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Datacenter waste heat even a problem? I only ever heard of nuclear power plants waste heat being a problem when the cooling water is dumped directly into rivers (instead of the ocean).

I’d love that heat in the winter. Imagine, free heat! Linus heats his pool with excess cpu heat. It’s all about using things wisely and not panicking. AI and datacenters are here to stay, you can’t fight them, but you can leverage their waste for profit.

Maybe, that's why they want Greenland so bad. Low temperature, many free spaces, no significant nature and if there is one, not enough citizen who can complain. And if they still need water for cooling, there is probably enough from the melting ice they can use.

article also says:

"The geography caveat matters. A data center in the Scottish Highlands and one in Phoenix, Arizona, face very different realities. But even in warmer climates, the shift toward 45-degrees-Celsius coolant moves operators significantly closer to that chiller-less ideal — where chillers may turn on just a few days a year when the outside air temperature demands it."

Classic "solve one problem, create another" move. At least they are honest about the tradeoffs I guess.

I'd say that in cooler countries, warm water could be very useful, e.g. for heating houses.

Canada is building a ton of datacenters with this built in.

It's not a sleight of hand.

Datacenter locations mainly optimize power, cooling, and fibre.

Cooling is not the same everywhere, even the US has places that are cool enough to not need evaporative cooling water use.

You can’t beat thermodynamics no matter how hard you try.

This shouldn’t be a surprised to the majority of people.

With LLM latencies, you won't notice it much.

Can't beat thermodynamics - there's no free lunch there.

Waste heat into the atmosphere is hardly pollution. I think you don’t understand the scales involved

To be fair to Nvidia, they are not the first person to dump their waste heat to a Tmin environment. There's a reason most power plants are near bodies of water.

Wouldn't building in the far North be easier than Space? At least better than the desert like Arizona?

Waste heat from these things is negligible compared to the sun heat. I know people love to hate on these things, but come on...

Trust me. In the depths of a northern winter, nobody will complain about "waste heat". Just ask the manetees that huddle near reactor outflows in florida.

On an unrelated note, there are so many em dashes in this article I have to wonder if there was any human involved in the process at all. They could've at least signed Nemotron underneath as to not to offend reality.

Have you stopped for a second to consider the utter mathematical absurdity of what you’re suggesting here?

It is impossible for a datacenter to meaningfully heat more than the air in its immediate vicinity.

Microsoft's already building data centers hooked up to district heating (Espoo and Kirkkonummi, Finland). Heatpumps are amazing.

(Seasonal heat storage is also a thing, Espoo's neighbours have tens of GWh of storage, with a new 90 GWh cavern in the works. Not sure if the systems are interlinked.)

In Finland the datacentre heat is boosted to 60–90°C for district heating (new builds tend to use heat pumps) [1]

A 75-MW data center in Mäntsälä has provided 2/3 of the heat for the town (2,500 homes) for a decade [2]

1. https://www.creatingsustainablecities.org.uk/post/case-study...

2. https://www.sustainabilitymenews.com/waste-management/how-fi...

In the Netherlands we are already transporting “waste energy” in the form of heat to greenhouses to warm them in winter.

Also interesting that the article states that this engineering problem hadn’t been solved before. Google pioneered running chips hotter than before. Moreover, we have had water cooling in consumer setups for ages. (At least 30 years.) So what is new is that all chips have been attached to the loop. I couldn’t find what they did with PSU though.

45 is the cool temp so they could send the community a higher temp water to their heat exchanger?

Then 45 or below is sent back on the return.

Already done and in use in the nordics. Most likely in most dc:s in the northern hemisphere with cold winters.

Of old... https://web.archive.org/web/20210115152829/https://www.nrel....

It's got a "heat energy to/from campus" exchange in there.

That's a link in March and the air temperature was 31°F.

https://web.archive.org/web/20210708150410/https://www.nrel.... is later with air temperature of 68°F.

The data centers can also be used to heat swimming pools [1].

[1]: https://www.bbc.com/news/technology-64939558

Heat pumps can effectively bring that temp up higher.

The problem is really how much energy is actually available.

European cities are doing it already.

What's the problem with skylights?

> 45C is low but not unworkable for a district heating loop,

*55C is on the output, read article first pls

Main problem is that it wouldn't work with buildings designed for higher heating temperature so it is limited to new builds. And it is not limited just to replacing heaters, hot water system is also designed to work with higher temperatures so heat exchanger used would have to be significantly larger

Another one is that load is not constant on both sides and not exactly something that can be increased on demand (unless you're fine with burning cycles just to electrically heat, but that's massively inefficient)

Do you live near a datacenter? Property value goes down, constant humming.. the way we heat up the earth right now, i don't think you have to worry about heating

> This brings the value to the local community of a nearby datacenter up from near zero to potentially a few million dollars per year.

