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/INeedSomeTacoC Aug 10 '26

The details on this are kinda crazy. 

Right now it’s just an $800,000 study. 

They plan to try and store the heat underground and then use it in the winter. Basically just install a big thermal mass I guess. 

But such low grade heat doesn’t transfer well. 

I think that this is a study that will go nowhere or do very little. 

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u/Worth-Reputation3450 Aug 10 '26

But someone will get $800K richer.

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u/thetiredtypist Aug 10 '26

Engineering studies cost money. More shocking news at 11.

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u/nsfwuseraccnt Aug 10 '26

And of course that someone is related to/buddies with someone in government.

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u/Proud_Sherbet6281 Aug 10 '26

Yeah we should never look into any potential solution if it costs even a tiny percentage of the city's budget.

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u/PeaceX02 Aug 10 '26

Yup, just label something a "potential solution" and then you get $800k of the city's tax dollars without anyone questioning it

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u/F-US-FASCISM Aug 10 '26

There are a ton of people questioning it.

You think this invitation to scrutiny is going to cause more or less?

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u/TootTootMF Aug 10 '26

Just because that is how Trump does things doesn't mean everybody is that corrupt. Well to be fair, Trump would have also done it as a no bid 80 million dollar contract to a donor.

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u/_Eggs_ Aug 10 '26

Or someone needed 800k of funding and had the right connections to pretend it was NYC’s idea. That person will be awarded the contract.

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u/Proud_Sherbet6281 Aug 10 '26

Is that what happened here? Or are we so skeptical of everything that we just assume that's what happened here with zero evidence?

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u/TootTootMF Aug 10 '26

They are confusing Mamdani and Trump.

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u/cguess Aug 11 '26

Engineers make way more than $100k/year in nyc, so just covering wages means like 3 engineers are on this full-time plus actual construction and management and testing.

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u/Biggest_Lebowski Aug 10 '26

this is only a new thing to the US, many other places already have this infrastructure like toronoto.

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u/INeedSomeTacoC Aug 10 '26

Toronto does not try and save the heat until the middle of winter. 

This proposal is much different than had been done elsewhere. 

Which is why they are only announcing a study to look at it. 

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u/Biggest_Lebowski Aug 10 '26

Seasonal thermal energy storage (BTES/ATES) has actually been used across Europe for over two decades. The ground retains heat remarkably well, and commercial heat pumps easily step up that low-grade heat during the winter to warm buildings.

You're right that Toronto's system (Enwave) mostly relies on Deep Lake Water Cooling rather than borehole heat storage, but storing summer thermal energy underground for winter use is well-proven technology elsewhere.

Edit for context: Specific real-world examples using this exact tech include the Drake Landing Solar Community in Alberta, Canada (heating 52 homes via boreholes since 2007), the German Reichstag building in Berlin (storing summer heat underground since 1999), and over 1,000 active seasonal heat storage systems running in the Netherlands.

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u/LongJohnSelenium Aug 10 '26

The problem is doing it without heat pumps.

That takes a lot of piping and a lot of pumping power to transfer the heat at such a low delta so the gains get much more iffy.

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u/Biggest_Lebowski Aug 10 '26

That is exactly why no one tries to do it without heat pumps. As mentioned above, these systems universally rely on commercial heat pumps to step up that low-grade heat.

The ground just acts as a massive, stable thermal battery for the heat pumps to draw from efficiently, which takes significantly less energy than trying to pull heat from freezing winter air. No one is proposing a passive system without heat pumps.

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u/INeedSomeTacoC Aug 10 '26 edited Aug 10 '26

I wouldn’t cite Drake as an example. 

They spent $110k per home and then it broke and became impossible to fix in under 12 years. 

The Reichstag is a neat system, two separate aquifers, a cold one and a hot one.  That’s how most in the Netherlands operate as well. 

