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Waste heat vs greenhouse warming

Posted on 27 July 2010 by John Cook

A vigorous discussion has erupted on the waste heat page. Problem is, there's not meant to be a waste heat page! As I encounter new skeptic arguments, I add them to the to-do list and gradually (very gradually) research the peer-reviewed literature then write an explanation of what the science says, usually in order of popularity. I hadn't got around to looking into the issue of waste heat. Nevertheless, one intrepid Skeptical Science user found the empty page waiting to be populated and began a discussion there (j'accuse Doug Bostrom). So let's look at waste heat...

Firstly, what is waste heat? When humans use energy, it gives off heat. Whenever we burn fossil fuels, heat is emitted. This heat doesn't just disappear - it dissipates into our environment. How much does waste heat contribute to global warming? This has been calculated in Flanner 2009 (if you want to read the full paper, access details are posted here). Flanner contributes that the contribution of waste heat to the global climate is 0.028 W/m2. In contrast, the contribution from human greenhouse gases is 2.9 W/m2 (IPCC AR4 Section 2.1). Waste heat is about 1% of greenhouse warming.

Radiative forcing from waste heat vs anthropogenic greenhouse gas radiative forcing

What do these numbers mean? They refer to radiative forcing, the change in energy flux at the top of the atmosphere. Or putting it in plain English, the amount of heat being added to our climate. Greenhouse warming is currently adding about 100 times more heat to our climate than waste heat.

UPDATE 27 July: there is some confusion about the term 'waste heat'. Here, what I'm talking about is all the heat generated by energy use. When humans generate energy, much of it is immediately dissipated as heat. The rest is converted to electricity or energy of some sort (eg - mechanical, chemical, etc). But even this energy eventually dissipates as heat into the environment. So yes, 'waste heat' is not an ideal term. Flanner uses the term "anthropogenic heat flux".

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Comments 401 to 431 out of 431:

