Photovoltaics? Who in the world would want to spend money on such a silly idea?

The "Solar Roadways" plant in Idaho in an image from the "EmphaseEnergy" site. The performance of this expensive plant is abysmally low and, with the best of good will, I can't see it as anything but a propaganda stunt to denigrate renewable energy. Not the only example of this strategy.

  

I have to confess to you one of my darkest sins: I read the unnameable blog by Anthony Whatever "What's down with this" and, occasionally, I even enjoy it. Probably, this sin of mine is condemning me to Hell, where I will be punished by having to spend eternity trying to teach thermodynamics to an audience of neoclassical economists.

Sometimes, however, the unnameable blog is worth reading. For instance, in a recent post, Will Eschenbach engages in an all-out attack against the "solar roads" plant in Idaho. The post is appropriately titled, "The Road to Hell is Paved with Solar Panels" and, in it, Mr. Eschenbach criticizes the plant mainly in terms of the cost of the energy produced. He says that it produced 246 kWh in one year. Comparing with the total cost of the plant, said to be more than 4 million dollars, then, clearly, it is a bad deal.

Eschenbach has a point here, although, for fairness, we must note that the plant was never conceived as a commercial plant, it is a prototype or a demonstrator which involved a cost in terms of the development of special panels for a specific task. It is unfair to pretend from a prototype to generate a profit. The question is, rather, is the performance of the prototype good enough to be worth reproducing it at a commercial scale?

Clearly, the people of solar roadways have grand plans. In their site, they speak of paving all the roads in the 48 contiguous states and produce something like 15,847 Billion Kilowatt-hours per year, which is three times the total consumed today. There is a little problem, though: how efficiently could that be done? In their site, nowhere you can find the rated power and the actual performance of the prototype system. But, with some work, we can estimate these parameters.

First if all, they say that they installed 30 panels of 44 W each, The number is confirmed by counting the panels on the pictures of the plant. So, that makes a total rated power of 1.3 kW. Then, the data at http://pvwatts.nrel.gov/pvwatts.php tell us that a zero-tilt, 1.3 kW fixed solar plant in Idaho is expected to produce about 1600 kWh/year.

Comparing this result with the 246 kWh reported by Eschenbach, we see that the plant has big problems: it produces less than 20% of what it should produce. There are various reasons that may explain the poor performance of a PV plant. In this case, it seems reasonable to me that a plant located in the middle of a parking lot - with people walking on it - produces much less than a standard plant would do.

So, Eschenbach is correct in noting the poor performance of the plant - nobody would ever want to use these devices for anything more than an expensive toy in a parking lot. But, in the end, that's not so much the point. The point is that the idea of "solar roadways" just makes no sense. Do you really want trucks to run over solar cells? I mean, think about that for two seconds and you can realize how silly the idea is.


This is not the only case I know of badly overpriced and poorly conceived solar plants. In the picture, here, you can see the "solar diamond," another high-cost PV installation built by ENEL in 2009 in Italy. (BTW, it stands close to where I live!)

Maybe you could find this object aesthetically pleasing, but the shape is wrong for a PV plant and its performance is abysmally low. You may also be interested to know that the cost of the whole plant, which includes a fancy hydrogen storage system, was about a million Euros for a total rated power of 13 kW. A better ratio of cost to power than the "solar road" in Idaho and, at least, this one is not supposed to have trucks running on it. But a big waste of money anyway.

So, how come that people engage in these silly ideas? Hard to say, there surely holds the principle that Eschenbach paraphrased in the title of his post "The road to hell is paved with good intentions." But, in addition to that, I can't avoid thinking that the people who promoted the idea and financed these plants did that with the specific idea to pass the message that PV is expensive and useless (*). As usual, propaganda rules the world.




(*) Note: this statement doesn't imply that the people behind the Idaho plant (Scott and Julie Brusaw) are evil or trolls paid by the fossil fuel industry. They may well be true believers in solar roads. Ufortunately, their work is being exploited by the enemies of renewable energy and they are helping to disparage the ideas that they try to promote. Propaganda is an opportunistic beast, extremely dangerous and always hungry.

Our Photovoltaic Future: The Metabolic Revolutions of the Earth's History.

Illustration from the recent paper by Olivia Judson on "Nature Ecology & Evolution (2017) "The Energy Expansions of Evolution". 

Olivia Judson published a very interesting paper this March on "Nature Ecology & Evolution". It is a wonderful cavalcade along 4 billion years of the history of the Earth, seeing it in terms of five "metabolic revolutions." It is an approach that goes in parallel with a paper that I wrote last year on BERQ; even though I focussed on the future rather than on the past. But my paper was very much along the same lines, noting how some of some of the major discontinuities in the Earth's geological record are caused by metabolic changes. That is, the Earth's changes as the life inhabiting it "learns" how to exploit the potential gradients offered by the environment: geochemical energy at the very beginning and, later on, solar energy.

Seen in these terms, the Earth system is a gigantic autocatalytic reaction that was ignited some four billion years ago, when the planet became cool enough to have liquid water on its surface. Since then, it has been flaring in a slow-motion explosion that has been going faster and faster for billions of years, until it is literally engulfing the whole planet, sending offshoots to other planets of the solar system and even outside it.

Judson correctly identifies the ability to control fire as the latest feature of this ongoing explosion. Fire is a characteristic ability of human beings and can be argued that it is the defining feature of the latest time subdivision of the planet's history: the Anthropocene.

Judson stops with fire, calling it "a source of energy" and proposing that "The technology of fire may also, perhaps, mark an inflection point for the Solar System and beyond. Spacecraft from Earth may, intentionally or not, take Earthly life to other celestial objects." Here, I think the paper goes somewhat astray. Calling fire a "source" of energy is not wrong, but we need to distinguish whether we intend fire as the combustion of wood, that humans have been using for more than a million years, and the combustion of fossil hydrocarbons, used only during the past few centuries. There is a big difference: wood fires could never take humans to contemplate the idea of expanding beyond their planetary boundaries. But fossil energy could fuel this expansion at most for a few centuries and this big fire is already on its way to exhaustion. If the Anthropocene is to be based on fossil fuels, it is destined to fade away rather rapidly.

Does this mean that we have reached the peak of the great metabolic cycle of planet Earth? Not necessarily so. Judson seems to miss in her paper that the next metabolic revolution has already started: it is called photovoltaic conversion and it is a way to transform solar energy into an electric potential, coupled with the capability of controlling the motion of electrons in solid state conductors. It is a big step beyond fire and thermal machinery (*). It is, by all means, a new form of metabolism (**) and it is generating a new ecology of silicon-based life-forms, as I discussed in a previous post that I titled "Five Billion Years of Photovoltaic Energy". 

