Something I have been wondering: Why don't data centres use the excess heat for a sort of energy recuperation, turning at least some of it back into electricity?
There's lots of district heating in Germany for example, but it's usually fed from either big heat pumps, bio mass plants, or heat from waste incineration plants. There's no reason to not use excess heat from data centres too - I'm pretty sure I read that already being done in several places.
But in some cases, a data centre might be too remotely located, or the infrastructure is too lacking to make it economically feasible, which still leaves me wondering why you couldn't try to recuperate at least some of it as electricity on-site...
Yes, it's not an identical situation, but I thought it was relevant because of the concept of recovering a dead body's resources for consumption by the remaining living humans.
It actually is, just not water steam. There's a hot springs resort in Alaska that uses pentane (boiling point 38C) to generate energy. The efficiency is terrible, of course.
True. Chena Hot Springs [1]. They are famous in the "direct use" geothermal community.
A lot of the thermal energy is not used for electrical generation. Although a small portion actually is -- made possible by the \Delta T rejecting heat at a low annual average atmospheric T.
Most of the rest of the heat is used to run an absorption chiller to maintain the ice "palace" in the summer.
(This info might be slightly outdated. It was true about 2018 or thereabouts when I met the owner of the resort at a geothermal conference.)
Because it's not economical, the required hardware is unlikely to pay for itself during its lifetime. The gradient is too small (~50C), which means low Carnot efficiency. Additionally, extraction of low-enthalpy energy involves obstruction of heat transfer, meaning lower cooling efficiency. It may have been a different story if we had computer hardware able to efficiently operate at 200-300C.
Even steel plants which deal with significantly higher waste heat gradients rarely bother with recovering energy.
The degree to which you can extract energy from heat depends on the temperature difference compared to ambient. Efficient power stations all need super heated steam (like 600C). This would be like 100C max which is not very useful for generating electricity. It's fine for heating houses and swimming pools though.
The concept of waste-heat-to-power (WHP) exists, but its efficiency is limited by thermodynamics.
Basically, heat energy is not equal to usable energy. All energy ultimately wants to be heat energy, and it is much easier and more efficient to go from electrical or mechanical energy to heat than vice-versa. Therefore, when you do have an application that actually wants heat, not electricity, such as a public swimming pool or district heating, it is way more efficient to use your waste heat as heat. Even in cases where the desired temperature is wildly different from that of your waste heat, you can convert one heat level into another very efficiently using heat pumps.
Look up Carnot efficiency. The maximum amount of work you can theoretically extract depends only on a temperature difference. For a datacenter running chips at 100C into ambient air at 60F, it's about 25%. So even with perfect capture, you are guaranteed to lose 3/4 of your input energy to the datacenter as heat anyway.
For comparison, an IC engine has a Carnot efficiency of something like 80% on paper, but the reality you get is only 20-30%
Undecided just did an episode on a waste heat machine that is being slowly rolled out to industry.
The founder of the company is also the guy who invented the Super Soaker.
I don't understand how a server (the "washing-machine-sized datacenter") can heat up any fraction of a swimming pool appreciably. Wouldn't it be a few kW tops?
A 30C swimming pool vs a 70C GPU is plenty of temperature difference for a heat exchanger to work with. And even indoor swimming pools have horrific levels of heat loss due to evaporation. But I think the key thing here is that they've undersized the server rack - if its only offsetting 60% of the heating bill, there's a fair margin still being handled by a regular heat pump, which can cycle down in warmer weather.
Pre-GPU times you'd be right, but these days a 4U server could have 8 GPUs pulling 350+ watts each. A washing machine sized unit could contain perhaps 4 of these 4U servers so the unit as a whole could be drawing upwards of 11kW.
This washing machine sized box draws 50kW of power. It wouldn't be able to heat up a cold swimming pool very much, but it would be enough to keep a pool that's already hot at a stable temperature.