You are not wrong, but the whole issue is a bit silly: there should be legal ways for data centres (and other commercial operations) to just send a few million dollars a year to whichever community they need to convince; instead of having to dress it up as free heating.

The value of an AI data center in your area is negative, not near zero. Pollution, water use, heat, infrasound (https://www.youtube.com/watch?v=_bP80DEAbuo) and so much more... But at least we may get some cheap heat in the future

Doesn't matter that's it's a myth, it's salient and has become a layperson talking point. This is an official post on nvidia.com that can be quoted: "The NVIDIA DSX reference design for AI factories has zero water consumption"

Do you have any references for this comment: '"water use" thing is a myth anyway'. I would like to show my kid who keeps complaining to me about AI water usage.

It always seemed weird - where does the water go, after all? I gather it isn't turned in to H2 and O2. I assume it leaves the data center hotter than when it came in, which seems like the real issue?

Yeah and it's a myth that fracking makes water undrinkable.

I'll bet anything you'd be the guy that won't drink a glass of the "perfectly safe, completely unaffected" water while making such utterly absurd claims.

The "innovation" is that everything is now attached to a watercooled block.

The rest is marketing: The Cray supercomputer were fluid cooled back in the 1980's, the entire board had an inert liquid flowing across it.

> Surely in all the previous datacenters that have been designed there has been someone doing the math and determining what temperature things need to run at, how much energy it will use, how much heat it all will produce, etc.

It seemed like a pretty big deal ~ 2011 when big companies were running their (air cooled) datacenters closer to 95F (35C) vs the traditional 72F (22C). So jumping up a little more is maybe not super exciting, but it's still innovation.

You have to design your hardware to tolerate being run in consistently hotter conditions. There's a tradeoff between cooling cost and failure rate / capex.

Speculating here - “effectively” cooling the CPU and GPU materially using this technique at datacenter scale may have never been done. Those things than run hot, easily crossing 100C. So the loop is doing a lot of work to keep them stable at 55C.

The innovation may be in the speed or volume flow of the coolant through different parts of the data centre to regulate the temperature. And of course, redesigning every component to be compatible with this fan-less design.

I think it’s only possibly because NVIDIA is much more vertically integrated than ever before.

There's never been a reason a sealed water-cooled system ever had to use vast amounts of water. But State Of The Art wound up being using and expelling the water. It seems like data centers operate like other industrial enterprises - locate in the city/county/state that gives you carte blanche, do whatever is convenient, get used to the idea that this the only way things can be done.

So a multitude of communities rebelling and complaints about environmental damage fell on deaf ears but a technical spec might be paid attention to.

Is this not how it was already done? Huh.

Ai slop from Nvidia, who would have thunk.

May I ask where this datacenter you're referring to is located? State and country would be super helpful.

I disagree if there is an assumption or premise that all datacenters use water for cooling. Datacenters are not built or operated the same, nor have a requirement for water cooling, or evaporative cooling.

Water use is partially a myth for sure, because it's not a certainty or requirement in every datacenter, ever.

If water is used for evaporative cooling, it's used in places that the cooling can't work above a certain temperature. Say, for example the US where it gets over 120 degrees farenheit.

The inability for cooling equipment to perform when it's extremely hot might be supplemented my multiple technologies cooling together, including evaporative cooling. So evaporative cooling might be common in the US or other regions like it.

There are many datacenters that don't need to consume water at all for cooling, except for a water cooler to drink from, and sprinkler systems for fire suppression. They are engineered and cooled just fine.

The demand for datacenters and money in this space will likely solve the water usage, if for no other reason, than to increase flexibility of locations.

If anyone is curious a bit more about how:

Datacenters locations optimize 3 main factors.. Power, Cooling, and Fibre.

We know the climate of location isn't the same everywhere in the world where datacenters are located.

One thing that can get missed among the water hyperventilating crowd is that datacenters are designed for the need of the location's climate, and what it takes to cool. Too many folks spreading the information are usually non-technical, and get their education about datacenters from social media.

There are many places in the world, including in Canada, where cooling is built in 6 months of the year to outdoor air. The temperature isn't high enough in the summer to warrant or require evaporative cooling. They can just vent outside, or capture the heat for other purposes.

In other areas still, proven building approaches such as countersinking the datacenter for some additional geothermal benefit, local power generation (Solar, Natural gas) and a unique path to the same datacenter is possible.

Of course, if foreign companies are wanting to build in a different country, they might by default build how they know for their region and assume it's ok.

There is a massive build out of datacenters occurring in Canada right now, they will be built according to how buildings are built in that climate, not importing cooling technology from regions where it's too hot, or evaporative cooling is the only, or most available option. In temperate climates, considerations have to be made for keeping keep buildings warm (not just cool) year round.

