Thursday, March 11, 2010

Limits on the Thermodynamic Potential of Archdruids

I often read John Michael Greer, the Archdruid. He's a smart and thoughtful guy who worries about some of the same things I worry about, though he tends to have decided they are all hopeless, whereas I tend to see society as having a lot more options than he perceives.  He has read very widely and often comes up with interesting historical analogies that hadn't occurred to me, so he's well worth the spot in my reader.

Where he tends to go horribly wrong, and why I think his overall take on the subject is too negative, is when he tries to talk about physics. In a recent series of three posts:
He has been trying to argue that there are fundamental physical barriers to society surviving the transition away from fossil fuels, and getting horribly snarled up.

Now, I am not a working physicist, but I may well be the nearest thing that will admit to reading the Archdruid - I trained in Physics, have a PhD in the subject, and then went into Computer Science.  But the points at issue are pretty elementary here, so let me try to straighten the Archdruid out, and at least place something in the record for anyone that might be confused by his arguments.

In short, there are no fundamental physical barriers to a non-fossil-fuel based economy - the main problems are social, economic, and practical, not issues of physical law.
Here's the nub of his argument:
The second issue, though, is the one I want to stress here. It’s seen a lot less discussion, but it’s even more important than the issue of net energy, and it unfolds from the most ironclad of all the laws of physics, the second law of thermodynamics. The point that needs to be understood is that how much energy you happen to have on hand, even after subtracting the energy cost, doesn’t actually matter a bit when it comes to doing work. The amount of work you get out of a given energy source depends, not on the amount of energy, but on the difference in energy concentration between the energy source and the environment.

Please read that again: The amount of work you get out of a given energy source depends, not on the amount of energy it contains, but on the difference in energy concentration between the energy source and the environment.

Got that? Now let’s take a closer look at it.

Left to itself, energy always moves from more concentrated states to less concentrated states; this is why the coffee in your morning cuppa gets cold if you leave it on the table too long. The heat that was in the coffee still exists, because energy is neither created nor destroyed; it’s simply become useless to you, because most of it’s dispersed into the environment, raising the air temperature in your dining room by a fraction of a degree. There’s still heat in the coffee as well, since it stops losing heat when it reaches room temperature and doesn’t continue down to absolute zero, but room temperature coffee is not going to do the work of warming your insides on a cold winter morning.
And he then goes on to argue that since sunshine is dilute, not concentrated, it doesn't have very much usable energy in, and therefore cannot power civilization (eg via PVs or concentrated solar power).

The trouble here is that a) normal daily use of the term energy is different than it's technical use in physics, and b) the Archdruid is conflating two different issues - the potential for work due to the temperature difference of two things, and the spatial concentration of that potential.

Let's do a very brief review of the two main principles of thermodynamics that were worked out in the nineteenth century (basically coming about during the time when society was developing better and better steam engines, and engineers and scientists were working through the underlying physical principles that governed their operations).

The first is called "The First Law of Thermodynamics", or "Conservation of Energy".
Energy can neither be created nor destroyed. It can only change forms.

In any process in an isolated system, the total energy remains the same.

For a thermodynamic cycle the net heat supplied to the system equals the net work done by the system.
This basically says that there is some quantity in physical systems and it's conserved. Obviously, this would be less meaningful except for the fact that people had already worked out that various things were forms of energy - for example, a hot body (like the Archdruid's coffee) contains a certain amount of energy on account of it's temperature. If he throws the cup across the room, it will have some kinetic energy - one half of it's mass times the square of it's velocity, and so forth.

The big discovery, which was originally made empirically, was that the total amount of all these different forms of energy, in a closed or isolated system, is constant. The nineteenth century physicists didn't realize, and it's still not widely known outside of physics circles today, but there is actually a really deep theoretical reason for this. Noether's theorem, named after twentieth century mathematician Emmy Noether, says that any (differentiable) symmetry in a physical system must give rise to a conserved quantity. And the conserved quantity due to the time-translation invariance of physics is what gives rise to the conserved quantity of energy.  In other words, the fact that the laws of physics appear to work the same regardless of time - if you do your experiments carefully, you'll get the same answer regardless of which day, week, or year, you do them in, is what gives rise to the conservation of energy.

However, again, I warn that "energy" as used by physicists and other physical scientists - the conserved quantity arising out of physical law - and "energy" as used by non-specialists in daily life (and by economists in their literature) are subtly different - though they are measured in the same units.  Let's proceed to explore that.

The second law of thermodynamics can be defined in various ways:
There are many ways of stating the second law of thermodynamics, but all are equivalent in the sense that each form of the second law logically implies every other form. Thus, the theorems of thermodynamics can be proved using any form of the second law and third law.

The formulation of the second law that refers to entropy directly is as follows:

In a system, a process that occurs will tend to increase the total entropy of the universe.

Thus, while a system can go through some physical process that decreases its own entropy, the entropy of the universe (which includes the system and its surroundings) must increase overall. (An exception to this rule is a reversible or "isentropic" process, such as frictionless adiabatic compression.) Processes that decrease the total entropy of the universe are impossible. If a system is at equilibrium, by definition no spontaneous processes occur, and therefore the system is at maximum entropy.

A second formulation, due to Rudolf Clausius, is the simplest formulation of the second law, the heat formulation or Clausius statement:

Heat generally cannot flow spontaneously from a material at lower temperature to a material at higher temperature.

Informally, "Heat doesn't flow from cold to hot (without work input)", which is true obviously from ordinary experience. For example in a refrigerator, heat flows from cold to hot, but only when aided by an external agent (i.e. the compressor). Note that from the mathematical definition of entropy, a process in which heat flows from cold to hot has decreasing entropy. This can happen in a non-isolated system if entropy is created elsewhere, such that the total entropy is constant or increasing, as required by the second law. For example, the electrical energy going into a refrigerator is converted to heat and goes out the back, representing a net increase in entropy.

