6 ms·

This reminds me of Solar updraft tower prototypes [1], which concentrates heat at the bottom of the chimney instead of expecting cold air at the top of the chim

by vmarsy 9y ago

This reminds me of Solar updraft tower prototypes [1], which concentrates heat at the bottom of the chimney instead of expecting cold air at the top of the chimney. There's still a delta of temperature between the top and the bottom, but instead of T_bottom_chimney = T_hot_ambient_air_bottom T_top_chimney = T_cold_ambient_air_top it is : T_bottom_chimney = T_much_hotter_than_ambient_air_top T_top_chimney = T_ambient_air_top Everytime I start reading things like this, I wish I had a home with similar 'magic', like Solar chimneys[2] and other techniques[3], [1] https://en.wikipedia.org/wiki/Solar_updraft_tower https://en.wikipedia.org/wiki/Solar_updraft_tower [2] https://en.wikipedia.org/wiki/Solar_chimney https://en.wikipedia.org/wiki/Solar_chimney [3] https://en.wikipedia.org/wiki/Ground-coupled_heat_exchanger https://en.wikipedia.org/wiki/Ground-coupled_heat_exchanger

SubiculumCode 9y ago
This may be relevant: Free-standing inflatable solar chimney: experiment and theoryhttps://works.bepress.com/nima-fathi/9/ https://works.bepress.com/nima-fathi/9/
- SubiculumCode 9y ago
  I was getting convinced by the comments below that this is a nutty idea, but then ran across this review by real researchers in a real journal (impact factor: 8) in which they discuss super chimneys and other methods. Abstract and links below: Fighting global warming by climate engineering: Is the Earth radiation management and the solar radiation management any option for fighting climate change? Abstract The best way to reduce global warming is, without any doubt, cutting down our anthropogenic emissions of greenhouse gases. But the world economy is addict to energy, which is mainly produced by fossil carbon fuels. As economic growth and increasing world population require more and more energy, we cannot stop using fossil fuels quickly, nor in a short term. On the one hand, replacing this addiction with carbon dioxide-free renewable energies, and energy efficiency will be long, expensive and difficult. On the other hand, meanwhile effective solutions are developed (i.e. fusion energy), global warming can be alleviated by other methods. Some geoengineering schemes propose solar radiation management technologies that modify terrestrial albedo or reflect incoming shortwave solar radiation back to space. In this paper we analyze the physical and technical potential of several disrupting technologies that could combat climate change by enhancing outgoing longwave radiation and cooling down the Earth. The technologies proposed are power-generating systems that are able to transfer heat from the Earth surface to the upper layers of the troposphere and then to the space. The economical potential of some of these technologies is analyzed as they can at the same time produce renewable energy, thus reduce and prevent future greenhouse gases emissions, and also present a better societal acceptance comparatively to geoengineering. Here are links to the paper: http://www.sciencedirect.com/science/article/pii/S1364032113008460 http://www.sciencedirect.com/science/article/pii/S1364032113... or the research gate link: https://www.researchgate.net/publication/278826192_Fighting_globalwarmingbyclimateengineeringIstheEarthradiation_managementandthesolarradiationmanagementanyoption_for_fighting_climatechange https://www.researchgate.net/publication/278826192_Fighting_...
  - SubiculumCode 9y ago
    From http://www.sciencedirect.com/science/article/pii/S1364032113008460 http://www.sciencedirect.com/science/article/pii/S1364032113... 6.4. Super chimney The super-chimney imagined by Pesochinsky [150,154] consists in a huge vertical open duct at both ends, which works as a giant vacuum cleaner, transferring hot air from the sea level to the atmosphere 5 km higher, where temperature is 30 1C. The principle consists in the chimney effect based on the fact that hot air rises by buoyancy above cold air, because hot air is less dense and therefore lighter than cold air. But the process can be made more intense preventing the mixing of warm and cool air, so a chimney prevents inside air from mixing with the outside air until the air exits. The chimney stack effect needs a differential of temperature between the air inside and outside to run correctly. Moreover, the higher the chimney is, the more efﬁcient it is. It is a similar concept to previously described SCPP [148], except that there is no solar collector at the bottom of the tower, which usually couples the GH effect to the sucking effect of the