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An EROEI Review
Posted by Robert Rapier on March 18, 2008 - 11:03am
Topic: Supply/Production
Tags: energy return, eroei, eroi, sustainability [list all tags]
Introduction
I can be a very persistent (some might say hard-headed) person. If someone doesn't understand something that I think is important - and readily understandable - I will often continue to explain it until I am sure they either understand it and won't admit it, or they are incapable of understanding it. Because the topic of EROEI continues to be misunderstood (especially by those in the camp of "the only thing that matters is economics"), I will once again try.
Nate Hagens and I have discussed this subject at length on a number of occasions. He has written extensively on it, and I don't pretend that this essay can hold a candle to his magnum opus - and in my opinion best ever EROEI essay written at TOD - A Net Energy Parable - Why is EROI Important? (There's your dopamine fix for today, Nate.) This is just a little review of why I think EROEI matters.
EROEI Basics
There are a couple of important EROEI equations. The first is that EROEI = Energy Output/Energy Input. In other words, if we have to spend 10 BTUs (Input) to extract and refine 100 BTUs of oil (Output), then the EROEI is 100 to 10, or 10 to 1. Digressing for a moment, I recently had a conversation with someone who suggested that this is completely different from finance, where $105 returned on a $100 investment is a 5% return, not 105%. As I explained, the situation is the same. EROEI is a ratio. If I divide the $105 I get back from my $100 investment, then I get an output/input ratio of 1.05, but my return on investment is 5%. Likewise, if I input 100 BTUs and output 200 BTUs, the EROEI is 2 to 1, but the rate of return on my energy investment is 100%.
The second important equation concerns the net energy; that is how much energy was left after the energy input is accounted for. This equation is Net Energy = Energy Output - Energy Input. In our previous example, the net energy is (100 BTUs produced - 10 BTUs input), or 90 BTUs.
A couple of points here. First, the break even for EROEI is 1.0. In that case, you have input just as much energy into the process as you got back out. In some cases, that may make economic sense. For instance, if you input coal BTUs but got back out ethanol or diesel BTUs, then you have converted the coal into something of greater value. This is a source of the "only economics matter" argument. But this misses the larger point: EROEI is going to have a huge impact on economics, because it shows that in order to maintain current net energy for society, energy production must accelerate as EROEI declines. It isn't that planners are looking to EROEI to make their decisions; it is that a declining EROEI can indicate what those decisions will inevitably be.
However, if you input one transportation fuel and got another transportation fuel as output - as is mostly the case with corn ethanol (natural gas, diesel, and gasoline in; ethanol out) - then you are really just spinning your wheels. In a case like this, it would make more sense - given all of the negative externalities - to use the inputs directly as a transportation fuel. Funny that the shills will suggest that CNG infrastructure is lacking; these same shills are screaming for E85 pumps. Somehow countries like Brazil and India have managed to build out an impressive CNG infrastructure - yet we are being asked to believe this is not practical in the U.S.
Net Energy can also be negative and yet still make economic sense. But an important point here is that society can't run for long on an EROEI of less than 1.0 or on a negative Net Energy. Doing so is equivalent to withdrawing money from a bank - at some point you have to make some deposits - or at least stop the withdrawals.
The EROEI of Brazilian Ethanol
The case of Brazilian sugarcane ethanol deserves special mention. It is often quoted as having an EROEI of 8 to 1. I have even repeated that myself. But this is misleading, and I have to give credit to Nate for challenging me on this. The oft-cited Brazilian EROEI is really a cousin of EROEI. What is done to arrive at the 8 to 1 sugarcane EROEI is that they only count the fossil fuel inputs as energy. Boilers are powered by burning bagasse, but this energy input is not counted. (Also, electricity is sometimes exported, and credit is taken for this). For a true EROEI calculation, all energy inputs should be counted. So what we may see is that the EROEI for sugarcane is 2 to 1 (hypothetically) but since most inputs are not fossil-fuel based the EROEI based only on fossil-fuel inputs is 8 to 1.
