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Comment by fleebee | Hacker News Reader

One of the reasons to build them near populated areas is that it makes it easier to repurpose waste heat to, for example, heat houses in colder climates.

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Last I checked waste heat isn't energy dense enough for large-scale district heating. Small pilot projects yes, but it won't heat whole towns.

Denmark would disagree, but with the limitation that the data centre needs to be sited in an appropriate location.

https://danskfjernvarme.dk/viden-vaerktoejer/udgivelser/taen...

https://danmarksdagblad.dk/article/datacenter-paa-15-million...

https://pulse.microsoft.com/da-dk/transform-da-dk/government...

I don't think anywhere would want to be entirely reliant on a single datacentre, at least not at the scale of district heating use in Denmark.

(I gave some pages in Danish, you can search "Denmark datacentre district heat" yourself if you like.)

These are future plans and they lack specificity. I don't think they will come to fruition. The problem is that waste water from data centers isn't hot enough.

Facebook's datacentre is operating: https://www.ramboll.com/projects/energy/meta-surplus-heat-to...

AtNorth's are under construction: https://www.atnorth.com/news/selected-group-will-utilize-sur... and https://www.atnorth.com/news/denmark-data-center-to-supply-h...

Microsoft's is operating: https://danskfjernvarme.dk/aktuelt/nyheder/2026/dataskyen-se... (I can't find an English source.)

First link: "With the ambition to phase out its coal-fired plant by 2025, Denmark’s third largest district heating company, Fjernvarme Fyn, has established Denmark’s biggest heat pump plant. The plant will recover 215,000 MWh of energy from Meta’s hyperscale Tietgenbyen data centre and redistribute the surplus heat to the district heating network of the city of Odense."

"Will" means "in the future".

Other parts are in the present tense. It's probably written by a Danish speaker.

But you can do your own searching, you seen determined that this doesn't exist.

As it clearly says on the page, this project was completed in 2019. The commercial use began in early 2020.

Even in the very sentence you quoted they are writing about plans to retire a coal plant by 2025 in future tense. This should be a very obvious hint that the text was written some time ago - unless, of course, the reader is not aware of what year we currently are living in.

In 2024, Fjernvarme Fyn reported ([1], page 19) they were recovering enough heat from that very site to heat almost 7000 homes in Odense and that the number can still rise significantly as the data center expands.

[1] https://stateofgreen.com/en/wp-content/uploads/2024/12/SoG_W...

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