All data centers that are in controversial areas should offer free heated swimming pools for the neighborhood. You could add a giant pool complex as a percentage or two of the cost of a big data center.
Surely it's just cheaper to build further away from residential areas? For this to work you'd need to be close to residential areas, but that's where you get the most NIMBY opposition. And if the datacenter is in the middle of some industrial park, who would want to drive 30 minutes to an industrial park to have a swim?
The last place I lived, the nearest data centre was a few hundred meters from the local swimming pool, in a business park. Most people would never have known the data centre was there.
Elsewhere, e.g. in London, Docklands is both full of high density data centres and high-end residential buildings and offices that could certain use the waste heat in winter at least.
Most of the data centres there just looks like office buildings on the outside, and most residents won't know they are there.
The best waterparks in Tucson, AZ were on the outskirts of the city and worked great as a place to "travel" to for the parents as the kids would be wiped out on the way back. Breakers....Justins....how i miss those days of running around on hot pavement or gravel in bare feat only to also step on some cactus...
Hah yeah if you, as a parent, can survive a day at the water park in the sun then you’re all set for some quiet time when you get home. Waterparks zap kids and they pass out cold in the car as soon as the doors close. Same goes for the beach.
An outdoor heated pool that’s open all winter in a cold climate would be a destination worth a drive. A rather decadent use of energy otherwise, it’d be a good use for waste heat. There’s prior art in the Blue Lagoon in Iceland, a destination spa that uses water from a geothermal power plant.
As a kid I have memories of driving a bit out the edge of town to a big steel plant for almost exactly this reason, it's not totally insane.
There's plenty of free parking, free admission, giant pool with some small waterslides and stuff, a bunch of picnic tables and public barbecues, generally some nice greenery and trees for shade, ponds and fountains and stuff, a bandstand, etc.
It's not somewhere you'd pop over to for a "quick swim", but especially for lower income people it's a great place to have around as a "grab a pack of hotdogs and your swim trunks and make a day of it" sort of thing. As a kid we couldn't afford to, say, go to the actual waterslide park or anything so I have a lot of fond memories of visiting the steel plant.
I'm sure the construction and upkeep was less than a rounding error in terms of construction and upkeep costs for the plant itself.
Probably not, at least, I’m pretty sure the heat directly produced by power consumption is minuscule compared to the global warming contribution of the fossil fuels used to produce it, right?
I like to think that the heating, much like their ideal govermental oversight, would have no regulation. I can almost hear the anguished cries of pool goers when a new model gets released and the temperature spikes.
I feel like this is one of those things that sounds good, but it's not. It's probably cheaper to build it far away from residential areas, and it's probably better for the people living there to not live too close to a data center.
The new ones are being built with massive numbers of unpermitted gas turbines with the exhaust filters removed, because there's not enough electricity and there isn't enough grid power and exhaust filtering costs money. So they're giving entire nearby towns asthma. They're also so loud the whole town can't sleep.
Data centers were, and still can be, some of the cleanest industrial facilities - but the ones being built in this AI wave are not, because they are being built as cheaply and as quickly as possible and without regards to proper infrastructure.
> The new ones are being built with massive numbers of unpermitted gas turbines with the exhaust filters removed
That’s every local investigative journalist’s wet dream. Can you link us to a source please?
PS saw an interview with he who shouldn’t be named and they made an interesting point that there isn’t a way to scale the manufacturing of gas turbine blades, there will never be enough gas turbines for these DCs to come online as scheduled.
here's something more local and what i would expect. However, it's murky [link at the bottom]
"Mississippi officials told xAI it could run the generators without an air permit because they were deemed “temporary” and “mobile” units.". Makes sense because as far as i can tell they were on trailers.
but then there's this:
"But lawyers at the Southern Environmental Law Center, representing the NAACP in the federal lawsuit, have long maintained that such a loophole doesn’t exist, and that running such turbines without a permit violates the federal Clean Air Act.