  1. KR 386 "In fact, if waste heat was the cause of warming, we would see an increase in outward IR due to the planet being over equilibrium temperature, rather than the observed decrease as the climate catches up to the GHG forcing. " Another contradiction: Here you say there is now less outward IR being observed, when you have been saying that waste heat is "no different from any other radiative forcing", and that as temperatures go up, IR increases. Based on your "logic", the Earth must now be cooling.
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    Moderator Response: [DB] It all has to so with the definition of a "forcing". That is where you are having a disconnect.
  2. RSVP - The difference in TOA effects between AHF (more coming in) and greenhouse gases (less energy going out) is very clear. Think of a pot on a stove. Adding AHF is equivalent to turning up the burner. The stew gets hotter, more steam comes out, it recovers equilibrium (stops changing temperature) when in = out. GHG's are equivalent to putting a lid on the pot, reducing outgoing energy. Less steam comes out, the stew gets hotter, it recovers equilibrium when in = out. Even leaving aside the small matter (!!!) of two orders of magnitude difference in energy as you wish to, the decreased TOA IR demonstrates that the primary cause of global warming is a reduction in energy loss to space, not an increase in energy fed into the climate. AHF therefore cannot be the primary cause of global warming. Your fixation on this in the face of logic, numbers, and physics is most unfortunate.
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  3. To KR Comparing your remarks... exhibit A "Think of a pot on a stove. Adding AHF is equivalent to turning up the burner. The stew gets hotter, more steam comes out, it recovers equilibrium (stops changing temperature) when in = out. " exhibit B "In fact, if waste heat was the cause of warming, we would see an increase in outward IR due to the planet being over equilibrium temperature, rather than the observed decrease as the climate catches up to the GHG forcing. " In B, with respect to the analogy in A, you are basically saying less steam is observed to be coming out. If as you say, "Adding AHF is equivalent to turning up the burner.", it holds that AHF is contributing to warming. Up to there we appear to agree, but you go on to say that AHF is not the "primary" cause. This would be possible if at the same time AHF were not accumulating, but since energy cannot be destroyed, I am very afraid this needs to be accounted for before considering GHG effects.
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  4. To John Cook By the way, in the orignal article where it points to the IPCC reference: "2.9 W/m2 (IPCC AR4 Section 2.1). " it explains positive radiative forcing and negative radiative forcing, where negative would be something that would have a net cooling effect. Considering the symmetry between positive and negative, how exactly can something have a net cooling effect when it comes to thermal radiation? It could only mean less heat relative to some nominal value, while the 2.9 W/m2 is likewise more heat relative to some nominal value. When talking about less heat, we could only refer to less heat getting in during the day. If the terms positive and negative are symetrical, the 2.9 W/m2 only refers to more heat getting in during the day. Between day and night, this 100x reduces to 2.9 (day) - 2.9 (night) = 0. On the other hand, there is no waste heat day/night since this energy is being expended 24 hrs a day on the average. So the real comparision is 0.028 to 0.
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  5. Heat transfer is always from hot to cold. The article states... "This heat doesn't just disappear - it dissipates into our environment." A better word for "dissipation" is heat transfer, which means that warmer places loose their heat (i.e., cool), and cooler places warm up. The warming of cooler places like the Artic and glaciers is waste heat's fingerprint. A GHG effect should affect the entire planet equally. This is not what is happening.
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  6. RSVP#405: "warming of cooler places like the Artic and glaciers is waste heat's fingerprint." How do you know that? Do you have any research to back it up or is it just another unsubstantiated assertion? Where are the waste heat sources in the Arctic? "A GHG effect should affect the entire planet equally." How do you know that? Do you have any research to back it up or is it just another unsubstantiated assertion? Do you know what Arctic amplification is and why the GHG should not warm the planet equally?
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  7. RSVP @ 405: If "heat transfer" means warmer places cool and vice versa and that, under this proposition, the heating of the Arctic is a fingerprint of waste heat, where is the concomitant cooling of warm places? Why, as I sit in Phoenix, AZ, am I not experiencing any type of cooling trend? Also, from where do you get the idea that a "GHG effect should affect the entire planet equally"?
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  8. muoncounter 406, mclamb6 407 "How do you know that?" This is dictated by heat transfer fundamentals. Heat transfers via conduction, convection, and radiation. In all three cases it always goes from a material with a higher state of energy to a lower state of energy. All materials behave this way, so heat always migrates from a warmer place to a cooler place. This is what the word "dissipation" in the article refers to. In Phoenix Arizona, you have a daylight pulse wherein the net heat builds, yet even so, heat is constantly radiating, even during the day. This loss of heat due to radiation, is considered "cooling", because not all the heat from the Sun is accumulating. Given the respite night provides, most of the heat taken in during the previous day gets radiated out into space, and its then that cooling is most noticable. Heating from all the air conditioners running in Phoenix offsets the natural thermal equilibrium that existed in nature. It can only be warmer in Phoenix as a result of these and other human induced heat sources. And although temperatures in Phoenix might be a tad higher, this extra energy is drawn off by surrounding desert air due to thermals and cyclical wind conditions. This extra energy is not lost however and dissipates as the article states. The cumulative effect of heat generated from industry in the northern hemisphere acts like a thermal noose around the Artic. That GHG should affect the entire planet equally refers to the assumption that CO2 is in general evenly distributed throughtout the atmosphere. So to whatever extent CO2 has acted in the past as GHG (whether locally or otherwise), it should do so in like manner even as its concentration rises.
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  9. Except your position is that waste heat is the source of a long term overall heating trend. If the heat transfer requires heat to move from higher to lower temperatures, there should be some place that is experiencing a long term cooling trend. What areas are experiencing a long term cooling trend? It's certainly not Phoenix.
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  10. RSVP#408: "This is dictated by heat transfer fundamentals." Of course. To solve a complex problem, you pick out a single concept and develop a simple explanation. Without benefit of any actual evidence. Despite hundreds of posts with evidence to the contrary. "industry in the northern hemisphere acts like a thermal noose around the Artic." It's been demonstrated to you that the total industrial energy is insufficient. It's been demonstrated to you that industrial energy radiates to the environment, where it behaves just like all other energy; much of it escaping to space, unless, of course, it is constrained by GHGs. Industrial energy does not have a preferential path to the Arctic. North is not up. "the air conditioners running in Phoenix" If you are truly concerned about this, you should be campaigning actively to eliminate them (good luck with that). How do the air conditioners of Phoenix not warm the nearby desert, which cools rapidly at night? Are you aware that Phoenix has a well-documented 'CO2 dome' due to its peculiar topography, winds and locally high emissions rate? "GHG should affect the entire planet equally refers to the assumption that CO2 is in general evenly distributed throughtout" It's actually not that evenly distributed; the concentration has much greater variation as a function of in latitude than your 'assume' (see NOAA's Carbontracker). What about solar input? Unevenly applied at TOA due to time of year and latitude; unevenly reflected at surface due to locally differing albedo. This uneven heating alters temperature due to locally varying thermal properties of earth, air and water. In the short term, the result of those discrepancies is what we call 'weather.' If industrial energy is such a huge input, why do your industries not create their own weather patterns? Why did the planet warm in the late '30s, when industrial output was low due to the depression? Why did the planet then cool during the post-war industrial expansion? No, 'heat transfer fundamentals' are not enough to explain this behavior.
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  11. mclamb 406 "What areas are experiencing a long term cooling trend? It's certainly not Phoenix. " With a PC turned on, the CPU can be "cooling constantly" while at the same time maintaining operation at a constant temperature. Heat is being drawn away. This is called cooling, even if its temperature is not dropping. Likewise, according to KR, all energy associated with waste heat must vanish through radiation as soon as temperature increases. If this were true (which it is not) temperatures would never increase, since all energy would radiate the moment something got warm, which it wouldnt, since all warmth would radiate before it could get warm (following KRs "logic").