That isn't to say that the 8 to 1 is an invalid measurement; just a different one. We need to bear that in mind when making comparisons. What is overlooked by touting the EROEI of 8 to 1 and skipping over the true EROEI is an evaluation of whether those other energy inputs could be better utilized. For instance, that bagasse that doesn't get counted could be used to make more electricity instead. Probably in the case of sugarcane, firing boilers is the best utilization. But the lesson from this digression is to be careful when people are touting very high EROEIs. They probably aren't really talking about EROEI.
Calculations
Now for some calculations that show the challenge of energy production if the EROEI of our energy sources continues to decline. In the early days of oil production, the EROEI was over 100. Now, it has declined to somewhere between 10 and 20. So let's look at the implications as the EROEI declines from 20. Here is what it takes to get 10 units of energy (gross, not net) at various EROEI values.
A 20 to 1 EROEI takes an investment of 0.5 energy units to get 10 out
At 10 to 1 it takes 1 energy unit to get 10 out
At 5 to 1 it takes 2 energy units to get 10 out
At 2 to 1 it takes 5 energy units to get 10 out
At 1.5 to 1 it takes 6.67 energy units to get 10 out
At 1.3 to 1 it takes 7.69 energy units to get 10 out
At 1 to 1 it takes 10 energy units to get 10 out
So, dropping from an EROEI of 20 to 1 down to 1.3 to 1 takes over 15 times the energy inputs (7.69/0.5) to output the same amount of energy.
Net Energy
But here is where many miss the plot. Look at the net energy.
At 20 to 1, an investment of 0.5 units got 10 back out. The net is 9.5 units.
At 1.3 to 1, it took an investment of 7.69 units to get 10 back out. The net is 2.31 units.
At 1 to 1, an investment of 10 units got 10 back out. The net is 0 units - all you have done is converted one energy form into another. (And of course at less than 1 to 1, you have actually lost usable energy during the process - clearly an unsustainable process).
If we wish to net 10 units, then at 20 to 1 we have to produce a total of 10.53 units (you are solving 2 equations here; EROEI = Out/In and Net = Out - In; For EROEI = 20, the solution is Out = 10.53 and In = 0.53). For an economy that requires 10 units of energy to run, we need an excess of 0.53 units to net that 10. (And if you want to pick nits or do the calculation yourself, 10.53 is rounded from 10.5263157894737).
Now drop the EROEI to 1.3. We now have to produce a total of 43.33 – an excess of 33.33 - to get the 10 we need to run the economy (Out = 43.33, In = 33.33; EROEI = 1.3 = 43.33/33.33; Net = 10 = 43.33 - 33.33). Thus, the requirement from dropping the EROEI from 20 to 1 down to 1.3 to 1 requires a production excess of (33.33/0.53), or over 60 times the high EROEI case.
Running Faster to Stay in Place
Therein EROEI illustrates clearly the challenge we face. As EROEI declines, energy production must accelerate just to maintain the same net energy for society. At an EROEI of less than 2, the amount of energy required to net our current energy usage far exceeds even the most optimistic proposals for our production capacity. Others have concluded much the same: The status quo can't be maintained if EROEI continues to decline. But by understanding the implications of EROEI, we can see this coming, and perhaps(?) start to change the status quo.
Yet I say with confidence that some will comment and still not grasp this concept. If they did, they would understand why a falling EROEI is reason for concern - and that concern is why I can be persistent over explaining the implications.
Previous Essays on EROEI/EROI
North American Natural Gas Production and EROI Decline
At $100 Oil, What Can the Scientist Say to the Investor?
The Energy Return on Time
Peak Oil - Why Smart Folks Disagree - Part II
Ten Fundamental Truths about Net Energy
The North American Red Queen - Our Natural Gas Treadmill
Energy From Wind - A Discussion of the EROI Research
A Net Energy Parable - Why is EROI Important?
