[exmadscientist]

Option A is to build a closed-loop system, that runs a million gallons of water per day through chillers and recirculates it. You need to find chillers that can handle that load continuously and enough power to run them.

Option B is an open-loop system where you run a million gallons of water through exchangers, heat it up, then dump the hot water and find a way to get a new million gallons of water from the local municipality.

Option B is cheaper, so they do that. Higher water prices would change that equation, but that's not what we have now, and it's hard to pitch an Option A project if anyone else is willing to offer rates that make Option B work. The Prisoner's Dilemma strikes again.

[tomatotomato37]

I find it hard to believe continuous consumption of potable municipal water is cheaper than running chillers or exchangers cooled by a river/ocean, especially considering powerplants and the like have been doing the latter for decades

[Veserv]

Why? It is only a measly 500,000 gallons a day.

That is only ~2,000 m^3/day (~2 acre*foot/day). Even if they exclusively used the most expensive source of water, seawater desalination, that would only be ~800 $/day.

Your average almond tree uses 3-4 acre*foot per year [1]. So the yearly water consumption of the data center is ~200 almond trees. Your average almond tree produces ~50-60 pounds per year [2] and ~4500 pounds per hectare (2.5 acres), so that is the water consumption of a tiny 5 acre almond farm producing ~10,000 pounds of almonds per year.

The internet indicates the wholesale price of almonds is ~2 $/pound, so you can either have a data center or 20,000 $ worth of almonds.

[1] https://www.c-win.org/cwin-water-blog/2022/7/11/california-a...

[2] https://wikifarmer.com/library/en/article/almond-tree-harves...

[nimish]

That consumption figure is per acre of almonds. But your point is still valid. In total almonds or other crops like alfalfa consume millions of acre-feet of water a year in a dry state like California while a single data center only consumes ~500-1000.

[Veserv]

Indeed, that is my mistake. I misread the denominator of the consumption figure. Luckily the orders of magnitude are so dissimilar that mere factors of 100x do not affect the calculation.

3-4 acre*foot per year per acre of almonds results in the data center consuming ~200 acres of almond. ~4500 pounds per hectare results in ~1800 pounds per acre. So, that would produce about 360,000 pounds of almonds or ~720,000 $ worth of almonds.

That is certainly vastly less economically productive per unit of water consumed compared to a 750,000,000 $ data center which probably has a expected payback period of 10-20 years or about 37,500,000-75,000,000 $ of produced value per year.

[tharkun__]

How much is that in "Libraries of congress" worth of water consumption?

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[exmadscientist]

It really shouldn't be, but part of the site selection process for these things is finding a place with cheap enough power and cheap enough water that you can rip them off by dangling the "jobs!" carrot. So it's not exactly random. And there are enough locations in the US that view providing cheap utilities to their citizens as a benefit (which, when things weren't getting arbitraged on a national scale, was probably a reasonable policy) that they can always find someone.

[pxeger1]

Maybe building a heat exchanger in a river requires loads of environmental / planning permits, but just producing millions of gallons of (warm) "sewage" doesn't, because it's already allowed?

[FL33TW00D]

Stargate is closed loop.