7 ms·

I wonder if putting a semi transparent white dome or covering over a city could effectively cool it by reducing net sunlight. Kinda like permanent artificial cl

I wonder if putting a semi transparent white dome or covering over a city could effectively cool it by reducing net sunlight. Kinda like permanent artificial clouds

entropicdrifter 6y ago
It'd probably heat it up because of the greenhouse effect, just from the hot air coming from all the cars and people not being able to escape, let alone heat from sunlight not being cooled by breezes/convection
- sjg007 6y ago
  Maybe have a hole in the top like a giant chimney.
  - gabrielsroka 6y ago
    Many geodesic domes were designed exactly this way. And with vents at the bottom to let in cool air. Eg http://www.eps2016-wiki4.dee.isep.ipp.pt/lib/exe/fetch.php?media=ventilationdome.png http://www.eps2016-wiki4.dee.isep.ipp.pt/lib/exe/fetch.php?m...
- cogman10 6y ago
  It'd be interesting to see if there were some economies of scale for heating cooling. For example, I could imagine that a nuclear power plant in the center of the city could provide the whole city with both heat and power at a fairly low cost for both. On the flip side, you might be able to do city wide geothermal cooling. It'd be an interesting experiment to say the least.
  - deleted 6y ago
    [deleted]
  - zkms 6y ago
    There definitely are economies of scale for heating and cooling, and doubly so when you're generating electrical power as well; this is known as "cogeneration" or "combined heat and power". Generating electrical power inherently generates waste heat as well, and a perfect use for this heat is generating steam and/or running an absorption chiller. The canonical example is the combined heat/power/chilled-water plants often found in university campuses. There's a gas turbine, usually running on natural gas, and its hot exhaust gas is used to make steam. The chilled water is usually generated by variable-speed centrifugal chillers, which are remarkably efficient machines compared to smaller-scale refrigeration systems. Nowadays, there's centrifugal chillers that don't even need oil in the refrigerant to lubricate the bearings because the bearings are active magnetic bearings (like in turbomolecular vacuum pumps and uranium enrichment centrifuges): the shaft with the turbine/motor is made to levitate and a computer actively controls its position to micrometer accuracy. Oil-free magnetic bearings not only eliminate a source of frictional loss but also allow for more efficient heat transfer in the heat exchangers (https://mnashrae.org/downloads/Presentations/magnetic_bearing_oil_free_technology_mn_ashrae.pdf https://mnashrae.org/downloads/Presentations/magnetic_bearin...) because there's no oil to provide unwanted insulation between the copper surface and the refrigerant inside. Since a single entity controls the buildings and the utility tunnels alike, there are steam and chilled water pipes going to every building. In each building the steam is passed through heat exchangers to heat potable/domestic hot water and also heat hot water that'll be used for heating air. (It's also possible to have a single-phase system where no steam is generated at the central plant -- just hot water; apparently there are efficiency gains from doing so). The chilled water is directly used for cooling air. Equipment that needs heating or cooling can be plumbed into the facility's heating hot water or chilled water systems, rather than requiring their own (smaller