The exception to this is for statistically unlikely events where hot particles will "steal" the energy of cold particles enough that the cold side gets colder and the hot side gets hotter, for an instant. Such events have been observed at a small enough scale where the likelihood of such a thing happening is significant.[2] The mathematics involved in such an event are described by fluctuation theorem.

A third formulation of the second law, by Lord Kelvin, is the heat engine formulation, or Kelvin statement:

It is impossible to convert heat completely into work in a cyclic process.

That is, it is impossible to extract energy by heat from a high-temperature energy source and then convert all of the energy into work. At least some of the energy must be passed on to heat a low-temperature energy sink. Thus, a heat engine with 100% efficiency is thermodynamically impossible.

A fourth version of the second law was deduced by the Greek mathematician Constantin Carathéodory. The Carathéodory statement:

In the neighbourhood of any equilibrium state of a thermodynamic system, there are equilibrium states that are adiabatically inaccessible.

A final version of the second law was put to rhyme by Flanders and Swann[3], based on the Clausius statement:

Heat won't pass from a cooler to a hotter
You can try it if you like but you far better notter
'cos the cold in the cooler will get hotter as a ruler
'cos the hotter body's heat will pass to the cooler!
Cute.

Entropy was initially defined by physicists without knowing the fundamental basis for it, but later work discovered that entropy is basically the degree of disorder of the microscopic description of the system. It turns out that the universe apparently began in a fairly unlikely state (high order, low entropy), and now always evolves in the direction of more likely conditions (lower order, more entropy).

Now, the second law gives us some idea that not all energy (in the physicist sense) is equally useful. Since heat (a form of energy) won't flow, for example between two bodies at the same temperature, a room-temperature cup of coffee cannot be used to generate energy. In contrast, a body at a high temperature (relative to the environment) can be put to use. (By "put to use" here, we mean "made to do work"). So when the gasoline inside your car engine burns, it's at a much higher temperature than the environment, which is why a car engine can do lots of useful work. In particular, and what I think the Archdruid is trying to grope towards, the second law of thermodynamics can be used to prove a fundamental theorem on the thermodynamic limits of the efficiency of any process for turning heat into work:

The second law of thermodynamics puts a fundamental limit on the thermal efficiency of all heat engines. Surprisingly, even an ideal, frictionless engine can't convert anywhere near 100% of its input heat into work. The limiting factors are the temperature at which the heat enters the engine, T_H\,, and the temperature of the environment into which the engine exhausts its waste heat, T_C\,, measured in an absolute scale, such as the Kelvin or Rankine scale. From Carnot's theorem, for any engine working between these two temperatures:[4]
\eta_{th} \le 1 - \frac{T_C}{T_H}\,
This limiting value is called the Carnot cycle efficiency because it is the efficiency of an unattainable, ideal, reversible engine cycle called the Carnot cycle. No device converting heat into mechanical energy, regardless of its construction, can exceed this efficiency.
Examples of T_H\, are the temperature of hot steam entering the turbine of a steam power plant, or the temperature at which the fuel burns in an internal combustion engineT_C\, is usually the ambient temperature where the engine is located, or the temperature of a lake or river that waste heat is discharged into. For example, if an automobile engine burns gasoline at a temperature of T_H = 1500^\circ F = 1089 K\, and the ambient temperature is T_C = 70^\circ F = 294 K\,, then its maximum possible efficiency is:
\eta_{th} \le 1 - \frac{294 K}{1089 K} = 73.0%\,
This is the fundamental problem with the luke warm coffee - it's temperature is very similar to the environment, so it doesn't have much potential to do work.  Not only is there not that much energy in the heat difference to begin with, but even what there is is doing to have a very small efficiency in the usage - say the room is at 70F = 294K and the coffee is at 86F = 304K, then the thermodynamic efficiency of a heat engine using the coffee is at most 1 - 294/304 = 3.3%.

And it's this amount of useful work that you can get out of something (the exergy in a fairly modern christening) that we really care about.  My observation is that ordinary daily use of the term "energy" means something like "The amount of useful work we could get out of this if we could do it at 100% efficiency".  That's roughly what we mean by the energy content of gasoline, for example.  So the luke warm coffee has much less useful energy than it appears, because the thermodynamic efficiency of using it is inevitably going to be so low.  In the modern coinage of "exergy = useful work obtainable from the system", the exergy content is much less than the energy content.

However, it's not the fundamental problem with sunlight.  By trying to use "concentration" to cover both thermodynamic potential to do work, and concentration in space, the Archdruid is getting confused. Sunlight is (pretty close to) black-body radiation at an effective temperature of the surface of the sun - around 5500K.  So the thermodynamic constraints on using sunlight to do work in an environment at the temperature of the surface of the earth are not an issue 1 - 294/5500 = 94%.  Practical efficiencies are far lower (for example PV panels generally achieve 10-20% efficiency, which is still an order of magnitude better than plants).

It is true that sunlight is dilute, but that's a different issue, and a practical engineering and economic one.  Basically, it comes down to the net energy of whatever collecting environment you have - it better take less energy to build and deploy it than you get out of it.  But look, really, the high positive net energy of solar panels was settled long ago.  Do a quick literature search on, say, net energy photovoltaic, and you'll come up with boatloads of relevant papers. For example, here's a 2004 paper by Richardson and Watt in Renewable and Sustainable Energy Reviews:
EYR values for three different PV products (a single multicrystalline silicon module, 2 kW rooftop grid-connected system, and a solar home system) are determined to be 4.8–13.9, many times the energy inputs required to fabricate the system.
Or, here's a table from Application of Life-Cycle Energy Analysis to PhotoVoltaic Module Design, a 1997 paper by Keoleian and Lewis, using very conservative PV solar efficiencies by modern standards:



The last column indicates that, at least in sunny places, you get many times the energy out that you put in, and even in Detroit, you get several times more.

