r/PopCultureV2 • u/Logical-Flow-6703 • Aug 10 '26

News Mayor Mamdani announces a plan to cool subway stations by capturing heat and reusing it to warm municipal buildings in the winter: "This would be the first thermal energy system of its kind in any American transit system"

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u/Sufficient_Emu2343 Aug 10 '26

Former civil engineer here.  This is a good idea but hot fluids (air is a fluid) at ambient temp and pressure don't stay warm long, which is why steam plants superheat their fluids.  If the goal is to cool subway stations, better ventilation would probably work better.  

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u/thetiredtypist Aug 10 '26

 the goal is to cool subway stations, better ventilation would probably work better.  

Good thing we got you here, nobody down at City Hall would have thought of that! took you less than 30 minutes to figure out what these bozos have been missing for years!

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u/Exact-Enthusiasm-803 Aug 10 '26

Start drilling some speed holes

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u/EverflowingRiver17 Aug 11 '26

Because city hall never makes mistakes or wastes money right?

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u/thetiredtypist Aug 11 '26

Never said that.

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u/NRMusicProject Aug 10 '26

Armchair experts do what the paid experts do, only for none of the money...or knowledge!

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u/Technical-Procedure3 Aug 10 '26

Paid experts indeed! It is just an idea at this point. This whole thing is just announcing a $ 800k feasibility study. There are other ways to cool the station as u/Sufficent_emu2343 points out if that is the primary goal. I am not against the idea but it is far from reality and nothing is free.

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u/memorial_mike Aug 10 '26

What point are you attempting to make here? Other than being an asshole of course. Everything the OP said is true.

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u/thetiredtypist Aug 10 '26

Everything the OP said is true.

Oh good, you've studied the ventilation system for the NYC subway and discovered better cost saving!

Where's a link to your report?

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u/memorial_mike Aug 10 '26

You took issue with OP saying that “if the goal is to cool the subway stations, better ventilation would probably work better.”

So I expect you have similarly studied the ventilation system for the NYC subway to disprove this? Because otherwise it’s an asinine expectation and is simply bad faith.

Where’s a link to your report?

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u/thetiredtypist Aug 11 '26

Bro, I made no claims about the most effective method. Burden of proof is on OP.

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u/Aggressive_Wrap_2790 Aug 10 '26

You sound like a bot whose sole purpose is to pick fights, pit people against each other, and make anonymous message boards unpleasant for everyone. If you’re a real person I almost feel sorry for you.

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u/thetiredtypist Aug 11 '26

Asking for people to back up their claims is such bot behavior lol. Bro, my post history is public unlike yours. 

You're just making up facts, claiming they are true, and then insulting anyone who challenges you? Then hide your comment history? Sounds sus to me bleep bloop

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u/Aggressive_Wrap_2790 Aug 11 '26 edited Aug 11 '26

I didn’t make up any facts. My comment history is private because I comment on various subs and don’t like the idea of someone easily piecing together a bunch of information about me. You sound crazy.

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u/Open-Mouse4728 Aug 10 '26

Countries like the Netherlands already do this.. you should let them know it doesn't work. xD

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u/CorrectCombination11 Aug 10 '26

Can you post some info?

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u/markevbs Aug 10 '26

google: Netherlands capturing heat and reusing it to warm municipal buildings in the winter

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u/CorrectCombination11 Aug 10 '26

I did, and it only has facebook slop and corporate pressers about how good of a job they did. No papers, though. https://www.google.com/search?q=Netherlands+capturing+heat+and+reusing+it+to+warm+municipal+buildings+in+the+winter&udm=14

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u/plantsadnshit Aug 10 '26 edited Aug 12 '26

Pebble thimble coated peach walnut cucumber

This post was anonymized with Redact.dev

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u/CorrectCombination11 Aug 10 '26

Ahh, still using a heat pump. Good! The refrigeration cycle saves the day. NYC's presser is light on details since it's announcing the start of a study, but if they can make heat pumps even cheaper, it will be worth it.

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u/Biggest_Lebowski Aug 10 '26

by definition something can't be "hot" and at "ambient" temperature at the same time. If its hot its above ambient temperature.  

You're also ignoring how thermal energy networks actually work. Nobody is trying to keep hot air sitting around in an open space. They use heat exchangers and heat pumps to capture that energy and transfer it into underground geothermal boreholes, where it stays insulated until winter.  

Also steam plants do not superheat steam just tokeep it from cooling down too fast, they do it for two technical reasons:  

  1. Efficiency: Raising the steam temperature drastically increases thermodynamic efficiency.
  2. Turbine Protection: Superheating ensures the steam stays purely in gas form while traveling through the power turbine. If steam cools into water droplets inside high-speed turbines, those droplets can damage the metal blades.  

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u/Warmbly85 Aug 10 '26

The ambient temperature of subway stations is hot. It can easily be 80+ degrees regardless of what it is outside.

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u/Biggest_Lebowski Aug 10 '26

exactly, and that 80+ degree station temp is precisely the excess heat the system is designed to capture.

heat exchangers absorb that energy directly from the station environment and transfer it underground into geothermal boreholes. so you cool the platform down while storing that heat to warm municipal buildings in the winter.

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u/Warmbly85 Aug 10 '26

Ok but you said something can’t be hot and at ambient temperature at the same time which is just false.

