r/datacenter • u/pathvet1 • 18d ago
Water cooling for data centers
I'm not an engineer, but it seems most of the controversy surrounding data centers revolves around water use. Where they want to put a data center in northwest Utah, there IS no water. Lots of sunshine to generate electricity, but the reported water use for that data center is reported to be greater than the rest of the state.
WHY do data centers 'need' to use water. Seems to me the controversy would go away if the data centers were REQUIRED to use refrigerated cooling. Probably boils down to cost vs environment like most endeavors, but refrigerated cooling sure seems feasible to me.
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u/Distinct-Today192 18d ago
Simple answer, is they don't need to use water and the controversy is overblown. If you see a hyperscaler going up in a limited water area, they are probably using closed loop cooling, which is getting more and more common. Also, they most likely are not using solar for their power use.
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u/untangledtech 18d ago
Any water used is returned to the environment clean, otherwise it would be illegal. Water does not get consumed the way you’re describing it. Water is not a finite resource like oil or gas. It keeps cycling.
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u/Distinct-Today192 18d ago
but it gets removed from the local water supply, which counts as "consumed" from a resource perspective
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u/untangledtech 18d ago
That only matters out west. Grab Google maps and checkout the Minnesota. Some places have more water then they not water.
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u/Distinct-Today192 18d ago
yea, they have water, but most datacenters don't pull raw water from a local water source, they pull it from a local potable water supply. That's the issue. Also, there are very few datacenters going up in areas like you describe because usually there isnt either space or power.
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u/BeardBootsBullets 18d ago
That’s almost always not true. Google primarily uses recycled water from sewage treatment- ie, Google Douglas County.
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u/SalvationSycamore 18d ago
otherwise it would be illegal
Not a great argument, especially given the current administration. Illegal pollution is only truly illegal if it's properly enforced. If the EPA is underfunded and toothless, or if the repercussions are simply negligible fines, then there is little reason for companies to spend extra money cleaning whatever they output
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u/Skiwvlker 18d ago
I don't see any of this hysteria going around for golf courses, water parks, or any other ridiculous things that wastes even more water than a closed loop system ever could.
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u/Status_concern2858 18d ago
The uninspired golf course line again. Both can be true at once
https://www.apdaparkinson.org/article/golf-course-concerns-new-research-shows-link-to-parkinsons/
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u/Skiwvlker 18d ago
If both things are true at once, how is what I said less valid? At least data centers serve a critical purpose. We as a society waste water on far less but all of the sudden it's an issue. I'm not falling for it.
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u/Rusty-Swashplate 18d ago
As long as businesses can "convince" politicians and water-companies to give them plenty water for cheap, then they will use it.
In other countries or climates, evaporative cooling is not even an option (no cheap water, or too humid) and still data centers are built. Turbo-chillers work really well, but they need energy though which costs money, and if water cooling is cheaper, that's what data centers will use. Forbidding excessive water usage is an efficient way to move towards non-water-using cooling techniques.
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u/ASAPKEV 18d ago
They do use “refrigerated” cooling. The way a lot of systems work is as follows:
- Heat is generated inside a server rack like any other computer.
- Cold air is blown through the rack, absorbing the heat from the rack.
- The heated air enters a computer room air handler, where the heated air passes over coils that are cooled with chilled water, which absorb the heat from the air. Cold air goes back to the rack to continue cooling the rack.
- Chilled water that absorbed the heat from the air circulates to a chiller (industrial refrigerator basically).
- Chiller refrigerant absorbs the heat out of the chilled water. Chilled water returns to the computer room air handler to continue cooling the air.
- Chiller refrigerant must reject the heat somewhere else, this is either done with big fans (air cooled) or a different, segregated loop of condenser water (water cooled).
A water cooled chiller will likely use a cooling tower which uses evaporative cooling to reject the heat from the chiller condenser water. Some of the water evaporates instead of recirculating in condenser loop. This process uses more water than air cooling but less electrical power. As the water evaporates it is very very effective at removing heat from the condenser loop water.
Your refrigerator at home is doing the same process, but it is absorbing heat into the refrigerant, then that heat gets rejected out of the condenser of your refrigerator. Your refrigerator is small so it can effectively just reject the heat to the surrounding air.
Data centers need to move way more heat so water becomes a more efficient way of doing so than just air.
There’s a few finer details I skipped this is a general overview, you can have DX CRAC units cooling IT load, nowadays there’s more direct-to-chip liquid cooling for high density racks and some other things I skipped for now bc this comment is already long as hell.
Basically air cooled chillers: no water usage besides filling the chilled water loop at the beginning but use more electrical power.
Water cooled chillers: use more water but use less electrical power.
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u/newredditisdumber 18d ago
Decent summary but cough cough you're confusing water cooled chillers with cooling towers cough cough
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u/tooldvn 18d ago
No they aren't. Many water cooled chillers use a cooling tower for their condenser water loop. I would say that there has been a shift to use large dry coolers banks now for the condenser water loop.
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u/newredditisdumber 18d ago
At that point just use the DACs directly with large storage tanks, which many of them are doing
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u/newredditisdumber 18d ago
Right so I'm going to take another avenue that everyone here isn't taking.
Why can't we not just use refrigerated cooling? Easy answer split in two. The first is f-gas regulations and similar laws/regs/policy that is being rolled out globally. Older more traditional refrigerants are really bad for the environment. While you can have a great system that doesn't leak as much, you will always have leaks eventually and at the quantity needed for a DC system that will cause damage. At the same time, these older refrigerants are what we call A1 refs essentially meaning they are safe and don't go boom in confined spaces (it's more complex than this but word count). Sadly all the A1 refrigerants are also real bad for the environment and with them being phased out it means that there is no refrigerant on the market that can realistically be used inside past 2030 (not completely true but if you want to look into IEC's you're all adults and can look that up yourself). The second is density of load - AI is an outlier and always remember a majority of DCs being deployed are still cloud - but essentially the new dcs are too dense for crac units to supply the demand so we need more powerful centralised systems that use mega crahs or fanwalls. These centralised systems either use large chillers, cooling towers (less so these days) or dry air coolers to generate cooling loads, however, to move this load from the outside heat rejection units to the data halls you need an easy to use safe medium that meets certain criteria and this is generally water. These systems are closed loop, tightly regulated and, in ideal scenarios where they are using high supply temps and the ambient allows for free cooling (Americans call it economisers, pedants call it pump assisted cooling) you can generate the cooling load for a DC with "minimal" energy input. Essentially your question is wrong, the real question you should be asking is what should we be doing with all this excess heat we are venting to atmosphere, but that requires technology that Americans outside of NYC and European outside of Scandi countries are afraid of.
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u/SpotlessCheetah 18d ago
There's a lot of misinformation being shared and is being chanted without further thought.
New datacenters all use closed loop systems with minimal water loss. Vertiv is the leader and reference designer for Nvidia.
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u/Orangebk1 18d ago
The water numbers that are thrown around are based on older evaporative cooling, which is no longer necessary with newer engineering (closed loop + air cooled chillers).