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Comment by Barrin92 | Hacker News Reader

>"In addition, the waste heat produced by LUMI will be utilised in the district heating network of Kajaani, which means that its overall carbon footprint is negative. The waste heat produced by LUMI will provide 20 percent of Kajaani’s annual demand for district heat"

Pretty cool honestly. Reminds me of the datacenter that Microsoft built in a harbor to cool with the surrounding seawater.

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There are now several datacenters in Finland that link into local district heating.

Microsoft recently announced that they build similar data center in Finland too https://www.fortum.com/media/2022/03/fortum-and-microsoft-an...

Their definition of negative carbon footprint is broken. Unless there is something in the computer that permanently binds carbon from the atmosphere.

Not when it is replacing gas heat, as it likely is!

That would make it neutral not negative, but only if it was powered fully by renewables which were constructed and operated in a fully carbon neutral way.

It could be that electrical district heating has a lower carbon footprint than gas heating (if the electricity is sufficiently low-carbon).

Still doesn't make it "carbon-negative," just kills two birds with one stone by using the same energy both for heating and computing.

I see what you're saying with this, but the comparison isn't a world where electricity is used for the heating, it's one where gas is (gas heating is almost always more efficient than electric heating, since you lose a lot of heat at the generator). So either the heat is radiated out into the atmosphere uselessly, and some amount of natural gas is burned, or the heat is used and 20% less natural gas is burned. That's a carbon footprint of -20%.

They run the computer carbon neutral and then use the excess heat to replace carbon derived heat. Hence, there is less carbon emission while the computer is running. Their definition is not broken, just based on comparison to the initial state (that emmits CO2) and not a zero emission state. Like Google's supposed carbon negativity by reducing the emission of other peoples cow sheds.

Decreasing carbon emissions is not "carbon negative" in my world. A "carbon negative" machine would be something that e.g. plants trees.

Negative carbon emissions are those that remove carbon from the atmosphere. This project doesn’t remove carbon from the atmosphere, it’s preventing more carbon from being released into the atmosphere which is usually called carbon neutral.

[Cloud and Heat](https://www.cloudandheat.com/hardware/) offers liquid cooling systems that purport to offer waste hot water on the town/small city scale.

Www.qscale.com recuperate heat for 100+ Football field of greenhouse in North America And FYI a properly designed liquid cooling facility is cheaper and more efficient then an air cooled one. Hopefully everything will switch to liquid cooling just like car engines are all liquid cooled !

I hope no datacenters these days are built on the idea of just running cooling with straight electricity (e.g. no cooling water) and shifting the heat straight out to the air (no waste heat recovery). Even in the late 90's that sounds like a poor design.

that's how all of Google's datacenters are built in my understanding. Water cooling is very expensive compared to air cooling, and only used for their supercomputer-esque applications like TPU pods. I don't know about waste heat recovery but I don't think they use that either.

There is also immersion cooling. The liquid is not water and it seems is pretty efficient:

https://submer.com/immersion-cooling/

Exceedingly efficient (PUEs of 1.0X) vs cold plate liquid cooled or air cooled. The tradeoff is that mineral oil is annoying (messy especially if leaked but even with maintenance) and fluorinated fluids are bad for the environment (high GWP, tend to evaporate) and crazy expensive. In either case, the fluids tend to have weird effects on plastics or other components, so you have to spend a good amount of time testing your components and ensuring that someone doesn't switch components on your motherboards without you knowing, lest it not play well.

At the low cost of a nitrogen blanket for fire safety, something like n-pentane should be suitable for immersion nucleate boiling cooling with the added benefit of not needing a heart exchanger been the immersion pool and a possible outside air hat rejection condenser.

The solvent effects are relatively well understood for these medium-light alliaphatic hydrocarbons, done care ensure that aren't particularly toxic, and a nitrogen blanket for the rooms takes care of the inherent flammability issue associated with what's basically boiling gasoline on the CPU.

Depending on what you define as water cooling, Google most definitely uses watercooling in all their datacenters.

https://www.datacenterknowledge.com/archives/2012/10/17/how-...

https://arstechnica.com/tech-policy/2012/03/google-flushes-h...

"A case in point is our technologically advanced, first-of-its-kind cooling system that uses seawater from the Bay of Finland, which reduces energy use." https://www.google.com/about/datacenters/locations/hamina/

You don't need to water cooled machines, you can use use cold water to chill air.

Heating a community of houses rather than emitting into the air seems like it should be a requirement for building any power hungry industry.

Using the water directly is a lot better for your efficiency, because the computers are quite a bit hotter than the air that cools them so you get higher quality heat from there.

Yes but that requires special gear I assume, that might drive up the cost. Just using cold water for a cheaper heat exchanger (Than some pumped medium) seems like the simple solution if you have unlimited cool water.

I don't know why you're being downvoted. Something like a third of GHG emissions come from heating, if you can extract the heat from a datacentre you're displacing something like gas, it is something to hope for.

That's also in Finland. The district heating infrastructure is already in place, so if you're producing heat, its not hard to push steam in a nearby pipe and make an easy PR statement about sustainability.

though couldn't the district then save money by either reducing their own infra, or eliminating it entirely?

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