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    Moderator Response: [DB] Again, as has been pointed out to you several times, you are conflating temperatures and forcings. Forcings due to temperature increases go away as soon as the TOA reaches radiative equilibrium. And you would do well to unlock that mindset you have and learn some of KR's "logic".
  12. RSVP#411: "all energy associated with waste heat must vanish through radiation as soon as temperature increases. If this were true (which it is not) ... " Let us view some evidence, in the form of thermal IR photos: Power plant from a distance of 5.2 miles: Ground in large area around plant is at same temperature. Heat from plant does not affect surroundings at this distance. Parked Ford SUV: Hot surfaces of car, radiated IR reflecting from pavement underneath. Surrounding area cool. Nevada casino from a distance: Building is colder than surrounding ground, which is presumably warmed by the sun. There are 14 pages of these images. Waste heat seems to 'vanish' from the larger environment, without heating it in any perceptible way. Isn't that exactly what KR said?
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  13. The IR photography proves nothing, or at best reveals lack of grounding. Temperature is not energy, just as voltage is not energy. The familiar shock from static discharge involves a very high voltage, yet is harmless (although a nuisance). And more to the point, there is way more energy contained in the water of a swimming pool at 20 C than a hot skewer at 300 C.
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  14. continuing 413 ... that is, thermal energy in the water of a swimming pool. This can be understood clearly if for instance you compare the rise in temperature of the pool vs. the skewer. Adding 1000 W for 2 minutes to the skewer may raise its temperature hundreds of degrees (depending on its size), whereas a temperature change of the pool after doing the same might not be detected at all. Both have acquired the same energy. In the same way, you are unlikely to "see" waste heat with IR cameras.
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  15. RSVP#414: "you are unlikely to "see" waste heat with IR cameras." Except when you do. And voltage = Joules/Coulomb, energy per unit charge, which is an energy density.
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  16. muoncounter 415 Interestingly, the equation you provide for voltage resembles the heat formula q = mC deltaT, which when turned around demonstrates how voltage can be likened to temperature such that deltaT = q/mC. As you can see, for a given energy q, the change in temperature is directly related to specific heat and mass. So the detection of a large temperature change can be relatively meaningless if it has to do with heating of small masses.
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  17. RSVP#416: "the equation you provide for voltage " I did not provide; that is the definition of electrical potential. The difference in potential between two points is what is commonly referred to as 'voltage.' "a large temperature change can be relatively meaningless if it has to do with heating of small masses." Your exercise in high school algebra proves your thesis incorrect. There is no visible deltaT due to waste heat, for large mass: In case you did not read the caption, the first IR photo was taken 5.2 miles away from the power plant. The mass of the ground in that image is not small. Low deltaT with large mass requires q to be small: waste heat is insignificant. On the other hand, there is a very visible deltaT over a small patch of ground (low mass) under the car. But the small amount of heat energy does not warm a large mass. Once again, proving KR's point.
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  18. muoncounter 417 Somewhere around posts 389 or so, there was denial about the need to consider the heat that goes beyond skin depth. In order for anything to have a "large mass", there is a need to consider just a little more than surface area. One must multiply volume by density. ... and the following sentence... "Your exercise in high school algebra proves your thesis incorrect" is pure garbage.
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  19. RSVP - "Likewise, according to KR, all energy associated with waste heat must vanish through radiation as soon as temperature increases. If this were true (which it is not) temperatures would never increase, since all energy would radiate the moment something got warm, which it wouldnt, since all warmth would radiate before it could get warm (following KRs "logic")." Totally, completely incorrect. Given 0.028 W/m^2 forcing from AHF, and a warming of ~3/4°C per watt of forcing, AHF's contribution drives the climate warmer by an extra ~0.021°C. With that change the extra IR emitted from the top of the atmosphere will balance the AHF input. And if that was the only forcing on climate change, we likely wouldn't even notice. AHF forcings are trivial in comparison to greenhouse gases. You need to consider relative energies.
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  20. RSVP#418: "In order for anything to have a "large mass", there is a need to consider just a little more than surface area." So you contend that the area shown in the power plant photo or the ground shown in the third photo do not represent large thermal mass? The power plant, a poster child for your waste heat, has not changed the temperature of the larger surrounding area. The waste heat is irrelevant. No, sir, continuing to cling to this thread, without showing a shred of evidence for your thesis; that's pure garbage.
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  21. muoncounter 420 "The waste heat is irrelevant." If the waste heat coming out of a power plant was on whole being lost in the form of thermal radiation, no one would be able to approach it. Instead of requiring an ultra sensitive CCD to amplify this energy for your photos, you could just raise your hand and feel it. The plant is cooled by the mass of fluids (air and water) carrying 99.999% of the heat away, and it appears you are underestimating the mass associated with these fluids.
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  22. KR 419 When the sun shines, it is because there is an open sky. The ground warms, and this heat sees the same open sky. Cooling by radiation is optimal. When the sun doesnt shine due to cloud cover, while conditions for radiative cooling are less optimal, there is also less heat to radiate in the first place (due to the clouds). Along comes humanity doing something else. Adding heat incessantly, regardless of cloud cover night or whatever. Then come the denialists saying this isnt a problem, and that things are warming mainly due to the extra CO2. Extra heat being trapped when radiative cooling conditions are optimal (i.e. see first paragraph above).
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  23. RSVP - I considered providing a detailed response to your last posting. The thing is, I would just be repeating what I and other posters have said, over and over and ... (repeat as desired). I believe, instead, that I'll just leave that as a coda to this discussion. You've consistently displayed what I consider a cardinal sin of intellect - You have failed to learn in the face of obvious errors in your thinking. You're locked into your opinion, come Hades or high water. Your opinion holds proof against both quantitative and qualitative evidence to the contrary. There's nothing I can do about that - a rational discussion seems impossible. I believe readers can peruse this thread and come to their own conclusions based on what has been presented. Finis.
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  24. KR 423 "Your opinion holds proof against both quantitative and qualitative evidence to the contrary." This discussion is only about two quantities. The amount of the Sun's energy (which is unchanging), and civilization's waste heat, which has only been on the increase over the last 150 years. You've consistently displayed what I consider a cardinal sin of intellect, not thinking for yourself, that is, uncritically parrotting GHG doctrine. It is one thing for temperature distribution to possibly change, and a very different thing for the total entropy of the Earth to go up or down. Since you dont appear to understand this fundamental difference (which has its basis in the second law of thermodynamics, not my "opinion"), it is quite understandable that all you can do is repeat yourself "over and over".
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  25. muoncounter 410 "No, 'heat transfer fundamentals' are not enough to explain this behavior" In reference to the graph appearing above this sentence, and all other hockey stick curves for that matter. Supposedly, GHG warming increases as a log of CO2 doubling, and yet the portion of the graph where temperature starts to "take off" is always a straight line, or at best global temperature increase tracks linearly with CO2 concentration. Nevertheless, the caption here reads, "No, 'heat transfer fundamentals' are not enough to explain this behavior". I would say its just the other way around. Given this jibberish about logarithic behavior, a GHG temperature increase would be bending over asymptotically for a linear increase in GHG.
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    Response:

