Zombie asks a question

Zombie, of San Francisco’s “Zombietime” fame, writes in with a question that he has graciously allowed to be given to our readers.

He writes:

I’m preparing to write an essay on the following hypothesis:

Solar power installations, especially in desert areas, replace light-colored high-albedo sand/rock ground surface with very low albedo black solar panels. The “side effect” (in fact, the whole purpose) of solar panels is therefore to capture radiant energy coming from the sun that would otherwise reflect back into space. Because this energy is then converted into electricity, which is then used to power devices and inevitably degrade into atmospheric heat (which does NOT as easily radiate back out into space), the overall result of large solar panel installations is to heat up the planet more than it would be heated without the solar installations.

But of course the solar-energy advocates will say that the solar installation is replacing a carbon-burning power plant, which produces greenhouse gases that the solar facility does not.

The question I seek to answer is: 

Has anybody ever actually sat down and calculated whether the CO2 greenhouse effect caused by a carbon-based power plant generating one megawatt of electricity is more or less than the warming effect caused by the lowering of the earth’s surface albedo from a black-panel solar installation with power output large enough to completely replace the carbon-burning power plant?

I suspect that no calculations of this type have ever actually been done, and that solar panels may in fact contribute more to global warming than anyone previously realized — and in fact may cause just as much warming as the power sources they replace.
I have searched but cannot find such a study; but the reason I’m writing to you is that I have some vague memory of this thesis once being discussed on WattsUpWithThat — although I no longer can track down where exactly.

So I ask: Do YOU (without any time investment) remember offhand where or when this hypothesis was discussed on WattsUpWithThat? And if not, do you think this is a worthy line of investigation?

I know this is a somewhat vague question, but your guidance is invaluable!
– zombie

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176 Responses to Zombie asks a question

  1. Amatør1 says:

    Since the effect of CO2 is zero, the warming effect of solar panels are infinitely greater.

  2. Jack McGrats says:

    I have also entertained that question and it will be interesting if someone ever sat down and did the calculations. Another similar question would be: what kind of imbalance in the earths composition is created by removing heat via thermal means, ie using earth’s interior heat to warm a home, etc?

  3. Terry Hoffman says:

    This is an excellent question but part of a larger one:-) where is the thermodynamic equivalent of a free body diagram? Just as CO2 respiration is ignored, I suspect that the heat generated from biological processes is significant but ignored by the geologists, politicians and lawyers who mostly represent CAGW levels to use indolent minorities.

  4. Dave D says:

    Amatori: I think you mean approaching zero, beyond our current technologies ability to differentiate, a third decimal place, well, yeah, OK – zero.

  5. Doug Danhoff says:

    I believe that the “warming effect” of additional CO2 is actually a cooling factor in the atmoshere.
    When you consider that CO2 does not produce any heat, (It is not a heat source) It re-emits energy as it recieves it, and a bit more than half is radiated away from the earth in each exchange, creating a negative balance. When this is considered in light of the logarithmic nature of additional CO2, I would agree with you that a gas fired power plant would be less warming than the solar farms that are supposed to replace them.
    Good topic…. sorry I do not have a lead to the former debate on WUWT.

  6. Eric Eikenberry says:

    Heat generated from biological processes is insignificant, as the ice ages have repeatedly shown. Heat generated from CO2 is insignificant for the same reason mentioned above. Neither tail can wag the dog, nor will they ever.

  7. Eyal Porat says:

    I did not calculate it but instinctively it seems to me that the environmental problem of solar panels is that it will reduce the surrounding areas temperature significantly, thus causing alteration of the habitat around it.
    The better the absorption, the less heat reaches the land.
    In Israel there is a crazy plan on its way to erect a huge solar plant in the Negev desert.
    People are beginning to realize that like the wind farms, this will cause a grave damage too.
    Hopefully common sense will prevail.

  8. Adam says:

    This is a great point. I wonder what the answer will be. I suspect that when the IPCC estimates of climate sensitivity are used then the “CO2 effect” will be larger than the Solar Panel effect. I say this because we know that they have got their sensitivities too high already, which is why their models produce higher simulated temperatures than have been observed.

    @Amatør1, let’s use the IPCC estimates – even if we disagree with them. We could also determine the sensitivity at which solar panels break even.

  9. The difference is that a CO2 molecule yields useful energy only once, but can contribute to warming the atmosphere by absorbing and back-radiating infrared photons multiple times, for as long as it stays in the atmosphere. Estimating the exact number of those back-radiated photons is not trivial, but I would expect their cumulative energy to be orders of magnitude greater than the amount of energy generated by the combustion of the carbon that yielded the CO2.

  10. Barry Cullen says:

    Absolutely brilliant question! I’m looking for an old envelope or napkin to do the calculations.

    Amator1 is close but there is still 5 – 7% energy absorption available (maybe a little more due to band broadening) by CO2 bands in LWIR going from ~300 ppm to 1,000,000 ppm (100%) CO2. The increased energy absorption just from doubling CO2 to 560 – 600 ppm is small.

  11. David says:

    Neat question. This is the reason I like to come to WUWT. Can’t wait for the answer.

  12. Werner Brozek says:

    I read that a 1% or 2% increase in cloud cover effectively nullifies a doubling of CO2. So if your solar panels effectively “decrease cloud cover” so to speak, then it would seem that the warming effect is larger than the cooling effect. Another area that could be looked at is how does the darkness or lightness of our highways affect global warming or cooling? Since the areas of our roads is much larger than the areas of solar panels, this may be another project to undertake next.

  13. jai mitchell says:


    Modifications to the surface albedo through the deployment of cool roofs and pavements
    (reflective materials) and photovoltaic arrays (low reflection) have the potential to change
    radiative forcing, surface temperatures, and regional weather patterns. In this work we
    investigate the regional climate and radiative effects of modifying surface albedo to mimic
    massive deployment of cool surfaces (roofs and pavements) and, separately, photovoltaic arrays
    across the United States. We use a fully coupled regional climate model, the Weather Research
    and Forecasting (WRF) model, to investigate feedbacks between surface albedo changes,
    surface temperature, precipitation and average cloud cover. With the adoption of cool roofs and
    pavements, domain-wide annual average outgoing radiation increased by 0.16 ± 0.03 W m−2
    (mean ± 95% C.I.) and afternoon summertime temperature in urban locations was reduced by
    0.11–0.53 “C, although some urban areas showed no statistically significant temperature
    changes. In response to increased urban albedo, some rural locations showed summer afternoon
    temperature increases of up to +0.27 “C and these regionswere correlated with less cloud cover
    and lower precipitation. The emissions offset obtained by this increase in outgoing radiation is
    calculated to be 3.3 ± 0.5 Gt CO2 (mean ± 95% C.I.). The hypothetical solar arrays were
    designed to be able to produce one terawatt of peak energy and were located in the Mojave
    Desert of California. To simulate the arrays, the desert surface albedo was darkened, causing
    local afternoon temperature increases of up to +0.4 “C. Due to the solar arrays, local and
    regional wind patterns within a 300 km radius were affected. Statistically significant but lower
    magnitude changes to temperature and radiation could be seen across the domain due to the
    introduction of the solar arrays. The addition of photovoltaic arrays caused no significant
    change to summertime outgoing radiation when averaged over the full domain, as interannual
    variation across the continent obscured more consistent local forcing.

    –you’re welcome

  14. RichardLH says:

    Energy is neither created or destroyed, merely transported. Sure the desert area will be slightly cooler (because some energy has been removed locally) and some other place has been heated (because of the final thermal degradation) but the overall effect will be, by definition zero.

  15. MarkB says:

    oebele bruinsma says:
    December 10, 2013 at 11:17 am

    A quick search delivered this: http://www.clca.columbia.edu/13_39th%20IEEE%20PVSC_%20VMF_YY_Heat%20Island%20Effect.pdf

    Good find. From the abstract of the 2nd reference in that paper:
    If photovoltaics (PV) are to contribute significantly to stabilizing the climate, they will need to be deployed on the scale of multiple terawatts. Installation of that much PV would cover substantial portions of the Earthʼs surface with dark-colored, sunlight-absorbing panels, reducing the Earth’s albedo. How much radiative forcing would result from this change in land use? How does this amount compare to the radiative forcing avoided by substituting PV for fossil fuels? This analysis uses a series of simple equations to compare the two effects and finds that substitution dominates; the avoided radiative forcing due to substitution of PV for fossil fuels is approximately 30 times larger than the forcing due to albedo modification. Sensitivity analysis, including discounting of future costs and benefits, identifies unfavorable yet plausible configurations in which the albedo effect substantially reduces the climatic benefits of PV. The value of PV as a climate mitigation option depends on how it is deployed, not just how much it is deployed—efficiency of PV systems and the carbon intensity of the substituted energy are particularly important.


  16. Tom in Florida says:

    What must also be considered is the efficiency decline of the solar panels as they become covered with desert sand.

  17. I have not done or seen such a calculation, but I have seen articles suggesting we paint roads or rooftops white (which is probably dumb for other reasons) so we should identify greenies and ask them to crunch the numbers. I would pay to see figures on how many ounces of coal have been saved by all the US wind “farms”. Spiegel claimed that all wind, pv, biogas etc in Germany has not saved a single gram of CO2… I wonder… Can greenies convert grams of CO2 into ounces of coal?

  18. Roger Dewhurst says:

    These solar panels convert sunlight into heat, one way or another, with extraordinary efficiency. Thus I suggest that the OP is entirely correct in his supposition.

  19. I think that very soon we will have to call in The Colonel (http://en.wikipedia.org/wiki/The_Colonel_(Monty_Python)) to put a stop to all this “silliness.” Maybe the chaps at CRU already did.

  20. J Martin says:

    Perhaps If the rate of road building has declined over recent years that may show a better correlation with temperatures than co2. /sarc

    Perhaps the link sought is this;


  21. Rob Dawg says:

    Bright sunny places become dark electricity eventually to heat places. Why is there a question?

  22. David, UK says:

    I’m no professional scientist, but it seems obvious to me that solar panels – in the numbers that exist and are likely to exist in the foreseeable future – would have an infinitesimally tiny effect on global temperature – much like the much bigger UHI effect (said effect being local rather than global).

    I suppose it is worthy of investigation if there is a possibility that this tiny effect is nevertheless greater than the effect that the panels are supposedly designed to mitigate.

    If I’m talking BS, I apologise!

  23. DirkH says:

    The local endothermic, cooling effect is compensated for when the produced energy is used.

    “Has anybody ever actually sat down and calculated whether the CO2 greenhouse effect caused by a carbon-based power plant generating one megawatt of electricity is more or less than the warming effect caused by the lowering of the earth’s surface albedo from a black-panel solar installation with power output large enough to completely replace the carbon-burning power plant?”

    Solar panels are expensive because a lot of energy is needed to create them. This energy comes in the form of electricity from coal power plants in China. Solar panels are made in China because coal-generated electricity is especially cheap over there. Meaning: Solar panels probably do not save any CO2 output but increase total CO2 output.

    Economic inefficiency translates into energetic inefficiency. If solar panels were useful / energetically efficient, they would not need to be subsidized.

    Production processes are constantly optimized; even without subsidies the cost of solar panels halfed once per decade due to ever decreasing energy and resource usage in production. It is not a natural law that solar panels increase the total CO2 output, it is just so that it is currently the case; and will likely not be the case anymore in one or two decades.

    You will recognize the shift to that situation by the removal of the subsidies.

  24. X Anonymous says:

    ray pierre @ real climate did this in response to freakonomics, and found it to be a non issue. Levitt is at his uni….

  25. tteclod says:

    If you take research such as this:
    and calculate the expected energy for the solar cell, you may be able to get a fair understanding of the heat load transmitted to underlying surfaces, lost to the atmosphere, and converted to electricity or other conversions. In any case, there’s some data available.
    It may also be worthwhile to investigate some building science research.

  26. Brent Seufert says:

    I’ve often contemplated a similar question, that is: Given the green’s penchant for complaining about the disruption of the environment by the Alberta oil sands mining (at least the part that is still above ground) how much land is being disrupted by these utility scale solar installations, and for how long, compared to the oil sands mining. Keep in mind, the oil sands mined land is recovered to natural state one cannot tell the difference from surrounding undisturbed lands.