So, we are living in interesting times, something that we could take as a curse. But it is not a choice that we are facing: we are entering a new era, not necessarily a good thing for humans, but most likely an unavoidable change; whether we like it or not may be of little importance. It is a new discontinuity in the billion years long history of planet Earth that will lead to an increased capability of capturing and dissipating the energy coming from the sun.

The great chemical reaction is still flaring up and its expansion is going to take us somewhere far away, even though, at present, we can't say where. 


A new lifeform, just appeared in the Earth's ecosystem:

(*) The Jews have been arguing for about a century whether electricity has to be considered a form of fire and therefore prohibited during the Sabbath. It is surely an interesting theological discussion, but for what we are considering here there is no doubt that fire (a hot plasma ignited in air) is not the same as electricity (controlled movement of electrons in solids)

(**) The supporters of nuclear energy may argue that the next metabolic revolution should be seen as the production of energy from nuclear fission or fusion. The problem is that the resources of fissionable material in the whole solar system are too small that they could hardly fuel a truly new geological epoch. As for fusion, we haven't found a technology able to control it in such a way to make it an earth-based source of energy and it may very well be that such a technology doesn't exist. But, on the sun, fusion works very well, so why bother?

Stereocene: The Future of The Ecosystem

 During the "golden age" of science fiction, a popular theme was that of silicon-based life. Above, you can see a depiction of a silicon creature described by Stanley Weinbaum in his "A Martian Odyssey" of 1934. The creature was endowed with a metabolism that would make it would "breathe" metallic silicon, oxidizing it to silicon dioxide, hence it would excrete silica bricks: truly a solid-state creature. It is hard to think of an environment where such a creature could evolve, surely not on Mars. But, here on the Earth, some kind of silicon-based metabolism seems to have evolved during the past decades. We call it "photovoltaics." Some reflections of mine on how this metabolism could evolve in the future are reported below, where I argue that this new metabolic system could usher a new geological era which we might call "Stereocene", the era of solid-state devices.

 

What Future for the Anthropocene? A Biophysical Interpretation 

An abridged version of a paper published in 2016 in "Biophysical Economics and Resource Quality"

Ugo Bardi
Dipartimento di Chimica - Università di Firenze

The history of the earth system is normally described in terms of a series of time subdivisions defined by discrete (or “punctuated”) stratigraphic changes in the geological record, mainly in terms of biotic composition (Aunger 2007a, b). The most recent of these subdivisions is the proposed “Anthropocene,” a term related to the strong perturbation of the ecosystem created by human activity. The starting date of the Anthropocene is not yet officially established, but it is normally identified with the start of the large-scale combustion of fossil carbon compounds stored in the earth’s crust (“fossil fuels”) on the part of the human industrial system. In this case, it could be located at some moment during the eighteenth century CE (Crutzen 2002; Lewis and Maslin 2015). So, we may ask the question of what the evolution of the Anthropocene could be as a function of the decreasing availability of fossil carbon compounds. Will the Anthropocene decline and the earth system return to conditions similar to the previous geologic subdivision, the Holocene?

The earth system is a nonequilibrium system whose behavior is determined by the flows of energy it receives. This kind of systems tends to act energy transducers and to dissipate the available energy potentials at the fastest possible rate (Sharma and Annila 2007). Nonequilibrium systems tend to attain the property called “homeostasis” if the potentials they dissipate remain approximately constant (Kleidon 2004). In the case of the earth system, by far, the largest flow of energy comes from the sun. It is approximately constant (Iqbal 1983), except for very long timescales, since it gradually increases by a factor of about 10 % per billion years (Schroeder and Connon Smith 2008). Therefore, the earth’s ecosystem would be expected to reach and maintain homeostatic conditions over timescales of the order of hundreds of millions of years. However, this does not happen because of geological perturbations that generate the punctuated transitions observed in the stratigraphic record.

The transition that generated the Anthropocene is related to a discontinuity in the energy dissipation rate of the ecosystem. This discontinuity appeared when the ecosystem (more exactly, the “homo sapiens” species) learned how to dissipate the energy potential of the carbon compounds stored in the earth’s crust, mainly in the form of crude oil, natural gas, and coal). These compounds had slowly accumulated as the result of the sedimentation of organic matter mainly over the Phanerozoic era, that is over a timescale of the order of hundreds of millions of years (Raupach and Canadell 2010). The rate of energy dissipation of this fossil potential, at present, can be estimated in terms of the “primary energy” use per unit time at the input of the human economic system. In 2013, this amount corresponded to ca. 18 TW (IEA 2015). Of this power, about 86 % (or ca. 15 TW) were produced by the combustion of fossil carbon compounds.

The thermal energy directly produced by combustion is just a trigger for other, more important effects that have created the Anthropocene. Among these, we may list as the dispersion of large amounts of heavy metals and radioactive isotopes in the ecosphere, the extended paving of large surface areas by inorganic compounds (Schneider et al. 2009), the destruction of a large fraction of the continental shelf surface by the practice known as “bottom trawling” (Zalasiewicz et al. 2011), and more. The most important indirect effect on the ecosystem of the combustion of fossil carbon is the emission of greenhouse gases as combustion products, mainly carbon dioxide, CO2, (Stocker et al. 2013). The thermal forcing generated by CO2 alone can be calculated as approximately 900 TW or about 1 % of the solar radiative effect (Zhang and Caldeira 2015), hence a nonnegligible effect that generates an already detectable greenhouse warming of the atmosphere. This warming, together with other effects such as oceanic acidification, has the potential of deeply changing the ecosystem in the same way as, in ancient times, LIPs have generated mass extinctions (Wignall 2005; Bond and Wignall 2014).

Burning fossil fuels generate the exergy needed to create industrial structures which, in turn, are used to extract more fossil fuels and burn them. In this sense, the human industrial system can be seen as a metabolic system, akin to biological ones (Malhi 2014). The structures of this nonbiological metabolic system can be examined in light of concepts such as “net energy” (Odum 1973) defined as the exergy generated by the transduction of an energy stock into another form of energy stock. A similar concept is the “energy return for energy invested” (EROI or EROEI), first defined in 1986 (Hall et al. 1986) [see also (Hall et al. 2014)]. EROEI is defined as the ratio of the exergy obtained by means of a certain dissipation structure to the amount of exergy necessary to create and maintain the structure. If the EROEI associated with a dissipation process is larger than one, the excess can be used to replicate the process in new structures. On a large scale, this process can create the complex system that we call the “industrial society.” The growth of the human civilization as we know it today, and the whole Anthropocene, can be seen as the effect of the relatively large EROEI, of the order of 20–30 and perhaps more, associated with the combustion of fossil carbon compounds (Lambert et al. 2014).