    [DB] Both here and elsewhere: PRATT.

  26. Can someone please point out where I am making a mistake? In 2009 we burned 7,557,37 Million Short Tons of Coal which equals 1.51148E+16 pounds of coal. Coal has heat value of between 10,000 and 15,000 BTUs/pound depending on type. So at 10,000 BTU/pound the burning of this coal released 1.51148E+20 BTUs/year or 1.72543E+16 BTUs/hr. Since 1 Btu/hr. = 0.293 watts this equals 5.05551E+15 Watts. Dividing the Watts by the area of the earth 5.112E+14 meters squared you get 9.9 Watts/meter squared for just coal. This 35000% higher than the 0.028 Watts/meter squared sited on this site and else where for coal, oil, natural gas and nuclear power
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  27. dunc461: "we burned 7,557,37 Million Short Tons of Coal" It would be helpful if you cite where you found your figures. According to the EIA, 2010 world coal consumption was approx 7.5 billion short tons, vastly less from your figure (which seems to be missing a digit or has an extra 2 digits).
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  28. dunc461, muoncounter, The World Coal Association puts the 2009 production to be 6823Mt, which agrees with 7.5 billion short tons figure. This translates to 1.5E13 pounds, so dunc461's figure is probably off by a factor of 1000. This puts the heat released to be 0.0099W/m2
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  29. Thanks! The number I used was 7,557,379 Million Short Tons from http://www.indexmundi.com/energy.aspx?product=coal&graph=consumption which is apparently incorrect.
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  30. http://www.treehugger.com/fossil-fuels/world-energy-use-over-last-200-years-graphs.html