  27. wws says:

    If you’re in a very sunny place (Like Phoenix) I do think it makes sense to color a rooftop white, especially on a commercial building where the default choice would be a flat, black tar roof. The effect is small, but measurable. It’s all about albedo.

    And let me assure you, you don’t want to be in a black car with a black interior in Phoenix in the summertime!

  28. Chris B says:

    There’s a similar problem with wind turbines altering normal surface wind patterns, with unintended consequences.

  29. Bloke down the pub says:

    My solar pv system is fitted on my roof which is covered with concrete tiles. As such I don’t expect there’d be much difference in the albedo.

  30. Petrossa says:

    puzzled @ ted palmer. Redistributing the same energy multiple times increases the heat content? Have we finally invented the perpetual motion device?

  31. Andrew30 says:

    “solar installation with power output large enough to completely replace the carbon-burning power plant”
    Fools errand.
    It is not possible to have a solar array on Earth that ‘could replace a carbon-burning power plant’. Carbon-burning power plants operate 24 hours a day, a solar array on Earth can not.

  32. DirkH says:

    Archaeos Pteryx says:
    December 10, 2013 at 11:37 am
    “I have not done or seen such a calculation, but I have seen articles suggesting we paint roads or rooftops white (which is probably dumb for other reasons) so we should identify greenies and ask them to crunch the numbers.”

    One of Barack Hussein Obama’s henchmen, Steven Chu, proposed this, together with a mandated switch of the economy to glucose.


    Somehow the Chicago machine never jumped on the glucose bandwagon though.

    “Spiegel claimed that all wind, pv, biogas etc in Germany has not saved a single gram of CO2…”

    Next, they probably demanded the government double its efforts. Would be typical German logic.
    German Greens to this day demand that more efforts be made to slow down Climate Change to protect the drought-stricken German trees. (Don’t worry. Germany is the wettest country I know, just not in the mind of a German Green. Some like it moist.) But how do you slow down something that stopped 17 years ago? German Greens never explain.

  33. Mark Bofill says:

    Holy smokes, that’s true! Mainstream climate science tells us it’s not about atmospheric temperature, but about the energy budget of the system. If that energy isn’t being reflected back into space, you can bet your bottom dollar that it will end up as heat in the system at the end of the day. If solar ever got into use on a really massive scale…
    …oh. Well, hypothetically speaking I guess it could eventually be an issue. :)

  34. Reg Nelson says:

    O/T, but I had a similar common sense question regarding “The Missing Heat”. The current theory is the that the planet is actually warming, but this increased warming is hidden in the ocean.

    My question is this: If the planet is warming, and two thirds of the planet is covered by water, wouldn’t this lead to greater evaporation, which would 1) cause a decrease in SST (evaporative cooling) and 2) increase albedo — in the form of cloud cover?

    Or would this process be constrained by humidity?

  35. Hope you didn’t miss this little gem from last nights Colbert Report on the comedy channel;
    “A Case For Climate Engineering” author David Keith discusses his proposal to fight climate change.

  36. DirkH says:

    jai mitchell says:
    December 10, 2013 at 11:34 am
    “To simulate the arrays, the desert surface albedo was darkened, causing
    local afternoon temperature increases of up to +0.4 “C.”

    A sunny afternoon in a desert, and darkening the albedo leads to 0.4 deg C.

    I don’t know what Barack Hussein Obama’s government employees computed there but it looks like they dropped two decimals. Maybe not that experienced with the Celsius scale?

  37. ronald says:

    Difficult question! Why bother? Sounds strange but ever considerer the question you ask for any construction material? Or for that mater any dark material. There is a totally different problem, CO2 dose nothing for warming so thats not the problem. Cleaner environment is more reasonable to look at. And yes solar panels are cleaner, not considering the production of it. But there is alway a but and yes its the same problems as whit wind mills they don’t work all the time. And the moment they not work cane be longer then the moments they work or the production is less. And less production means less power. You need your power so an conventional power plant needs to take over. There is your biggest problem a power plant needs to run beside the mill and the solar collector to make power. Shutting down a power plant is no option because it takes hours to even days to start up a plant. Even lowering the output of an power plant to say 25% of capacity cost more power to restart and work up to 100% and cost more fuel and so makes more CO2. In total you could say the effect is negative.

  38. Olavi says:

    1000 MWh coalplant has side effect of cooling process steam to water . Operating efficiency is typically 30% so. 1000 MWh electric power is 30% total of app. 3400 MWh of heat.

  39. Ian says:


    This question has indeed been addressed, with “back of the envelope” calculations. If you can look past the usual nauseatingly arrogant and condescending tone of RealClimate, please see Ray Pierrehumbert’s open letter to Steve Levitt, as it is still an interesting read:



  40. Roy Spencer says:

    the proportion of the Earth covered by solar panels is vanishingly small, and will remain very small in the future. So the panels’ “extra heating” effect will pale in comparison to CO2-induced warming…assuming that warming is non-zero, of course. ;-)

    Reg, yes ocean warming leads to more evaporation, and more precipitation. This effect is already contained in the climate models. The effect on cloud formation, though, is a huge wild card. The reason why is that all ascending air in clouds has to be balanced by descending air, which is usually cloud-free. So an increase in the atmospheric hydrologic cycle can lead to either more or less cloudiness. I predict more (a negative feedback on warming), the models say less (positive feedback on warming)…but no one really knows for sure.

  41. andrews51 says:

    Regardless of the amount of overall heating or cooling effect of CO2 vs. industrial heating vs. heat island effect… A photoelectric solar panel generating an electrical current is generally going to provide that electrical current to a electrical machine [solid state circuits are machines of sorts]. These machines do work [the physics definition]. In the process of doing work, there are losses [heat] and changes in potential energy [work done]. So a very basic assumption would be that whatever possible heating effect is equal to the net electrical panel output [efficiency of the panel multiplied by the incident convertible photon energy] minus the net work done by the electrical current which should equal the losses [heating]…

    eff * incident photon – electrical work done = delta t

    This would be a very simplistic start, but it clearly shows that the overall heating effect of the PV unit plus the electrical system it’s connected to would not be directly equatable to the captured incident photon energy…

    However, since determining the comparative heating or cooling effect of all industrial processes is a nearly impossible feat – I doubt any conclusion beyond the very simplistic statement above would be possible…

    It’s also good to note that not all photons hitting the panel meet the requirements to be eligible for capture. This is in addition to the loss of the non-100% efficiency of the panel — which refers to the efficiency of the conversion of eligible photons only… not all photons are created equal…

  42. Reg Nelson says:

    Thank you, Dr. Spencer, for the explanation.

  43. RERT says:

    I had cause to do a similar calculation a while ago when I wondered whether carbon offset forestation would actually warm the earth by decreasing the albedo. The conclusion was that it actually cools the earth, under reasonable assumptions.

    The electrical power generated by a 1 meter square panel is at most (1365/4)*0.2, as the panels are around 20% efficient. So how much coal is burnt to produce that much power? Wiki says that coal has about 32MJ/kg energy content. Every year the panels generate 0.2*(1365/4)*365*24*60*60 Joules of electric power, or about 2000 MJ. At reasonable efficiency, coal is producing 10MJ(e)/Kg. So, the Panel saves about 200Kg of coal (say Carbon) a year. There are roughly 900GT of Carbon in the atmosphere. so the proportionate rise in carbon is 200Kg/900GT=0.2T/9×10^11=2.2*10^-13. For the sake of argument the panel operates indefinitely, so that we will just see a linear rise in temperature forever, which I make around 6*10^-13 degrees C per year at a climate sensitivity of 2K/doubling.

    Say, at worst, each square metre of panel takes the albedo from 70% reflection to 0% reflection. Crazily, this raises ‘radiative temperature’ by about 70C. Let’s just go with that for a minute, as it is obviously pessimistic in the sense that it minimizes the benefit of the panel. 70C over 1 square metre averages about 1.5*10^-13 K over the earth’s surface.

    So there you have it. The panel will raise the remperature of the earth by 1.5*10^-13 K, and then cool it by 6*10^-13 per year thereafter. There is a net cooling after about 3 months.

    Of course, that’s not the conclusion most of us were hoping for, so you might want to consider the energy used to make the panel. However, I’ve had enough fun for one night!

  44. Sparks says:

    I read somewhere that the energy used for all the stages from mining the raw materials, processing, manufacturing, logistics/transportation, installation and the maintenance of a square mile solar panel array is 60-70% grater than the energy produced by the solar array over a 50 year period.

  45. Col Mosby says:

    I have posed exactly the same question and have no ability
    to determine the answer, but I did several calculations,
    using published data about California solar farms.
    The first thing to be aware of with solar power is that
    rated capacity means nothing – those ratings usually
    quoted are not realistic – they overstate outputs by 12%.
    There are also inversion losses when going from DC to AC
    There are also deterioration losses due to age , anywhere up
    to 1% per year.
    I suggested that someone with ability to obtain surface
    temps from satellite measurements do so for some of the
    California solar farms to see how they are affecting the
    local climate.
    I did , however, calculate the land required to produce gross
    output equal to a modern nuclear plant of 1500 MW (90% capacity)
    and estimated that such a solar farm required around 80,000 acres.

  46. Those who are saying the effect should be zero due to conservation of energy are neglecting the point the questioner raises about solar panels changing albedo. Energy that would have been reflected back into space is now being turned into heat here on earth, whether on site or at some other location. The difference created by this change in albedo is what needs to be calculated.

  47. Jim S says:

    Won’t a large array of solar panels cast a shadow on the ground and thus induce cooling?

  48. Roy Spencer says:

    Jim, yes it casts a shadow, but as Conrad has alluded to, the reflective ground is now replaced by the black (absorptive) solar panel.

  49. commieBob says:

    PV panels have a surprisingly high albedo, approx. 0.3*
    Desert sand has an albedo of approx. 0.4**
    The difference isn’t as dramatic as you might expect.


  50. arthur4563 says:

    As to roof mounted solar panels, they would obviously be no worse off than a black shingled roof, but here the economics are horrible, owing to the cost of labor installing the panels plus the
    sad fact that normally a roof needs to be reshingled before the panels wear out, requiring another installation after a de-installaion. I found the costs of this type of solar to be perhaps 5 to 10 times that of nuclear.

  51. Resourceguy says:

    Not to worry, almost all of the project hype on Federal lands is just hype and not actual projects. The tortoise and the paperwork will render those numbers just political progress. Beyond that, the largest solar project underway in the world (Topaz) is one in which the private developers had to agree to hand over the property in total to a conservancy group at the end of the power purchase agreement. There are not many projects prepared to do that. It amounts to peak solar in effect.

  52. chris y says:

    The formerly laudable Scientific American had a short article on the albedo effect of solar panels.


  53. RACookPE1978 says:

    Col Mosby says:
    December 10, 2013 at 12:34 pm

    I have posed exactly the same question and have no ability
    to determine the answer, but I did several calculations,
    using published data about California solar farms.
    The first thing to be aware of with solar power is that
    rated capacity means nothing – those ratings usually
    quoted are not realistic – they overstate outputs by 12%.
    There are also inversion losses when going from DC to AC
    There are also deterioration losses due to age , anywhere up
    to 1% per year.
    I suggested that someone with ability to obtain surface
    temps from satellite measurements do so for some of the
    California solar farms to see how they are affecting the
    local climate.
    I did , however, calculate the land required to produce gross
    output equal to a modern nuclear plant of 1500 MW (90% capacity)
    and estimated that such a solar farm required around 80,000 acres.