“Mobile, temporary, portable, whatever you want to call them, turbines need air permits,” Patrick Anderson, a center attorney, told Mississippi Today."
why must we tear up undeveloped areas for data centers instead of backfilling vacant industrial areas? Humanity will never rest until all of the world is a brownfield
It's cheaper to build on vacant land than to get construction equipment and materials into a built up area, possibly discovering underground tanks and other surprises that can inflate the project cost, etc. City ordinances may also limit work hours and/or noise.
Rural land is cheap and there are fewer neighbors to annoy with the 24/7 construction activity.
Personally, I think these data centers should be championing and pushing for district heating and cooling.
Even smaller data centers will be producing enough waste heat to heat 10s of thousands of homes. So why not make residents love you by funding the installation of a district heating system which gives your compute power a symbiotic relationship with the community. Their energy bills go down naturally because your cooling efforts are heating their homes and cooling their homes and you spend less in the winter cooling your servers because that heat is being distributed throughout the community.
It doesn't even have to be free district heating/cooling, just cheaper than using electric or gas heaters.
Equinix AM3 provides heat to the Amsterdam Science Park.
Undisclosed large Swiss private corporate datacenter provides heat to residential complexes in the surrounding area, as well as being integrated with the grid operator and required to spin up generators and island itself on demand, as part of the license to operate.
Some people use cryptocurrency miners to heat their homes. It's certainly better than dumb resistive heating, but depending on various conditions it can cost more than installing a heat pump.
A dedicated heat pump would be cheaper if we consider heating to be the device's primary purpose. The idea is the computers are doing all sorts of useful things, and the heat is just a free byproduct of that activity.
I have a pool heater and an air conditioner, and I'm running both at the same time. They're fifty feet apart, but this thought crosses my mind constantly.
The sticker on the side of the doohickey in the video really gives the whole thing a feeling of "a dude makes these by hand in his garage." I looked up "AC pool heat exchanger" and lo and behold, the same company showed up as the first result:
I have connected the radiator of my homeserver liquid cooling setup to the heat exchanger of my hot water heat pump. Not sure how efficient it is, but I get a measurable drop in CPU temperatures while the heat pump runs.
Linus Tech Talk (LTT) did a whole series on doing this on the pool at the channel hosts’ house. Extravagant home upgrades are a frequent topic on that YouTube channel… business expense write off yada yada. My general takeaway was, yikes, all that piping and infrastructure would be a nightmare to maintain and will likely just be closed off whenever an issue comes up (or he sells). I’m no expert, but I am a home owner, and have come to form a deep appreciation for maintaining simplicity when it comes to the operation of your house.
Some heat pumps do this. E.g. Panasonic Aquarea EcoFleX. When cooling the house, the domestic hot water tank is used to dump heat into (up to a certain temperature).
You need a lot of heat to do anything useful. I would need to run something like 14 kW of servers to heat my home through winter - that's a couple of hundred thousand in hardware at current prices.
This is mostly just due to how nonprofits work. If you have excess revenue, you can’t return it to shareholders so you might as well spend it on mission-oriented activities.
You can do this up to a point but if it looks like you're actually making a profit it might raise questions eventually. Keeping enough to cover one year's operating costs is pretty common though.
Non-profits usually don't "compete" at least in the economic sense. They exist for a charitable purpose that isn't normally well-served by the competitive market.
First of all, charity is a christian concept that has no role in modern secular society. Anything worth doing out of the kindness of our hearts is worth doing collectively without expecting individuals do disproportionately sacrifice.
Second, of course zero-margin processes have an economic role. That is what market efficiency looks like. The entire point of competition is to produce these economic processes. The american brain can't fathom getting their money's worth lol
> Anything worth doing out of the kindness of our hearts is worth doing collectively without expecting individuals do disproportionately sacrifice.