and less efficient) heating or vapor-compression refrigeration systems. The electricity generated on-site might be somewhat more expensive than grid rates since your utility's large-scale generation facilities are hopefully more efficient. In exchange, the waste heat from the generation process -- which would otherwise be discarded -- will keep your buildings and equipment warm for free (well, for the cost of moving steam / hot water around and maintaining the system). You can be clever and throttle your gas turbine based on the facility's instantaneous electrical / chilled-water / steam requirements (and even import power from the grid if it's economical); or run the chillers a bit more than necessary overnight (and store the chilled water in tanks) so during the day there's less load required on the system.
  - Nasrudith 6y ago
    Europe already has utility heating. I know I first heard of it from Cities Skylines and my first thought was "That sounds like a silly excuse to add another utility." Then I looked it up and found it was a real thing. NYC has a steam network which has remarkable versatile functions - in addition to heating, resturant dish cleaning, and humidity control.
    - imtringued 6y ago
      Silly excuse? What else are you going to do with the waste heat?
      - entropicdrifter 6y ago
        I think that part of the comment was specific to the game Cities Skylines. Like, "Oh they added another utility to manage... wtf is this? I haven't ever heard of cities doing this." But then they looked it up and found out it's a real practice.
    - LargoLasskhyfv 6y ago
      The weirdest "utility" I've ever heard of is centralized liquid soap pumping for the rest rooms in an office building. [1] https://www.mopo.de/hamburg/von-panzermotor-bis-kegelbahn-die-skurrilen-geheimnisse-dieses-hamburger-hochhauses-33701356 https://www.mopo.de/hamburg/von-panzermotor-bis-kegelbahn-di... <- Nr. 1: Zentrale Seifenspenderanlage Deepl: "In a high-rise building of this size there are many toilets and accordingly many soap dispensers that would have to be refilled. Not so with Euler-Hermes: a central dispenser in the basement is filled with 200 litres of liquid soap, and a pump "shoots" the cleaning agent with nine bar pressure into the 200 dispensers on 22 floors. Practical!" It is this building [2] https://commons.wikimedia.org/wiki/Category:Euler_Hermes_building https://commons.wikimedia.org/wiki/Category:Euler_Hermes_bui... which is currently prepared for being torn down.
  - LargoLasskhyfv 6y ago
    Hmm. "NPP in the center of the city." What could go wrong?
deleted 6y ago
[deleted]
MR4D 6y ago
In Minnesota, you’d want to heat it up, not cool it. Winter in MN is extremely cold, especially in the northern half.
- HeyLaughingBoy 6y ago
  Yeah, and summer is extremely hot, so...
  - CyberDildonics 6y ago
    Normalizing it to the outside temperature would be a matter of airflow, unlike heating, which requires energy from somewhere. Running fans would not require much energy by comparison.
    - HeyLaughingBoy 6y ago
      Huh? If it's 95F outside how does that help?
      - CyberDildonics 6y ago
        If you gain lots of heat during the winter and none during the summer, you would still save an enormous amount of money.
Nasrudith 6y ago
Technically but there is a matter of expense and lack of crossbreezes for a solid dome and indoor air pollution issues. Active ventilation is a possibility but it seems like it would be of questionable worth unless the outside is far worse.

