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Comment by dylan604 | Hacker News Reader

I just heard this while driving, and I couldn't stop laughing at how confident the lady was in this being a solution. The storage pools will not suddenly no longer be needed because people stop syncing their devices to the cloud. It will just be used by something else.

One question I had is what would replacing fresh water with saltwater be viable? We have endless amounts of saltwater that would solve the wasting fresh water issue. I'm assuming some sort of closed system where evaporation isn't an issue to leave deposits. Saltwater would also have a lower freezing temp, so you could chill the water cooler than fresh as well.

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I'm kind of suspicious of the water for datacenter stats, because I'm skeptical of the extent to which evaporation-based cooling is used rather than just air-to-air cooling. Wouldn't this result in visible plumes of condensation, as it does with power station cooling towers?

Also commercial water rates appear to be about £2.50 / cubic meter.

Desalination depends on electricity prices, which are fairly high in the UK at the moment.

My parent's hometown blocked data center construction because of concerns about traffic and water consumption.

This is the mid Atlantic where the wet bulb and dry bulb temperature are always very close so the water would be useless for cooling. And of course there are few things that add less traffic than empty buildings full of computers.

Also a lot of the non-AI stuff is still air cooled. In fact I know people at a couple large public tech companies spinning up AI hardware and even for that they're going with air cooling because it's all their OPs people are familiar with.

I wish people were more precise with communicating the actual problem.

> Also commercial water rates appear to be about £2.50 / cubic meter.

I even became interested in how much energy is needed to desalinate water by boiling it, taking into account recuperation and everything else.

> Desalination depends on electricity prices, which are fairly high in the UK at the moment.

Electricity prices are largely dependent on the need to deliver a steady flow of energy and store it, which are not a concern in the context of desalination water.

Engineers are pretty clever, but salt water is some nasty stuff.

Desalination is cheap though. It's just never really been needed at scale in the UK because of rainfall. Maybe it's time to reassess

Desalination is energy expensive, and results in a pretty nasty waste. Removing the salt loses the benefit of lower temperatures.

Desalination is expensive

I’ve always thought desalination would make a nice shiftable load to incentivize renewable build-out.

Not really. https://www.sustainabilitybynumbers.com/p/how-much-energy-do...

Ok, its maybe more expensive than I realised according to that source, but I would argue that comparing it to something like charging EVs or running a fridge is not a fair comparison. If you desalinate 1000 litres of water it's not the same as a household using 1000 litres of water. Not exactly. Once water is in a municipal system it's cleaned and reused many many times. Desalination could overcome water shortages by topping up water in a system, in times of drought, rather than just waiting for rain.

Hm, the only reuse of municipal water I know is using treated sewer water for watering plants. I don't think any US cities recycle water back into a potable water system -- have you heard of that happening anywhere?

(I don't remember how this relates to the original argument)

Edit: oh if you meant "data center" by "municipal" then I guess! I thought you meant city drinking water

Ok I had heard of it happening in the UK but now I can't find any evidence of such, apart from a just approved scheme to treat wastewater and pump it into the Thames upstream, which is then used to source drinking water in London. So in a way, its going to happen in London, even if it hadn't already been, as I had believed.

But I would hope datacentres could use recycled or desalinated water for cooling rather than using drinking water.

I see a few obvious problems:

1. A closed system cannot exhaust heat via evaporative cooling, which would defeat the purpose.

2. Many datacenters are no where near salt water.

3. There are likely reliability issues that would need to be overcome and it is simply cheaper to use fresh water.

> 2. Many datacenters are no where near salt water.

If only we had a way of moving water around from places where it was plentiful to places that are not. Seriously though, this is a limitation? Vegas is no where near water, and that didn't stop it from being.

> Vegas is no where near water...

Las Vegas is very close to water. 90% of their water from the Hoover Dam, which is only 30 miles away. They don't pipe it in. Of course, this has created a severe risk of water shortages due to falling water levels on the Colorado River.

Using chilled brine as a cooling medium is common in industrial processes, unfortunately it needs to be chilled and that usually comes via an evaporative cooling tower. Assuming the sea is close and the temperature low enough, an open loop pulling from and discharging to the sea isn't than big of an engineering challenge.

Closed loop water cooling probably doesn't make a lot of sense at scale; radiators aren't very efficient at the relatively cool temperatures this sort of system would be operating at. Maybe if the water loop was cooled by refrigeration systems? That would be expensive though.

Closed loop water systems is a common form of cooling in large/commercial buildings. Typically, a large chiller unit on the roof with the cold water piped throughout the building connected to individual blowers. I've been told it is much more cost efficient.

If that's not how they are using the water, then what are they using it for? Swamp coolers?

Adding an evaporative cooling tower to a chilled water loop can up the COP to 7ish, an air-cooled chiller by itself maxes out around 4. It’s almost twice as effective at removing heat.

Air cooled chillers are fine for a commercial office building or tip-up warehouse, but data centers need to remove an enormous amount of heat.

A closed loop water system by definition doesn't "use up" water! It only matters for this discussion if there's a continuous supply of new fresh water going in.

> It only matters for this discussion if there's a continuous supply of new fresh water going in.

No... Proposed solutions should be practical from every angle, not just that single angle.

oh, where was this on? Was it the MP on the press release? I'll see if I can get it off iplayer or something, I wanna hear this

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