total of all the prices of all the various kinds of energy used to make something.
Substituting machines and microprocessors for humans reduces the high energy cost inputs (i.e. a BTU of oil costs less than a BTU of human food.)
The thing you leave out of the calculation is metals recycling.
A large fraction of the energy cost of the next truck has already been paid for.
Think about the decades long stagnation of copper prices. Why? Well the telcos replaced a lot of copper with fiber.
In fact our biggest inventories of many metals is above ground.
The key to the future is that capitalism forces a continual process of doing more with less.
If transportation becomes more of a problem America has a lot of modems.
Things will change depending on price signals.
The minus one is useful if you are trying to figure out the net rate of flow and increase.
Say it costs 10% to maintain a system (oiling the bearings - building the next generator - maintaining the wires). With that you can replace the generator every 10 years. Which takes 10 years to build.
Say your generator has a gain of 10. That means you have 9 units to do with as you please. If you use 1 more unit you can build 2 generators in 10 years (yeah, I know there are other factors but I want to keep this simple). That leaves you 8 net units and you double the number of generators every 10 years.
If you could get by on 6 units of energy you could quadruple your output every 10 years.
Let us say that you didn't need any of the energy. That says that you could build 9 additional windmills in 10 years.
Thus the minus one.
However, it has no practical meaning because at the end of 10 years you will have 10 windmills which can each spawn 9 more giving 100 windmills at the end of the following 10 year cycle.
I hope both sides are satisfied.
EROEI is a nice concept, but not good enough if we want to be scientifically precise. The flaw of this concept is precisely the comment that began this blog, the past energy invested that allows present day use of energy.
This past energy investment is precisely: machinery, dams, roads, railroads, trains, etc. etc. that were built mostly upon hydrocarbon burning. So how can you evaluate the energy "embedded" (another nice concept) in a car today? You can evaluate direct fuel / electricity consumed but you cannot evaluate the energy invested in the factory, transport, human labor, etc.
As to wind energy, have you seen those huge german eolic generators, that are maintained with a... helicopter??!! Please, how are we to change parts when oil becomes scarce? on a wood ship?
"EROEI is a nice concept, but not good enough if we want to be scientifically precise."
Not good enough for what? It is a fine concept, but people misuse it. They try to cast doubt on the EROEI of an energy conversion system by requiring infinite regression of the energy used in a process or in the making of a machine. If they actually did the calculations they would see that after acounting for the major sources of energy they would get a pretty accurate number, backing up one level would make it a lttle more accurate.. and so on until it is clear that the calculated EROEI is approaching a certain number, just like finding limits in calculus.
"Please, how are we to change parts when oil becomes scarce? on a wood ship?"
What are you talking about? Are you trying to say that the oil needed by the helicopter would be significant compared to the energy generated by the wind turbine? That seems pretty absurd. Even if we didn't have oil, we could use electric cranes.