A peculiarity of the dissipation of potentials associated with fossil hydrocarbons is that the system cannot attain homeostasis. The progressive depletion of the high-EROEI fossil resources leads to a progressive decline of the EROEI associated with fossil potentials. For instance, Hall et al. (2014) show that the EROEI of oil extraction in the USA peaked at around 30 in the 1960s, to decline to values lower than 20 at present. A further factor to be taken into account is called “pollution,” which accelerates the degradation of the accumulated capital stock and hence reduces the EROEI of the system as it requires more exergy for its maintenance (Meadows et al. 1972).

Only a small fraction of the crustal fossil carbon compounds can provide an EROEI >  1, the consequence is that the active phase of the Anthropocene is destined to last only a relatively short time for a geological time subdivision, a few centuries and no more. Assuming that humans will still exist during the post-Anthropocene tail, they would not have access to fossil fuels. As a consequence, their impact on the ecosystem would be mainly related to agricultural activities and, therefore, small in comparison with the present one, although likely not negligible, as it has been in the past (Ruddiman 2013; Mysak 2008).

However, we should also take into account that fossil carbon is not the only energy potential available to the human industrial system. Fissile nuclei (such as uranium and thorium) can also generate potentials that can be dissipated. However, this potential is limited in extent and cannot be reformed by Earth-based processes. Barring radical new developments, depletion of mineral uranium and thorium is expected to prevent this process from playing an important role in the future (Zittel et al. 2013). Nuclear fusion of light nuclei may also be considered but, so far, there is no evidence that the potential associated with the fusion of deuterium nuclei can generate an EROEI sufficient to maintain an industrial civilization, or even to maintain itself. Other potentials exist at the earth’s surface in the form of geothermal energy (Davies and Davies 2010) and tidal energy (Munk and Wunsch 1998); both are, however, limited in extent and unlikely to be able to provide the same flow of exergy generated today by fossil carbon compounds.

There remains the possibility of processing the flow of solar energy at the earth surface that, as mentioned earlier on, is large [89,000 TW (Tsao et al. 2006) or 87,000 TW (Szargut 2003)]. Note also that the atmospheric circulation generated by the sun’s irradiation produces some 1000 TW of kinetic energy (Tsao et al. 2006). These flows are orders of magnitude larger than the flow of primary energy associated with the Anthropocene (ca. 17 TW). Of course, as discussed earlier on, the capability of a transduction system to create complex structures depends on the EROEI of the process. This EROEI is difficult to evaluate with certainty, because of the continuous evolution of the technologies. We can say that all the recent studies on photovoltaic systems report EROEIs larger than one for the production of electric power by means of photovoltaic devices (Rydh and Sandén 2005; Richards and Watt 2007; Weißbach et al. 2013; Bekkelund 2013; Carbajales-Dale et al. 2015; Bhandari et al. 2015) even though some studies report smaller values than the average reported ones (Prieto and Hall 2011). In most cases, the EROEI of PV systems seems to be smaller than that of fossil burning systems, but, in some cases, it is reported to be larger (Raugei et al. 2012), with even larger values being reported for CSP (Montgomery 2009; Chu 2011). Overall, values of the EROEI of the order of 5–10 for direct transduction of solar energy can be considered as reasonable estimates (Green and Emery 2010). Even larger values of the EROEI are reported for wind energy plants (Kubiszewski et al. 2010). These values may increase as the result of technological developments, but also decline facing the progressive occupation of the best sites for the plants and to the increasing energy costs related to the depletion of the minerals needed to build the plants.

The current photovoltaic technology may use, but do not necessarily need, rare elements that could face near-term exhaustion problems (García-Olivares et al. 2012). Photovoltaic cells are manufactured using mainly silicon and aluminum, both common elements in the earth’s crust. So there do not appear to exist fundamental barriers to “close the cycle” and to use the exergy generated by human-made solar-powered devices (in particular PV systems) to recycle the systems for a very long time.

Various estimates exist on the ultimate limits of energy generation from photovoltaic systems. The “technical potential” in terms of solar energy production in the USA alone is estimated at more than 150 TW (Lopez et al. 2012). According to the data reported in (Liu et al. 2009), about 1/5 of the area of the Sahara desert (2 million square km) could generate around 50 TW at an overall PV panel area conversion efficiency of 10 %. Summing up similar fractions of the areas of major deserts, PV plants (or CSP ones) could generate around 500–1000 TW, possibly more than that, without significantly impacting on agricultural land. The contribution of wind energy has been estimated to be no more than 1 TW (de Castro et al. 2011) in some assumptions that have been criticized in (Garcia-Olivares 2016) Other calculations indicate that wind could generate as much as about 80 TW, (Jacobson and Archer 2012), or somewhat smaller values (Miller et al. 2011). Overall, these values are much larger than those associated with the combustion of fossil fuels, with the added advantage that renewables such as PV and wind produce higher quality energy in the form of electric power.

From these data, we can conclude that the transduction of the solar energy flow by means of inorganic devices could represent a future new metabolic “revolution” of the kind described by (Szathmáry and Smith 1995). (Lenton and Watson 2011) that could bootstrap the ecosphere to a new and higher level of transduction. It is too early to say if such a transition is possible, but, if it were to take place at its maximum potential, its effects could lead to transformations larger than those associated with the Anthropocene as it is currently understood. These effects are hard to predict at present, but they may involve changes in the planetary albedo, in the weather patterns, and in the general management of the land surface. Overall, the effect might be considered as a new geological transition.

As these effects would be mainly associated with solid-state devices (PV cells), perhaps we need a different term than “Anthropocene” to describe this new phase of the earth’s history. The term “Stereocene” (the age of solid-state devices) could be suitable to describe a new stage of the earth system in which humans could have access to truly gigantic amounts of useful energy, without necessarily perturbing the ecosystem in the highly destructive ways that have been the consequence of the use of fossil fuels during the past few centuries.

References (see original article)

Photovoltaics: cultural rape?

Those of you who can read French may be interested in this rant by Nicolas Casaux at

http://partage-le.com/…/le-desastre-ecologique-renouvelabl…/

Apparently, the government of New Zealand financed a large PV installation in the Tokelau island, somewhere in the middle of the Pacific Ocean. The plant is backed up by lead batteries, so it can provide 24/24 power to the islanders. (some 1400 people). That allows islanders to have TV, high-speed Internet, and mail ordering from Amazon and Ebay.

