3 ms·

For datacenters specifically I've never understood what specifically consumes the water. Arent the water-cooling loops closed, so the water just cycles around a

For datacenters specifically I've never understood what specifically consumes the water. Arent the water-cooling loops closed, so the water just cycles around and around and around?

justincormack 1mo ago
Yes they are for water cooling.
SirMaster 1mo ago
They evaporate the water which is what makes it cool so effeciently.
- Ductapemaster 1mo ago
  Evaporative cooling does not necessitate an open loop system
  - Eisenstein 1mo ago
    The system which runs coolant over the chips can be closed but the part which uses an evaporative system to cool that is still open loop and vents water into the air, no?
    - Ductapemaster 1mo ago
      Nope, it doesn't have to be open loop! Example of such a system being used specifically for datacenters: https://blog.vantage-dc.com/2026/04/22/cooling-without-the-drain-how-closed-loop-systems-cut-day-to-day-water-use/ https://blog.vantage-dc.com/2026/04/22/cooling-without-the-d... Evaporated water is condensed, and in the process transfers its heat into another place that removes it. Another simple example is a pot of boiling water with a lid on it.
      - Eisenstein 1mo ago
        The link you cited is not evaporative cooling and a pot of boiling water with a sealed lid on it is a pressure vessel which eventually explodes.
        Ductapemaster 1mo ago
        If you were to remove the heat at a sufficient rate by, say, turning the lid into a heat exchanger, you would have a stable system.
        Eisenstein 1mo ago
        How is that different from not using evaporative cooling and just putting the heat exchanger on the burner?
        Ductapemaster 1mo ago
        Water is being used to get heat from one place to another. The idea is being able to separate the heat generation and the heat extraction
        Eisenstein 1mo ago
        You are adding an extra step though. Use a closed loop coolant and remove the heat from that coolant with the heat exchanger. Why would evaporation in between be more efficient?
        gorbypark 1mo ago
        That's the problem, removing heat at a sufficient rate. Of course it can be done, but the most efficient way (in terms of cost) is just open loop evaporation. I'm not a datacenter engineer, but I used to work in the ski industry. Snowmaking systems use vast quantities of compressed air. It works better if that air is cool. Blowing hot compressed air out of a snow cannon means the air temperature (wet bulb to be specific) needs to be colder to make snow. Anyways, most air compression stations use water to cool the air, and then evaporative coolers to cool the water. The water is reused, but a ton (not sure of the percentage) is lost into the air. It's more or less a tower with a big fan on top, and water percolates down from the top, being cooled by the air as it goes. The water is then collected and pumped through the system again (but of course has to be always topped up to counteract what was lost to evaporation). Anyways, long story short is it's most cost effective to just spray water into the air to cool water, as long as water is free/cheap.
  - SirMaster 1mo ago
    I didn't say evaporative HAS to be open loop, but many are, which answers the question why they use up a bunch of water.
0xbadcafebee 1mo ago
At the datacenter side, it depends on the method of cooling. You can chill the air or the chips directly (or both), doesn't matter, you still need to cool, and that still needs water. The question is, where is the water being used? - If they use either evaporative cooling or a liquid-cooled heat exchanger, that uses tons of water consistently. This requires less energy (it's mostly passive) so you use more water. - If they use closed-loop water cooling and/or heat pumps/electric chillers, that uses much less water - at the DC. But it does require more energy to circulate the water, run fans, etc. If you are using more energy, where is the energy coming from? It's coming from power plants, which require... you guessed it... more water (e.g. thermoelectric, hydroelectric, geothermal, concentrated solar). They need water in order to generate the power, and lots of it. Coal, natural gas, nuclear, and concentrated solar, all use steam to generate energy. Nuclear also uses water to cool the reactor. And water is used extensively to extract coal, oil, and natural gas. Geothermal uses water in the ground. You can't not use a ton of water in one fashion or another. It just depends what method, and on what end the water is used. And the crazy thing is, most new datacenters are being built in places with extremely little water. Guess how that's gonna work out as the planet gets hotter? I don't know why I got downvoted to hell for stating facts every datacenter architect knows. HN be HN'in.