    This figure shows energy consumption increasing linearly to 100 exaJoule per year from 1820 to 1950.  The sum is 1/2 100 (1950-1820) = 6.5 ZJ.

    From 1950 to 2010 it went from 100 to 550 exajoules. The sum is (450/2)(60)+100*60 = 19.5 ZJ.

    Assuming a 50% efficiency, that leaves 13 ZJ went to waste heat from 1820 to 2010.

    It takes 4.179 Joules to raise the temperature of 1 gram of water 1 oC

    The volume of oceans (70% of earth, 510e14 m^2) down to 200 meters is 7.14e22 grams

    If none of the human energy consumption over the last 190 years was rejected to space the surface temperature of the ocean would be 23 degrees C warmer.

    Clearly, a lot of that energy was rejected to space and some was used to melt ice. 

    Equally clear is the fact that an increase 1.5 oC in surface temperature could easily be the result of accumulated waste heat from human consumption over this interval. 

    https://www.epa.gov/climate-indicators/climate-change-indicators-sea-surface-temperature

    Ignoring human energy consumption as a forcing factor, almost all from fossil fuels, by the IPCC is easily challenged. 

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    Moderator Response:

    [TD] An important aside: Your use of the term “rejected” is unusual. If you mean “reflected” you need to use that term. If you mean “emitted” you need to use that term.

  31. Aaron Davis:

    In post 30 you say: "Assuming a 50% efficiency".  The internal combustion engine in your car is about 25% efficient at its most efficient RPM.  When you apply the brakes you covert any usable work into waste heat.  Ultimately, all the potential energy in the fuel is converted into waste heat.  Most processes in society ultimately yield no usable work, all the input energy is converted into waste heat.  Your calculation would be much more accurate if you used a 100% connversion for energy into waste heat.

    Your choice of 50% demonstrates that you have no basic knowledge of thermodynamics and no idea how to do your calculation.  Combined with your attitude that you seem to think you know it all, why should I engage with you? 

    If you actually read the links the moderator gave you, you will be able to make better arguments.  It is generally better to work on one issue at a time.  Choose the problem you are most interested in and focus on that.

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