Natural Gas and Complacency
Robert - a few thoughts on your nice summary.
1)In a pending paper, "A Consistent Definition for EROEI", Mulder, Lillies and Hagens point out that in situations where a co-product is used in the energy harnessing process itself (bagasse for sugarcane ethanol as an example), the traditional EROEI formulation does not account for the opportunity cost of the precursor energy input and thus overestimates the EROEI of the process.
The above graphics from that paper show the same process (cellulosic or sugar cane ethanol) measured in two ways. The bottom diagram shows traditional EROEI = energy out / energy in. The top graphic indicates that the intermediate step biomass K2 (the bagasse) has an energy opportunity cost as it could be used for other energy uses. This 'loss' of availability has to be considered, which translates to EROEI = (Eout +(E lost-Ein)) / E lost.
From our paper:
As you rightly point out Robert, the bagasse is probably being used for its best use, but in a different economy it might be used in many other energy technologies; heat, biogas, electricity, etc. that would have higher social efficiencies. So the bagasse has to be considered an energy opportunity cost, and if not counted as an input it will overstate the EROEI. This is relevant if we would change how society used energy. There would be less need for high energy surplus liquid fuels if things were done more locally, or with more electricity, etc.
2)You are absolutely right about declining EROEI forcing our hand. We can 'grow' with lower net energy, but only if the smaller energy surplus is offset by some mix of a)conservation b)efficiency or c)move to lower energy footprint infrastructure.
This all boils down to an acceleration of pulling in resources, both energy and non-energy inputs, in order to continue the ICE mode of transportation - a path chosen for efficiency and ease many decades ago. The more we try to generate liquid fuels with low energy gain, the faster we will use water, natural gas, corn, coal, etc. - the things that have NOT been in shortage heretofore.
I think as soon as there are more limiting inputs than just liquid fuels people will start to internalize the biophysical angle on this story. After all, dollars are infinite, but high density, easily transportable energy is not.
So what you are saying is that if you burn biomass A and B together in a power plant and use the electricity to power a BEV, then that could (depending on the efficiency of the plant, transmission and batteries) be more efficient than using the energy in biomass A to convert biomass B to ethanol and run the car on that? Interesting.
Yes, This is the ridiculous thing about the obsession with liquid fuels. An internal combustion engine with an optimistic efficiency of 30% has an EROEI of 0.30 whereas you could expects a BEV to be 0.8+. The whole thing is based on the continuation of ICE based transport which are the "installed base" creating inertia in the re-engineering of the system. The justification is "Range", evidently though 80%+ of trips are under 40k's we require ranges which match liquid fuel cars, this is clearly untrue.
There is some truth in the old joke "God managed to make the world in seven days because (s)he had no installed base"
There are some signs of sanity in the asylum though, I see VW have totally dismissed Hydrogen and are delaying their entry into the hybrid fad as long as possible, VW and Toyota must be licking their lips at their prospects in the US in the coming years
Neven MacEwan B.E. E&E
Which is silly, because the useful lifespan of a light-duty vehicle is ~17 years and 50% of the lifetime mileage is driven in the first 6 years. Designing infrastructure with a 50-year lifespan to suit ephemeral vehicles is letting the tail wag the dog.
The PHEV is the solution to that.
Good and bad, respectively. Hybrids are no fad; the PHEV is an evolutionary path to the pure BEV as battery technology improves and prices fall.
Well, the problem here is the boundary of the system. When you have a system and moving the boundaries you get different results for the same indicator referred to the same variable then it means that there is something wrong going on... In this case what is wrong is the indicator itself. EROEI is an easy indicator but should be used always the same way. In fact, it changes simply moving the boundary. Then this means you have to decide: using it as in the first case (arrows generated within the boundary and used in the processes within the boundary must remain in the boundary) or as in the second case (arrows must exit and then go back inside if they are meant to go in a process within the boundary).
If you assess a system using LCA, for example, you don't have these problems. Moving the boundary would generate the same results...