    Not immediately going to disagree with you, but list your assumptions please, and show your calculations. I get far, far more land required.:

    1. On the equator, at 30 degree latitude, 45 degree latitude, and 60 north latitude, your calculation will be very, very different.
    2. Are you using the “rated” instantaneous output of the assumed solar power plant (at noon, at mid-summer’s maximum sunshine level, with perfectly clean solar panels on a perfectly clear day?)
    3. Solar power is only available 6 hours a day (9:00 AM through 3:00 PM (effectively) and generally loses 1 day in 4 to bad weather and clouds/dust/aerosol losses, but the nuclear plant is producing power 24 hours a day. How do you account for the “lost hours” when a solar plant is not producing power to the grid?
    4. If storing power, all methods require accepting 80% – 85% conversion factor (going FROM the solar DC power INTO the storage, then another 80-85% conversion efficiency coming BACK from the stored energy BACK INTO the grid. (Pumped storage, for example, requires more energy go INTO the pump motor and MORE losses inside the pump impeller INSIDE the pumps, evaporation and ground water seepage losses in the stored lake at high elevation, friction and pump efficiency losses both ways in the pipes going to and from the pumps. The water is now stored at high elevation, and undergoes even more losses going back into the impeller and impeller piping when drawn down, then electrical generator losses inside the generator and converter and transformers going back to the grid.

  54. Good question my friend. No, I do not believe (simply because I have found no proof thereof) that anybody have ever done any calculations (all the necessary correct numbers are missing – or not available due to lack of all the correct, or necessary, research)

    Back radiation does exist – of course it does – But c.mon guys how many times can solar energy warm the Earth’s surface?

    Reading through some of previous comments I get the impression that some people – who should know better – do think that a ‘motor-car’ or automobile, if you like – can run on its own exhaust fumes. Once energy has been used – in our case – to warm the earth’s surface – that’s it. The fabled “Back Radiation” is impotent and has no power to penetrate another medium, thus causing increased atomic movements

  55. Box of Rocks says:

    Roy Spencer says:
    December 10, 2013 at 12:21 pm
    the proportion of the Earth covered by solar panels is vanishingly small, and will remain very small in the future. So the panels’ “extra heating” effect will pale in comparison to CO2-induced warming…assuming that warming is non-zero, of course. ;-)

    Reg, yes ocean warming leads to more evaporation, and more precipitation. This effect is already contained in the climate models. The effect on cloud formation, though, is a huge wild card. The reason why is that all ascending air in clouds has to be balanced by descending air, which is usually cloud-free. So an increase in the atmospheric hydrologic cycle can lead to either more or less cloudiness. I predict more (a negative feedback on warming), the models say less (positive feedback on warming)…but no one really knows for sure.

    Dr Spencer – what is the time scale? IF more leads to less or less leads to more clouds?

  56. EWF says:

    The surface area involved is negligible. The excess heat (as little as there is) just gets radiated back into space anyway. That’s the skeptics’ point, that “forcing” is so small that it makes no practical effect compared with natural variations. Maybe you could use this angle to make a rhetorical point using the warmists’ own perspective, so long as your own thinking stays clear.

  57. EternalOptimist says:

    We also need to consider male demograhics, an older population with more baldy patches will alter the human albedo quite a bit. Plus as more people reject CAGW as an ideology, the ‘white hatters’ will become more prevelant, leading to an increased albedo and to a frenzied ‘tipping point’ ice age

  58. Jeff L says:

    I did a similar calculation on electric cars a few years ago, as these are essentially “coal powered vehicles “, as the bulk of electricity is generated by coal. I really expected to find that from a net CO2 emissions standpoint that they would less efficient than gas powered engine, however, when I crunched the numbers , I did find they had a net benefit in reducing CO2 per mile driven (assuming that is actually beneficial ). Not dissimilar to the conclusion RERT reached on solar panels (using a reasonable sensitivity at that ).

  59. parks says on:December 10, 2013 at 12:33 pm:

    “I read somewhere that the energy used for all the stages from mining the raw materials, processing, manufacturing, logistics/transportation,”

    Yes, energy wasted to prove that energy is used wastefully by us peasants is essential to make us see the error of our ways

  60. Willis Eschenbach says:

    Well, I have a bit of experience in these kind of back-of-the-envelope estimates …

    I’ve taken the following information from the reference above:

    A terawatt of peak capacity PV is a target value to reduce a gigaton of CO2 emissions per year (Kantner et al 2009).

    In total 30 grid cells were modified covering 18750 km2 of land area.

    That plus some constants gives us the information we need to calculate the change in heating (in watts per square metre [W/m2]). The calculations look like this:

    18750 = km2 solar cells
    1.88E+10 = m2 solar cells
    5.11E+14 = m2 earth area
    0.004% = of total earth area
    35% = albedo of sand
    7% = albedo of solar cells
    28% = increased absorption
    0.001% = global increased absorption
    342 = W/m2 incident sunlight
    0.004 = W/m2 total heating from reduced albedo

    1 = gigatonne reduction in CO2
    0.27 = gigatonne reduction in C
    9 = gigatonnes total human emission C
    8.73 = gT with PV
    2.13 = gigatonnes per ppmv
    45% = airborne fraction
    1.90 = ppmv increase w/o PV
    1.84 = ppmv increase w/PV
    390 = ppmv CO2
    391.90 = next year w/o PV
    391.84 = next year w/PV
    0.0070 = log change w/o PV
    0.0068 = log change w/ PV
    0.0008 = W/m2 at 3.7 watts/doubling CO2
    0.0007 = heat generation (see below)
    0.0014 = W/m2 total heating from fossil fuel generation + CO2

    10% = typical load factor (capacity factor) for PV system
    1.00E+11 = watts average from 1 TW peak
    8.77E+14 = watt-hours annual actual generation
    30% = generation efficiency
    0.0007 = W/m2 from fossil fuel combustion

    So to my surprise, the two options are of the same order of magnitude, and the extra heat absorbed by the PV (.004 W/m2) is about three times the forcing change of the CO2 emitted.

    Spreadsheet here. I invite people to check my figures, I’ve been wrong before …


  61. rgbatduke says:

    I was going to reply, but there is no need. Roy has already pointed out that we’re talking a negligible fraction of the Earth’s surface at best. Even if you raised the temperature of the entire converter array surface compared to what it was before by 10C it would be essentially invisible against the overall average temperature, even allowing for some downwind elevation as well. We will never ever cover 10%, or even 1%, of the Earth’s surface in solar cells, that is.

    Even so, it looks like somebody has published quantitative estimates because there could well be a local warming as a variant of sorts of the UHI effect. If one replaces green trees or green meadowlands with solar cells one will likely get a different delta than if one replaces south-facing asphalt shingles on rooftops with solar cells, so quantitative estimates probably have to be done on a very much ad hoc basis for each given case. CO_2-linked warming, however, is global in extent, not local, so one cannot really compare the two by asserting that solar cells create “more warming” than CO_2. Where they produce a UHI-like effect, sure they do. Everywhere else, their net impact could be almost invisibly small but negative to the extent that they displace CO_2 sources and the climate is moderately sensitive. As Roy also pointed out, the specific value of the climate sensitivity is far from clear at the moment as best estimates are in free fall as long as “the pause” continues.

    But in the end, one doesn’t need complex arguments. All one needs to do is look at the map:


    This map is assuming 100% of the Earth’s energy consumption is being provided by solar cells at 8% efficiency, allowing for the mean insolation at the locations shown. Of course this doesn’t allow for storage or transportation, but then, we are a long, long ways away from providing 100% of the Earth’s energy via solar power. OTOH, it isn’t clear that PV cells are ultimately the most efficient solar technology, and there are efforts underway to build solar concentrator generators that would have much higher efficiency and that would reduce the absorptivity of the collector area compared to almost anything. Upward facing mirrors that rotated vertically at night to let the ground underneath cool would have a strong local (negligible global) cooling effect. No matter how you slice it, though, we won’t even be able to cover 0.01% of the 30% of the Earth’s surface that is land area, if we work for decades at it. So whatever happens to the local temperatures on those sites, it is going to be a negligible contributor to AGW or AGC either way.


  62. Pat Lane says:

    I had a good laugh when I read this.

    I live in a small town in Victoria and a couple of years ago, I wrote a letter to our local paper about this very thing.

    I had done a rough, back-of-the envelope calculation using the estimated size of a solar collector large enough to replace all coal fired generation on Earth and then estimated the amount of waste heat that would be generated. From that I got an atmospheric temperature increase of about 4 degrees C. The number is almost certainly nonsense, like so much of ‘climate science.’

    One of the local greenies responded and said I was wrong. He said solar panels “would have a slight cooling effect.” So help me, the man’s a SCIENCE TEACHER!

    I wrote back, suggesting an experiment: I suggested he put a solar panel out in his backyard on a nice hot day, connect it up and let it run for several hours, then go out and pick it up.

    I recommended he wear gloves.


  63. David, UK says:

    Reg Nelson says:
    December 10, 2013 at 12:02 pm

    My question is this: If the planet is warming, and two thirds of the planet is covered by water, wouldn’t this lead to greater evaporation…?

    No. The reason being that the missing heat has been supposedly magically transported to the lower ocean depths where it of course cannot evaporate (or be detected at present – but hey, have faith). The surface temps show no rise of late.

  64. Konrad says:

    Zombie asks a good question regarding PV panels. Similar questions have been asked about the effect of wind power altering atmospheric circulation if the 17 tetrawatts was extracted by turbines to replace current fuels.



    With regard to PV panels with lower albedo than the surface placed in a desert the answer would be net warming. Under 20% of visible (SW) spectrum is converted to electricity by PV panels. Some solar radiation is reflected but the SW, UV and IR absorbed directly heats the air at the panels location. The small amount of electricity transmitted from the panels eventually becomes heat at a separate location.

    But what of the reduction of CO2 warming? There is no reduction. CO2 is a radiative gas. Adding radiative gases to the atmosphere does not reduce the atmospheres radiative cooling ability.

    However just like wind turbines, the environmental impact of PV panel manufacturing should also be considered. Look at the neodymium mines in China producing the magnets for bird blenders -


    Now look at a typical subsidised PV installation on a suburban home. Too few panels to power the house. Typically no storage. Electricity being “sold” back to the grid, destabilising the network. And all mounted on an aluminium frame that took 11 megawatt hours per tonne just to smelt excluding mining and transport. Will those cheap, dirty, de-laminating Chinese panels ever produce even the energy to manufacture the aluminium they are mounted on? How is China dealing with pollution of manufacturing of polycrystalline silicone? Lets check that as well -


    The only justifiable use for PV and wind power is to provide power in remote locations. The real environmental impact of these technologies is far too great to justify replacing natural gas or full base load thorium power for our near future energy needs.

  65. Hartog says:

    I am happy to see this being discussed. Always had a gut feel that, if on a scale large enough to fix the ‘CO2 problem’, there is that effect on the total energy budget. There is not really any free lunch. Similarly, if enough wind farms are installed, all that wind will also not be dong what it used to.

  66. Dr. Delos says:

    It is quite possible that even a couple of 100 square mile PV facilities would be trivial in comparison to the 19,000 square miles of asphalt already incorporated in the US highway system.

    The asphalt number came from a (probably inaccurate) factoid on the History channel this morning. The 200 square mile figure comes from a lecture given by solar proponents at the University of NM a couple of years ago. Their claim was that *all* of the electric power needs of the US could be satisfied by high efficiency, 30% plus, solar cells covering 100 sq. mi in Nevada and another 100 in NM. They changed the subject when they were asked about power use at night.

  67. I think everyone on any side of this debate understands that the warming from an albedo change caused by solar panels would be vanishingly small. As would the warming effect of a single coal plant’s CO2 emissions. The question is not relevant when discussing actual temperature effects on the atmosphere.
    However the question he asked as to the difference between the two is relevant to the climate discussion because policy is being used that proposed solar energy will have less effect on heating the earth than coal emissions of CO2.

  68. Auto says:

    Off thread = I guess – but:

    [link removed.]

    try it.


    [No. Either the wrong link was attached, or you do not understand the purpose of this site, and "off-topic" topics. Mod]

  69. zombietimedotcom says:

    Thanks everyone for your comments. Most appreciated! I’m going to bookmark this page and carefully digest each one of them over time. If a link/reference from your comment is used in my article (presuming I ever write it), proper citation (of your user name) will be given. Thanks!

  70. StephenP says:

    Also off-topic, but of interest as a comment on scientific journals

  71. son of mulder says:

    1. A kilowatt of heat produced by electricity generated by a coal powered plant warms the earth by the same amount as a kilowatt of heat produced by a PV array.

    2. Heat is wasted in the coal powerstation so additional heating occurs there.

    3. Then a calculation is needed to identify how much heat per KWH lifetime capacity is liberated in the creation of a coal Power station vs a PV array.

