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Comment by rutierut | Hacker News Reader

> Additionally, a lot of water is also used in cooling for the servers that run all that software. Per conversation of about 20 to 50 queries, half a litre of water evaporates – a small bottle, in other words.

What? I have no idea about server farm cooling, can anyone explain this to me?

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Here's one example: https://www.google.com/about/datacenters/locations/st-ghisla... In this case, they pull grey water (like the water you get from a clothes washing machine) from a nearby source, pump the water past the server's hot parts, and the water evaporates, absorbing heat in the process (https://en.wikipedia.org/wiki/Enthalpy_of_vaporization).

Alternatively, you can cycle closed-loop water through a chiller to a hot server and back, or just cool the air around the server (CRACs and CRAHs) using either water or refrigerant as the heat-carrying material.

For datacentres that require air conditioning as opposed to natural ventilation (most of them) a very popular approach is to use evaporative cooling towers [1] in combination with W2W chiller units [2]. The chillers cool the internal water circuit and heat the external water circuit, the excess heat is dumped to the environment by evaporating water in the cooling towers.

Of course it's possible to use air-cooled equipment and this is more common in cooler climates or smaller data centres, so it's not a rule of nature that cooling servers wastes water but it's certainly a very common outcome.

[1]: https://en.wikipedia.org/wiki/Cooling_tower [2]: https://en.wikipedia.org/wiki/Chiller

I really don't think that is how that works? Water cooling in servers works the same as in desktops, just with way bigger radiators. Maybe there are tapping into some other available way of cooling

> Water cooling in servers works the same as in desktops, just with way bigger radiators.

Data centers have separate systems to remove heat from the entire datacenter. These are often evaporative coolers, which means the water is evaporated away.

A better analogy would be the HVAC system for your house. Your computer dumps heat into the house, the HVAC system removes the heat from the house to the environment. It's the latter part that uses evaporative cooling in many data centers.

What about it? Some Datacenters use evaporative cooling.

This metric is completely useless if the water is reused. No idea whether that’s the case, but the metric sounds highly questionable.

The whole point of water cooling on electronics is that the closed loop cycles the vapor away from the heat generating part and is then cooled by a radiator, making it condense back to a liquid and flow back to the hot thing, so whoever wrote that line is severely misinformed.

By heating a river to cool the cooling system.

is there a way to harness this heat for reusable energy?

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