What are you saying here? Like, how are you distinguishing individual charity from the thing "worth doing collectively"? Presumably you don't consider individuals voluntarily giving and thus voluntarily organizing insofar as they coordinate to be the same as collective action, so I can't help but wonder which part is different, and I worry it's the voluntary bit....
Yes. I think people should be forced at gunpoint to contribute to their society. Typically that gunpoint is the state, but we seem to be allergic to having a functional society. Why be proud of your country when you can be a narcissist who steps over the homeless on the way to your job?
Keeping in mind that the datacenter operator is also paying the power bill for that (which presumably is roughly 28 kW), amounting to something like £65,000/year at current UK rates
> "Sean Day, who runs the leisure centre, said he had been expecting its energy bills to rise by £100,000 this year.
"The partnership has really helped us reduce the costs of what has been astronomical over the last 12 months - our energy prices and gas prices have gone through the roof," he said.
...
Last summer, BBC News revealed 65 swimming pools had closed since 2019, with rising energy costs cited as a significant reason."
That's terrible that pools are closing. No one even builds new public swimming pools anymore, so it's awful to close the few that exist.
In my home town the local steel plant has been connected to the district heating systems for half a century. This is extremely mature technology and widely used in parts of the world where heating homes is more important than cooling them.
> The data center delivers up to 1.7 MW of reusable heat – enough enough to warm 6,000 energy-efficient homes in winter or provide 20,000 five-minute showers every day in summer.
District heating is a mature technology. Direct Use geothermal heat is the one I am personally most familiar with -- as a geophysicist. However "waste" heat utilization is a definite thing for people with mechanical engineering/heat and mass transfer training.
(Edited to add: there are several examples of public swimming pools being heated with Low T geothermal heat in the Perth metropolitan region of Western Australia.)
9dev | 5 hours ago
[OP] breitling | 5 hours ago
We can just use data centers for heating too...maybe turn around all these protests against them
josefritzishere | 4 hours ago
9dev | 4 hours ago
But in some cases, a data centre might be too remotely located, or the infrastructure is too lacking to make it economically feasible, which still leaves me wondering why you couldn't try to recuperate at least some of it as electricity on-site...
Symbiote | 4 hours ago
Presumably you read this very recently, since it's mentioned at the end of the article.
SilasX | 4 hours ago
gruez | 4 hours ago
SilasX | 2 hours ago
wffurr | 4 hours ago
There are uses for low grade heat but they require colocation and careful design, which costs more than just dumping the heat.
cyberax | 4 hours ago
fghorow | 3 hours ago
A lot of the thermal energy is not used for electrical generation. Although a small portion actually is -- made possible by the \Delta T rejecting heat at a low annual average atmospheric T.
Most of the rest of the heat is used to run an absorption chiller to maintain the ice "palace" in the summer.
(This info might be slightly outdated. It was true about 2018 or thereabouts when I met the owner of the resort at a geothermal conference.)
[1] <https://www.chenahotsprings.com/>.
newpavlov | 4 hours ago
Even steel plants which deal with significantly higher waste heat gradients rarely bother with recovering energy.
soco | 3 hours ago
Do I see a market opening here?
IshKebab | 4 hours ago
muvlon | 4 hours ago
alnwlsn | 4 hours ago
For comparison, an IC engine has a Carnot efficiency of something like 80% on paper, but the reality you get is only 20-30%
snarf21 | 4 hours ago
https://www.youtube.com/watch?v=MuQRxatte5g
pocksuppet | 3 hours ago
Landauer's principle says that even if we could build computers to work at those temperatures, they'd need more power anyway.
fjni | 4 hours ago
https://help.abathhouse.com/hc/en-us/articles/16748674443924...
stavros | 4 hours ago
driverdan | 4 hours ago
gravel7623 | 4 hours ago
swiftcoder | an hour ago
chippiewill | 4 hours ago
chucksta | 4 hours ago
sushibowl | 4 hours ago
swiftcoder | 3 hours ago
cm2012 | 4 hours ago
bojangleslover | 4 hours ago
cyanydeez | 4 hours ago
amelius | 4 hours ago
gruez | 4 hours ago
vidarh | 4 hours ago
Elsewhere, e.g. in London, Docklands is both full of high density data centres and high-end residential buildings and offices that could certain use the waste heat in winter at least.
