Data centers use a lot of water (up to 5 million gallons daily) for cooling. Why can’t they recycle the water? Once it heats up, can they pump it underground (in pipes) to cool it, and then recirculate it?
Here’s an article describing how most data centers are being built in drought areas: Majority of US’s new AI datacenters to be built on drought-hit land
I have no doubt this is technically possible. I think the answer is money.
Pay to build a cooling loop and recycle the water or go free and suck up cool water from the city and dump the hot water back out?
Companies will go the cheap route almost every time if they can.
Cities where these datacenters live ought to demand better but they are so keen on the business they generally let them get away with whatever they want. If they do not the company will find a different city that does. All too easy for them.
They absolutely can and should be required too.
Geothermal Heating and Cooling is not exactly a new tech.
AFAIK, the cooling water isn’t dumped as hot water into the sewage or storm drains. It’s evaporated into the open air. That provides the most cooling w the least electricity consumption. When water is cheap & power is expensive that’s the only sensible thing for a business to do.
Which is why regulations need to exist to cause any pro-social behavior by business. Being anti-social is always cheaper or more profitable and usually both.
Yup. The entire point of water cooling is the enormous amount of heat that can be rejected into water if it is evaporated. The latent heat of evaporation of water is huge. Water is circulated around and around heat exchangers within the compute and up into cooling towers where rising air running against the falling water stream results in evaporation of some the water falling cooling the rest. It is a very cheap way of rejecting heat. But the water is lost. It will circulate quite a few times, but eventually it is lost. One does wonder if it there are enough huge buildouts of data centres that a microclimate will develop around them, but overall it will be a very minor gain. Another loss mechanism is that you can’t have all of the water evaporate, as salts will begin to concentrate in the water. So there is a need to remove some liquid water in order to keep the salt concentration low enough. This water will of course be salty enough that they don’t want it - and thus it itself is a problem.
You can add a heat pump to the mix, and a heat pump can achieve coefficients of performance of 6 or better running into a water cooling tower. Which is why you see such towers as part of HVAC systems on large buildings.
All water is recycled, or at least “all” for any practical considerations. It’s just that some recycling processes take a really long time before it gets back to a condition where you can drink it or swim in it or grow seaweed in it.
Out west, e.g. New Mexico from which I hailed before I relocated to the NYC environs, we have long-established “water rights” on all water sources. Neither you as an individual nor you as a corporation get to remove water that legally belongs to people down-river. I would think that extending this legal logic to locations not prevously known for drought conditions would be a good tactic, but I ain’t a lawyer or a politician.
I was at a trade show last week and there was a company proposing to do exactly that, in addition to carbon capture. The idea was to dissolve CO2 in data center wastewater, pump it into non-recoverable coal seams for CO2 absorption and cooling, then pump it back to the data center.
That sounds neat. Also very expensive. Not to mention the places you can put that in I would think are very limited.
We have coal seams across the entire country, just not necessarily economically viable for mining; the possible locations are less restricted than one might think!
Well, not the entire point. Even if you’re required to use closed-loop cooling, you’re likely to still be using water as the working fluid, since it’s cheap, low-viscosity, and has a very high specific heat per mass (all of which are also good properties for a heat-exchange medium to have).
But yeah, you can get several times as much cooling if you let it evaporate.
Which means that requiring that water be recycled also means that the businesses providing the service are no longer as profitable (if they are at all). Frankly, I doubt that such laws will ever come into existence unless we can out-bribe the AI companies.
I think I don’t understand why data centers couldn’t bring in the water, use it for cooling one time through, and then back into the water main, maybe with some required filtering. It would be warmer, but I wouldn’t think it would be contaminated.
Because the water has evaporated into the atmosphere.
I’m sure I don’t understand how this works, but the coolant in my car doesn’t evaporate. Run cool water through the pipes that cool the hardware and straight back out to the mains, without circulating it or evaporating it.
The problem is that evaporating the water is far more effective in cooling, so unless forced , for-profit companies will do it and use up water instead of returning it to the water main.
Your car uses closed-cycle cooling because it’d be really inconvenient to have to keep on refilling the evaporative-water tank every few miles. For a fixed-location plant, though, it’s easy to just attach a pipe to the city mains and get as much water as you want continually.
The main issue of injecting used cooling water directly back into a water supply system is guaranteeing it’s treated to required standards. In other words, the operator of the system requiring cooling would be obligated to operate a water treatment plant comparable to the utility-operated intake treatment plant that supplies the water system, plus ongoing operation, monitoring, and maintenance costs. Plus liability if your treatment system fails and you wind up poisoning downstream consumers with water polluted by your prior use of the water
Zero chance any for-profit operation would take on those costs and risks.
Well, if they were required to, by communities desperate for water.
I don’t even understand why running it through the pipes would contaminate the water, though.
Flint, MI, has entered the conversation
It wouldn’t be a deal breaker. The water should just be cycling. The main issue, as stated above, is that it is currently cheaper for the data center to evaporate the water than to use a closed cycle (either within the center or back to the mains).
Some companies have started looking at closed cycle cooling not for all but for a few centers, putatively for conservation reasons but the cost of increasingly bad PR is likely a significant factor.
Well, yes, if they used lead pipes, that would be a problem.
Cycling the water back is not an issue if proper pipes were used, which circles back to cost again. They’re currently doing what is most cost effective for them, which they will continue to do unless forced otherwise. That’s true of the use of evaporative cooling or the type of pipes or anything in between.