chimney. According to Pesochinsky the temperature difference between the bottom and the top of the tower is sufﬁcient. Another difference with conventional SCPPs concerns the size, 5–10 times bigger: up to 10 km high with a diameter of up to 1 km. Even if these heights have never been reached by human buildings, some GE / CE projects reported in the initial part of this review envisioned similar heights [59–65]. Furthermore, some authors reported, with such a large duct and in certain atmospheric conditions, that a cold air inﬂow could occur at the top and as a result a layer of cold air could get out at the bottom of the chimney, the hotter air surface being just pushed up, with the creation of a thermal inversion. In terms of heat transfer the result is nearly the same: cold air down and hoIndeed, on some Pesochinskys designs, the tower is alongside a mountain slope or drilled inside a mountain (which seems too expensive) and numerous air pipes are connected on the sides. Di Bella [155] suggested a similar concept by using giant open pit-mines and also recycling waste-heat from power plants. This heat input could be useful to prevent cold inﬂow entering these large diameter chimneys. To illustrate the potential of these devices, according to Pesochinskys calculations [156] only 10 super chim-neys 5 km high can offset the heat surplus in the Earth atmo- sphere, which causes current global warming. This would mean that all the atmospheric circulation would be completely reorga-nized from only 10 points on the Earth’s surface: the climate induced perturbations could be much worse than what we want toavoid. Hopefully with smaller, cheaper and more numerous superchimneys, better distributed on the surface of the planet, thisdeleterious effect can be avoided. The calculations done are rather simple, and were conﬁrmed by Mudde [157] from Delft Universityof Technology. They are based on a difference of temperature of 50 1C and as the super-chimney will facilitate air convection bybringing masses of warm air up to 5 km, then when the heat from the air radiates out, as it will be already at high altitude, lessenergy will be reabsorbed by the atmosphere, due to a thinner layer of atmosphere to go through. Therefore, more heat will beleaving the atmosphere, thus reducing the global atmospherictemperature. The authors believe that more scientiﬁc studies areneeded to prove the concept, and that the techology still fairly mature to build 5 km high chimneys.Constructional generalities are given by Pesochinsky with no real details: tall skyscrapers already exist; unlike chimneys, build-ings entail much heavier construction because there are ﬂoors, ceilings, several ﬂuids and lifts going up and down, and all otherelements within buildings which are necessary to make it useful for humans. A chimney is just a cylinder, thus is a much lighterstructure and can be build a lot taller than any building with new “super-strong”materials, not even described by Pesochinsky
- taneq 9y ago
  A Wacky Waving Inflatable Solar Chimney! It kind of lost me when they started talking about the expected power output, though. A kilometer-tall tower seems like a very expensive and fragile way to generate ~200MW, compared with solar panels. I guess if you're primarily using it as a climate-engineering system, though, the free power is a bonus.
  - SubiculumCode 9y ago
    If water collection idea is a thin that can happen, that might have interesting implications too.
grecy 9y ago
They almost got funding to build one that was going to be 1km high right next to my home town [1] in rural Australia. [1] https://en.wikipedia.org/wiki/Mildura_Solar_Concentrator_Power_Station https://en.wikipedia.org/wiki/Mildura_Solar_Concentrator_Pow... Back in the day dad and I figured out we would easily see the tower from home, and the shadow would cross our house. Also it would be possible to see the curve of the earth from the top, so there was talk of allowing tourists up there.
- jdavis703 9y ago
  Can you really see the curve of the earth from 1km? I can't really even see the curve of the earth from an airplane (or can people with 20/20 vision see the curve from commercial aviation altitudes?)
  - Simon_says 9y ago
    The declination of the horizon is a couple degrees at altitudes that commercial flights fly at. It can be measured with standard carpentry tools.
    - codecamper 9y ago
      Now how did you get carpentry tools into an airplane?
      - andy_ppp 9y ago
        Disguise them as 100ml bottles of liquid...
      - lucisferre 9y ago
        Like this obviously: https://www.youtube.com/watch?v=6nNUEU8gnf4 https://www.youtube.com/watch?v=6nNUEU8gnf4
        Simon_says 9y ago