Most of the data centres there just looks like office buildings on the outside, and most residents won't know they are there.
lvspiff | 4 hours ago
chasd00 | 3 hours ago
macNchz | 4 hours ago
fmbb | 3 hours ago
nucleardog | 2 hours ago
There's plenty of free parking, free admission, giant pool with some small waterslides and stuff, a bunch of picnic tables and public barbecues, generally some nice greenery and trees for shade, ponds and fountains and stuff, a bandstand, etc.
It's not somewhere you'd pop over to for a "quick swim", but especially for lower income people it's a great place to have around as a "grab a pack of hotdogs and your swim trunks and make a day of it" sort of thing. As a kid we couldn't afford to, say, go to the actual waterslide park or anything so I have a lot of fond memories of visiting the steel plant.
I'm sure the construction and upkeep was less than a rounding error in terms of construction and upkeep costs for the plant itself.
bee_rider | 4 hours ago
bryanrasmussen | 4 hours ago
pletnes | 3 hours ago
bee_rider | 2 hours ago
kobalsky | 4 hours ago
21asdffdsa12 | 3 hours ago
NBJack | 26 minutes ago
victorbjorklund | 4 hours ago
gigatree | 3 hours ago
pocksuppet | 3 hours ago
Data centers were, and still can be, some of the cleanest industrial facilities - but the ones being built in this AI wave are not, because they are being built as cheaply and as quickly as possible and without regards to proper infrastructure.
chasd00 | 3 hours ago
That’s every local investigative journalist’s wet dream. Can you link us to a source please?
PS saw an interview with he who shouldn’t be named and they made an interesting point that there isn’t a way to scale the manufacturing of gas turbine blades, there will never be enough gas turbines for these DCs to come online as scheduled.
Konnstann | 3 hours ago
chasd00 | an hour ago
"Mississippi officials told xAI it could run the generators without an air permit because they were deemed “temporary” and “mobile” units.". Makes sense because as far as i can tell they were on trailers.
but then there's this: "But lawyers at the Southern Environmental Law Center, representing the NAACP in the federal lawsuit, have long maintained that such a loophole doesn’t exist, and that running such turbines without a permit violates the federal Clean Air Act.
“Mobile, temporary, portable, whatever you want to call them, turbines need air permits,” Patrick Anderson, a center attorney, told Mississippi Today."
as per typical, it's not clear who's right
https://mississippitoday.org/2026/04/15/data-center-turbines...
1234letshaveatw | 3 hours ago
SoftTalker | 3 hours ago
Rural land is cheap and there are fewer neighbors to annoy with the 24/7 construction activity.
chasd00 | 3 hours ago
doron | 3 hours ago
erelong | 3 hours ago
free hot tub
free publicity and good will gathered
("free")
cogman10 | an hour ago
Even smaller data centers will be producing enough waste heat to heat 10s of thousands of homes. So why not make residents love you by funding the installation of a district heating system which gives your compute power a symbiotic relationship with the community. Their energy bills go down naturally because your cooling efforts are heating their homes and cooling their homes and you spend less in the winter cooling your servers because that heat is being distributed throughout the community.
It doesn't even have to be free district heating/cooling, just cheaper than using electric or gas heaters.
theodric | 4 hours ago
Undisclosed large Swiss private corporate datacenter provides heat to residential complexes in the surrounding area, as well as being integrated with the grid operator and required to spin up generators and island itself on demand, as part of the license to operate.