Casaux takes all this as the reason for a screed in which he rants against renewable energy for several paragraphs, then compares PV-ization of the islands to their conversion to the Catholic religion. Basically, it is a "cultural rape" that has left the islanders dependent on a sophisticated technology of which, according to him, they had no need, having been self-sufficient for centuries and happy to bake the fish they capture wrapped in bamboo leaves, rather than in aluminum foil.

I don't say that Casaux is wrong; on the other hand, I am a little uneasy at a Westerners who claim to be sure that those islanders were happier before having PV without having asked for their opinion (It doesn't appear that he asked). I find also objectionable to use the title "renewables ecological disaster" when clearly there has been none.

On the other hand, the piece is interesting as evidence of a widespread negative attitude against renewable energy (at least in the West). It raises also a legitimate point: how is renewable energy going to affect our lives? My impression is that most of what's being said about this matter simply derives from the refusal to accept change, of any kind. But it is clear that the diffusion of PV is going to bring many changes - and big ones. And these big changes won't take place only on the island of Tokelau. 

So, take a look at Casaux's post (maybe with the help of Google translate), and maybe you can comment on it on the Cassandra blog.

Le désastre écologique « renouvelable » des Tokelau

Que vous vous intéressiez de près ou de loin à l’écologie, vous avez très certainement déjà discuté de ce que l’on nomme les énergies "renouvelables", notamment du solaire et de l’éolien. Symptôme d’un diagnostic mal établi, cette…

Another failure of scientific peer-review: a wrong paper on the energy return of photovoltaic energy

Theoretically, whatever is published in a scientific journal should go through a rigorous review process that ensures that it is correct and reliable. Unfortunately, it doesn't work that way.

If you follow the debate on renewable energy, you know how important is the question of the energy return (or EROEI) of the various sources. An EROEI lower than one would make the source - PV, wind, or whatever, an energy sink, not a source. And this is exactly what Ferruccio Ferroni and Richard Hopkirk have been claimed with a paper recently published in "Energy Policy" that arrives to results that are completely different than to those of all the other studies on the subject.

The paper by Ferroni and Hopkirk is simply wrong. You can read below a complete demolition of their arguments performed by Maury Markowitz. But, no matter how wrong is the paper - and it is wrong - this story raises some disturbing points about how scientific information is validated and diffused.


1. Any paper, no matter how bad, poorly conceived, and ultimately totally wrong, can be published in a scientific journal if the authors are persistent enough and try many times. Eventually, they will find a combination of editors and reviewers sufficiently incompetent, sloppy, or biased that they will accept it.

2. There is no way to correct the mistakes of a wrong paper once it is published. The journal will retract it only if it is possible to prove that the authors are guilty of evident fraud or plagiarism. But "simple" mistakes, things such as wrong citations, misinterpreted data, inappropriate data treatment and the like are rarely sufficient to force retraction.

3. The only way to protest against a wrong paper is to ask to the journal to publish a rebuttal. They will do that with the same degree of willingness that you feel about having a tooth pulled, but they will do that, asking also to the authors of the original paper to write a counter-rebuttal. The whole task is long, painful, and ultimately useless as it may end up giving more visibility to the initial paper.

4. Mark Twain is reported to have said that "A Lie Can Travel Halfway Around the World While the Truth Is Putting On Its Shoes". That's exactly what happens when a wrong paper sees the light in a scientific journal. It will spread fast with the people who are seeking for whatever can help them with their confirmation bias. And the rebuttals will be considered as proof of the conspiracy by the PTBs to suppress the Truth.


That's exactly what's happening with the F&H paper, gleefully paraded around as proof that photovoltaic energy is a scam and a waste of money. A rebuttal to the paper is in preparation by a group of scientists, but it will arrive late and will do little to correct the wrong information already diffused on the Web. The problem is that this information affects choices that will determine our future: we can't afford to base them on wrong studies that somehow managed to get published.

So, how did we find ourselves into this mess? Who created a scientific review system that has no quality standards, no independent quality control, no audits, no nothing? I have no idea, but it is clear that the system badly needs a serious reform.


Here is the demolition of the Ferroni and Hopkirk paper, reproduced from Markowits's blog

__________________________________________________________________

From Energy Matters by Maury Markowitz

Another PV ERoEI debacle May 17, 2016

Posted by Maury Markowitz in balonium, solar.
Tags: bolognium, solar power trackback

Your face should have this expression when you read Ferroni and Hopkirk’s paper.

A recent report by Ferroni and Hopkirk explores the energy balance of solar power, and concludes that using PV is energy negative. That is, building PV requires more energy than the panel will produce over its lifetime.
 
Claims like these pop up from time to time, and normally end up being based on definitional tricks on the part of the authors. This example is no different in that respect, but in this case they also add a liberal dose of bad data.
 
The paper is so filled with errors and omissions that’s it’s almost breathtaking. Once again, dear reader, it’s time for the deep dive.

The sincerest flattery

While googling myself (I can’t remember my URL any more than you can) I found to my delight that the name of this blog has been taken up by a pair of bloggers from Aberdeen. How I never came across this previously is something of a mystery; I guess the web is deeper than one would imagine.
 
In any event, a May 9 post by one of the authors pointed me to the paper that is the topic of the rest of this article. After stating that the topic of ERoEI is new to the blog, he goes on to note that when he came across this paper, “the findings are so stunning that I felt compelled to write this post immediately.”
 
When I come across a study in the renewables field with findings that are “stunning”, I normally hold it at arm’s length until I can run the numbers myself. That’s because the field is utterly filled with bogus information from thinly disguised coal company shills to the nuclear true believers. 

Don’t get me wrong, there’s just as much BS going the other way, from the usual suspects to the space heads, which is all the more reason to be super-skeptical. While Mr. Mearns does make some comments about the validity of certain inputs in theoretical terms, in the end, he quotes the bottom line:

Solar panels will produce only 0.83 times the amount of energy they take to produce… If correct, that means more energy is used to make the PV panels than will ever be recovered from them during their 25 year lifetime.

That’s a big “if correct.”
 
And guess what, it’s not correct.

Start bad…

So let’s get into the meat of it. The paper starts with the authors having examined 28 other papers on the topic and found they had a wide variability of Cumulative Energy Demand (CED), the amount of energy used by a product over its lifetime. They conclude that “the authors … were not following the same criteria in determining the boundaries of the PV system.”

Now getting the CED is important, because the overall energy balance, ERoEI,i s basically energy out divided by energy in. So you’re going to need to have a good value for that CED, and there’re all over the map. So their solution is to define an entirely new version – yay!
 
But now they change gears, and work on the other side of the equation, the total energy produced. 

And they attempt to do this in per-square-meter terms.
 
Now stop right there.
 
