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Comment by contravariant | Hacker News Reader

>Doing so required the construction of a specialized plant, which captures and concentrates the heat generated by the datacenter before distributing it via existing water pipes.

I'm kind of curious how this is done. It must cost energy somehow otherwise this would be heat flowing from a cold to a warm reservoir.

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Generally yes. There might be 5000l/min of 30c fluid but what you really want is 2500l/min of 60c fluid. So you use a refrigerant cycle to do that with the hot side going to district heating and the cold side going to the data center.

It's very much like an air conditioner but with liquid.

Also known as a heat pump. Depending on the temperature lift, these can be very efficient. Low temperature district heating networks are an interesting thing to look into: Low temperature means the heat losses in the network are smaller (heat losses, if I remember correctly, are proportional to the temperature difference) and at the consumer side, a heat pump can lift it back up to the temperature required for a floor (or ceiling) heating. This is _way_ more efficient than an air-to-air heat pump or even an air-to-water heat pump. [Citation Required]

Interestingly, some large buildings in NYC also use a "steam chiller" hooked into the city steam system to provide air conditioning: https://untappedcities.com/2021/07/09/new-york-city-steam-sy...

Downtown Chicago has something similar, one of the largest chilling networks in North America.

https://youtu.be/H50FNOgkpik

Toronto, Canada also:

https://www.toronto.ca/services-payments/water-environment/e...

Lots of opportunities for thermal efficiencies in dense urban areas.

My university had its own combined cycle power/steam/chiller plant, although in structure you could think of it as a steam plant with generators and chillers that could be switched as needed. I would have guessed that a number of universities do, but my university had a relatively larger power systems program than others regionally.

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