Many such cases!
matheusmoreira | 4 hours ago
Air conditioners could do it too, right? Pump heat into a water reservoir instead of just throwing it away?
newpavlov | 4 hours ago
matheusmoreira | 4 hours ago
RulerOf | 4 hours ago
alexpotato | 4 hours ago
It's a stainless steel coil that you can put on your A/C and then run water from your pool over it to heat the pool.
https://www.youtube.com/watch?v=J7fB8ul9dZw
ryukoposting | 3 hours ago
https://www.hotspotenergy.com/titanium-pool-heat-exchangers/
thomas-skowron | 4 hours ago
arscan | 3 hours ago
meindnoch | 3 hours ago
Some heat pumps do this. E.g. Panasonic Aquarea EcoFleX. When cooling the house, the domestic hot water tank is used to dump heat into (up to a certain temperature).
SoftTalker | 3 hours ago
hkt | 3 hours ago
(I work there)
swiftcoder | 3 hours ago
You need a lot of heat to do anything useful. I would need to run something like 14 kW of servers to heat my home through winter - that's a couple of hundred thousand in hardware at current prices.
teeray | 4 hours ago
What about running the compute workloads of the municipality instead?
avianlyric | 4 hours ago
sschueller | 4 hours ago
[1] https://www.computerwoche.de/article/2690747/rechenzentrum-h...
[2] https://stefan.schueller.net/posts/kva-winterthur/
dn3500 | 4 hours ago
https://www.techspot.com/news/97995-data-center-uses-waste-h...
The "data center" produces about 28 kW of heat and the swimming pool has cut its gas bill by 62%. They are saving US$24,000 per year.
alexpotato | 4 hours ago
- Revenue: $25.01M
- Expenses: $25M
So "small savings" like this can add up for them.
appplication | 4 hours ago
pocksuppet | 3 hours ago
SoftTalker | 3 hours ago
throwaway27448 | 3 hours ago
SoftTalker | an hour ago
throwaway27448 | 46 minutes ago
Second, of course zero-margin processes have an economic role. That is what market efficiency looks like. The entire point of competition is to produce these economic processes. The american brain can't fathom getting their money's worth lol
akramachamarei | 37 minutes ago
What are you saying here? Like, how are you distinguishing individual charity from the thing "worth doing collectively"? Presumably you don't consider individuals voluntarily giving and thus voluntarily organizing insofar as they coordinate to be the same as collective action, so I can't help but wonder which part is different, and I worry it's the voluntary bit....
throwaway27448 | 8 minutes ago
swiftcoder | 3 hours ago
Keeping in mind that the datacenter operator is also paying the power bill for that (which presumably is roughly 28 kW), amounting to something like £65,000/year at current UK rates
hahn-kev | 4 hours ago
You mean server.
hkt | 3 hours ago
Schlagbohrer | 4 hours ago
"The partnership has really helped us reduce the costs of what has been astronomical over the last 12 months - our energy prices and gas prices have gone through the roof," he said.
...
Last summer, BBC News revealed 65 swimming pools had closed since 2019, with rising energy costs cited as a significant reason."
That's terrible that pools are closing. No one even builds new public swimming pools anymore, so it's awful to close the few that exist.
designerarvid | 4 hours ago
sjs382 | 3 hours ago
khurs | 3 hours ago
ano-ther | 3 hours ago
https://d4project.org/
> The data center delivers up to 1.7 MW of reusable heat – enough enough to warm 6,000 energy-efficient homes in winter or provide 20,000 five-minute showers every day in summer.
https://blog.siemens.com/2026/05/sustainable-data-infomaniak...
https://news.infomaniak.com/en/infomaniak-inaugurates-a-revo...
hnburnsy | 3 hours ago
Paris 2024: Excess Data Center Heat Used to Warm Olympic Swimming Pools
https://www.datacenterknowledge.com/sustainability/paris-202...
fghorow | 3 hours ago
(Edited to add: there are several examples of public swimming pools being heated with Low T geothermal heat in the Perth metropolitan region of Western Australia.)