The industry, and I mean the entire power industry here, not just the renewables industry, measures everything in either per-watt or per-kilowatt-hour terms. That’s because the physical mechanisms of the generators differ wildly, but a watt is a watt, so when you convert to those terms you have a real apples-to-apples comparison.
 
Consider an example; if I tell you a hydro dam cost $2/Watt and a new wind turbine costs $1.50/W,well, there you have it. Now what if I told you that the dam cost $2 per square meter and the turbine $10? Well, does that area include the reservoir? Does the turbine include all the area around it, or just the actual footprint on the ground? See the problem? Area is tough to pin down. Dollars are not.

So why would the authors pick such an odd unit? I can’t say for sure, but in the abstract they mention something about how “solar radiation exhibits a rather low power density”. Well, sure, and that’s important why? Apparently it’s not, because it only figures in very peripherally in the calculations, and has no effect on the bottom line.
Whatever, let’s get to the numbers at hand:

The data are available in the Swiss annual energy statistics … and show an average value of 400 kW ht/m2 yr (suffix “t” means “thermal”) for the last 10 years. This is an indication of the rather low effective level of the insolation in Switzerland. … The uptake from the incoming solar radiation is converted into electrical energy by the photovoltaic effect. The conversion process is subject to the Shockley-Queisser Limit, which indicates for the silicon technology a maximum theoretical energy conversion ef- ficiency of 31%. Since the maximum measured efficiency under standard test conditions (vertical irradiation and temperature below 25 °C) is lower, at approximately 20%, the yearly energy return derived by this first method in the form of electricity gen- erated, amounts to only 80 kW he/m2 yr.

Ok, if you don’t really know much about solar power, you might not immediately see the problem with this statement. What they’re doing is a double conversion – they’re not calculating the amount of energy produced by a PV panel, they’re taking the amount of heat collected by a thermal panel, then applying a formula to convert that to expected electrical power production.

 

But that conversion is totally wrong. The Shockley-Queisser Limit doesn’t work on thermal energy, it works on the original solar energy. And no, the thermal energy is not a good proxy for the original solar energy. The main contribution to the losses in PV, the SQ limit, is wavelength, which doesn’t come into play in thermal collectors at all. And the main contributor to losses in thermal collectors is ambient temperature, which has a minor effect on PV.
 
The two are just not the same, you can’t do that.
 
But more to the point, why would they do that? Because the same source they quote for the thermal value publishes actual electrical output figures as well, which they then go on to quote:

According to the official Swiss energy statistics (Swiss Federal Office of Energy, 2015), an average for the last 10 years of 106 kWhe/m2 yr is obtained for relatively new modules.

This number is 30% higher than their calculation based on thermal, a discrepancy they don’t even try to explain.
 
Beyond that, any number that is “an average for the last 10 years” is, by definition, not talking about “relatively new modules”. Ten years ago the average panel was about 160 Watts and cost about $5.00/Wp. Today they’re around 280 Watts and cost about $0.45/Wp. The vast majority of the world’s PV was installed in the last three years, so any calculation based on data older than that is just plain wrong.

 

And even this number, 106, is significantly lower than 

I would expect given that Switzerland has fairly average insolation for mid-latitude Europe. So what’s up with that?
 
Well when I checked the cited source I found that no such number is actually reported. One can only find total output numbers and then work back from there, but the authors fail to give their calculation. And those totals  -wait for it- go back over a decade, so we’re right back to that problem again.
 
Which is all the more funny when you consider that such data is trivially available on the ‘net. Anyone who wants do to do this calculation should do what we all do; use NREL’s PVWatts. It has highly accurate weather data going back 30 years taken only from first-class sensors.
 
I typed in Zurich for the location, and selected the TMY3 data set. For the system size, I considered a typical modern 280 Watt panel at 1.6 m², or 175 W/m², and typed 0.175 into the System Size. I also changed the tilt from 20, which is good for California, to 30, which is good for Zurich. And here it is:


 
They said 106. We’re at the very first number in the paper, and they’re already off by a factor of 60% from what the industry standard tool suggests.No attempt is made to explain this, except for dismissive comments about industry calculators.

 …get worse…

Now the authors turn their attention to expected lifetime of the panels, which is needed in order to calculate the overall lifetime energy production. They do so in a rather convoluted fashion, starting by considering the amount of panels recycled in Germany:

This was 7637 t. A module of 1 m2 weighs 16 kg and 1 kWp peak rating needs 9 m2 and consequently, scaling this up, a 1 MWp module will weigh approximately 144 t.

Hmmm. A SolarWorld 280, a typical modern panel, masses 17.9 kg. That’s 17.9/1.6 = 11.2 kg/m². I really have no idea where they got their value, and they don’t include any sort of reference. A 1 MWp system using these panels would require 1 million / 280 ~= 3570 panels, or 3570 x 17.9 = 63,903 kg = 64 t. So now we’re at calculation number two, and we find they’re off by another factor of two.
 
The paper goes on to use these numbers to suggest a real lifetime is about 17 years. Now the problem is that if older panels are heavier, then the number on a per-kg basis is automatically skewed towards older panels again. Or to put it another way, if you had 10 panels from each year since 1990 and scrapped one from each year, when measured by weight it would seem that more older panels are dying.
 
And once again I’m left scratching my head why they would use this convoluted magic, when one can find real values in seconds. In fact, one of the most quoted examples is right up the road from them on the LEEE-TISO buildings. The vast majority of these panels, apparently the first grid-tie system in the world, are still running fine after almost 35 years now. They calculate the losses at 0.2 to 0.5% a year, which corresponds to a panel lifetime on the order of 60 years.

…a little more…

They then ignore their previous calculations, and use a 25 year lifetime. So apparently all of that was for nothing! And that brings us to this:

Experience has shown that, on average, efficiency and hence performance de- gradations of around 1% per year of operation must be expected (Jordan and Kurtz, 2012).

Now we go from bad to terrible. They claim this 1% number comes from a paper by Jordan and Kurtz. Well that paper is available online, and actually states the measured rate varies widely, from 0.23% to as much as 2%. And the mode among that data is between 0.4 and 0.5%, which you can see on page 4 of the paper.
 
So if the paper they quote says it is 0.5%, how do they get 1% from the same report? Because they chose the figure on the right of page 4, which includes low-quality data. And what is the difference between the two? Well, the low-quality data is:

very sensitive to several sources of error that could skew the results. Soiling, maintaining calibration and cleanliness of irradiance sensors, module baseline data (nameplate vs. flash test), and not appropriately accounting for LID are just a few major sources of data errors.

In other words, the high-quality data is based on controlled measurements, where they account for these effects and report only the actual panel degradation. In contrast, the low-quality data does not account for these issues, so it includes all sorts of external environmental effects. They fail to mention any of this, they knowingly use the bad data.