Nate, I'd be very interested in reading your paper when it is released.
I'm curious how you derived some of the figures you have in your example. I can't replicate what is often offered as energy balance of a (theoretical) cellulosic ethanol plant when tracking the mass balance of the plant.
Take 1 kg of switchgrass for example.
It's 42% cellulose, 31% hemicellulose, and 27% lignin (including 0.7% ash).
From the cellulose, assuming 100% recovery, the stoichiometric ethanol yield of 51%, and 75% fermentation efficiency of glucose, you get 0.16 kg (0.20 l) of ethanol, 0.21 kg of CO2, and 0.05 kg of other mass (additional bacteria body mass; dilute solids)
From the hemicellulose, assuming 100% recovery, and 50% fermentation efficiency of xylose, you get 0.08 kg (0.10 l) of ethanol, 0.15 kg of CO2 emission, and 0.08 kg of other mass.
The balance is 0.27 kg of lignin, at 21 MJ/kg energy content, or 5.7 MJ. Biorefinery direct energy requirement for cellulosic ethanol production is 28 MJ/l-output (EBAMM 1.1), or 8.2 MJ to produce the 0.30 liters from the 1 kg of switchgrass input.
My question is, how does this 5.7 MJ of lignin per kg of switchgrass input provide all the processing energy in the plant (including drying the lignin, which is in solution when separated) and generate enough electricity to export 1.9 - 5.4 MJ/l of electricity? (Range in Hammerschlag)
If you zero out the lignin "credit" in the biorefinery in the EBAMM model, the EROI drops to 0.88, including the 4.8 MJ/l "credit" for some undefined byproduct.
Anaerobic digesters use wet biomass to generate methane which can then be used by the biorefinery instead of natural gas(fossil methane). An Iowa engineer figured that a distillery's entire energy needs can be met by digesting the cellulose and lignin portions of the corn kernels.
The problem with ignoring the energy costs of the biomass can easily be seen when you are working with wood. (I have heard people in the cellulosic ethanol field say that they prefer wood to switchgrass, because it is much easier to transport and store.) If you use a huge amount of wood to power your process for converting wood to cellulosic ethanol, you will have a high return on the fossil fuel inputs, but you are likely to have a very expensive process, since wood has other uses.
Nate,
It is customary not to count the renewable energy input in such calculations. About 2000 times more energy in sunlight falls on a cane field than ever comes out as ethanol. So, roughly, EROEI=0.0005 if the renewable energy in is counted. It seems to me that you are beginning to venture in this direction with your modification. I suppose you could say that the bagasse is processed so it is no longer just sunshine, but then, how do you count the wind that dries it so that it can be burned? I think you are OK counting ethanol burned in a truck to bring the cane to the plant as an energy input, but I'm not sure that counting the biomass after squeezing it is right.
Chris
The problem with thinking within EROEI is that although it's a good method to evaluate systems on paper, it isn't a wide enough scope to understand whether it's a good idea in the real world. These are some items from an essay I wrote a while back on evaluating renewable energy systems.
Factors for Evaluating Renewable Energy Systems
loss of energy during transmission is a major factor in total system feasibility. The closer the renewable power generation system is to the consumer, the more efficient the total system is. If the system is used to manufacture energy transport media, the distance the energy product needs to be transported is also important.
The guideline from the utility companies is at around 10% intermittent generation to maintain grid stability.
The other portion of reliability is related to serviceability and generally the less moving parts and simpler the system the less chance that a
component or the system will fail.
energy efficiency than systems that are not serviceable and need to be replaced completely at the end of there usable life span.
hydroelectric dams usually require major disruptive changes to waterways and the local environment. The manufacture of the components may also have an substantial environmental impact and in the case of converting an existing waste product to fuel there may be a positive environment change.
The total system efficiency is affected by the engine used to convert the energy transport media to work by the consumer.
available to the general public.
replicated by the community or will be controlled by agencies that will arbitrarily set the market price once the system is in place.
Some good points, Rohar1.