    4. Then a similar calculation for lifetime CO2 for each lifetime KWH

    5. Now calculate how much sunlight is blanked out by smoke and steam from the coal powersation ie cooling vs increase IR/albedo feedback from the released soot, water vapour and aerosols.

    6. Then as a shortcut calculate the amount of heat generated by all coal powered powerstations and realise it is a trivial amount compared to global insolation, but may well contribute to some significant UHI effects.

    7. Have a stiff drink and think about wild geese.

    PS Do PV arrays on roofs in hot countries reduce the use of airconditioners in attics?

  72. Peter Miller says:

    For me, reading all these comments is a stark reminder of just how little we really understand, or can accurately quantify, about the factors affecting our world’s climate.

    True, we have some dodgy inaccurate climate models and are now spending almost $1.0 billion per day on trying to combat something inconsequential, which we can not accurately measure.

    Can anyone doubt we live in a world gone mad?

  73. Alan Robertson says:

    “Zombie… with a question that he…”
    …or would that be she?

  74. DanMet'al says:

    A really good conversation on this topic. But many of the arguments. . . to me. . . are inch-bugging along the periphery of the critical question. Here it is: Were we (all of us collectively) in position to make the binary decision to either solely use (1) carbon resources (coal, gas, oil) or (2) equally efficient solar panels — to meet our global energy needs. . . which would have the greatest impact on global temperature. . . or alternatively the earth’s heat balance? I think I know the answer, but maybe I’m wrong.

  75. Robertvd says:

    What would Earth’s surface temperature be in a 100% CO2 atmosphere ?

  76. John Morpuss says:

    I think We should be looking at things that will take our homes of grid. Things like using a rectenna insted of a of a antenna Most of the electrical appliances in our homes can be run on 12 volts just look at the modern day mobile home . They can stay of grid by using solar and a small generator for those cloudy days If we where to use a rectenna for reciving radio and tv signels we could capture the free electrons used to propergate the signel at the rectenna. At this time it is illegal for the public to use a rectenna, its regarded as steeling power People in the know have been using a small array to steel power from high voltage power lines and charging up their batteries. A rectenna works in the IR window and would collect power 24/7 night and day cloudy or not. Leave the electrical grid for industry were high power electric potential (work) is neaded . Just think how much money would be saved if their was no power lines in residential areas no polls no matenence and no ozone emitting transformers This idear was created by Tesla to supply free energy to the people . We need to use all the tech’s avalible and scale them down so we can use them on our homes. We don’t need a wind turbine that creates terrawatts of power to sit on our roof we only need enough power to charge up 12v batteries
    ” A rectenna is a rectifying antenna, a special type of antenna that is used to convert microwave energy into direct current electricity. They are used in wireless power transmission systems that transmit power by radio waves. A simple rectenna element consists of a dipole antenna with an RF diode connected across the dipole elements. The diode rectifies the AC current induced in the antenna by the microwaves, to produce DC power, which powers a load connected across the diode. Schottky diodes are usually used because they have the lowest voltage drop and highest speed and therefore have the lowest power losses due to conduction and switching. Large rectennas consist of an array of many such dipole elements.” http://en.wikipedia.org/wiki/Rectenna

    Temperature is electric potential at work

  77. Alan Robertson says:

    There will be some minor local effect, just like when someone builds a chicken coop. Collectively, everything we do doesn’t amount to a hill of beans against the backdrop of the planet and its climate. Build all the solar whatevers in the desert that can be built and it won’t make a bit of difference, in the end.

  78. upcountrywater says:

    Well you not have this problem at night, so the solar panels array will need to be 50% larger. Additionally the panels array will need to be larger due to the low sun angle in the morning and evening…. and cloudy days….
    Say you could offset the panel array with mirrors on the unused part of the desert.

  79. Zeke says:

    Why doesn’t Zombie just go to Ted Turner’s massive (ratepayer funded) solar farm in NM and get some answers.

  80. Enginear says:

    The coal fired power plants operate at best 40% thermodynamic efficiency. That means 60% of the energy relessed from burning the coal goes into the atmosphere. That heat is much more than tiny difference PV makes. Don’t worry about CO2 as we really have no idea what the true forcing is.

    The real problem with PV is it only works when it’s light outside. To keep the country running that won’t cut it. So we run generators to back up the PV installation24/7. Now how efficient can that be? In sunny areas I can believe the use of PV to peak shave the load in the afternoon on hot days can be effective. But at what cost? Any other use except for remote areas is senseless.

    That’s my two cents,

    Barry Strayer

  81. lurker, passing through laughing says:

    Actually the panels will be casting a huge amount of shadow, and are reflective in many wave lengths. A fraction of the energy is of course converted into electricity and shipped out to consumers and industry. My bet is that if you walked under the panels, it would be noticably cooler. The heat re-released as waste heat from electrical power usage is very dilute. The real issues are do we want solar panel clutter in our open spaces,a nd waht impact will these uneconomical panels have on native wildlife adapted to strong sun, not strong shade?

  82. Hans Erren says:

    The correct answer is: we don’t know!

    Zombie wants to know the result of a climate model on a regional scale. However, all current climate models do not have any regional skill. It is not, as some commenters suggest, a simple back-of-an-envelope exercise, as it invokes many unknown feedback mechanisms of which water vapour is the biggest unknown on a regional scale.

  83. EWF says:

    Robertvd says: “What would Earth’s surface temperature be in a 100% CO2 atmosphere ?”

    Thanks to Venus, this is easily calculated. Venus’s atmosphere is 99% CO2 and its temperature is 735K (462C). It is 0.723 Earth’s distance from the Sun. Therefore Earth’s irradiation is (0.723)^2 = 0.523 of Venus’s. Therefore if Venus was placed into Earth’s orbit, its temperature would be 735K x 0.523 = 384K = 101C. So there’s your answer.

  84. EWF says:

    111C, that is. (384 – 273 = 111)

  85. _Jim says:

    John Morpuss says December 10, 2013 at 2:36 pm

    I think We should be looking at things that will take our homes of grid. Things like using a rectenna insted of … ” A rectenna is a rectifying antenna, a special type of antenna that is used to convert microwave energy into direct current electricity.

    More John Morpuss stuff huh?

    John, big foot went that-a-way ——>


  86. Matthew W says:

    Certainly there is a model that than calculate, er, project/predicate this?

  87. _Jim says:

    Anthony , mods – this John Morpuss guy may seem harmless, but he is stinking up the joint.

    I’m going to feel compelled to rebut some of his silliness if it is allowed to stand .. just a heads up, guys.

  88. Anthony S says:

    O. H. Dahlsveen says:
    December 10, 2013 at 1:08 pm

    Reading through some of previous comments I get the impression that some people – who should know better – do think that a ‘motor-car’ or automobile, if you like – can run on its own exhaust fumes.

    That’s already been done, and was a popular troll topic on automotive forums a couple years ago.


  89. eco-geek says:

    Well the hard number I saw for the greenhouse effect was 1.7 Watts extra heat at the surface due to CO2 whereas a solar panel will obviously produce much more than that by generating power which always ends up as heat. They have an efficiency of about 18% but I guess the reflectivity is low say 30% as opposed to 80% for a desert area so you are going to get 78% of incoming radiation converted to heat per square meter which is gonna be about 900 Watts for North Africa against say 300 Watts for bare desert. So I guess you are producing an extra 600 Watts per square meter of global warming for every 200 Watts of power at midday. So a megawatt of electrical would result in 3 mega Watts of warming. More for the “Absolute Black” Panels.

    So roughly speaking solar panels produce about 300 times the warming that CO2 supposedly does per square meter. So if you keep the solar panel area less than 1/300th the land area of the planet you will not warm up the planet as much as CO2 does. Of course if you allow for night and cloud cover solar panels capabilities come down somewhat so maybe you need to keep coverage down to less than 1/1000th of the land area or about 44,000 sq kilometers.

    I’m gibbering now. Time for bed.

  90. DonV says:

    Good start Willis. I love the way you think and the math skills you have!

    However, IMHO gases like CO2 and materials like silicon dioxide (glass, sand) and silicon (with a glass cover layer) may all have different albedos (reflectivities), but they also have different absorbances of the suns energy and different emissivities. Absorbance plus emissivity then would be a second source of heat shedding difference between a “solar panel” and a change in CO2 caused by a power plant.

    I have a question for Zombie to help us sort out the issue:
    What specific type of solar panel were you thinking of? I think everyone is assuming silicon solar cells, but solar panels also come in other varieties each of which have different solar energy absorbances, reflectivities, and emissivities. For example, if the solar panel is designed to heat up a fluid for driving a turbine, then it will be designed with mirrors (high reflectivity) and/or glass tubes (low reflectivity) that has very high solar absorbance. In contrast the outer glass layer on a silicon solar cell will have low absorbance and be optimized to transmit as much of the incident solar energy that matches silicons to optimize conversion of light to charge carriers. See for example the following lectures:


    This last lecture in particular, has a lot of good information about solar cells.

    You have to dig for it but a good series of lectures about solar irradiation absorption and losses pertaining to gasses. (vegetation, soils and sand) can be found in this interesting series of chapters/(lectures?):


    Especially, this chapter!
    In this chapter Figure 3.1 shows the reflectivity (albedo) for “Sand, desert” to be
    “25 – 40″ %. This means that the absorbance is most likely 60 – 75% across the spectrum.

    I found a figure for the radiative emissivity of sand equal to ~.95 – .96

    Finally, in addition a power plant’s inefficiencies are most often lost in the form of heat. So a better stab at the power generator’s contribution would be to assess that the conversion of potential energy in the fuel that does NOT go into generating the power, gets converted to some form of heat, and add that to CO2 side of the equation.

  91. John Hanson says:

    What I never see is the analysis of the battery arrays (massive) needed to effectively store the power generated during the likely no more than 10 hours a day of effective energy gathering (even in deserts) so the output power can be provided 24/7. This is needed if solar is ever to replace base power stations, and not just be used for extra capacity in afternoons. (Or massive arrays across the entire planet and a global solar array/energy transport system to provide energy 24/7 around the world, haven’t seen this proposed either. I’m sure someone must have done the larger scale analysis. Or is there some other answer to energy storage. Environmental damage from manufacturing and set up of Terrawatts of batteries, with servicing and replacement is not ignorable either.

  92. John Morpuss says:

    @ Jim Your either part of the sollution or part of the problem. and I’m starting to see you as part of the problem. Seeing your responce adds nothing apart from insults mabe the same mod that deleted my other answers could do the same to you . It will be good to see if this forum is fairdinkem or just another propaganda site for the sheep.

  93. David L. Hagen says:

    Best perspective by Roy Spencer – the uncertainties are so great, we do not know whether it will cool or warm. For some results of conventional modeling see:
    The potential for air-temperature impact from large-scale deployment of solar photovoltaic arrays in urban areas, Haider Taha, Solar Energy Volume 91, May 2013, Pages 358–367

    Among the many benefits of solar photovoltaic (PV) systems, the direct effects are those of providing local power and the indirect ones include avoided generation from fossil-fuel power plants. The latter translate into reduced emissions of greenhouse gas (thus reduced radiative forcing) and other pollutants, such as ozone precursors (thus improved air quality). Because large-scale PV deployments can alter the radiative balance at the surface-atmosphere interface, they can exert certain impacts on the temperature and flow fields.

    In this analysis, meteorological modeling was performed for the Los Angeles region as a case study to evaluate the potential atmospheric effects of solar PV deployment. The simulations show no adverse impacts on air temperature and urban heat islands from large-scale PV deployment. For the range of solar conversion efficiencies currently available or expected to become attainable in the near future, the deployment of solar PV can cool the urban environment. The cooling can reach up to 0.2 C in the Los Angeles region. Under hypothetical future-year scenarios of cool cities (urban areas with extensive implementations of highly-reflective roofs and pavements) and high-density deployments of urban solar PV arrays, some adverse impacts (0.1 C or less in warming) might occur. However, such extreme high-density deployments of cool surfaces are not expected and thus the warming effects are unlikely to result.
    ► Large-scale deployment of solar PV arrays has no adverse impact on the atmosphere. ► At solar conversion efficiency of 20% or higher, PV arrays can cool the air. ► Very high-density deployment of PV can cause some warming but also larger cooling. ► Increasing roof albedo by 0.05 and PV efficiency from 10% to 20% are equivalent.