33 comments:

Sam Norton said...

Thanks for writing this. Even though the math is over my head it chimes with my own instinct.

Mike Aucott said...

Well said. Solar thermal is also attractive from a net energy standpoint, and probably so is wind.

Then there's 4th generation nuclear, the "fast-reactor" technology. My understanding is that these reactors could essentially eat up most of the existing nuclear waste, and also make it economical to extract uranium from seawater, which would enable running such plants for several billion years. Needless to say, a lot of research, discussion and development work needs to happen before we start deploying these in quantity, but I'd argue that nuclear and solar power, with a little help from wind, are indeed capable of providing enough energy to keep civilization going.

none said...

Well the maths isn't over my head. I understand your point, but I think you miss his, in which he placed your isolated response in a wider context.

Greer's postings are cumulative, and his point rests on a wider point of cultural expectation.

With energy you can do anything. In particular, with energy you can create technologies, which in turn allow us to solve most sorts of problems. Greer argues that we've allowed ourselves to succumb to a subtle failure of reasoning: that we can reverse causality and use technology to solve the problem of "creating" (or harnessing) energy. Energy isn't a problem to be solved - it is the means by which we solve problems. Declining energy means declining ability to solve problems, including the problem of arresting energy decline.

Elsewhere, Greer states the problem clearly: Hydrocarbon is the concentration of millions of years of sunlight over millions of acres of forest, refined by trillions of Joules of "geological" energy. Our contribution to that process in technology terms has been, effectively, to stick a straw in it and suck. We need to recreate the entire energy chain now, and at a scale and rate proportional to the rate at which affordable, energy dense hydrocarbon is depleting (about 4 million barrels per day each year).

Greer is seeking to explain to a general audience -- some of whom have difficulty, through no fault of their own, in locating the Y axis on a graph -- that this task is fundamentally constrained by certain physical laws. Those laws convey serious limitations on what is possible, they are immutable and most people have NO idea they even exist. They dominate the related economic and social issues.

Yes, an energy source that returns even fractionally more energy than is required by its construction, operation and decommissioning can theoretically be scaled and concentrated to generate sufficient high quality energy for our needs. But long before then in the scaling process you exhaust some related essential factor of production.

Greer if anything understates just how diffuse alternate technologies truly are - none currently returns more than it consumes. Everything you (and your 2004 references) believe is an "alternative" source floats on a vast floor of hydrocarbon energy, much of which is not even recognised. Those studies which purport to show positive net energy have simply excluded large chunks from the necessary life-cycle analysis. Just enumerate the energy cost of the factory to make the truck to mine the silicon ore, the energy to make the truck to transport that ore to another factory and its construction and operating energy cost, the energy to design, fabricate, transport, construct, operate, maintain, repair and recycle the cells. All of that is currently powered by hydrocarbon. Now plug that entire supply chain back into its own energy output and try and maintain "business as usual" in a world that until now didn't have to do *any* of that and is struggling with hydrocarbon depletion.

Meanwhile, our consumption of that energy must grow exponentially. Say it takes 30 years to change out a multi-trillion hydrocarbon infrastructure that took 110 years to build in an environment of an abundant, rapidly expanding energy source. At 2% energy growth rate (our 30 year historical average), we will be consuming twice the energy we consume today. And we need to do it from an energy source which, in my country at least, only requires you to wear sunblock about 5 days a year. Thermodynamics sets an upper limit on the pace of this process long before considerations of resource, capital or manpower do.

So I respect your point about thermodynamics, but I'm giving this one to Greer.

KLR said...

I've always found fault with Greer's writing on a scientific basis, too; his scenarios have the ring of Just So stories, for instance this canard that, with society slowly collapsing, oil production will continue to gently decline. Well, a very large portion of that production is from exceedingly complex deepwater facilities, which would break down in a matter of months without maintenance. Even a meager stripper well needs some occasional TLC, a replacement sucker rod or motor. These things don't fabricate themselves; what if the parts distributor's city is suffering an extended blackout?

Then there's his position that we could have transferred to a renewable civilization in the 70's, but can't now. Well, what's stopping us? Efficiency and cost/kwh have gone down, techs that were wholly science fiction back then have made it to market. I don't see peak oil as some immovable juggernaut, consider for instance the potential held in simple conservation - 10% additional carpooling in the US would stave off quite a few years of declining supply.

Meanwhile, our consumption of that energy must grow exponentially.

Some nations get by just fine without expanding their consumption of energy - Germany went from 1991 to 2003 consuming around 330 mtoe, the total decreasing thereafter. The data is there in BP's Stat Review or the EIA International energy data, if you want to see for yourself.

jagged ben said...

Thanks for this Stuart. I tried to point this issue out over on the Archdruid Report, and got some qualified acknowledgment from Greer that he was oversimplifying a bit.

@none

I pretty much agree with everything you say, except for the following:

"[no alternative] currently returns more than it consumes."

In my opinion that is, at best, an educated guess. Granted there are a lot of questions about studies like the one's Staniford linked to, but pretending like these controversies are easy to resolve on one side or the other is, pardon my saying so, pretty arrogant in my view. Whether or not wind and solar can provide positive net energy without a fossil fuel infrastructure (some biofuel, but not too much, should also be allowed to figure in) is really an open question that is incredibly difficult to answer right now. Actually, it's THE open question...