I wonder if putting a semi transparent white dome or covering over a city could effectively cool it by reducing net sunlight. Kinda like permanent artificial clouds

entropicdrifter 6y ago

It'd probably heat it up because of the greenhouse effect, just from the hot air coming from all the cars and people not being able to escape, let alone heat from sunlight not being cooled by breezes/convection

sjg007 6y ago
Maybe have a hole in the top like a giant chimney.
- gabrielsroka 6y ago
  Many geodesic domes were designed exactly this way. And with vents at the bottom to let in cool air. Eg http://www.eps2016-wiki4.dee.isep.ipp.pt/lib/exe/fetch.php?media=ventilationdome.png http://www.eps2016-wiki4.dee.isep.ipp.pt/lib/exe/fetch.php?m...
cogman10 6y ago
It'd be interesting to see if there were some economies of scale for heating cooling. For example, I could imagine that a nuclear power plant in the center of the city could provide the whole city with both heat and power at a fairly low cost for both. On the flip side, you might be able to do city wide geothermal cooling. It'd be an interesting experiment to say the least.
- deleted 6y ago
  [deleted]
- zkms 6y ago
  There definitely are economies of scale for heating and cooling, and doubly so when you're generating electrical power as well; this is known as "cogeneration" or "combined heat and power". Generating electrical power inherently generates waste heat as well, and a perfect use for this heat is generating steam and/or running an absorption chiller. The canonical example is the combined heat/power/chilled-water plants often found in university campuses. There's a gas turbine, usually running on natural gas, and its hot exhaust gas is used to make steam. The chilled water is usually generated by variable-speed centrifugal chillers, which are remarkably efficient machines compared to smaller-scale refrigeration systems. Nowadays, there's centrifugal chillers that don't even need oil in the refrigerant to lubricate the bearings because the bearings are active magnetic bearings (like in turbomolecular vacuum pumps and uranium enrichment centrifuges): the shaft with the turbine/motor is made to levitate and a computer actively controls its position to micrometer accuracy. Oil-free magnetic bearings not only eliminate a source of frictional loss but also allow for more efficient heat transfer in the heat exchangers (https://mnashrae.org/downloads/Presentations/magnetic_bearing_oil_free_technology_mn_ashrae.pdf https://mnashrae.org/downloads/Presentations/magnetic_bearin...) because there's no oil to provide unwanted insulation between the copper surface and the refrigerant inside. Since a single entity controls the buildings and the utility tunnels alike, there are steam and chilled water pipes going to every building. In each building the steam is passed through heat exchangers to heat potable/domestic hot water and also heat hot water that'll be used for heating air. (It's also possible to have a single-phase system where no steam is generated at the central plant -- just hot water; apparently there are efficiency gains from doing so). The chilled water is directly used for cooling air. Equipment that needs heating or cooling can be plumbed into the facility's heating hot water or chilled water systems, rather than requiring their own (smaller and less efficient) heating or vapor-compression refrigeration systems. The electricity generated on-site might be somewhat more expensive than grid rates since your utility's large-scale generation facilities are hopefully more efficient. In exchange, the waste heat from the generation process -- which would otherwise be discarded -- will keep your buildings and equipment warm for free (well, for the cost of moving steam / hot water around and maintaining the system). You can be clever and throttle your gas turbine based on the facility's instantaneous electrical / chilled-water / steam requirements (and even import power from the grid if it's economical); or run the chillers a bit more than necessary overnight (and store the chilled water in tanks) so during the day there's less load required on the system.
- Nasrudith 6y ago
  Europe already has utility heating. I know I first heard of it from Cities Skylines and my first thought was "That sounds like a silly excuse to add another utility." Then I looked it up and found it was a real thing. NYC has a steam network which has remarkable versatile functions - in addition to heating, resturant dish cleaning, and humidity control.
  - imtringued 6y ago
    Silly excuse? What else are you going to do with the waste heat?
    - entropicdrifter 6y ago
      I think that part of the comment was specific to the game Cities Skylines. Like, "Oh they added another utility to manage... wtf is this? I haven't ever heard of cities doing this." But then they looked it up and found out it's a real practice.
  - LargoLasskhyfv 6y ago
    The weirdest "utility" I've ever heard of is centralized liquid soap pumping for the rest rooms in an office building. [1] https://www.mopo.de/hamburg/von-panzermotor-bis-kegelbahn-die-skurrilen-geheimnisse-dieses-hamburger-hochhauses-33701356 https://www.mopo.de/hamburg/von-panzermotor-bis-kegelbahn-di... <- Nr. 1: Zentrale Seifenspenderanlage Deepl: "In a high-rise building of this size there are many toilets and accordingly many soap dispensers that would have to be refilled. Not so with Euler-Hermes: a central dispenser in the basement is filled with 200 litres of liquid soap, and a pump "shoots" the cleaning agent with nine bar pressure into the 200 dispensers on 22 floors. Practical!" It is this building [2] https://commons.wikimedia.org/wiki/Category:Euler_Hermes_building https://commons.wikimedia.org/wiki/Category:Euler_Hermes_bui... which is currently prepared for being torn down.
- LargoLasskhyfv 6y ago
  Hmm. "NPP in the center of the city." What could go wrong?

deleted 6y ago

[deleted]

MR4D 6y ago

In Minnesota, you’d want to heat it up, not cool it. Winter in MN is extremely cold, especially in the northern half.

HeyLaughingBoy 6y ago
Yeah, and summer is extremely hot, so...
- CyberDildonics 6y ago
  Normalizing it to the outside temperature would be a matter of airflow, unlike heating, which requires energy from somewhere. Running fans would not require much energy by comparison.
  - HeyLaughingBoy 6y ago
    Huh? If it's 95F outside how does that help?
    - CyberDildonics 6y ago
      If you gain lots of heat during the winter and none during the summer, you would still save an enormous amount of money.

Nasrudith 6y ago

Technically but there is a matter of expense and lack of crossbreezes for a solid dome and indoor air pollution issues. Active ventilation is a possibility but it seems like it would be of questionable worth unless the outside is far worse.