They also fail to mention that while the 1% value was indeed used by the industry in the past, they number the industry now uses is 0.5%. And that’s because a number of long-period studies demonstrated 1% was too high. In particular, a NREL study found that panels made before 2000 had a degradation rate of 0.5%, and those after 2000 fell to 0.4%. That indicates the sorts of improvement processes that continue to this day. And, of course, they have the LEEE-TISO numbers, which strongly agree with both of the sources quoted above.
Ferroni and Hopkirk then claim:

There are also other, external factors, which can reduce PV module lifetime, for instance the site, the weather and indeed climatic conditions. These aspects do not appear to have been treated in the scientific literature in connection with photovoltaic energy usage.

Oh come on! They actually talk about these factors in the paper they’re quoting! These sorts of effects are also considered in every tool that predicts output, including PVWatts. And what, do they think their weather would be any different than the LEEE-TISO install down the road from them? Ugh.

…which brings us to…

Ok so now all of this feeds into this equation:

What this does is add up all the yearly power production figures over the lifetime of the panel to produce the total energy output of the panel. And using their figures they get 2203 kWhe/m².

Ok, just for funzies, let’s run the exact same equation,but we’ll use NREL’s 30-year climatic data, and the industry-standard 0.5% degradation. That gets you 3795 kWhe/m². Almost double.
And I need to point out that I’m using industry standard numbers, and in one case, from the same paper they quote. Their result is lower simply because they have selected worst-case-scenarios for all of these numbers. Normally one would indicate this with error bars or using the mode or mean values, like I’m doing here, but they haven’t done that. They just say these numbers are correct. They aren’t.

So, now, the other side of the equation

Ok, so the authors have now developed a number for the total output of the panel, now it’s time to consider the total energy input. And that starts like this:

The average weight of a photovoltaic module is 16 kg/m2

As I noted earlier, the SolarWorld example I linked to above is 17.9 kg for 1.6 m², or 11 kg/m². I assure you this is typical, but feel free to Google “solar panel weight” if you don’t believe me. And then they go on to state:

and the weight of the support system, inverter and the balance of the system is at least 25 kg/m2

25 kg for every square meter? I’ve installed a number of crazy systems, and I can assure you, we never came even close to that. Invariably the heaviest part was the panel.

So let’s check on their sources. Well, first of all they don’t actually quote the original source for those numbers, they quote a University of Toronto thesis from 2009 where you’ll find that:

Support structures for PV panels are made from aluminum or steel, with the majority of systems using steel.

The majority use steel? Uhh, no. And the 25 kg/m² figure in there? It comes from two even earlier papers from 2007. And when I looked there, the one that did have the 25 figure was quoting that from the other, which didn’t have that number in it. I really have no idea where it comes from.

There’s only so much time we can spend on that madness. So let’s just use the power of the internet to find modern values. Check out page 6 of this fairly modern product guide to mountings, which puts the total weight of mounts and panels at 16 kg/m². If we use the modern figure of 11 kg/m² for the panel, that puts the weight of the support structure at 5 kg/m². That same guide also includes values up to 50 kg/m², but that’s for ballast on flat roofs, which are concrete blocks, not steel. This is not used on sloped roofs or ground mounts, but as it might represent as much as 15% of the market, you can factor that in as you wish.

Ok, let’s keep going.

16 kg (module) + 25 kg (balance of plant) + 3.5 kg (significant chemicals) = 44.5 kg/m2

Ok, let’s use our numbers from real sources instead: 11 + 5 + 3.5 = 19.5 kg/m²
Which brings us to:

Since the total lifetime energy return is 2203 kW he/m2, we obtain a material flow of 20.2 g per kWhe

Maybe. Or maybe it’s 19,500 / 3795 = 5.1 g/kWh? Once again, using numbers from the industry I get a number four times “better” than they do.

Now why is this important? Because that number is basically how you calculate the energy needed to make the panel and rest of the system. So much weight of steel takes so much energy to make, and so forth. So if you reduce that by four, you’re almost reducing the CED by four, right off the bat.

Show me da money!

So now the authors move onto the “use of capital.” The basic idea here is that money embodies energy, in a way. Basically everything requires energy to build and ship to you, so if you spend $1 on something, some of that is paying for that energy. So, on average, you can say that a dollar of capital has a certain average energy content, which for convenience, we’ll express in kWh.

So if we’re going to start down that road, we need to have some sort of value for how much capital we need. Here’s the relevant part:

The actual capital cost for a sample group of fully installed PV units, 2/3 roof-mounted and 1/3 free-field-mounted, in Switzerland lies at or above 1000 CHF/m2 with large cost variations of up to 30%, due principally to the uncertainty in the price develop- ments of PV modules. The NREL (National Renewable Energy Laboratory of the U.S. DOE) reports capital cost for fully installed PV units in the lower end of the price range given above. The 1000 CHF/m2 cost, translated into specific cost for installed peak power is 6000 CHF/kWp and is a result of personal experience of the authors.

Ok ok, let’s take this bit by bit. First they have a 2/3 roof and 1/3 field split. They don’t provide a source,of course. I’ve never seen numbers anything like this, and it is trivially easy to find industry values that show the opposite.

For instance, even in Germany where the majority of installs were residential, they represent only 35% of the total buildout. In the US, where the split used to be about 50/50, utility installations now far outnumber residential. Now I mention this because utility installs are ground-mount, so according to these recent sources, the total installed base should be at least the opposite of what they use in this paper.

And this is important, because the capital cost of the system is roughly double for roof mounts, especially residential. That’s because you’re installing far less panels per job, so setup and administration is a lot more on a percentage basis. And for that reason, utility scale installs are dwarfing residential these days, a move that continues to accelerate every year.

Which brings us to the second number, the actual capex value they will use from here on in. That number is 1000 CHF/m2, but that translates into 6000 CHF/kWp based on the “personal experience of the authors”?!

Really. In a peer reviewed paper, we’re being told just to take their word for it. Wow.

Well they can’t be bothered to cite their numbers, but I’ll cite mine. I will refer to the most comprehensive and up-to-date industry-measured values one can easily get, the yearly Lazard LCoE report. And that number, averaged across the western world, is found on page 11, and it is $1500/kWp for utility and $3500/kWp for residential.

Using the modern 1/3rd residential, 2/3rds commercial split, that gives us (3.5*.33)+(1.5*.66) = $2145/kWp average. Now to make a kWp of panel using those SolarWorlds, we need 1000 / 280 = 3.57 panels, and since each panel is 1.6 m², we need 3.57 x 1.6 = 5.7 m², so on a per-m² basis that’s $2145 / 5.7m² = $376 / m².