Stuart Staniford said...

none - if you don't like the energy analyses I cited, can you point to some that you prefer which do the calculations the way you think they should be done?

Mike Aucott said...

In my view, an even bigger question is whether we are going to get serious about 3rd generation(modular design thermal with passive safety features) and 4th generation nuclear(aka "fast" or "breeder" reactors). The energy returned/invested ratio for 4th generation nuclear should be hugely favorable.

But "none" seems almost certainly correct that the declining curve of readily-available energy for all the necessary infrastructure and support (e.g., money) will make any transition very difficult.

jagged ben said...

KLR said:

"Then there's his position that we could have transferred to a renewable civilization in the 70's, but can't now."

I don't think you're stating his position very accurately: his view is simply that because we have delayed for so long we are now in for a lot more pain and difficulty than we might have been. Imagine if we had invested significant oil energy in building an alternative infrastructure, while existing uses in the 70s were kept steady or grown much slower. Now that global oil production is at or near its peak, the energy to build an alternative infrastructure has to be taken away from existing uses. That is politically and economically much more difficult. Put another way, it's not an argument about technological feasibility.

kjmclark said...

"can you point to some that you prefer which do the calculations the way you think they should be done?"

That requires something with a broad view, like the Hirsch report. Recall that it concluded, "Waiting until world oil production peaks before taking crash program action would leave the world with a significant liquid fuel deficit for more than two decades." and, "If mitigation were to be too little, too late, world supply/demand balance will be achieved through massive demand destruction (shortages), which would translate to significant economic hardship." (p 65) It's too bad Hirsch, Bezdel, and Wendling didn't go into more detail in their analysis.

I don't know if that results in "catabolic collapse", Great Recession, or something else, but we don't seem to be doing much crash mitigation.

Datamunger said...

In short, there are no fundamental physical barriers to a non-fossil-fuel based economy - the main problems are social, economic, and practical, not issues of physical law.

Well put.

The Archdruid is hobbled a bit by his grand narrative. Or rather, he'd like say that his is grounded in physics. But, in reality, it's a powerful intuition ( he is a religious thinker after all ).

But, at the same time, Stuart and others have used the metaphor of a runaway train when characterizing our growth-addicted civilization. (maybe sometimes even with a sense of deterministic fatality??) Is it that different from Greer's intuition?

We know, as Stuart pointed out, that the laws of physics aren't a brick wall (to change the image). Yet we do in fact sense a brick wall, a derailment at high speed, whatever.

Why?

Because the myth of limitless growth is dying in many of us: a psychological event of importance which may explain much of our preoccupation with these matters. I'm tempted to claim I accepted limits to growth half a decade back. But that's false. It was part of the structure of my psyche and the dying took years.

What has gradually emerged for me instead is a cyclical view of the economy with a lot going on under the the hood. This includes a strong suspicion that technology will find a way to advance (maybe just creep at times or mutate 'sideways') even if world GDP in 2030 hasn't advanced massively from current levels and even with some nuclear detonations in the interval plus add your favourite catastrophe.

No flat crash, no long descent, no stair step down, no flat-line stagnation, no singularity. Wouldn't hurt for us to get used to not knowing what is coming while keeping in mind civilization's truly enormous homeostatic capacity.

kjmclark said...

I suppose there's also the GAO report: http://www.gao.gov/new.items/d07283.pdf. It largely agrees with the Hirsch report.

It does seem odd that those reports don't give much credence to conservation. I suppose that counts as demand destruction.

Stuart's right, of course, that the problem isn't physics or engineering. It's the social and political will to deal with the problem. But that's also the difficulty with the US long-term health and debt issues and climate change, which we're largely hoping will just go away or denying exist at all.

KLR said...

jagged ben - we can't gauge the response of the developed world to a sustained oil shock; perhaps we will react in a bad way (war, riots, GDP through the floor), perhaps in a productive way (successful rationing programs, patriotic citizens working overtime to build out alternatives, etc). We only have a few examples to go by - WWII, GD, 70s oil shocks. How that will play out in the future is a real wild card, but I don't see energy per se as being the real limitation; I highly recommend the IEA document Saving Oil in a Hurry if you're not familiar with it already. There's a whole slab of fat we could trim, which could buy who knows how much time; I don't recall Greer ever commenting on this simplistic enough solution.

As I said, the real time response to oil shortages is up in the air. I was fairly disheartened by how my countrymen and elected reps in the US behaved in mid 2008, by the way. But I still think there's potential, even for curbing demand effectively through the boring old marketplace and its plug in hybrids; the jury's still out there, and believe me, I've messed about with the available data a lot.

Now, on the very long term I'm more on JMG's side. We can't just take a crap on the planet forever, barring some fantastic method of scrubbing all the feces away as we squat, powered by some energetic deus ex machina of course. Even with that in place we'd have to eventually move out into space, unless we want to live in a realized John Brunner/Robert Silverberg novel. Or become The People of Sand and Slag, wholly indifferent to burnt out landscapes.

aargh! said...

It might be helpful if we were to define a barrel of oil in terms of energy gathered from sunlight. It would be interesting to have some idea of scale.

none said...

Sorry for the "none" business - I don't see how to set my name (Rich Lyon).

@klr Some nations get by just fine without expanding their consumption of energy

OECD do, but only because we consume so much energy that we can create tertiary economic services (like selling insurance and Starbucks to each other) that look like meaningful economc activity and don't consume much energy - but we export all the energy heavy lifting to China. And THAT only works for as long as distance is free, which of course it won't be shortly. Then we have to start making steel and concrete here again, and we'll discover the tertiary economy was an illusion brought about by vast energy surplus while wondering why our financial system just shut down.