by vmarsy 9y ago

SubiculumCode 9y ago

This may be relevant: Free-standing inflatable solar chimney: experiment and theoryhttps://works.bepress.com/nima-fathi/9/ https://works.bepress.com/nima-fathi/9/

SubiculumCode 9y ago
I was getting convinced by the comments below that this is a nutty idea, but then ran across this review by real researchers in a real journal (impact factor: 8) in which they discuss super chimneys and other methods. Abstract and links below: Fighting global warming by climate engineering: Is the Earth radiation management and the solar radiation management any option for fighting climate change? Abstract The best way to reduce global warming is, without any doubt, cutting down our anthropogenic emissions of greenhouse gases. But the world economy is addict to energy, which is mainly produced by fossil carbon fuels. As economic growth and increasing world population require more and more energy, we cannot stop using fossil fuels quickly, nor in a short term. On the one hand, replacing this addiction with carbon dioxide-free renewable energies, and energy efficiency will be long, expensive and difficult. On the other hand, meanwhile effective solutions are developed (i.e. fusion energy), global warming can be alleviated by other methods. Some geoengineering schemes propose solar radiation management technologies that modify terrestrial albedo or reflect incoming shortwave solar radiation back to space. In this paper we analyze the physical and technical potential of several disrupting technologies that could combat climate change by enhancing outgoing longwave radiation and cooling down the Earth. The technologies proposed are power-generating systems that are able to transfer heat from the Earth surface to the upper layers of the troposphere and then to the space. The economical potential of some of these technologies is analyzed as they can at the same time produce renewable energy, thus reduce and prevent future greenhouse gases emissions, and also present a better societal acceptance comparatively to geoengineering. Here are links to the paper: http://www.sciencedirect.com/science/article/pii/S1364032113008460 http://www.sciencedirect.com/science/article/pii/S1364032113... or the research gate link: https://www.researchgate.net/publication/278826192_Fighting_globalwarmingbyclimateengineeringIstheEarthradiation_managementandthesolarradiationmanagementanyoption_for_fighting_climatechange https://www.researchgate.net/publication/278826192_Fighting_...
- SubiculumCode 9y ago
  From http://www.sciencedirect.com/science/article/pii/S1364032113008460 http://www.sciencedirect.com/science/article/pii/S1364032113... 6.4. Super chimney The super-chimney imagined by Pesochinsky [150,154] consists in a huge vertical open duct at both ends, which works as a giant vacuum cleaner, transferring hot air from the sea level to the atmosphere 5 km higher, where temperature is 30 1C. The principle consists in the chimney effect based on the fact that hot air rises by buoyancy above cold air, because hot air is less dense and therefore lighter than cold air. But the process can be made more intense preventing the mixing of warm and cool air, so a chimney prevents inside air from mixing with the outside air until the air exits. The chimney stack effect needs a differential of temperature between the air inside and outside to run correctly. Moreover, the higher the chimney is, the more efﬁcient it is. It is a similar concept to previously described SCPP [148], except that there is no solar collector at the bottom of the tower, which usually couples the GH effect to the sucking effect of the chimney. According to Pesochinsky the temperature difference between the bottom and the top of the tower is sufﬁcient. Another difference with conventional SCPPs concerns the size, 5–10 times bigger: up to 10 km high with a diameter of up to 1 km. Even if these heights have never been reached by human buildings, some GE / CE projects reported in the initial part of this review envisioned similar heights [59–65]. Furthermore, some authors reported, with such a large duct and in certain atmospheric conditions, that