Let me add a scenario. Let's take a situation where the world market is Saturated with Sugar (pretty much like the present.) BUT, Country A (Brazil, say) has hundreds of acres lying fallow which Could be used in Sugar Production.
Let's do something different. Let's SEPARATE the process of growing the sugarcane, EROEI-wise, from the process of making ethanol. In other words, let's assign the cane it's own btu number, and a number for the EROEI of producing the cane. And, yes, let's consider the Solar Energy as a freebie. Would this help?
All good real-world considerations.
It's also important to realize that one cannot simply chain together EROEI calculations in a purely mathematical way. If that were possible, one could end up with the following infinite progression:
1 unit energy -> process producing 1.5 EROEI -> 1.5 units energy
chain this together a few times and you would get:
1-> *1.5 -> 1.5-> * 1.5-> 2.25-> * 1.5-> 3.375 giving a total of EROEI of 3.375 (or however far you want to take the thought experiment)
Giving the impression that if you chain up a number of ethanol plants and consider the whole system, you get way better than 1.5 EROEI. What is wrong with this picture?
What wrong is that the equation utilizes ALL of the net energy from each step as input for the next iteration. Civilization, society, industry or a single organism trying to survive needs to access a portion of that net for other functions. That's why it makes a HUGE difference as we shift from 100:1 easy oil, when our industrial economy could utilize 99 barrels of oil to build stuff and bustle around like bees on ecstasy, to energy sources in the 10:1 range, where the non-energy producing part of the economy only gets 9 barrels to buzz around on for every 1 needed for re-investment in producing more. And that's why we won't be running an industrial economy (or probably any kind of civilization) on 1.3:1 ethanol, or any other low single digit EROEI source. Now some folks, like posters below who insist that $ matters more than EROEI, or that EROEI is some kind of religion that we worship, may not agree, but to me, this is a simple concept that gets grossly misunderstood or more often just ignored. We're not talking about the efficiency of a system or a process, per se(so engine efficiency is not comparable to EROEI). We're talking about how many barrels of oil (or of ethanol, or any other energy SOURCE) it takes to get more, leaving the balance for other uses - like growing food, heating homes, and transporting people and stuff. Once it takes all - or even most - of the energy just to get more energy, that is, as EROEI approaches unity, industrial society is screwed. I'm not here arguing whether that's a good or bad thing, but it will be a big thing. Some also try to debunk EROEI by comparing it to the generation of electricity. But that is comparing the conversion of one form of energy that is a source (coal, for example) into another form of energy that is a carrier (electricity). The electricity is tremendously useful to us, yes, but electricity itself is never a source for humanity - it is always generated from something else. Ultimately, there are only two sources of energy for humans - the sun (fossil fuels, solar, wind, hydro) and nuclear decay. I'm not a physicist, or anything close to it, so perhaps there's really only one ultimate source, but that's beyond the practical point I'm (very windily, I know) trying to make. As for where to draw the boundary in analysis, I say apply KISS. Picture a broad plain, a tribe of humans, a barrel of oil. They want more. They invest that barrel into the infrastructure to extract more from the ground. The work that one barrel does produces ten more. They take one and repeat the process, and have 9 left over to party with. This goes on for some time. But then the source rock gets stingy. Now they only get 2 barrels for each one invested. Party slows down. Big chief says, my father rode a camel, I flew a jet, son, you can still drive a car, but your son, when that one barrel allows us to extract only one barrel, will again be riding a camel. OK, I give up. It's a simple concept, I suppose folks will either get it or they won't. But we'll all be living by its impact, as William Catton laid out clearly way back in '80 in "Overshoot: The Ecological Basis of Revolutionary Change." (Oh, and sorry, ET, I know you're not one who misses the point, I merely took the opportunity of your hypothetical scenario to launch into my little rant...)
But that is exactly the point of my post. If we theoretically take ALL the energy output in a multi-staged process and apply it once again to the same process, we get, theoretically, an infinitely increasing ER on a given EI for the entire process. Obviously this cannot be even remotely real even if the math works out.
