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Comment by SoftTalker | Hacker News Reader

Why Phoenix? I would assume a plant like this has high cooling and water demands?

Phoenix already has a lot of the infrastructure and regulation in place thanks to Intel. And the consistent dry climate is a perk for fabrication. ASM, who works closely with TSMC, has an HQ just up in Scottsdale. Water recycling is a pretty simple problem for fab designers/engineers to deal with compared to the problems they're institutionally dedicated to.

No water demand is high relative to agriculture. Industrial use is a drop in the bucket (pun intended).

Cooling is sort of a thing, but AC is pretty good now, and construction / compliance / land costs in other places vastly outweigh the (cheap, in AZ) energy needed.

Wow, by like an order of magnitude. TSMc used 100 million metric tons of water in 2023 - a single californian farm apparently can use 2.9 acre feet per acre, for 8.4 million acres. And acre foot is 325851 gallons… For a total of 2.7e12 gallons!!!

"The primary use of water in semiconductor fabs is for cleaning and rinsing silicon wafers during production. This requires ultrapure water (UPW), which is thousands of times purer than drinking water"

So it's not water usage that evaporates and can cause droughts, it can be heavily recycled back into the system.

Correct!

Arizona is dropping the hammer on a bunch of alfalfa farms here. Interesting side note is that most of them were run and owned by Saudi companies or company. There are markedly less cotton farms than when I was a kid. The farms that I have direct knowledge of are very progressive and not afraid of innovation/change which is very encouraging.

Also of note is what Arizona does with it's share of the Colorado river. My city chose to recharge the ground water and I believe the results have been acceptable.

I have heard the water needs are massive, but the reclamation tech is mind blowing. I haven't dug into it.

It is hot here in Arizona, but its generally a dry heat. We have humidity in 15% range for most of the year. Our winters are very, very awesome and generally dry as well.

Just replace Palo Verde with PV and batteries. Huge amounts of evaporated cooling water would be saved. 6.6 GW of waste heat is a lot of evaporation.

It will happen eventually, as Palo Verede continues to have to reduce its use of wastewater for cooling [1]. The US gov recently approved 31 million acres of federal land in the west for solar generation [2]. Assuming ~8 acres per MW of solar generation capacity (per the NREL) and 20% capacity factor, total land needed is ~168k acres (4.2GW nuclear vs 21GW solar needed). Plenty of land available directly near Palo Verde for this, and some already used for solar immediately south and southwest (Mesquite Solar Complex, Sun Stream Solar Park, Agave Solar).

Edit: Fixed my land use math.

[1] https://cronkitenews.azpbs.org/2020/02/25/palo-verde-nuclear...

[2] https://news.ycombinator.com/item?id=41407984

[3] https://en.wikipedia.org/wiki/Palo_Verde_Nuclear_Generating_...

I believe utility-scale solar in Arizona achieves a 30% capacity factor with 1-axis tracking (which is the default these days for utility-scale solar in the desert SW). Not sure if this is DC capacity factor or AC; the latter is typically smaller because the PV is oversized for the inverters, although the discrepancy is lower with 1-axis tracking as the peak gets spread out more, justifying more inverter capacity.

Cheap solar power is also abundant in the Southwest.

Workforces are in or like cities.

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