    Energy from the Desert: Feasibility of Very Large Scale Power Generation (VLS-PV) Systems edited by Kosuke Kurokawa. Routledge, May 4, 2012 – Technology & Engineering – 236 pages; see discussion on albedo

    Meteorological, emissions and air-quality modeling of heat-island mitigation: recent findings for California, USA Haider Taha Int. J. Low-Carbon Tech. (2013) doi: 10.1093/ijlct/ctt010 First published online: April 4, 2013

  94. wayne says:

    Robertvd says:
    December 10, 2013 at 2:35 pm

    What would Earth’s surface temperature be in a 100% CO2 atmosphere ?

    Basically the same as it is now. Catrefully check what EWF proposes, he is assuming a Venus, I find that logic not correct. The vast majority of Venus’s high surface temperature with 96.5% CO2 and 3.5% N2 is due to the high unit columnar mass.

    You more have something more like this:

    Ts.earth = ( (10332*0.0153 + (1362/4*(1-0.30)) )/‹kSB›)^(1/4) = 289.2 K

    Ts.venus = ( (1051000*0.0157 + (2614/4*(1-0.90)) )/‹kSB›)^(1/4) = 735.2 K

    The first value is the mass of a unit atmosphere column. The 0.0153 and 0.0157 are the approximate number of watts abosorbed/reflected per kilogram as the surface flux travels upward (Beer-Lambert related). The tail calculation is the respective OLRs entering and leaving, in and out per their TSI and albedoes, and that radiation power is then converted to equivalent surface temperatures.

    Using Earth with Venus’s W/kg value gives:
    Ts.earth = ( (10332*0.0157 + (1362/4*(1-0.30)) )/‹kSB›)^(1/4) = 289.9 K
    a 0.7°C rise all else assumed the same.

  95. Curt says:

    Zombie: Good question, and worth some back-of-the-envelope calculations.

    Note to others: I am using “mainstream” assumptions and analytic methods, which I don’t care to debate – substitute your own if you don’t like mine. Zombie appears to want to use methods his green friends will accept.

    In a low-latitude desert, peak solar insolation at the surface is about 1000 W/m2. A rule of thumb for this is that you have the effective equivalent of this for 8 hours out of the 24 hour day, so averaged it is 333 W/m2.

    Desert surface albedo is generally given as about 0.40, so 60% of this is absorbed, or 200 W/m2, with 133 W/m2 reflected back to space (averaged over a full day, of course).

    A photovoltaic panel will have an albedo of about 0.10, so 90% of this is absorbed, or 300 W/m2, for an increase of 100 W/m2.

    The panel will have an overall electrical conversion efficiency of about 15% (maybe 20% at the panel itself, but you lose about a quarter of this in processing and nighttime storage). So averaged over a full day, you can generate 333 * 0.15 = 50 W/m2 (half of the extra power absorbed).

    For the 1 MW generating capacity you ask about, you would require 20,000 m2, and this would cause 2 MW of extra power absorption by the earth. (Note that the 1MW converted to electrical power is not thermalized at the panel, but it will eventually be converted to thermal power.)

    Let’s compare this first to a 1 MW coal-fired plant operating at 40% conversion efficiency. As it produces 1MW of electrical power, it is producing 1.5MW of thermal power for a total of 2.5MW additional thermal power liberated from the chemical bonds in the coal. A little worse here than the solar panels on this count.

    But what I think you are really asking is how the (supposed) warming from the CO2 emissions would compare to the warming from extra albedo. Here you cannot make such a direct comparison, because, in the mainstream analysis, at least, the effects of added CO2 are cumulative. Let’s go through the analysis:

    Typical CO2 emissions for coal-generated electricity are usually given as 1000g/kWhe, that is, 1.0kg of CO2 for each kilowatt-hour of electrical energy generated. One kWh is equal to 3.6MJ, or 3.6MW*sec. So to generate at 1MW power, you would generate CO2 at 1.0/3.6 = 0.278 kg/sec.

    But by mainstream greenhouse theory, the added power is a function of the resulting concentration of CO2, not by its rate of change. So we have to see how this added CO2 accumulates over time. We’ll use a period of 20 years.

    0.278 kg/sec for 20 years comes out to 1.74×10^8 kg. It is generally accepted that about half of the added emissions stay in the atmosphere short term, so will have added 8.7×10^7 kg at the end of 20 years. Various sources give the total mass of CO2 in the atmosphere as about 3.16×10^15 kg.

    In mainstream climate science, the key equation for the added “radiative forcing” is:

    DeltaF (W/m2) = 5.35 * ln (C/C0)

    where C0 is the reference concentration and C is the new concentration. To use concentration values, we would need to divide both numerator and denominator by the total atmosphere, but those operations would cancel out, so we can just use the mass numbers. So we get

    DeltaF = 5.35 * ln ([3.16x10^15 + 8.7x10^7] / [3.16x10^15])

    DeltaF = 1.47×10^-7 Watts per square meter of the earth’s surface

    The earth’s surface area is 5.15×10^14 m2, so the added retained power at the end of the 20 year period would be:

    DeltaP = 1.47×10^-7 W/m2 * 5.15×10^14 m2 = 76 MW

    Over the 20 years, this added power level would steadily increase (roughly linearly) from 0 to 76 MW. Even using half of this value results in a much larger value than the added solar absorption of PV panels. So you could not use this basic analysis to make the point you want to make.

    The latest combined cycle gas turbines (CCGTs) put out about half the CO2 of coal plants per unit of electrical energy generated. Simpler open cycle gas turbines (OCGTs) put out two-thirds (or more) of the CO2 of coal plants, half again as much as the CCGTs. But OCGTs can be ramped up and down much more quickly, so they are used where there are large amounts of variable renewable power. Close analysis of real electrical grids indicates that heavy use of renewables may not be reducing CO2 emissions at all due to the need for lower-efficiency backup.

  96. aaron says:

    Thought about it a long time ago, but didn’t get far. My WAG is that the efficiency is what matters, and that when the efficiency is high enough to compete with fossil power plants, then it will produce less heat.

    It depends on the waste heat of burning fossil fuels, the residency time of GHGs, and the log forcing of GHGs. Where it really gets difficult is the maintenance and life of solar sources which are really unknown.

  97. So many lizards and other little desert creatures will die because they cannot get enough sun, but that is accounted for by all the birds that would have eaten them will be dead as well, because the wind beaters will swipe them from the sky. It will all be worth it, though, because all those nasty rattlesnakes will be dead. Good riddance to them!

  98. Adam says:

    @David, UK

    The point is that if we replace a Coal Power Station with Solar Panels then what is the net temperature change caused by the two factors:

    1) The presumed decrease in global temperature due to the reduction in CO2 emitted;
    2) The presumed increase in global temperature due to the energy absorbed by the solar panels which would otherwise have reflected back into space.

    Whilst there are an infinitesimal number of panels today, the assumption has always been that by replacing Coal Stations with Solar Panels would reduce the planetary temperature because only the first factor had been considered. This post is asking the question: How big is the second factor compared to the first factor.

  99. bw says:

    Replacing a 1 gigawatt electric coal power plant would take a solar photovoltaic array of about 10 million square meters of arid land surface of 0.4 albedo in the SW USA.
    The solar energy absorbed above land surface would increase by about 6 gigawatts average over a year. The coal plant also dumps about 2 gigawatts of waste heat for a total of 3 gigawatts of net heat since all electricity ends up as thermal heat.

    Therefore, any photovoltaic energy used to displace coal generated energy about doubles the net heating to the planet. In both cases the amount is negligible to global temps.

    Surface energy data have already been measured and are available from the National Renewable Energy Lab (NREL) for land based flat surface plates.
    Note that surface albedo over tropical ocean would be INcreased by photovoltaic arrays.

  100. Scott says:

    There’s no need to think about the effect of solar panels on global warming because there’s simply not enough available silver to make enough solar panels to ever make a difference.

  101. aaron says:

    Another question I’d like answered is, “How efficient is current solar tech compared to photo synthesis?”

    The reason, I’m wondering if perhaps the future of solar is going to be a hybrid of genetically engineered plant material, bacterial material, and nano-tech. I imagine dynamic systems which produce energy through photo-synthesis and immediately convert this to electricity, or depending on demand, into liquid fuel.

  102. EWF says:

    In response to Wayne, here is my simple column density calculation: Venus has 96% CO2 x 90 bar pressure and Earth has 0.04% CO2 and 1 bar, thus Venus’s column density of CO2 is 90×96/0.04=216,000 times that of Earth. This is 17.72 doublings of CO2. In my previous posting I calculated 97C of warming due to Venus’s atmosphere, thus this shows 97/17.72 = 5.5C of warming per doubling of CO2. Uh oh, isn’t that Trenberth’s figure? I uphold my calculation but disavow the results. :-)

  103. bw says:

    Curt posts similar numbers, except he uses a 1 megawatt reference.
    The basic idea remains that at photovoltaic power plant produces twice as much thermal energy as a coal fired (or nuclear) plant. Coal plant CO2 emissions have no measurable thermal effects on land temperatures. Fossil fuel emissions add about 3 percent to the natural global biogeochemical Carbon cycle. Natural variations in biological surface albedo are much larger.

  104. Mario Lento says:

    Roy Spencer did a pretty interesting study on heat released by resistance losses associated with electricity being used, if I recall. Eventually the electricity that does work will end up as heat if I recall correctly.

  105. John Morpuss says:

    Here is another known fact that will provide us with free energy once constructed. One thing I see is we could use personal exersize equipment to generate powerI don’t know if you ever pegged a card to your frame which made contact with the spokes and mad a motor sound. Well replace the card with piezoelectric material and charge up home batteries. Jim stop running around the room screaming HE’S DOING IT AGAIN This would help kill [two] birds with the one stone by giving people a reason to exersize and fight the obesity problem you would be saving money every Km you peddel Or we could conect a piezoelectric device to that whirley bird that sucks hot air from the inside of our roof space http://en.wikipedia.org/wiki/Piezoelectricity

  106. Gunga Din says:

    Most people like Merry-Go-Rounds.
    So the question is: “Are Man-made efforts to prevent Global Warming causing Man-made Global Warming?”

  107. DanMet'al says:

    There’s certainly a lot of intelligent and thoughtful people posting on this topic. . . but please try to get out of the weeds as you think about the energy balance. The more energy we capture via solar or even wind, the less is transmitted (reflected) back to space! Remember most, if not all, of the captured solar and wind energy is ultimately dissipated at heat! Maybe I’m wrong, but this seems simple and only gets confused by all the uncertain discussions of heat losses, efficiencies of all the subcomponents and processes etc. . Let’s put it another way. . . if a fraction of solar radiation, normally reflected back to space, is instead retained/absorbed, in part, by a solar collector, the wind, and other downstream processes, is not the outgoing heat loss reduced, thereby increasing the global heat retention? I’m simple minded so correct me if I’m wrong.
    My point is that the AGW solutions seem both juvenile and futile?


  108. wayne says:

    EWF, it has to do more with the same properties of any atmosphere as to why you can look directly at the sun without harm as the sun nears the horizon. The solar radiation which our atmosphere is ‘transparent’ is reduced to 1/30th it’s zenith power. You seem to be treating co2 as unique. Now that is shortwave but do you not see the same occurs with longwave in any mixture of gases, a complete spectrum of all frequencies involved? You look only at co2, I try to stay away from such mis-assumptions and I feel it is better dealing all gases as a whole. I believe the topics are more found under air mass, atmospheric mass attenuation, optical path length when comparing two different atmosphere compositions than IPCC’s story-line.

  109. Quinn says:

    eco-geek alluded to this, but solar arrays convert much of the incident solar radiation directly into heat. For silicon cells, all radiation absorbed above 1.1 microns wavelength is converted directly to heat, and a substantial portion of the absorbed radiation below 1.1 microns (including the visible) is also converted to heat, due to the limited quantum efficiency of the conversion (electrons out / photons in).