The nice thing is this is not hypothetical.

There is of course, equipment that can have liquid cooling, or we see those fun videos of equipment submerged in liquid operating. These seem to not be the common.

The university where i studied uses high temperature cooling since a few years. The weather on Germany ranges to quite high temperatures, but according to the tech stuff they only need active (as in AC) cooling for the higher end of the 30 degrees. The technology is quite fascinating.

https://www.kit.edu/kit/english/pi_2024_038_kit-supercompute...

Yeah, this is part of the issue to be honest. You'd need outdoor air to be below ~37°C to guarantee 45°C water outlet temperature. In most locations you still need cooling towers or compressors some of the time, so you still have to build all the infrastructure that comes with them; though reducing their use is still great, saving serious amounts of water or energy.

For e.g you might think of the outskirts of London as fairly moderate, but this week it's been hot enough that supplemental cooling would likely have been needed at points. For a data centre here you'd typically design the cooling system to cope with outdoor temps in excess of 40°C, which is not a conservative number anymore.

Also, while Nvidia might be happy with you supplying water at 45°C I suspect you will get better longevity of the hardware at lower temps like say 35°C. GPUs are expensive, and extending longevity may well be 'worth' a bit more water or energy to you. In practice you are also likely to have air cooled systems that sit 'beside' the AI compute like storage severs, any extra CPU compute and network switches. So you are likely to need a separate room and cooling system for that. Great progress though.

"compared to various other uses"

You realize how that vague and open ended clause completely undermines any point you are trying to make, right?

For those of us that use metric/SI units, 90F is 32.22C/305.37K.

Don't the US Military and NASA use metric now?

As long as the water that goes in, doesn’t come out. The inital water requirement is fine. What is problematic in most cases is the warm water containing pollutants is just pumped straight into our local waste water systems or rivers.

The entire room wouldn't be 45˚C, or even the entire machine, just the liquid-cooled components.

Semiconducting materials have relatively small band gaps, they are insulators that take very little additional energy to become conductors. In contrast good insulators incinerate before they start conducting (or turn into plasma).

Energy being energy means that high enough ambient heat can kick electrons into the higher orbitals because the band gap is so small. This also happens at normal ambient temperatures, but those electrons don’t make it very far and there aren’t that many. At 200c a closed gate is not stopping enough electrons from moving through it anymore.

At least this is the slightly hand waved technical explanation. Project in Flight on Youtube has an excellent video on how semiconductors work.

It’d be very hard to make these chips work at 200C, the electrical properties of semiconductors vary significantly with temperature.

It would require entirely different chips with entirely different manufacturing processes.

Not yet, the Microsoft center is still in planning/construction.

But up north there's at least one city (Kajaani) on data center heat; details in another comment.

Evaporative cooling consumes less expensive electricity than air conditioning. Electricity is much more expensive than water (for the same cooling load) in most places DCs are located.

It’s usually open loop - closed loop, so closed loop goes through CRACs or liquid cooled equipment manifolds. That heated water circulates through an heat exchanger on the roof that uses open loop cooling to shed the heat to the surrounding environment.

(ab)using fresh water in vast quantities is cheaper.

currently.

and also more energy efficient, because evaporating water away takes a lot of energy with it. you have to raise radiators to a higher temperature to keep up with that, or have much more surface area.

It’s very efficient. The net electrical energy saved using the latent heat of water is 30 to 100+ times greater than the energy required to desalinate or wastewater recycle the same volume of water.

the unfathomable reason is that it is significantly more energy efficient.

Yes, they are using evaporative cooling.

At the scale DCs are operating at, losses from flexible tubing are not negligible either.

1gw of power converts approx 400 liters of cold water into steam _per second_.

Evaporative cooling is practically a cooling cheat code. Why unfathomable? What's more efficient?

As someone else noted - it's effectively zero compared to the water evaporated in evaporative chillers.

But it's still misleading. The major source of water use in datacenters, by _far_, is the water used in power generation. This improves PUE, which reduces power draw, but the savings are almost certainly under about 20% given that many modern datacenters already operate at a PUE of under 1.2. So if you're running on coal or gas, you're still consuming quite a bit of water indirectly.

Now that said again - the water consumption part of this equation is generally overhyped. The power draw is the problem, as are the really bad temporary hacks to the power problem (e.g., what x.ai is doing with "temporary" gas turbines).

I understood that to mean zero steady state water consumption?

After filling the tanks once, subsequent draw would be zero. Most data centers currently use evaporative cooling - where they pull tons of water in, and then... Let it evaporate.

Imagine a residential building that reclaims and reprocesses and purifies 100% of all the water it uses. This would be dramatically more difficult and better than the status quo, and would be called 'net zero' by any sensible accounting method.