Non-OECD don't - and they are the other 80% of the population. Neither do all the oil exporters, who sell oil to themselves at 7c a gallon and are doubling domestic power consumption every decade or so running desalination plants while trying to figure out how to avoid having to grow their food in the Sudan because their aquifers are at 20%.

@jagged - I didn't mean to sound arrogant - sorry. Its fairly easy to answer, though. We know the watts/m2 of all of the technologies (wind, solar, biofuel, biomass) and, even with generous allowances for tech efficiencies, you run out of land / material / money long before you get to meaningful fractions of 84 million barrels a day oil equivalent energy. How small a fraction that is "too small" is of academic, but not practical, relevance. Our path lies in radical demand destruction - there are no meaningful supply solutions. Which is Greer's point, think.

jagged ben said...

none (Rich) said:

My disagreement with you was about whether there are any renewable alternatives to oil have a sufficient net energy to support themselves without fossil fuel inputs, not about whether such alternatives can scale globally to replace 84 million bpd of oil. I firmly agree with you and Greer that they cannot, and that we are in for some level of energy descent.

However, if there are renewables that can stand on their own, how small a fraction of current petroleum energy they can supply is far from "academic". Rather, it could be THE important question in predicting how far our energy supply is going to fall and when the fall might stop.

I'm not going to take the time to rehash every controversy about net energy calculations of renewables. Instead I'll just say that you've offered no additional information to sway my current opinion (which is "we don't know!"). Nor did you respond to Stuarts request that you supply some alternative numbers to those he cited.

In summary, I think this discussion I think is just extra evidence that the questions are NOT easy to answer.

none said...

@jagged ben

I'm not sure what question you are asking, so I can't really comment on whether it is easy to answer or not. The poster of the article has made an interesting point about thermodynamics and, in my view, slightly misrepresented an argument in the process. I didn't really consider myself trying to change your opinion on anything, so if you are content with your views then that is fine by me.

My point about the energy studies is that no-one has done one that encompasses the whole supply chain. So your request to provide an example of one that does doesn't make a lot of sense to me.

I would only say in response to your assertion that "we don't know" is that the nature of the problem means that we know enough.

The irreconcilable, orthogonal features of "alternative" energy (or more accurately, "hydrocarbon extenders") are that they (1) are diffuse and (2) exhibit low net energy. In combination that necessitates massive scale.

Some things we need precision for before drawing conclusions, some we don't and "scale" is one of those things that we don't. A mouse, scaled to the size of an elephant, collapses because its legs get only 4 times stronger where its weight gets 8 times heavier. I don't need a 3 year research programme and 6 significant figures of accuracy to determine that - I need the back of an envelope.

By extension, it is axiomatic that complex politico-economic systems that work at small scale fail utterly at large. This blindness to scale and its implications is the most striking shortcoming of utopian thinkers.

But the whole argument is irrelevant anyway, to my mind. The capacity to create such scale even if were possible, not to mention the essential factors of production that govern mortality rate (food, clean hot water and medical facilities) depend on a functioning complex society, which in turn depends on a functioning financial system. Fiat currency fractional lending systems cannot function under conditions of contraction - you need to make slightly more each year to repay the previous year's debt, or the whole thing ceases to function.

So your argument that there is some key uncertainty we don't know about how far our energy supply is going to fall sounds a lot like the uncertainty of whether we are running a little bit slower or a lot slower than the bear that's chasing us.

My conclusion from this is Greer is right on another point - it is so easy to fall into traps of self-delusion and overlook the obvious when faced with deeply unpleasant prospects.

--Rich

jagged ben said...

Rich (none) said:

"I'm not sure what question you are asking"

The question is whether alternatives to oil provide a sufficient return on energy invested. Or, a related point, whether alternatives can be self-sustaining without a fossil fuel powered infrastructure.

You said:

"My point about the energy studies is that no-one has done one that encompasses the whole supply chain."

Which is exactly why I say that the questions above are difficult to answer. (Also, if you look at the "price-as-proxy" , problematic as that methodology is, it suggests renewables have positive net energy with supply chains included.)

"The irreconcilable, orthogonal features of "alternative" energy (or more accurately, "hydrocarbon extenders") are that they (1) are diffuse and (2) exhibit low net energy. In combination that necessitates massive scale."

How massive a scale is necessitated, and whether that makes it irreconcilable, is a quantitative question; it can be guessed at by doing calculations. Such calculations suggest that replacing the current US fossil fuel usage with solar would take up anywhere from about %1 of US land area to at least 10 times that. The former is at least imaginable, the latter really is not. (For reference, urban areas of the US cover a couple percent.) What accounts for the difference of an order of magnitude is the unknown net energy factor. It makes a huge difference.

none said...

@Jagged ben - OK I think Greer's point about the ease of self-deception has been more than adequately illustrated by now.

China's oil demand jumped 28% in January and the oil price today is pushing $83 (at which price the US economy has always crashed since 1960) and all the emergency bank bail out funds are blown.

California, Arizona, Rhode Island, Michegan, Oregan, Nevada, Florida, New Jersey, Illinois and Wisconsin are all in massive budget shortfall. It's the third year of economic recession, all the "fat" and "nice-to-do" spending has been eliminated and on 1st July the next fiscal year starts, with the states preparing to declare massive layoffs of state employees.

Federal Housing Association loan loss reserves are now almost exhausted. US mortgage delinquency is skyrocketing just as the mortgage resets start rising again.

The US can't write cheques to keep its school system solvent, it is on the verge of the next, effectively permanent recession and liquidating 50% of federal tax receipts on two separate wars to secure future oil reserves and you are suggesting that it has the means to install PV arrays over 1% of its surface (96 thousand square kilometres) and construct the necessary infrastructure to support them ?