That’s less than 1/3rd the number they’re quoting, although they do so out of thin air. Even this number overestimates the contribution of residential installs moving forward. I prefer to use the utility rate as more indicative of the real capex of PV; $1500 / 5.7m² = $263 / m².

Working in a coal mine

The paper then moves onto breaking out the various components of that cost and calculating the energy value of each one. They start with labour. After quoting four year old figures, they say:

Based upon the authors’ experiences for typical local labour costs per square meter of PV module are: project management (10% of capital cost), installation (506 CHF per m2), operation for 25 years, including insurance (1.67% of capital cost per year for 25 years) and decommissioning (30% of installation). The total labour costs amount to 1175 CHF/m2.

Now in case it’s not obvious, I want to point out that all of these measurements are based on the capital cost. So if your capital cost is off, this is too. And their capex is off by a factor of three to four. Because, once again, it’s just “the authors’ experiences”.

And to make my point, consider that value in the middle, the installation costs. They’ve already said that the total capex for the system is 1100 CHF / m², and here they say that installation labour is over 500 of that, roughly half.

Really? According to these numbers, published only months ago, all soft costs put together cost around 52% of the system price. And you’ll note that number puts all-in prices at 1300 Euro, basically identical to the Lazard number at $1500 US, and, once again, 1/4 the number Ferroni and Hopkirk create out of thin air.

So for the moment, lets ignore their made-up numbers and use these industry standard ones. They calculate 505 kWhe/m² based on 1175 CHF/m² of labour. Using these figures we see that all the soft costs are 52% of 1300 Euro per kWp, or 748 CHF/kWp, or 209 kWhe/m².

But what’s another factor of two between frenemies?

And finally, in section 5.5.3, the duo calculate the energy value of the capital itself. Basically the idea here is that if you have to borrow the money (or you can flip that to opportunity cost, same thing) then you could express that in terms of panels you could have bought with that interest (so to speak). You can think of that as “lost energy” in a way…

• Using their rate of 1100 CHF/m², they get a value of 420.
• Using the industry rate above, 1300 Euro/kWp, that gets us around 120.

Show me da money (again)!

Which brings us, finally, to their totals in Table 4:

Now let’s do the exact same thing using the numbers we’ve calculated:

CED	1300
Integration	349
Labour	209
Faulty equipment	90
Capital	120
Total	2068

So basically, just considering the known-good, widely-available capex number, we’ve reduced the “energy investment” by 22%.

All of this goes back to the original claim. They claim that the ERoEI is 2203/2664 = 83%. But a whole lot of that is made up by the cost of capital, based on a bogus number. By changing that one number to the one actually measured in the field, we get 2203/2068 = ERoEI 1.06.

And if we instead insert NREL’s number for the insolation, and use the industry standard degradation, it becomes 3795/2203 = ERoEI 1.7. That’s better than fracked oil in the US.

And we haven’t even touched that CED number, which, as you can see above, is based on some rather odd numbers about system weights.

That’s not all folks…

Now we come to the issue of recycling. In the calculations in the paper, the authors consider the panels to have a 30% decommissioning fee, which is added in the labour term.

But they totally ignore the salvage value of the panels. Panels are basically glass, aluminum, some silver and some copper. People pay for these things, which is precisely why the Europeans have a recycling program for panels.

Given an average 50% energy recovery for recycling, we can reduce the CED of a 2nd generation panel to 650. Running the same calculation gets us 1419, so 2203/1419 = 1.55, or 3795/1419 = 2.7.

And if you do consider the recycling as a potential revenue stream, then the labour line is reduced by some portion of that 30%, which brings the denominator to 1340. And that gives 2203/1340 = 1.64 or 3795/1340 = 2.83.

So in the end

Consider this: the calculation they use in their paper would produce different results if the interest rate changes, the FX rate between the Yuan and Swiss Franc changes, or the price of installations continues its astonishing downward fall.

So, what exactly is this figure measuring?


It’s certainly not measuring anything like the “embedded energy content” of the panels. That wouldn’t change just because someone types a number into a Bloomberg terminal. Yet that’s precisely what happens using their calculation.
 
And finally, I need to point out the glaring fact that the authors don’t run the same calculation on any other power source. Given that sources like nuclear are far more capital intensive than PV (which is why no one is building them) their calculation of “ERoEI” is worse.

 This paper is just plain bogus. The entire methodology is based on numbers that have no physical reality (money) and the authors deliberately cherry pick data to make those numbers “prove” their point, or just make up values out of the air. All of this is glaringly obvious, and is simply yet another example of the sorts of attacks renewables face at the hands of the true believers in the nuclear field.

Five billion years of energy supply: the "stereosphere" and the upcoming photovoltaic revolution

It seems to be popular nowadays to maintain that photovoltaic energy is just an "extension" of fossil energy and that it will fade away soon after we run out of fossils fuels. But photovoltaics is much more than just a spinoff of fossil energy, it is a major metabolic revolution in the ecosystem, potentially able to create a "stereosphere" analogous to the "biosphere" that could last as long as the remaining lifetime of the earth's ecosystem and possibly much more. Here are some reflections of mine, not meant to be the last word on the subject, but part of an ongoing study that I am performing. You can find more on a similar subject in a paper of mine on Biophysical Economics and Resource Quality, (BERQ)

"Life is nothing but an electron looking for a place to rest," is a sentence attributed to Albert Szent-Györgyi. It is true: the basis of organic life as we know it is the result of the energy flow generated by photosynthesis. Sunlight promotes an electron to a high energy state in the molecule of chlorophyll. Then, the excited electron comes to rest when a CO2 molecule reacts with hydrogen stripped away from an H2O molecule in order to form the organic molecules that are the basis of biological organisms. That includes replacing degraded chlorophyll molecules and the chloroplasts that contain them with new ones. The cycle is called "metabolism" and it has been going on for billions of years on the earth's surface. It will keep going as long as there is sunlight to power it and there are nutrients that can be extracted from the environment. 

But, if life means using light to excite an electron to a higher energy state, there follows that chlorophyll is not the only entity that can do that. In the figure at the beginning of this post, you see the solid state equivalent of a chlorophyll molecule: a silicon-based photovoltaic cell. It promotes an electron to a higher energy state; then this electron finds rest after having dissipated its potential by means of chemical reactions or physical processes. That includes using the potentials generated to manufacturing new photovoltaic cells and the related structures to replace the degraded ones. In analogy with the biological metabolism, we could call this process "solid state metabolism". Then, the similarities between the carbon-based metabolic chain and the silicon-based one are many. So much that we could coin the term "stereosphere" (from the Greek term meaning "solid.") as the solid-state equivalent of the well known "biosphere". Both the biosphere and the stereosphere use solar light as the energy potential necessary to keep the metabolic cycle going and they build-up metabolic structures using nutrients taken from the earth's surface environment.