---

Obviously, evaporative cooling is net-zero water use when accounted across the entire globe (the water falls as rain, somewhere, eventually), but it is net-negative for a local community.

The article implied (but did not seem to ever state) that they simply added liquid cooled cold plates to all the other components that were previously air cooled.

But it did not sound like they were describing a Cray 2 style liquid immersion cooling system.

Too little thermal gradient.

What you could do is to use a heat pump to spend a little electricity and turn the waste heat to hot water usable for heating (winter).

The heat exchange between that fluid and the ambient air isn't infinitely fast, if it's low enough they can just run "normal" A/C at low power for the humans. They just need to keep the heat in the fluid until it reaches… well… whatever heat dump there is. (cf. top-level post)

> Heat exchange is used instead of refrigerating the coolant.

There are some systems that pipe refrigerant around the building, but they’re relatively uncommon (VRF or variable refrigerant flow if you want more details).

Glycol and water is cheaper than refrigerant so there’s usually a chilled water loop that passes thru a heat exchanger that interfaces with a chiller (vapor compression refrigeration) to reject the heat from the chilled water loop.

This eliminates the need for evaporative cooling towers.

This approach appears to directly reduce energy use (that's what the articles says). The heat would still be going into the local environment, but if there is a reduction in energy use, there should be less of it.

Actual heating due to human energy use is not really a big deal except perhaps locally. Climate change is caused by changing how much heat the earth retains from the sun. Maybe if we stopped using fossil fuels and used immense amounts of nuclear power, we would care about the waste heat. But solar and wind power largely redirect energy flows.

It’s kind of like how brine from desalination is not a global problem for the oceans at all — all that matters is diluting it enough that it doesn’t poison the local ecosystem.

The temperature is independent of the actual heat flux. Also - a quick search suggests that at best the data center coolers run at COP of little more than 10. The inverse of that is the amount of heat wasted just on cooling. Having a system not relying on heat pumps would only make it better. A back of the envelope calculation based on PC AIOs suggests they would achieve a COP of 20 or more. A scaled up system would be more efficient than that, if not just for wider tubes.

I wish there was more transparency and discussion brought to the water and power consumption of other major industries today, as well as the historical use and environmental impact of pre-EPA industries and early manufacturing. I want to believe that relatively, AI data centers and hyperscalers are much less damaging than the industrial revolution-era factories, but without knowing the absolute impacts of both to compare, all this fear mongering and propaganda is going to continue to drive knee-jerk reactions as opposed to well-informed analysis and discussion.

Does anyone have any sources for this sort of data?

It's a response to the FUD that is water usage in data centers. Data centers don't use a meaningful amount of water when compared to just about any other industrial application, or many recreational ones. Data centers used about 66 billion liters 2023. source: https://escholarship.org/uc/item/32d6m0d1 Golf courses used 2 trillion liters in 2020. We won't even bring up almond production.

> Claude write good.

> Nvidia has so much money and they can’t afford to pay a human for a day of their time to write a blog post?

The shareholders desperately need that money.

Their valuation is based on their software stacks’s ability to displace human labor, this is just them eating their dogfood.

I feel that the sad reality is that most blogs in the future will be addressed to AI and not humans, it's gonna be quite rare to read directly something as we will have built-in tools within browser and phone and OS and so-on that always rewrite on-demand based on current expertise, wanted tone and so-on. There is a recent study I believe that demonstrated that AIs digest better articles made by AI, which means that it might be just better to let AI write the articles so others AI have a better accuracy in digesting it (and incorporating it in their training data as well).

The same as technical docs for any codebase, humans will not read them anymore, only AIs which then translate it to human on-demand, it's already happening, I've worked recently with many new frameworks/codebases without even opening the doc (not even the Github page) and solely asking the agent to gather info for me about it.

PS: The reason I feel it will be this way is that it will allow to legitimatize mass data collection indirectly, instead of doing telemetry on page and software level, we will just send all the content automatically to some inference providers (probably provided for free by Google, MS and so-on)

How does that change the calculus for space datacenters? There is still no reasons or benefits to having them in space. You still have to rely solely on radiative cooling. That doesn’t solve any of the maintenance problems. Space datacenters is a really dumb and unrealistic idea Musk is talking about to hype his companies, it’s not meant to actually be done. Anything in space is more expensive and way harder to do, for a datacenter there is no benefit. We aren’t lacking places where to have them on earth

Space based data centers make no economic sense compared to land based.

The only reason is to remove them from local/regional, and potentially national/international jurisdictions.

Oh, and of course, the other reason is to give SpaceX to have a reason for xAI to be part of its structure.

Starlink makes sense, LEO comms using a mesh makes sense.

LEO/geosync satellite data processing doesn't.

This relies on transferring heat to the outdoor air. Can't do that in space.