  110. Matthew W says:

    DanMet’al says:
    December 10, 2013 at 4:43 pm
    My point is that the AGW solutions seem both juvenile and futile?
    Don’t forget counter productive and excessively expensive.

  111. Catcracking says:

    I find this to be an interesting question, and I have previously raised the point that solar panels trap heat on the earth that would not happen if the Solar Panels did not exist. It is simple thermodynamics, the sun’s rays are converted to electricity which ultimately becomes heat that is released mostly at another location and only a portion of which is radiated back into outer space. Advocates of solar panels either do not understand this or dismiss it as trivial. There is a net heating. Of course burning fossil fuels similarly releases heat into the earths system a portion of which is radiated into outer space even if CO2 contribution is nil. Others are more qualified than I am to calculate the relative effect of solar panels versus conventional fuels.
    I accept the theory that solar panel impact is presently trivial, but one needs to address the proposals for significantly more solar energy being brought into the earth via solar collectors in various forms including the following:
    Note that none of these advocates address the issue raised by this post since they are obsessed with the theoretical impact of CO2 and ignore the downside of the alternatives. We need to do the calculations accurately to understand the issue.

  112. John Morpuss says:

    While planned obsolecence is being used as the primary driver of western econamies we will never look outside the box http://www.youtube.com/watch?v=24fJn7jzGSE I wounder were Jim stands on this

  113. EWF says:

    Wayne, what you say is true but the way to do any physical calculation is to first quantify the primary component and then quantify the perturbations. I kept it simple to use CO2 (the primary component) only. Presuming my calculation is accurate, then it’s a big ask to perturb well away from the primary outcome.

  114. Willis Eschenbach says:

    DonV says:
    December 10, 2013 at 3:34 pm

    Good start Willis. I love the way you think and the math skills you have!

    However, IMHO gases like CO2 and materials like silicon dioxide (glass, sand) and silicon (with a glass cover layer) may all have different albedos (reflectivities), but they also have different absorbances of the suns energy and different emissivities. Absorbance plus emissivity then would be a second source of heat shedding difference between a “solar panel” and a change in CO2 caused by a power plant.

    Thanks, Don. My calcs are above for those who missed them.

    In my analysis, I assumed that whatever energy wasn’t reflected was either turned into electricity and eventually into heat, or turned directly into heat. I estimated total heat by calculating the increase in absorbed energy due to increased albedo.

    Since I’ve included all of the captured energy, I don’t think that your issues of various emissivities and absorptivities come into play.

    All the best,


  115. Alan Robertson says:

    Michael Gersh says:
    December 10, 2013 at 4:04 pm

    … all those nasty rattlesnakes will be dead. Good riddance to them!”
    I can agree with parts of your light- hearted words, but don’t know where you got the idea that Rattlers are nasty or don’t have a place. They will not kill a small animal if they are not hungry. I have watched them be pestered by mice, which will eat the dead skin off their hides and eat their rattles and the mouse will have his way with the snake if he’s not hungry. Plenty of snake species will kill when not hungry- almost all the constrictors come to mind.
    Rattlers are very social and gather in enclaves in caves and dance with each other, etc.
    You can even dance with a rattler, but they won’t be treated disrespectfully.
    Rattlers will tell you to back off before they whack you, what more could you ask of them.
    Ps I’m no herpetologist

  116. Kip Hansen says:

    On our boat, we have mounted the solar panels with a six inch air space between the panel and the cabin top, to prevent the heat absorbed by the panels from mechanically transferring into the boat. The tropical breezes blow through the space and whisk away the heat. The panels, in the tropical sun, get hotter’n a pistol.

  117. LdB says:

    So many stupid answers and people but we have a winner

    Curt says:
    December 10, 2013 at 3:52 pm

    Who correctly identified that a solar panel will always rate lower than coal or any fossil fuel burning because the CO2 effect is cumulative.

    Repeating I am not a climate scientists so I am not saying what is wrong or right here just identifying the facts. This area was one thing that was tightened up by the IPPC 5th assessment and if you really are interested it is worth reading at least reading it before making further stupid comments.

    For those of you too lazy and/or stupid to bother reading the IPCC report the old version appears in Wikipedia (http://en.wikipedia.org/wiki/Greenhouse_gas) and it comes under the heading global warming potential (GWP) timescales and life cycles

    The global warming potential (GWP) depends on both the efficiency of the molecule as a greenhouse gas and its atmospheric lifetime. GWP is measured relative to the same mass of CO2 and evaluated for a specific timescale. Thus, if a gas has a high (positive) radiative forcing but also a short lifetime, it will have a large GWP on a 20-year scale but a small one on a 100-year scale. Conversely, if a molecule has a longer atmospheric lifetime than CO2 its GWP will increase with the timescale considered. Carbon dioxide is defined to have a GWP of 1 over all time periods.

    CO2 is defined as 1 on all timescales … AKA all effects are cumulative … they never diminish.

    So with all that plugged in go further down the Wikipedia page and you will find “Lifecycle greenhouse gas emissions by electricity source” and it gives you the answer

    Solar PV 46 gCO2/KWh
    Coal 1001 gCO2/KWh

    So there is the answer for Zombie as given by climate science and it wasn’t that hard to find … you just have to read.

    As I said the IPCC 5th assessment actually changed a fair bit of this it is actually quite different from IPCC 4 but just hasn’t got media time except really in the oil and gas industry itself.


  118. Alan Robertson says:

    DanMet’al says:
    December 10, 2013 at 4:43 pm
    It all gets radiated back to space, eventually. The amount of energy “delayed” by the panels (and downstream equipment powered by the panels) is almost immeasurably small in comparison to Earth’s daily energy budget. Local effect is lost in the grand scheme and ends up not rising to the effect of a pixel in the big picture.

  119. Alan Robertson says:

    LdB says:
    December 10, 2013 at 5:43 pm

    “So many stupid answers and people…”

    For those of you too lazy and/or stupid to bother reading…
    Solar PV 46 gCO2/KWh
    Coal 1001 gCO2/KWh

    So there is the answer for Zombie as given by climate science and it wasn’t that hard to find … you just have to read.”
    Pardon, but you answered a question which Zombie didn’t ask, all the while calling people here lazy and stupid.

    Ja Ja Ja Ja

    Oh, by the way, since you were so quick to agree with Curt, but apparently didn’t read or comprehend what he said, here’s the money quote for you:

    Curt says:
    December 10, 2013 at 3:52 pm

    “Close analysis of real electrical grids indicates that heavy use of renewables may not be reducing CO2 emissions at all due to the need for lower-efficiency backup.”

  120. LdB says:

    Alan Robertson says:
    December 10, 2013 at 6:22 pm

    In theory everything is supposed to be in the lifecycle number in the IPCC 5th data. The energy to make it, dispose of it after it dies and the life cycle losses such as transmission. Again read the report it’s all explained so that argument doesn’t wash.

    The problem for me is it all comes down to averages, average losses , average this, average that and when you take a specific site the number may be wildly differently. That is one of the weakness points about the approach is in certain sites you might get better results not doing the normal but climate science doesn’t allow that approach.

    I am not here to defend climate science I am just saying how it works in the framework they have created and all energy comes back to a CO2/KWH number over the lifecycle of the supply.

    Can I say what I think is the real issue an I really doubt that CO2 has a value of 1 over all lifespans do some reading on CO2 turnover. I think this is one of those political things because if it had a lifespan USA and Europe would be off the hook for past emissions and would not be expected to pay for past emissions. If any climate scientists are kicking around I would love to hear your argument of a value of 1 on hundred and 1000 year numbers.

  121. tobias smit says:

    As far as what the temp would be on Earth if the atmosphere was 100% CO2, I suspect we’d be living on Mars and using satellites to take the measurements.

  122. James at 48 says:

    I promise not to reveal whether Zombietime is M or F.

  123. Michael J says:

    Just to split a hair …

    jai mitchell (at December 10, 2013 at 11:34 am) mentioned the simulation of solar panels by making the surface black.

    I think there might be a significant difference between a blackened surface and a black solar panel. Energy absorbed by the solar panel is transmitted or stored, while the black surface would have to simply re-emit the absorbed energy.

    Of course (thinking globally) the stored energy will later be re-emitted when it is utilised, but the effect on local temperature might be a little different.

  124. Steve Garcia says:

    Hahahaha – FINALLY

    I asked this very question when I first saw a solar tower and mirror array. When was that? About 40 years ago? They were proposing these be spread out all over the deserts of the world – unused land, I think was the concept.

    And I think my question was, “What does that do to the planet’s albedo?” I didn’t see anything good coming out of it. In the long run it would have to affect the climate. In specific ways, beginning with local/regional changes in heat flux.

    This is the first time I have EVER heard anyone else think of this, that the albedo change would mean more heat energy trapped on Earth. And DID ANY OF THEM BACK THEN BOTHER TO THINK OF THAT?


  125. Steve Garcia says:

    I liken these cover-the-desert-with-solar-devices to the stupid idea of biofuels.

  126. rgbatduke says:

    It is quite possible that even a couple of 100 square mile PV facilities would be trivial in comparison to the 19,000 square miles of asphalt already incorporated in the US highway system.

    A very good point, actually. Bear in mind that the surface area of the US is 3.8 million square miles, so that 19,000 square miles of asphalt is a nice convenient 0.5%.

    I find it difficult to think in the English system — let’s go metric. In metric, the surface area of the US is roughly 10^7 square kilometers, or 10^14 square meters. A single square meter of solar panel receives an average of 150 to 250 watts/square meter over the lower 49 states (averaged over years of 24 hour days, not daylight hours that are 2-3 times this). The US consumes something like 20,000 TW-hours per year. If we set solar conversion to an easy number like 10% and assume 200 watts/square meter as some sort of mean insolation for the country (excluding Alaska, where solar panels will never make much sense) we can reap something like 20 Watts/meter squared times 24 hours a day times 365 days a year, or 175 kW-hours per square meter.

    Too hard, let’s call it 200 kW-hours/meter^2. Then we need 20,000 x 10^12 / 200 x 10^3 = 10^10 square meters of collector to provide all of our current consumption, assuming perfect ability to store and/or transport the energy. That’s a square 10^5 meters (100 km) on a side, or 10,000 square km. The US is 10^7 square km, so we would have to use just about exactly 0.1% of our surface area to provide all of our energy needs (again, idealizing a bit but not really that much). This is a far cry, of course, from 100 square miles — more like 100 miles SQUARED. But still, one could fit it all inside a comparatively small corner of southwest Texas or New Mexico or Arizona desert and never miss it. One could replace the tobacco fields of NC with solar farms and the whole world would only benefit (both ways!).

    Note well that concentrated solar power (mirror/heat based generators) have achieved something like 30% efficiency and would cut the area numbers by 1/3 if broadly implemented. It currently produces electricity at an amortized cost of around 12 to 18 US cents per kW-hour, competitive with fossil-fuel based production costs in certain venues (and within a factor of 2 of competitive in most venues). However, PV solar is passing it in cost-efficiency and so far PV solar has obeyed something like a Moore’s Law as far as fabrication and production costs are concerned. If PV solar production costs (per “watt” of delivered power) continue to ramp down for one or two more decades at the rate that they’ve been decreasing for the last two decades, PV solar will be cost competitive with most fossil fuel based energy production by 2020, and will be significantly cheaper by 2030, even ignoring the possibility of increased costs for extracting fossil fuels and completely ignoring the CO_2 issue for better or for worse.

    Personally, I think most of that is a done deal — I think that solar power is in our future barring the widespread implementation of e.g. Thorium based power generation or the invention of cheap, efficient, thermonuclear fusion based power generation. The existing technology is sufficient already given economies of scale, and there is considerable progress being made towards still better technologies (higher efficiencies, lower manufacturing costs) and nanoscale physics contributions to this developing science haven’t really had time to have an impact yet. Higher efficiency means less local heating — from the point of view of conversion, waste heat is wasted money, so there will be a lot of old fashioned self-interest driving the development of hybrid systems that waste less of it (for example, using the same panels to convert sunlight to electricity and to heat water for immediate use (and cooling the panels) or to heat a house at night).