The main nutrient for the biosphere is CO2, taken from the atmosphere, while the stereosphere consumes SiO2, taking it from the geosphere. Both metabolic chains use a variety of other nutrients: the stereosphere can reduce the oxides of metals such as aluminum, iron, and titanium, and use them as structural or functional elements in their metallic form; whereas the biosphere can only use carbon polymers. The biosphere stores information mostly in specialized carbon-based molecules called deoxyribonucleic acids (DNA). The stereosphere stores it mostly in silicon-based components called "transistors". Mechanical enactors are called "muscles" in the biosphere and are based on protein filaments that contract as a consequence of changing chemical potentials. The equivalent mechanical elements in the stereosphere are called "motors" and are based on the effects of magnetic fields on metallic elements. For each element of one of these systems, it is possible to find a functional equivalent of the other, even though their composition and mechanisms of operation are normally completely different.

A major difference in the two systems is that the biosphere is based on microscopic self-reproducing cells. The stereosphere, instead, has no recognizable cells and the smallest self-reproducing unit is something that could be defined as the "self-reproducing solar plant factory." A factory that can build not only solar plants but also new solar plant factories. Obviously, such an entity includes a variety of subsystems for mining, refining, transporting, processing, assembling, etc. and it has to be very large. Today, all these elements are embedded in the system called the "industrial system." (also definable as the "technosphere"). This system is powered, at present, mainly by fossil fuels but, in the future, it would be transformed into something fully powered by the dissipation of solar energy potentials. This is possible as long as the flow of energy generated by the system is as large or larger than the energy necessary to power the metabolic cycle. This requirement appears to be amply fulfilled by current photovoltaic technologies (and other renewable ones).

A crucial question for all metabolic processes is whether the supply of nutrients (i.e. minerals) can be maintained for a long time. About the biosphere, evidently, that's the case: the geological cycles that reform the necessary nutrients are part of the concept of "Gaia", the homeostatic system that has kept the biosphere alive for nearly four billion years. About the stereosphere, most of the necessary nutrients are abundant in the earth's crust (silicon and aluminum being the main ones) and easily recoverable and recyclable if sufficient energy is available. Of course, the stereosphere will also need other metals, several of which are rare in the earth's crust, but the same requirement has not prevented the biosphere from persisting for billions of years. The geosphere can recycle chemical elements by natural processes, provided that they are not consumed at an excessively fast rate. This is an obviously complex issue and we cannot exclude that the cost of recovering some rare element will turn out to be a fundamental obstacle to the diffusion of the stereosphere. At the same time, however, there is no evidence that this will be the case.

So, can the stereosphere expand on the earth's surface and become a large and long-lasting metabolic cycle? In principle, yes, but we should take into account a major obstacle that could prevent this evolution to occur. It is the "Allee effect" well known for the biosphere and that, by similarity, should be valid for the stereosphere as well. The idea of the Allee effect is that there exists  a minimum size for a biological population that allows it to be stable and recover from perturbations. Too few individuals may not have sufficient resources and reciprocal interactions to avoid extinction after a collapse. In the case of the stereosphere, the Allee effect means that there is a minimum size for the self-reproducing solar plant factory that will allow it to be self-sustaining and long-lasting. Have we reached the "tipping point" leading to this condition? At present, it is impossible to say, but we cannot exclude that it has been reached or that it will be reached before the depletion of fossil fuels will bring the collapse of the current industrial system.

The next question is whether a self-sustaining stereosphere can coexist with the organic biosphere. According to Gause's law, well known in biology, two different species cannot coexist in the same ecological niche; normally one of the two must go extinct or be marginalized. Solid state and photosynthetic systems are in competition with each other for solar light. There follows that the stereosphere could replace the biosphere if the efficiency of solid state transduction systems were to turn out higher than that of photosynthetic systems. But this is not obvious. PV cells today appear to be more efficient than photosynthetic plants in terms of the fraction of solar energy processed but we need to consider the whole life cycle of the systems and, at present, a reliable assessment is difficult. We should take into account, anyway, that solid state creatures don't need liquid water, don't need oxygen, are not limited to local nutrients, and can exist in a much wider range of temperatures than biological ones. It means that the stereosphere can expand to areas forbidden to the biosphere: dry deserts, mountaintops, polar deserts, and more. Silicon based creatures are also scarcely affected by ionizing radiation, so they can survive in space without problems. These considerations suggest that the stereosphere may occupy areas and volumes where it is not in direct competition with the biosphere.

The characteristics of the stereosphere also allow it the capability of surviving catastrophes that may deeply damage the biosphere and that will eventually cause its extinction. For instance, the stereosphere could survive an abrupt climate change (although not a "Venus Catastrophe" of the kind reported by James Hansen). Over the long run, in any case, the earth's biosphere is destined to be sterilized by the increasing intensity of the solar irradiation over times of the order of a billion years. (and smaller for multicellular organisms). The stereosphere would not be affected by this effect and could continue existing for the five billion of years in which the sun will remain in the main sequence. Possibly, it could persist for much longer, even after the complex transformations that would lead the sun to become a white dwarf. A white dwarf could, actually power PV systems perhaps for a trillion years!

A more detailed set of considerations of mine on a related subject can be found in this article on "Biophysical Economics and Resource Quality, BERQ). 

Notes: 

1. I am not discussing here whether the possible emergence of the stereosphere is a good or a bad thing from the viewpoint of humankind. It could give us billions of years of prosperity or lead us to rapid extinction. It seems unlikely, anyway, that humans will choose whether they want to have it or not on the basis of rational arguments while they still have the power to decide something on the matter. 

2. The concept of a terrestrial metabolic system called the stereosphere is not equivalent, and probably not even similar, to the idea of the "technological singularity" which supposes a very fast increase of artificial intelligence. The "self-reproducing solar plant factory" needs not be more intelligent than a bacterium; it just needs to store a blueprint of itself and instructions about replication. Intelligence is not necessarily useful for survival, as humans may well discover to their chagrin in the near future.

3. About the possibility of a photovoltaic-powered Dyson sphere around a white dwarf, see this article by Ibrahim Semiz and Salim O˘gur.

4. The idea of "silicon-based life" was popularized perhaps for the first time by Stanley Weinbaum who proposed his "Pyramid Monster" in his short story "A Martian Odissey" published in 1933. Weinbaum's clumsy monster could not exist in the real universe, but it was a remarkable insight, nevertheless.