The larger point is that reality checks are always a good idea. When I see EROEI figures for solar PV of 10:1 bandied about, and look at the actual price, I know the figures are bullshit. Same with wind power.
Not sure that's true, and panel photovoltaic competes with me and my concentrating photovoltaic, partly. Mostly panel photovoltaic competes with distribution in a financial sense.
Most of the cost of photovoltaic is labor cost. Your are paying for the Ford F150 to haul the roofer around. In China the roofer costs less and travels by tram. Does that mean that panel photovoltaic has a higher EROEI in China?
We are on the same page ET.
My take on that situation is: Have the renewable-manufacturers utilize their own HOME MADE energy in all their necessary sub-processes (or as many as possible at least) and see where that bring them. Not far I’m afraid…
In the future when fossils are gone, we will be back to square-one and that is not a sophisticated square(!) I can see good old fashion windmills, various “easy” to make waterwheels some sort of sterling/steam-engine/generators and such driven by combustion
I have serious trouble to see modern WT-Nacelles and PV technologies made and maintained in that scenario, and by then their EROEI issues will be clear as the sun by midday.
In my mind we should develop “simple technologies” today, which are not focusing efficiency – BUT rather on simple functionality and easy to maintain demands (as good as it gets sort of thinking).
Let the Non-Engineer, also, expound a bit on "Civilization."
Successful ones tend to be made up to some degree by "Successful" people. Successful people tend to NOT be "Wasteful" people.
Will a Non-Wasteful Person ignore a fallow, but fertile, field as a source of energy just because it's a little harder to get energy out of than a barrel of "easy" oil? Even when the "easy" oil is getting harder?
I think that depends on what you mean by run the economy. Since oil is used at a practical efficiency of somewhere around a percent or so as long as we define it's use as that of personal transportation (for the most part) we have quite a ways to go in terms of smaller more efficient vehicles and to a less extent better drivetrain efficiency. If we define it as the transportation of people and tons of steel/plastic, then it's efficiency of use increases, but that's somewhat disingenuous since we could use even larger vehicles, say semis with 40,000lbs in the back, and see even higher efficiency of use because ICE efficiency tends to increase with load. What I'm saying is that we should look at efficiency from the point of view of consumption, not just efficiency for the sake of efficiency.
You wrote a hell of a lot of unneccesary words to get your (one line) point across.
"Once it takes all - or even most - of the energy just to get more energy, that is, as EROEI approaches unity, industrial society is screwed."
And THIS is the problem with the understanding of EROEI being propounded here.
We're NOT going to get down to unity. Not even close.
Wind power, wave power, hydro power, Solar power. Even growing vegetables.
All of these have EROEI of anywhere from the low single digits to the high twenties.
(Look at the footnotes on the original post).
Thus while it is true to say that we will have to produce MORE INFRASTRUCTURE and use a larger share of our economy to produce energy than we did before it is patently UNTRUE to say we are inexorably sliding towards an unproductive 1:1 situation.
There is a FLOOR under us and it's the lower limit of renewables.
Now taking this to it's LOGICAL CONCLUSION: Even if the return on energy invested is only 20% then that means you only have to build five wind turbines or wave generators or hydro plants or solar panels to get one FREE ONE each year.
Now by compound interest of EROEI that means that at 20% you double your installed base approximately every four years. If from that 20% you use 10% for other things than building your infrastructure you double your installed base every eight years.
So back to the point: We need to build INFRASTRUCTURE.
It also means that 80% of society's energy-production effort would be devoted just to obtaining more energy, and a mere 20% for the other things we need to do (like growing food). If you can't re-invest all energy to increase your installed base, you're screwed. On top of that, the source has to scale to nearly 5 times today's gross production for the same net.
Industrial society can't handle EROEI as low as 1.2. I'll bet that anything less than 8 is going to cause plenty of pain. Fortunately, most of our options are a lot better than that.