And while we don't know whether the land, materials, capital and manpower the US would need to achieve this is colossal or truly gargantuan, we know accurately the energy equivalent rate at which it will have to start coming on stream at whatever $m/Ktonne/km2 per MWh it turns out to be - 4 million barrels per day per year, pro rata, from 2013.

I think the uncertainty of whether it is 1% or 100% and the absence of sufficiently accurate studies to quantify that uncertainty is irrelevant, since even 1% is so far beyond reach it is breathtaking.

I dislike this type of thinking because it creates a dangerous distraction and sense of complacency for an already fatally distracted and complacent society.

And I think I will leave it at that.

Stuart Staniford said...

none (Rich):

As far as I can see, you are claiming that renewables can never scale up, but a) you cant/wont cite any references to support your viewpoint, and b) you haven't presented even the beginnings of a quantitative calculation. Instead, you are waving your hands arguing that something that is, in the end, profoundly a quantitative question is obvious. But if its so obvious, you ought to be able to put numbers on it. The fact that you can't, and make a bunch of erroneous statements even talking about it, suggests that in fact you have no idea what you are talking about, and, when you are so quick to accuse others of self-deception, you should consider the possibility of projection.

For example, one claim you made was that there will never be enough land for a renewably powered society because sunlight is too dilute. But this displays that you don't know the first thing about the issues. It's quite literally two minutes work for anyone to falsify this claim - google "global primary energy consumption", and the Wikipedia will tell you that global primary energy consumption is 474×10^18 J/year - thats what it currently takes to power the entire global civilization. Divide by 365*24*3600 to get 1.5 x 10^13 watts. Then Google "solar constant" to find it's 1368 watts/meter^2. Say knock it down to 300 watts/meter^2 for a back of the envelope calculation allowing for nighttime, low angles, atmosphere, etc. So then you need 5 x 10^10 m^2, or 50,000 km^2 if you had 100% efficiency, let's say 250,000 km^2 at 20% efficiency. Google global land area to get 148940000 km^2. So it would requires ballpark 0.15% of global land area to power civilization entirely with PVs.

Sam Norton said...

Stuart - those calculations are all very well, but we both know that the prospect of achieving that is remote (for the social/political etc reasons you mention). I think the question being asked of you is "can such a shift be done technically, in the absence of hydrocarbon inputs?"

To which I would say:
1) the hydrocarbons won't switch off overnight; in addition, the cultural shift (= panic in high places) which will follow from the general realisation of resource peaking will trigger a government-directed push towards huge development of renewables. Chatter about the economics is somewhat beside the point, IMHO, as the government can achieve its desires without cash, just with guns and uniforms (and they won't be needed that much as most people will willingly work for these outcomes).
2) I don't think the interesting question is whether we can replicate *existing* energy use from renewables. Maybe we could in an ideal scenario, and taking generations to build it up - but we're not facing that. For me the interesting question has two points: i) what is the minimum level of energy, as a ratio of present use, that would allow something recognisable as 'civilisation' to continue. I think the proportion is actually quite low, not least because there is so much waste, and it would emphasise electricity rather than direct use of fossil fuels. In other words, civilisation as such will not come to an end if we no longer have private transport or air conditioning, whereas if we lost electricity then I think we are looking at winding back civilisation by a century or two; ii) whatever that ratio is - say 20% for arguments sake - can that level of energy be sustained indefinitely without any further hydrocarbon input? I suspect that the answer to that is yes, but I haven't seen any hard and fast research on it (eg what it would take to maintain battery technologies and PV maintenance for the solar, similar issues for wind etc.) The transport side of things doesn't worry me so much as I think we'd just end up doing things more slowly. If humans can build the pyramids or Stonehenge without fossil fuel inputs, I'm pretty sure we can erect windmills.

As I see it the future will be much more local, but there will still be a lot of high-tech. My guesstimate of the future has a man on horseback still using his mobile phone...

none said...

Fascinating stuff.

@Stuart Staniford

I have refrained from quantitative calculation in the thesis that renewable energy technology can scale to the same magnitude as hydrocarbon for much the same reason that I would refrain from quantitative calculation in the thesis that I can flap my arms and traverse the room: the thesis can be falsified more efficiently with a simpler argument.

The "waving of my hands", as you put it, is to point out the rather inconvenient truth that, if you can't maintain a complex manufacturing process, you can't pave the planet with the product of a complex manufacturing process. An argument that renewables might someday be capable of substituting for hydrocarbon is irrelevant if the means of bringing about that substitution depends on its availability today. Your capacity to achieve your hypothesis presupposes the achievement of your hypothesis and your argument fails (amongst other reasons) on petitio principii grounds.

But to your substantive point: In the absence of theoretical studies, why not work from real world analogues and extend ? The Mulhausen solarpark in Bavaria is representative of the technology we have today, and will give about 5W/m2. (MacKay "Fantasy time: solar farming", Sustainable Energy Without the Hot Air (2009), pp41) (link)

Assuming the Bavarian plant uses best commercially achievable conversion efficiency of 20%, but that we can somehow achieve the theoretical maximum of 60%. Then the maximum output based on extrapolation of a real world analogue would be 15W/m2 - 25% of your estimate. (MacKay suggests 10W/m2). I think you are estimating (20% x 300W) = 60W/m2. Assuming your initial land estimate and optimistically that you have only overestimated real world output by 400%, that's a nice round 1 million square kilometres.

I do not claim that land is scarce (outside of Europe). I am using land as a proxy for all the other inputs which *are* scarce, which scale (some exponentially) with land use. Gauging 10^13 watts is a bit tricky. It becomes straightforward to assess your claim when visualised as a square 1,000 km on a side filled with the output of a complex industrial manufacturing process.