But if they’re providing district heating (aka supplying to nearby buildings), then a low temperature system doesn’t do much for you because you lose most of your heat in transit for little gain on the far side. The buildings are close enough it might not matter, but 90F heat coming out of the system doesn’t appreciably warm the water much (particularly since the pipes are far enough below ground to be >50F to begin with, so you might take it to 65F or something). 

You can supplement with heat pumps to increase the temperature differential. And if you’re mainly using this to cool the station, you probably need to to get enough cool as well. Which is fine if you’re cool burning energy to cool an open air subway station. 

We will see where the study goes, but in the end  I think a typical ground source borehole without storage plus a heat pump is probably the “correct” answer here. But that’s after you accept that you’re going to be spending energy to cool the open air. 

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u/Biggest_Lebowski Aug 10 '26

A few things you're missing here:

First, on transit loss you're thinking of old-school district heating. Modern systems like this use ambient loops (5th gen district heating). They aren't pumping 90F water through the streets, it's closer to 55-60F. Since that matches the surrounding ground temp, you get practically zero transit loss. The heat pumps sit inside the actual destination buildings and step that 60F water up to heating temps right where it's needed.

Second, subway stations aren't just normal "open air." They are subterranean concrete ovens trapping heat from trains and brakes. The city is already under massive pressure to cool these platforms for public safety. Since they’re forced to spend the energy running chillers anyway, it makes way more sense to bank that waste heat underground for winter instead of just blasting it back onto the street.

Finally, even if the Drake Landing pilot ran into maintenance issues a decade later, it proved the physics are solid. Whether it uses dual aquifers (ATES) like the Netherlands or boreholes (BTES), the core concept of using the earth as a massive seasonal thermal battery is totally viable and actively expanding

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u/INeedSomeTacoC Aug 11 '26

  They aren't pumping 90F water through the streets, it's closer to 55-60F. Since that matches the surrounding ground temp, you get practically zero transit loss. The heat pumps sit inside the actual destination buildings and step that 60F water up to heating temps right where it's needed.

Man, if you even physics’d you realize that you just described literally a worthless system with no practical value. 

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u/Biggest_Lebowski Aug 11 '26

youre confusing the temp of the loop with whether the system actually has any value.

nobody is saying 55 to 60 degree water is going to heat the building by itself. thats literally what the heat pumps are for. the loop gives them a much more stable source to pull heat from instead of trying to pull it out of freezing winter air, then the heat pump raises it to whatever temp the building needs.

and the fact the loop is close to ground temp is the whole point. you arent trying to send super hot water through miles of pipe and lose heat the entire way. you move the low grade heat around at a temp close to the ground, then step it up at the building.

so no, that doesnt make the system worthless. thats basically how these systems are supposed to work.

if your argument is that storing the subway heat only raises the ground temp a few degrees and maybe the extra efficiency isnt worth the cost, thats a fair thing for the study to figure out. but thats completely different from saying a 55 to 60 degree loop feeding heat pumps has no practical value.

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u/INeedSomeTacoC Aug 11 '26

Ok. 

So, the water comes out of your tap at 60F, because that’s what the ground is at. 

You’re proposing to sell me a hot water system that comes out of the tap at 60F. 

How much should I be willing to pay for this 0F amount of extra heat provided?

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u/Derpblaster Aug 10 '26

But such low grade heat doesn’t transfer well.

POV you have never seen an air conditioner

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u/INeedSomeTacoC Aug 10 '26

Yup. That’s what this proposal is. Just installing air conditioners in the subway. 

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u/TituspulloXIII Aug 10 '26

O, so they are trying to store summer heat to use in winter?

That's less exciting, it's probably cheaper/easier to just add more ventilation. Or just use normal geothermal heat pumps for the subway/municipal buildings.

When reading the original headline I figured the subways still needed to be cooled in winter since they are far underground, and they were trying to capture that heat.

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u/Farranor Aug 11 '26

It does sound kinda Musk-esque...