EP,
I agree with your point. But consider it a little more.
Even at 1.2, if they use half of the energy for other things (and we'll NEVER get that low) then it only takes 8 years to double the installed base, 16 years to quadruple the installed base etc.
Now go back and look at the actual EROEI numbers on the original post.
Wind, Solar etc are WAY better than 20%. And we STILL have a bunch of oil to get us kickstarted.
... you have 80% of the effort of society devoted to obtaining more energy.
Not unlike the times when 80% of people worked on farms.
You don't quite grasp how enormous a dislocation that would be. Industrial society needs more of a surplus than that.
EP,
I do understand the idea of using 1.2 I used it as an illustrative example because it's easier for people to understand 4 windmills gets you one free than it is to understand 320 windmills gets you 160.
I said "we'll NEVER get as low as that". If people just take the time to read the links at the bottom of the original poster's post (as I have) you'll see that the WORST of the renewables is nowhere near as bad as 1.2
Anyways, what's the matter EP? Have you become a doomer all of a sudden?
The problem is that the claimed EROEI for corn ethanol is greater than this, and it doesn't scale at all (neither does it include non-energy losses like topsoil). Using that as an example implicitly approves one of our most disastrous "energy" policies.
Hardly. Just reminding everybody that there are a lot more ways to screw up than to get it right.
not to be a doomer but:
1) i am uncertain how wide of boundaries those NREL EROI figures are - there is a good deal of infrastructure they may take for granted that is subsidized by oil
2) high EROI is great, but only part of the problem - we need high EROI that matches our current infrastructure. If we already had PHEV transport, rails, etc. then i would say that higher EROI solar would make oil a dinosaur. But clearly that is not the case. We need high energy gain consistent with what society is dependent on, OR high enough EROI to transition social infrastructure into a new era without too much pain
What's wrong with it?
Nothing, really. The only issue is that each cycle takes a full growing season, and it assumes that all of the production from the previous cycle is put back into the next cycle.
This is nice if you are bootstrapping a new infrastructure while society runs on some other source, but reality means you have to use some of the surplus outside the system that's normally defined when considering EROEI.
Reality therefore looks more like:
Ein*EROEI-Eext->Enext
or:
1.0*1.5-0.5->1.0
You are expanding the sytem the whole time. For oil, you are drilling more wells and building more refineries. For biofuels you are putting more fields under cultivation and building more distilleries. All the time you are not getting any net energy for other uses. Once you stop your expansion and start using energy elsewhere, you are back to your original EROEI. I think that if you think it through in this manner, you'll find that you never get more than the original EROEI even if you cease operations and take all the product from your last harvest for use elsewhere.
Chris
Excellent list and spot-on. It takes a comment I was going to make and expands it quite a bit.
That comment was that while the "quality" of energy is frequently discussed, I haven't seen it described in a simple way. That could be useful; seems like up until now energy has been valued mainly by cost of extraction and processing, and not by it 'intrinsic worth' to hominids wishing to perform 'magic'.
And the term 'magic' is used by me here because that's sort of the ultimate standard: a substance with infinite energy that anyone could pick up and use with no investment and store & transport at zero cost, causing no harm to the biosphere. We don't have any such stuff, but clearly some energy carriers approach that ideal more closely than others do, and where they fall on that line would be useful to consider.
The listing is good and more complete than my top-of the-head one, which was:
energy density
ease/cost of storage at earth-surface temps and pressures
Moving it around: threshold costs, complexity costs, etc
what stuff can currently or in theory be done with it
level of complexity investment to utilize it (ie, chain saw vs. fission plant,)
Investment thresholds for obtaining and using the energy carrier from where it starts (ie, gathering firewood vs. deep offshore oil drilling)
toxicity to the biosystem, in extraction, processing, or from use
safety
reliability
etc
It'd be nice to be able to assign a "quality coefficient" to different sorts of energy, even if it wasn't perfect. Clearly, kerosene is closer to being "magic" than is burning cowpies, since you can fly a jet halfway around the world on it nonstop, etc.