a cold air inﬂow could occur at the top and as a result a layer of cold air could get out at the bottom of the chimney, the hotter air surface being just pushed up, with the creation of a thermal inversion. In terms of heat transfer the result is nearly the same: cold air down and hoIndeed, on some Pesochinskys designs, the tower is alongside a mountain slope or drilled inside a mountain (which seems too expensive) and numerous air pipes are connected on the sides. Di Bella [155] suggested a similar concept by using giant open pit-mines and also recycling waste-heat from power plants. This heat input could be useful to prevent cold inﬂow entering these large diameter chimneys. To illustrate the potential of these devices, according to Pesochinskys calculations [156] only 10 super chim-neys 5 km high can offset the heat surplus in the Earth atmo- sphere, which causes current global warming. This would mean that all the atmospheric circulation would be completely reorga-nized from only 10 points on the Earth’s surface: the climate induced perturbations could be much worse than what we want toavoid. Hopefully with smaller, cheaper and more numerous superchimneys, better distributed on the surface of the planet, thisdeleterious effect can be avoided. The calculations done are rather simple, and were conﬁrmed by Mudde [157] from Delft Universityof Technology. They are based on a difference of temperature of 50 1C and as the super-chimney will facilitate air convection bybringing masses of warm air up to 5 km, then when the heat from the air radiates out, as it will be already at high altitude, lessenergy will be reabsorbed by the atmosphere, due to a thinner layer of atmosphere to go through. Therefore, more heat will beleaving the atmosphere, thus reducing the global atmospherictemperature. The authors believe that more scientiﬁc studies areneeded to prove the concept, and that the techology still fairly mature to build 5 km high chimneys.Constructional generalities are given by Pesochinsky with no real details: tall skyscrapers already exist; unlike chimneys, build-ings entail much heavier construction because there are ﬂoors, ceilings, several ﬂuids and lifts going up and down, and all otherelements within buildings which are necessary to make it useful for humans. A chimney is just a cylinder, thus is a much lighterstructure and can be build a lot taller than any building with new “super-strong”materials, not even described by Pesochinsky
taneq 9y ago
A Wacky Waving Inflatable Solar Chimney! It kind of lost me when they started talking about the expected power output, though. A kilometer-tall tower seems like a very expensive and fragile way to generate ~200MW, compared with solar panels. I guess if you're primarily using it as a climate-engineering system, though, the free power is a bonus.
- SubiculumCode 9y ago
  If water collection idea is a thin that can happen, that might have interesting implications too.

grecy 9y ago

They almost got funding to build one that was going to be 1km high right next to my home town [1] in rural Australia. [1] https://en.wikipedia.org/wiki/Mildura_Solar_Concentrator_Power_Station https://en.wikipedia.org/wiki/Mildura_Solar_Concentrator_Pow... Back in the day dad and I figured out we would easily see the tower from home, and the shadow would cross our house. Also it would be possible to see the curve of the earth from the top, so there was talk of allowing tourists up there.

jdavis703 9y ago
Can you really see the curve of the earth from 1km? I can't really even see the curve of the earth from an airplane (or can people with 20/20 vision see the curve from commercial aviation altitudes?)
- Simon_says 9y ago
  The declination of the horizon is a couple degrees at altitudes that commercial flights fly at. It can be measured with standard carpentry tools.
  - codecamper 9y ago
    Now how did you get carpentry tools into an airplane?
    - andy_ppp 9y ago
      Disguise them as 100ml bottles of liquid...
    - lucisferre 9y ago
      Like this obviously: https://www.youtube.com/watch?v=6nNUEU8gnf4 https://www.youtube.com/watch?v=6nNUEU8gnf4
      - Simon_says 9y ago