    The open questions are storage and long distance delivery. Solar power really would make sense as a complete replacement for fossil fuel based power — if one could efficiently bank it for at least days, possibly weeks. At the moment one can do little more than buffer it for minutes to hours and supplement it with natural gas generators that can be brought online “instantly” to make up for the natural fluctuations in production. One saves fuel (and fuel costs), but it is hardly a stable or particularly economic solution so far as it requires one to have almost twice the production capacity needed to deliver the expected load — as much as 100% from the natural gas generators (e.g. at night), and as much as 100% from the solar cells during the day, with a mix in between.

    Rooftop private domestic collectors are a better idea — they don’t cost a lot, they are break even or thereabouts over a reasonable lifetime of the hardware plus maintenance costs (with a still-too-long amortization, but one many people will borrow to pay now to be able to NOT pay for electrical power for 20 years) with reselling into the grid. This reduces load on the primary generation facilities during the day in useful, fairly predictable ways without the need for a particularly complex optimization system and twinned commercial production.

    Naturally, there is a lot of work being done on energy storage as well — both advanced battery designs and more exotic methods. There is an efficiency penalty and additional cost associated with storage, but one can still be optimistic that the problem will be solved within one to two more decades of focussed work. There is certainly a strong financial incentive to solve it.

    To conclude, if one takes the US as “typical” and wishes to produce energy on a similar per capita basis worldwide, one might expect to use between 0.03% and 0.1% of the land surface area to do so, which is less than 0.01% of the surface of the Earth proper (which is 70% ocean). If one heated all of that surface by 20 degrees Centrigrade over its usual average temperature, it would still heat the world far less than the urban heat island effect already is heating it — the heating of the roadways, buildings, tilled earth, parking lots of human civilization. Compare 3.8 million square miles to 19,000 square miles of roadway to 4000 square miles (10,000 square kilometers) of collectors. The latter is simply quantitatively negligible, no matter how hot you imagine the collectors make the ground there.


  127. Henry Clark says:

    While there are a handful of exceptions, overall that so much writing has been expended by so many without immediately seeing the obvious is borderline disturbing.

    As a thought experiment, even all power being produced by solar would have trivial (practically zero) effect on global temperature. Earth is hit by 200000 terawatts of sunlight. Human electricity generation averages 2 terawatts. Throw in inefficiencies of the solar panels plus other details, and somewhat more than 1 / 100000th of Earth’s area would be covered in that event — but such is still utterly trivial. (The same, incidentally, is also so for waste heat from nuclear power generation; it may warm up a local river, for instance, but not millions of cubic kilometers of ocean waters as a whole to any significant amount).

    (Human CO2 emissions don’t have much of a temperature effect either, like Dr. Shaviv, in one of his papers reference on sciencebits.com, calculated about 0.5C of the 0.6C of warming in the past century was solar/GCR and not anthropogenic, but the global temperature effect of multiple terawatts of solar power, multiple millions of megawatts, let alone a single megawatt, is insignificant).

    One of the causes for mathematical literacy being uncommon is that most people alternate between one of two states: (a) no quantitative thought, with assumptions often off by orders of magnitude versus (b) time-consuming “exact” formal calculations of the kind they were taught to do in school but never actually do in any other context due to such taking much effort. “Back-of-the-envelope” calculations or quantitative approximate assessments of the general order of magnitude of something tend to be quick, easy, practical, and vastly superior to the (a) which gets resorted to when few want to do (b).

  128. peat says:

    As Willis Eschenbach, Son of Mulder, and Enginear pointed out in their comments, a conventional power plant — be it coal, natural gas, or nuclear — produces waste heat. One can think of the extra light absorbed by solar panels (that which decreases the Earth’s albedo in excess of electricity produced) as a kind of waste heat. The heart of the matter is captured in a very succinct calculation; the trick is having realistic numbers. Willis Eschenbach suggested that a solar panel, compared to sand, causes an additional 28% of incident sunlight to remain earthbound instead of reflecting back to space. If a solar panel can convert 10% of sunlight into electricity, then the effective conversion efficiency (electrical output compared to extra captured sunlight) is 10/28=35%. This idealized case is remarkably similar to the efficiency of conventional power plants (electrical output compared to energy burned). That is, solar panels have a heat footprint per unit of electrical energy produced on par with conventional power plants. This is not a reason to pick on them.

  129. rgbatduke says:

    As usual, I made a late-night arithmetic error 20,000/200 = 100 = 10^2 (times 10^9) so it is 10^11 square meters or 0.03-1% of the surface area depending on efficiency and location. Oops.

    Still negligible even in the unlikely event that we ever get to where we are producing 20 TW-hours/year from PV solar alone.


  130. Jeff Alberts says:

    I just don’t think albedo has that much of an effect. A couple years ago when something like 80% of the northern hemisphere land mass was covered with snow, there wasn’t a subsequent lengthening of the winter, or extreme cold snaps as a result. The snow melted much as it always does.

    If that had no effect, the miniscule amount of land taken up by even hundreds of full-scale solar plants would have no calculable effect.

  131. Bob says:

    The problem is that while the heat produced by both the solar and coal fired plant radiates away relatively quickly, the greenhouse gases released stay in the atmosphere for decades, and in the biosphere for eons. integrated over time, there is no comparison. these calculations have been done, and over time the solar plant is vastly less damaging. warming is just one part of the problem- the other it’s ocean acidification.

  132. Eli Rabett says:

    [off topic - this thread has nothing to do with Gray -mod]

  133. LdB says:

    So while we have everybody doing crazy mathematics lets see if anyone can do this crazy calculation. There are currently 6 Billion people on the planet all eating and subsequently radiating heat 24 hours a day to hold a constant body temperature. The amount of heat given off depends directly on the activity level however lets go for the mid assuming half the population is asleep and the other half is very active. How much heat is given off by the citizens of the planet as an average?

  134. Hoser says:

    MarkB says:
    December 10, 2013 at 11:36 am

    Paraphrasing…. The substitution of PV for fossil fuel has a 30x benefit over albedo increase.

    Why do we always forget biology? Do we really want to cover that much surface area and starve out photosynthesis in those areas? I take it as true without proof biology is the key stabilizing factor in Earth’s climate. Obviously, having a planet with 70% oceans helps. Impacting photosynthesis on a very large scale could begin to alter the climate by changing atmospheric composition. A gedanken experiment in which all photosynthesis were blocked would result in an increase in CO2 and a decrease in O2, at least until respiration and combustion stops. However, changing our experiment to retain large areas of photosynthesis might permit biology to compensate and reach a new equilibrium state with a higher level of CO2. Maybe this is a smart approach to delay the next Ice Age. Well, it could be, except it’s stupid in so many ways.

  135. One issue I see here is that solar panels generally have low efficiciency of converting absorbed solar radiation to electricity. Solar radiation energy that gets absorbed but not converted to electricity sent down the wires, becomes heat. Likely, more heat is developed than if the solar power plant was not there. This has to be balanced against the issues of reduction of CO2 boosting.
    Also to be considered: Solar panels needing to be cleaned of dust, and likely needing protection from sometimes-abrasive-airborne desert winds.

  136. Curt says:

    LdB says:
    December 10, 2013 at 10:24 pm
    “How much heat is given off by the citizens of the planet as an average?”

    The rule of thumb is that the waking rest metabolic rate for an adult human is 100 Watts. (This is used by HVAC designers for air conditioning capacity for auditoriums, for example.) Given that active people use more, and sleeping people less, 100 Watts is a reasonable average.

    With 7 billion (7×10^9) people, this amounts to 7×10^11 Watts, and given the earth’s surface area of 5×10^14 m2, we get a power density of 1.4×10^-3 W/m2, or 1.4 milliwatts per m2, from human power output.

  137. Zeke says:

    _Jim, where is your Christmas Spirit? For Jim Morpuss, I suggest a special fund. This year, we can all chip in to get him his very own, sustainable, bicycle powered Christmas Tree! As he says, this would kill two birds with one stone. Not only would he have a copious, free source of electricity, he could watch his girlish figure as well!

  138. 4 eyes says:

    My calcs re waste heat:

    World Energy Usage Annually = 117 x 10^15 watt-hours (= 117 x 10^15 x 3600 watt-seconds = 421 x 10^18 Joules) from fossil fuels. Total consumption of energy is about 144 x 10^15 watt-hours per annum if nuclear and renewables are included. Another source says total world energy consumption is 465 x 10^15 BTU which is about 490 x 10^18 Joules. Most of this ends up ultimately as low grade waste heat in the atmosphere, some ends up as waste heat in the ocean by way of warm water from power plants etc. Some ends up as potential energy e.g. as concrete high up in skyscrapers, etc. For the sake of the following exercise I assume that 50% of this energy ends up in the atmosphere each year as heat.

    Specific Heat of Atmosphere, Cp, = 1005 J/kg

    Mass of Atmosphere, M, = 5 x 10^18 kg

    Q = M x Cp x T

     T (per year) = Q (per year) / (M x Cp)

    = (117 x 10^15 x 3600 x 0.5) / (5 x 10^18 x 1005)

    = 0.0419 degK per year

    = 0.419 degK per decade

    = 4.19 degK per century

    This is a first order approximation of the temperature rise of the total atmosphere cause by the addition of waste heat without consideration of any other heating mechanism.

    I don’t know how the waste heat and associated temperature rise is handled by the atmosphere and blackbody radiation out to space etc. but I think the calculation above is correct given the assumptions. There has been no temperature rise for 10-15 years i.e. a steady state condition exists, so none of this heat is heating up anything. So even if there is no net warming by CO2 as a greenhouse gas then a very serious cooling mechanism has been occurring for the last 10-15 years to maintain the temperature steady. Or if there is no hidden cooling effect the feedbacks resulting from changes caused by CO2 are highly negative. Either way there is a serious negative mechanism. I just don’t have time to review the literature properly – has this calculation been included in any energy balance summary for the atmosphere.

  139. rgbatduke says:

    How much heat is given off by the citizens of the planet as an average?

    The average power consumption of the human body at rest is around 100 watts. If you allow for activity, perhaps you double that or even triple it some of the time or generate more if you live in a cold climate. Still, 150 watts is a pretty reasonable estimate given big people and little people and everything in between. Multiply by 7 times 10^9 and you get roughly 10^12. So a terawatt. Maybe even 2. Which vanishes without a trace in the Earth’s energy budget.


  140. Silver Ralph says:

    I think Leif Svalgard put this question into context with an easy comparison.

    All of man’s energy output from heating, lights and machinery, is about the same as the reflected heat energy we receive from the Moon. In other words, not a lot in comparison to the Sun….!

  141. LdB says:

    rgbatduke says:
    December 11, 2013 at 1:55 am

    Which vanishes without a trace in the Earth’s energy budget.

    That was the point rgb I haven’t added in animals and other hot bodies but perhaps I should have used the heat from a volcano eruption or the countless other strange heat sources around. The message for Zombie was these levels of heating have to be able within Earths coping mechanisms or else it we would have long ceased to exist :-)

  142. Nylo says:

    Willis, I love your way of doing back-of-the-envelope calculations, you are my absolute hero :)
    However there’s one part of the whole ecuation that I think that you didn’t consider. While the warming that the CO2 would cause would be distributed throughout the whole planet, a big part of the extra warming accumulated by the solar panels would happen at the panels themselves. This would greatly increase their temperature compared to the temperature that the underlying sand would reach without the panels, and emissivity increases with the fourth power of temperature. In addition, the panels themselves are black, which implies high absorption but also high emisivity. What I want to get at is this: the extra warming of the panels comes with a significant extra emissivity as well. So the panels cause the planet to receive more energy from the sun, but also cause it to cool faster. This may greatly reduce the difference of extra heat accumulated compared to the CO2-emitting power plant scenario.
    Unfortunately my skills at back-of-the-envelope calculations are ridiculous compared to yours so I don’t feel like I could possibly do the numbers.
    Kind regards.

  143. DirkH says:

    LdB says:
    December 10, 2013 at 5:43 pm
    “”So there is the answer for Zombie as given by climate science and it wasn’t that hard to find … you just have to read.”

    Well, thanks for the “lazy and stupid”; you know; I NEVER look into the IPCC report for ANSWERS. I only look into it for lies. Zombietime wanted an answer; so the IPCC report is simply not the right place to look.