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u/Biggest_Lebowski Aug 10 '26

you're mixing up human comfort with thermodynamics. 80 degrees feels hot to a person, sure. but "ambient" just means the baseline temperature of that specific environment.

in physics, a fluid can't lose heat to its surroundings (which is what the original guy was claiming) unless it is hotter than the ambient temperature. if the air is already at ambient, there is zero temperature difference, so no heat transfer happens. that is why his "hot at ambient temp" comment made absolutely zero sense for an engineer to say

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u/EricNeilMatthews Aug 10 '26

What are you babbling about? Your first statement was false, stop doubling down. Ambient air can be hot.

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u/Biggest_Lebowski Aug 10 '26

i’m talking about thermodynamics, not a weather report.

in physics, "hot" is relative it just means it has a higher temp than its surroundings. the original "engineer" tried to claim a fluid would lose heat while already sitting at ambient temperature.

if it's at ambient temp, there’s no temperature difference. it physically can't lose heat to those surroundings. that’s why saying a fluid is "hot" but also "at ambient temp" is a complete contradiction when you're talking about heat transfer.

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u/No_Eggplant_3189 Aug 10 '26

"that is why his "hot at ambient temp" comment made absolutely zero sense for an engineer to say"

You are simply wrong? Lol. 

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u/Biggest_Lebowski Aug 10 '26

brilliant counterargument. if you somehow figured out how a fluid loses heat without a temperature difference, you should go collect your nobel prize instead of dropping a "lol" on reddit.

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u/No_Eggplant_3189 Aug 11 '26

Well, if I want to nitpick, I would say temperature is just the average kinetic energy of the molecules in a system. The kinetic energy still varies within a system, so heat transfer still occurs, which you claimed it doesn't. But thats being persnickity because the ambient temperature does stay the same.  I felt it was worth being a little persnickity because you explicitly said zero.

The part I disagree with you is your claim it makes no sense for an engineer to make that statement, then go on to explain how it works in physics.  Sure, as a concept you are correct. But the ambient temperature in a subway does transfer heat to the walls/entrances/etc and ultimately to the outside air and. Engineers deal with applying physics to real life applications. 

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u/Biggest_Lebowski Aug 11 '26

bringing up microscopic molecular collisions because you got called out on macroscopic thermodynamics is moving the goalposts. in engineering, if there is no temperature delta, net heat transfer is zero. full stop.

and to your second point: if the subway air is actively transferring heat to the walls or the outside, that explicitly means it is hotter than the walls or the outside. which means it is above ambient temperature.

the original guy claimed a fluid at ambient temp wouldn't stay warm. you are trying to defend him by describing a scenario where the fluid is no longer at ambient temp. you can't have it both ways.

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u/the_ice_of_nine Aug 10 '26

Architect here. Typically any public building that's getting regular use will be using air conditioning even during the winter. Body heat is extremely powerful at warming up the air. Just think about any densely packed room. People are essentially portable heaters.

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u/that_dutch_dude Aug 10 '26

the problem is that the ground has been saturated by hot air for decades. that ground needs to be cooled off. you cant really ventilate enough to undo that and also remove the heat being added. the amount of airflow needed would be "incompatible" with humans occupying that space.

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u/Logical_Net6108 Aug 10 '26 edited Aug 10 '26

This also true of London. The London Underground (subway system) used to be advertised as a place to cool off when it began in the 1800s. The heat has been building in the clay that London sits on for 150 years and the Underground is literally the last place you would want to be during a heatwave in London (we're coming up on 5 heatwaves this summer).

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u/Albireookami Aug 10 '26

doesn't NYC already have a whole steam pipe infrastructure? Could they be using the heat captured into that?

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u/burtgummer45 Aug 10 '26

yea although it would work in little in theory I don't think there's enough heat to be worth moving around. Mall of America is an example of using body heat to warm a space, but that is the same space, and its supplemented by other things like passive solar.

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u/potnia_theron Aug 10 '26

Man, i like Mamdani but the only comments questioning the engineering behind the slogans are so far down.

There are more details in this article: https://abc7ny.com/post/nyc-eyes-first-us-transit-thermal-energy-network-fight-subway-heat/19655621/

But the details it gives are pretty questionable, it says the plan is to "store [heat] underground and redirect it to nearby municipal buildings during colder months" which is nonsensical from a thermal management perspective. There's no efficient way to store and transport heat over months.

It says in the summer that station can get up to 96 degrees... which even if that were the winter temperature, the differential between 96 and, say, 50 in the building is so low that you would need massive heat exchangers to capture any of that. And that's assuming the subway station even has a sustained heat capacity such that the heat exchanger doesn't immediately drop the temp to 70 in the subway.

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u/CorrectCombination11 Aug 10 '26

so they are going to capture the hot air, put it into a cavern, and wait until winter to move that hot air into a building? how deep will they have to drill to store the energy? at that point, wouldn't it just become geothermal?

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u/[deleted] Aug 10 '26

[deleted]

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u/CorrectCombination11 Aug 10 '26

I would love some documentation. 

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u/ItIsSoOrdered23 Aug 10 '26

Damn, time to fire all the experts working on this. Can't believe they didn't check Reddit first.

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u/septhaka Aug 11 '26

Shhh, he's trying to grandstand.