At 1000 km on one side, the power losses in the transmission network just to transport energy *out* of the array exceed the current transmission losses of entire countries. Assuming 10% line transmission/conversion losses - current industry norms - implies 100,000 km2 of additional arrays to offset those losses, an area the size of Iceland. But those arrays need 10,000 km2 to handle *their* losses (an area the size of the Lebanon), and those need 1,000 km2 etc. etc. You forget about them like mouse scalers forget about legs because you are bound by the abundance thinking innate in hydrocarbon energy systems.

Constructing it isn't an event, but rather a process and the entire 1 million square kilometres must be kept dust free on a daily basis and undergo constant repairs to its convertors. Assuming you can access a 0.5km strip of arrays by vehicle either side of a road, you would need to construct 1,000,000 km of roadway to access each array in your grid (Canada has 900,000 km of roads). Assume a fuel efficiency of, etc. etc.

Assume it takes 30 years to construct such a grid (the existing hydrocarbon infrastructure took 110 years). Grid components have an average working life of 20-30 years. Energy consumption doubles every 30 years. So in 30 years we will be faced with the task of replacing the entire 1,000,000 km2 grid *and* building another 1,000,000 km2 grid, using the energy output of the grid - while living our own lives off the same grid's output. 30 years after that - replacing 2,000,000 km2 and constructing 2,000,000 km2. Etc. And we haven't yet talked about the other massive infrastructure builds implied by electrification competing for the same resources.

Ballpark.

wonderboy said...

@None/Rich Lyon.

I find your writing very interesting, do you happen to have a blog or other work?

none said...

@wonderboy - well, I appreciate it but I don't feel I have anything original to say on the subject - my views are pretty conventional "engineering/ pragmatism". My background is oil industry heavy engineering, but I'm currently switching into renewables via economics and policy studies. I don't have a blog that is ready for prime time yet.
- Rich

Stuart Staniford said...

BTW - just noticed a minor arithmetic error in the original version of this. I changed the luke warm coffee from 80F to 86F to correct it. Doesn't have any implications for the conclusion, however.

Tom Street said...

Could it be that this discussion is getting more complex than it need be. The Archdruid may have gotten the physics wrong, but does it really matter? Alternatives, even accepting your studies on energy return for solar,will not have near the net return that we have been getting from fossil fuels. Net return will make us poorer and more difficult to fulfill our needs, even needs that have been considerably powered down.

The open question is still what kind of society we will be capable of in the future. What kind of life will be able to lead when fossil fuels are substantially depleted.

I say press on with the alternatives as we are getting more efficient at producing them. In the future, we may discover that things will be much more difficult than under fossil fuels. In the long run, however, what real choices do we have.

The worst case may be that we have merely stored under some solar energy for the future through solar panels and wind generators.

At the end of the day, merrily proceeding as if fossil fuels can power our world indefinitely is clearly a disastrous strategy.

We may even end up going extinct or reduced for grubbing around in caves in a perpetual state of near starvation. In which case, we just join the crowd.

Walter said...

Thanks for the physics explanation. I have enormous respect for John Michael Greer (JMG), but I feel he has fallen into the ivory tower trap. His analyses, while mostly correct, feed upon each other and he takes the abstract for the real. We used to call this reification in grad school, but there may be another more relevant term now. I feel it is more important to be grounded in the work at hand. My work right now is building a sustainable agriculture model that will work in the post-peak world. I have had some success but the work is ongoing. I will think on your analyses while I plant potatoes.

jagged ben said...

@None/Rich Lyon

Your last reply to me is entirely a response to things I didn't say, things which indeed can't be deduced from things I did say. (Who said I thought the government would pay for anything, for example?) I'd appreciate it if you didn't ascribe to me opinions I don't have. That's basic courtesy.

In addition, you didn't respond whatsoever to what I actually did say, regarding EROEI.

As for hand waving, the entire debate here is whether investing in renewables such as solar PV is an exercise in hand waiving or not. Calling my efforts to interrogate the usefulness of renewables "hand waiving" is begging the question.

Finally, in your last response to Stuart, you engage in the strawman of discussing the obstacles to replacing all of current global energy use with solar. When it comes whether renewables are useful and worth pursuing in the short and medium term, this discussion is completely irrelevant. If it takes 200 years, then takes 200 years. How long it would take is a different question from whether it can happen.

Michael said...

I think the author and the Greer are talking about minor nuances – i.e. relative level of optimism.

However, the signal many people will get from this essay is "Ah, good, we can go on after all, just switch energy sources and then business-more-or-less- as-usual."

The above deception is so ingrained in our society that I have found Greer's analysis a breath of fresh air – bringing some reality to the scale of the problem we face. Confronting a naive belief that society is just a little bit non-sustainable. Easy to tweak back on track.

In 30 years of energy related debate I have come to understand that most people's attitudes to energy are faith based. Especially for males of our species who have become deeply enamoured by one 'alternative' technology or another. Nothing will shake their faith.

As a number of posters above have surmised the solution will end up with breeder reactors, but not many 'alternative energy' devotees realize that is what they are, in effect, championing.

So far past the tipping point, this is the only energy source on the horizon having adequate intensity to keep our kind of society going, though there will be much investment in softer options.

Nuclear devotees will see fourth generation reactors as a panacea, others cringe at the inevitable risks these will pose. Yet, it's the future that we are all beckoning with our naive societal obsession with supply side solutions to energy dilemmas.

none said...

@jagged ben

I'd appreciate it if you didn't ascribe to me opinions I don't have. That's basic courtesy OK. Sorry for that. But if you don't think public investment will fund this, you presumably think that private will. At the point public finances fail, private finance fails and I don't see the relevance of your distinction.