For datacenters specifically I've never understood what specifically consumes the water. Arent the water-cooling loops closed, so the water just cycles around and around and around?

justincormack 1mo ago

Yes they are for water cooling.

SirMaster 1mo ago

They evaporate the water which is what makes it cool so effeciently.

Ductapemaster 1mo ago
Evaporative cooling does not necessitate an open loop system
- Eisenstein 1mo ago
  The system which runs coolant over the chips can be closed but the part which uses an evaporative system to cool that is still open loop and vents water into the air, no?
  - Ductapemaster 1mo ago
    Nope, it doesn't have to be open loop! Example of such a system being used specifically for datacenters: https://blog.vantage-dc.com/2026/04/22/cooling-without-the-drain-how-closed-loop-systems-cut-day-to-day-water-use/ https://blog.vantage-dc.com/2026/04/22/cooling-without-the-d... Evaporated water is condensed, and in the process transfers its heat into another place that removes it. Another simple example is a pot of boiling water with a lid on it.
    - Eisenstein 1mo ago
      The link you cited is not evaporative cooling and a pot of boiling water with a sealed lid on it is a pressure vessel which eventually explodes.
      - Ductapemaster 1mo ago
        If you were to remove the heat at a sufficient rate by, say, turning the lid into a heat exchanger, you would have a stable system.
        Eisenstein 1mo ago
        How is that different from not using evaporative cooling and just putting the heat exchanger on the burner?
        Ductapemaster 1mo ago
        Water is being used to get heat from one place to another. The idea is being able to separate the heat generation and the heat extraction
        Eisenstein 1mo ago
        You are adding an extra step though. Use a closed loop coolant and remove the heat from that coolant with the heat exchanger. Why would evaporation in between be more efficient?
        gorbypark 1mo ago
        That's the problem, removing heat at a sufficient rate. Of course it can be done, but the most efficient way (in terms of cost) is just open loop evaporation. I'm not a datacenter engineer, but I used to work in the ski industry. Snowmaking systems use vast quantities of compressed air. It works better if that air is cool. Blowing hot compressed air out of a snow cannon means the air temperature (wet bulb to be specific) needs to be colder to make snow. Anyways, most air compression stations use water to cool the air, and then evaporative coolers to cool the water. The water is reused, but a ton (not sure of the percentage) is lost into the air. It's more or less a tower with a big fan on top, and water percolates down from the top, being cooled by the air as it goes. The water is then collected and pumped through the system again (but of course has to be always topped up to counteract what was lost to evaporation). Anyways, long story short is it's most cost effective to just spray water into the air to cool water, as long as water is free/cheap.
- SirMaster 1mo ago
  I didn't say evaporative HAS to be open loop, but many are, which answers the question why they use up a bunch of water.

0xbadcafebee 1mo ago

At the datacenter side, it depends on the method of cooling. You can chill the air or the chips directly (or both), doesn't matter, you still need to cool, and that still needs water. The question is, where is the water being used? - If they use either evaporative cooling or a liquid-cooled heat exchanger, that uses tons of water consistently. This requires less energy (it's mostly passive) so you use more water. - If they use closed-loop water cooling and/or heat pumps/electric chillers, that uses much less water - at the DC. But it does require more energy to circulate the water, run fans, etc. If you are using more energy, where is the energy coming from? It's coming from power plants, which require... you guessed it... more water (e.g. thermoelectric, hydroelectric, geothermal, concentrated solar). They need water in order to generate the power, and lots of it. Coal, natural gas, nuclear, and concentrated solar, all use steam to generate energy. Nuclear also uses water to cool the reactor. And water is used extensively to extract coal, oil, and natural gas. Geothermal uses water in the ground. You can't not use a ton of water in one fashion or another. It just depends what method, and on what end the water is used. And the crazy thing is, most new datacenters are being built in places with extremely little water. Guess how that's gonna work out as the planet gets hotter? I don't know why I got downvoted to hell for stating facts every datacenter architect knows. HN be HN'in.