This is the complement to EROEI which is needed....
Great post, and continuing kudos to Nate for his work as well, can't want to see the next batch of stuff.
The problem is that 'quality' as defined by our current socio-political system is not the 'quality' that would be long term desirable or sustainable. We should set aside EROI for a moment and determine what type of society we can achieve post cheap oil - what infrastructure looks like. What the ecosystems look like. etc. This will then change the definition of quality - though I expect liquid fuels will always be valuable. But if transport fuels take up 1/10 as much % of our fuel mix in 20 years than they do today, the definition of 'quality' will have changed.
Next determine how much energy gain we can expect, not for next year but for next 100 years. This would require an analysis of best uses for the remaining high quality fossil stocks in order to turn them into renewables that could support the type of infrastructure in #1
Then we use net energy analysis as an allocation tool of how to properly allocate our energy stocks and flows into productive society.
We're kind of going about it backwards now - assuming that 'quality' is given by current conditions, and then bickering about which fuels have the better EROI, quality adjusted. Its the fixed cost nature of our current system that is the bugaboo. The barriers to change are so large that we will keep seeking liquid fuels without noticing we are destroying our life support systems to procure them
(p.s. Rohar -that is a nice list - all important things - tho energy surplus (via EROEI) is a biggie. Many of those things are also not accounted for in our present market system either - so 'energy analysis' as we speak of it has to include ecology and externalities.)
nice website too - if you want to write a guest post on that SHPEGS project let me know
So true. I actually find the quality of undrilled oil & pristine environment higher than jet fuel, perhaps why I didn't work out long-term as a doodlebugger. My "quality" comment had only to do with one of the confounding factors of having a conversation about energy with present-day humans, which is often unavoidable. BTU's are a pretty gross metric.
Well said. We should probably be thinking more in terms of Planetary Choices Created / Planetary Choices Foreclosed (PCC/PCF ?) which would treat energy as a sub-category, and for that matter human activity as a sub-category. I'll try thinking up a way to sell that & get back to you....
Elsewhere in the comments H. T. Odum is mentioned, as are the concepts of eMergy and Lifecycle Assessment (LCA) as analysis tools. Essential to understanding energy (according to the wikipedia bit on eMergy) is the concept of transformity or quality of energy. Elsewhere this appears to be related to the concept of exergy [Gibbs].
EROEI seems a useful concept specifically when addressing the dropping productivity of oil or other liquid or coal production. But I think the energy quality issue needs to be incorporated to avoid the twisted explaining away of Brazilian sugarcane EROEI.
Also, it is critical where you draw the system boundary in determining net energy, as the poster about LCA mentioned. I want to add the concept of energy yield [Mollison, Holmgren] to the discussion, that is, the net energy out of a system when all the systems energy needs are met. This is not, on the surface, different from net energy, except that it explicitly identifies the boundary / scale of the system as being a key determining factor.
Odum [The Energy Basis of Man and Nature] states that not all BTUs are the same- some have the ability to do mechanical work. This may be what the "economic value" folks have in mind. Odum proposes a Fossil Fuel Equivalent (FFE) as a way of converting all types of energy, as measured by heat (BTUs, calories, etc.) into a common base quality energy.
1 FFE =:
These were written in 1976 so the conversions may be somewhat different today. But it clearly shows that the analysis of return and net energy needs to be broadened.
Odum was a genius and I have learned a great deal from his work, and his students. But eMergy is something I just can't internalize-it complicates things even more.
The graphs I post do not twist EROEI of sugarcane at all - they just show that some energy is used to process it that could have a different use.
In the end, all we are trying to do here, with ecological economics, EROI, net energy etc. is to have more of a biphysical/ecological basis for our decisions. How we do that is of course important but I think we are still at the stage of convincing people it should be done.
I clearly get the relationship of energy in to energy out and how much of the energy out is net but the sour