In addition, you didn't respond whatsoever to what I actually did say, regarding EROEI I believe I've said two or three times that there are no studies which investigate EROEI over the entire value chain over the entire life cycle. I believe you have asked me two or three times to produce them. I don't really know what to do about that. Subsequently I have made the point that there are other considerations - such as that of scale at any likely EROEI - which renders those studies moot. You either accept that argument or you don't but I can't see how repeating it helps either of us.

Finally, in your last response to Stuart, you engage in the strawman of discussing the obstacles to replacing all of current global energy use with solar I'm not sure that not talking about those obstacles is an effective strategy for preparing for the future. With all due respect, Stuart chose the scalability of solar in his claim to the viability of renewable energy technology to replace oil, and demanded a numerical response. It's not really fair to dismiss my response as a "strawman" - by all means pick a stronger argument if you feel there is one.

At some point, we have to construct the equivalent of 1 million square kilometers of "something". It doesn't matter what that something is. Breaking it up into little pieces doesn't make it smaller, and giving yourself longer makes it much larger. A million square kilometer "thing" that needs a road system the size of Canada won't do what you are hoping it will. These obstacles are intrinsic and insurmountable, and solar is our highest areal density option i.e. best case. There is no plausible EROEI that you can present that alters that. And we don't have 200 years. We have about 24 months before the means by which we hope to undertake these massive projects begins to degrade.

I don't really know how to bridge the gulf in understanding between us. I agree with Michael - we are gripped by "magic" thinking, and reality is very painful. I'm sorry. I respect your effort.

Bill Pulliam said...

I think your use of 5500K (the blackbody temperature of the frequency spectrum of sunlight) in your calculation for the temperature of the heat source for a solar powered heat engine is incorrect. I've posted an (overly long) essay on my own blog addressing this whole issue, which lays out an alternative calculation along with my rationale for it. My number comes out a lot worse than yours (25% instead of 94%):

http://bbill.blogspot.com/2010/03/sunshine-and-entropy.html

I'd love for a physicist with a current working fluency in thermodynamics to go through it and tell me if I am near the mark or if I have made a freshman mistake.

cedris said...

Whether or not any civilization can have truly sustainable electricity production is the real question here. Whether or not our current infrastructure with all its inefficiencies in housing, transportation, manufacturing, etc. can be replaced with renewable energy resources seems highly unlikely. Of course, I'll admit that it is likely possible given the laws of physics, but no one could be sure of this with the current information and there are probably too many variables, many unknown, to do the calculation now. We are travelling way too fast in the wrong direction, and by the time we actually make an effort to turn around it will likely be impossible. And in reality, it seems that a huge crash in available energy is the only thing that is going to make this civilization have some sense about designing completely sustainable and efficient lives. Extreme energy surpluses have allowed us to do some amazing things and some horrible things, but most of all, it has encourage waste.

The future may have electricity and it may not, no one knows that. However, if it does, my bets are on local production. Houses and factories that use thermal energy whenever possible and generate their own electricity where needed for manufacturing and transportation. These massive solar arrays seem so silly to me. It's simply a way to extend the life of the status quo past the age of oil.

adam manchovie said...

Stuart, thanks for this article -- I've been trying to get my head around exactly these issues.

One point though, your comparison between the efficiency of plants and PV is fairly misleading, since you are comparing the production of biomass (which includes the production of human grade foods, medicines, and is packed full of genetic information) to the production of electricity. (Not to mention that the plants self replicate, self heal, build themselves out of on site materials, and provide all manner of ecosystem services not least of which is keeping the atmosphere out of 'thermodynamic equilibrium' by producing oxygen.)

To make a fairer comparison you might compare electricity to electricity, and at the cellular level, plants do produce electricity from the sun's rays. They do it with extraordinary efficiency.

See: http://www.lbl.gov/Science-Articles/Archive/PBD-quantum-secrets.html

Of course electricity comes in different levels of energy 'concentration' too.

Also I saw that two different PV technologies are reaching 19.5 and 19.9 % efficiency respectively. Are they approaching some other theoretical maximum here? Your 94% limit is to "do work", not to produce high quality electricity specifically.

none said...

re. EYR values for three different PV products (a single multicrystalline silicon module, 2 kW rooftop grid-connected system, and a solar home system) are determined to be 4.8–13.9, many times the energy inputs required to fabricate the system. (Richardson and Watt, 2004)

To build a single multicrystalline silicon module, you need a factory to build a truck to mine some ore to make a crystal to make an array. You also need a functioning monetary system, a functioning financial system, a functioning institutional trust network, a functioning global transportation system, a functioning digital infrastructure, a stable society and an army installed in each of your critical hydrocarbon production centres. (I simplify - you need many more things.)

Each component is a single point of failure in the manufacturing process---its absence renders industrial manufacturing impossible. Each one requires enormous quantities of energy to sustain. All are currently powered by hydrocarbon. How much? Don't know? Well that's funny - NEITHER DO RICHARDSON AND WATT. In fact, they just ignored it them entirely.

So they worked out that, GIVEN a functioning monetary system, financial system, trust network, global transportation system, digital infrastructure, stable society, big army, a truck factory and trucks, and a huge input of hydrocarbon energy, you could get 4.8-13.9 times the energy input out of a PV.

Can anyone see the flaw ? Bearing in mind that solar PV has best in class EROEI amongst renewable technologies, anyone now care to hazard a guess at the magnitude of the shortfall between our net renewable energy generating capacity and the total energy demand of the industrial manufacturing system (as distinct from the demand of isolated bits of it)?

Stuart I do appreciate what you are doing here, but this is a classic example of the difference between normative forecasting (working backward from some ideal future) and contingent extrapolation (working out where we can get to from here).

Rich Lyon, Dundee