  144. Leo Smith says:

    One calculation that is not hard to do is to take ones country – the UK in my case, and divide its total energy usage – about 300GW INPUT – by the land area to get a ‘total radiative imbalance’ figure.

    Its around 250,000 square kilometers, so to a first order that is about 1W/sq m.

    Remind me again of what ‘forcing’ CO2 is supposed to have?

    It could be met, with suitable storage of an entirely unspecified and imaginary nature, by covering the entire surface of the country with wind turbines – which average about 2W sq meter when not in the middle of a country entirely covered in wind turbines…Of course safety issues would mean that this would render the entire country permanently uninhabitable.

  145. TheLastDemocrat says:

    Side Note: I am glad Zombietime is seeking a decent answer to a good question here.
    Zombietime is great.

    So many of us democrats have bought the “McCarthyism” defense that “there are no communists here” that we are blinded to the take-over of our formerly American, decent political party. Zombietime is a resource for revealing to fellow democrats that, yes, great swaths of our allies in labor and environmentalism, and reproductive rights activists, are simply Un-American Marxists seeking to sow discord and bring down our nation.

  146. R. de Haan says:

    If you have the choice between a coal power plant or solar panels, go for the coal power plant:

  147. MarkB says:

    Willis Eschenbach says:
    December 10, 2013 at 1:26 pm

    . . .
    0.0008 = W/m2 at 3.7 watts/doubling CO2

    Doesn’t this term accumulate year after year? More properly, the accounting would have CO2 forcing accumulating at this rate and depreciating at the effective lifetime of atmospheric CO2.

  148. Gary Pearse says:

    Zombie, one should also do an audit of the CO2 and energy expended in producing the materials and installation of the panels. Glass furnaces have to heat the charge of silica sand, feldspar, etc (which has to be mined and processed) up to >1500C … etc..

  149. Lloyd Martin Hendaye says:

    Turning bright-white desert regions dark with costly, inefficient, disfiguring arrays of solar panels, then pejoratively calling such blighted acreage “black”, is a profoundly racist approach to making Gaia’s quietus with klimat kultists’ “bare bodkin.” We of the Green Gang know Thought Crime when we see it… off to ye killing fields you go.

  150. BillC says:

    Isn’t the simplest answer to this that whatever the original energy source (sun vs. chemical energy stored in fossil fuels), ultimately what we are doing is converting it into electricity which then, as Zombie says, “inevitably degrade[s] into atmospheric heat”. So yes, with solar energy we are adding heat to the atmosphere that otherwise would not be there but the same is true with fossil fuels. In the case of fossil fuels we are adding heat to the atmosphere that would otherwise have stayed trapped in those chemical bonds. So it seems to me, at least with regards to residual heat that gets added to the atmosphere as the electricity degrades back to heat, that it’s a wash. That happens no matter what so should not even be considered.

    Next question would be to consider how efficient each method is. A coal fired power plant I’m sure does not convert all of the heat from burning into electricity. So besides the heat that you get from the electricity it generates eventually degrading back into heat, you get a lot of waste heat that goes directly into the atmosphere when it burns.

    The only analogous thing I can think of with solar panels is that maybe they’re not 100% efficient either. And maybe, because solar panels are dark, that wasted energy is turned into excess heat that would normally have been radiated back into space because the ground is typically more reflective than a solar panel. Is that more than the waste heat from a typical coal-fueled power plant? I don’t know but my gut tells me no.

    But no matter what, one thing that solar has over fossil fuels is that there is no CO2 produced as a by-product (unless you consider CO2 produced during their manufacturing, but I don’t really think that was the point of the original question). I’m an AGW skeptic, so I’m not convinced this is a bad thing (or as bad as alarmists would have us believe) but it seems to me if you’re trying to convince a true believer using this argument, it’s not going to fly. If one accepts the premise that CO2 is bad and is raising the temperature of the earth, the argument that solar adds more heat to the atmosphere than fossil fuels doesn’t make sense.

  151. DrTorch says:

    Why talk about PVs? Solar thermal is a better plan for electricity production.

  152. OssQss says:

    This is reminiscent of a climate impact analysis on wind farms I recall. The numbers were quite staggering. (Actual paper embedded in the article)


    The same holds true with the environmental impact of hydroelectric power above and below a dam.

    I just wonder the total acreage required to replace 10% of the total global electrical output in today’s terms with the current and best solar solutions.

    Would the earth look like an 8 ball at the 50% replacement level?

    Lots of good food for thought in this thread. Thanks for that to everyone!

  153. apachewhoknows says:


    Ya never know when a Apache with tfk war paint on will be behind a hot rock in Az. or New Mexico looking for some good horses to steal and re-sell. Great great, great grand dad’s way was to get to a heard of U.S. Army horses and steal some 40 or 50 of them.

    About a week later one of his other brothers would show up with some horses stolen from over in Texas and sell them to the U.S. Army.

    The ones from New Mexico would be driven over to Ft. Sill in Ok. and sold.

    You have to watch out all the time for tfk types.

  154. apachewhoknows says:

    So, how much of the electricity made out in the desert by solar panels gets to the meters and used after pushing its way down 300 or 600 miles of transmission/distribution/transformer wires to a toaster in Lost Wages? There be resistance some say.

    That and the problem of the power factor thingy.

    Useless as breast on bore hogs some say.

  155. Paul Westhaver says:

    Stunning question really. Wish I thought of it….

    I know photo voltaic panels are very inefficient regarding the width of the band of absorption. So what happens to the rest of the heat?
    Reflected, absorbed and re-emitted as heat.

    Seems to me that this is easy to calculate and may have already been done. I wager that photo-voltaic panels are in fact a worse planet warmer than a coal fired plant, net KW for net KW. This is within my competence to broadly model and calculate but I am a bit busy. Has anyone else done this?

    Any takers?

  156. beng says:

    The “global” effect of such solar-arrays is negligible. What is worrying is the immediate local effect — it would prb’ly cause local extirpation of wildlife. Why aren’t the greenies worried about poor desert tortoises?

  157. J Martin says:

    Robertvd says: What would Earth’s surface temperature be in a 100% CO2 atmosphere ?

    It would not be much different from what it is now.

    Venus has 93 times as much atmosphere as Earth, many probes have been to Venus and allowing for the difference in distance from the Sun, at the point in Venus’s atmosphere the temperature is essentially the same as on Earth.


  158. nutso fasst says:

    Is exhaled CO2 reduced by the slaughter of big birds of prey or does the resulting increase in rodent populations more than make up for it?

  159. Steve from Rockwood says:

    An equally important question is … “what is the difference in CO2 output between a typical gas-fired generating station and a typical solar panel array plus gas-fired backup”? Is it 50%, 25%, 10% less? Then look at the CO2 cost of constructing and maintaining the solar panel array. Is it 5%, 10%, 25% equivalent to a gas-fired plant?

    We had a gas-fired plant recently installed about 20 km from our home, presumably as standby power for solar and wind and to replace coal-fired stations that were killing “tens of thousands each year”. The cost of this plant was several hundred million. The government cancelled two similar plants (because residents didn’t want a gas-fired generating station in their backyard) at a cost of $600 – $1,100 million (the figures vary depending on who in the government is giving the answers). Plus we now generate excess electricity that we sell out of province at a loss. All the while our electricity rates are $0.16 / kWh, up over 50% from less than 10 years ago.

    I guess my point is net/loss CO2 calculations are meaningless when the cost of such is not factored in. Cost is CO2 as well.

  160. EWF says:

    Whew, I knew I’d forgotten something in my Venusian calculation of CO2 forcing because in no way is Trenberth’s figure of 5.5C right. Now I realise I left out the albedo. Doh. The correct albedo to use is the “bond albedo” from de Pater & Lissauer, Planetary Sciences 2001 which gives 0.29 for Earth and 0.75 for Venus. So 5.5C x 0.29 / 0.75 = 2.1C per doubling of CO2. There, that’s better! My apologies for this oversight, especially to Wayne, wherever you are.

  161. EWF says:

    Whoops, the albedo goes the other way. OK, I abandon the battlefield, this battlefield anyway. Apologies for not having presented a comprehensive accounting.

  162. wayne says:

    4 eyes says:
    December 10, 2013 at 11:49 pm

    My calcs re waste heat:

    = 0.0419 degK per year
    = 0.419 degK per decade
    = 4.19 degK per century

    Either way there is a serious negative mechanism.

    Hold on. That is a classic “climate science” mistake. You cannot extrapolate that value accumulatively into the future, for the minute the Earth was about 0.01°C warmer, maybe 0.02°C all of humanity’s energy output would then be radiating to space, no accumulation occurring. End of story of humanity’s energy use raising Earth’s temperature at +0.01°C.

    Now if a century from now every human is consuming some 600 times more energy each second than today your 4.19 degK then may come to be true or so my calcs show.

  163. Robertvd says:

    To me it is still not clear why we should install photo voltaic panels in the desert to lower atmospheric CO2 if it is not clear what influence CO2 has on temperature. Photovoltaic is great to heat my warmwater reservoir to lower my energy costs. I could understand that burning coal or gas or oil is bad because of the fact that it destroys O2 what would have a huge impact on live on earth. But more CO2 would also support more plant life producing O2. So why solar panels if a coal power plant is much more efficient and use the money we safe for affordable health care and investments to rebuild the production industry and to eliminate poverty.

  164. Jean Parisot says:

    We need to remember to include a calculation for the value of shade for the tortoises

  165. Brian H says:

    oebele bruinsma says:
    December 10, 2013 at 11:17 am

    A quick search delivered this: http://www.clca.columbia.edu/13_39th%20IEEE%20PVSC_%20VMF_YY_Heat%20Island%20Effect.pdf

    Relevant and on point, thanks.

    But it mis-conceives the issue, I believe. Here’s a quote: at night the modules cool to temperatures below ambient; an example is shown in Fig. 9. Thus, this PV
    solar farm did not induce a day-after-day increase in ambient temperature, and therefore, adverse micro-climate changes from a potential PV plant are not a concern.

    The cooling is a transfer of heat energy either to air or space. The ambient night temperature in the local area is likely to be higher than in the absence of the panels.

  166. Robert Menzies of the Commonwealth of Australia says:

    just want to take this opp. to say thank you, Zombie. Your website is as illuminating within its sphere of interest as WUWT is in its sphere.

    In particular, I was completely unaware of how much lewdness and public indecency occurs at some of the events you cover.

  167. Myrrh says:

    DrTorch says:
    December 11, 2013 at 7:56 am
    Why talk about PVs? Solar thermal is a better plan for electricity production.

    Solar thermal does not exist in AGW – which has no direct downwelling of thermal from the Sun.

  168. TLM says:

    Back to the OP’s question; “it depends”.
    For instance number 1:
    What is done with the resulting electricity? If it is used in an endothermic reaction then the energy can be “locked up” in the product being produced. For instance “polymerisation” (eg making plastics) is an endothermic reaction that takes heat from its surroundings. Similarly cooking most foods (frying an egg, baking bread) are also endothermic. However, in those cases, the body eating the bread will convert most of the energy absorbed back into heat. Plastics, however, will probably almost never release the energy absorbed back into the environment.

    For instance number 2.
    What is the albedo of the surface being covered? Most solar panels in the world are not in deserts – which are actually a particularly hostile place to stick them. Most, such as in Germany and the UK, are put on open fields where grass would otherwise be. Grass is, of course, also absorbs sunlight and turns it into useful energy for cows and sheep and has a relatively low albedo.

    I suspect the actual answer is that the effect is vanishingly small. Probably not unlike the greenhouse effect from the extra CO2 from fossil fuels. Not so much a zero sum game, more a sum of zeros game!

  169. Shooper says:

    Many people just assume Zombie is a ‘he’. After reading many, many articles by this person, I am convinced she is a ‘she’. FWIW.

  170. lowercasefred says:

    @ Shooper 5:41 am

    Zombie’s gender is his/her business. “Those that tell, do not know, those that know, do not tell.”

  171. Shooper says:


    Yeah. I wasn’t making a case. Just sayin’. For What It’s Worth., Information, ya know.

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