The latest 300mm fabs use 10-50X the power of what the old 8" fabs used (I know this for a fact...). That power gets turned into heat and that heat has to be removed. I work at an "inefficient" 200mm factory that has pretty good internal recycling (~65%)...we still use 600K gallons per day.

A single state of the art EUV tool uses ~2MW of power...<0.1% of that gets to the wafer. Most of the rest of that is lost to heat...and that heat goes where?

An acre-foot is about 325K gallons, and an irrigated farm uses 1 or 2 acre-feet per acre per year. So the "inefficient" fab you work at uses less than 2 acre-feet/day, or maybe 700 per year. About what a 500-acre farm uses.

Arizona has about 1.3 million acres under irrigation. So 2,500 similar fabs would use all the irrigation water.

It's a lot of water, but maybe not a deal breaker?

The USDA says Arizona cotton farmers make 1,138lbs/acre/year (sorry world, not converting units this time). There are 165,500 acres growing cotton in Arizona, so the 500 we stop to get water for Intel is negligible.

So we are talking about agriculture forgoing 569,000 lbs of cotton per year. Farmers get about $0.60/lb for cotton. The impact on the agricultural industry is $341,000/year.

Buy out the worst cotton farmer in the state. Take his water. Move on.

Seeing those numbers, I wonder how much that affects the local microclimate, as that adds a lot of moisture and heat into the air. And if there are ways to add plant life in the surrounding areas that could benefit from it, and from which people can obtain a yield.

I'm not so sure about the hotter months, but during the colder months, it can potentially be used for greenhouses, or for when temperature dips during nighttimes. Lots of tropical plants want hotter, moist air and will die from frost.

Assuming that those 600kgal start out ice cold and all end up evaporated at the boiling point, that’s 146MW of cooling. LCoE for plain solar power is about $31/MWh. Assuming you could discharge heat without evaporation at a COP of 4, that’s about $26k/day to buy power. Not at all cheap, but not insane. Interestingly, that is a lot more than the cost to buy that much water wholesale, even in Arizona, so I guess this is why people like cooling towers.

600k gallons for us is not all evaporated, thats just what we take in from the city and discharge back to them. There are temperature requirements for discharge as well so you can't just discharge 200 degree water. That doesn't really work anyway since our process cooling water has to stay at ~70 degrees.

We have some evaporation loss, but in the Phoenix climate it would be a lot more.

Definitely not arguing that the heat doesn’t need to go somewhere. You’re absolutely right.

All I remember is family saying they had effective means for recycling the water without losing it in these boiler chambers.

I’m no expert, but they were saying significantly higher efficiency than 65%.

Right, I think the gp comment is referring to fabs being impacted by water shortages, not fabs causing water shortages.

Although if push comes to shove I guess all of this can be solved trivially by not growing ridiculous water intensive crops and not having golf courses and stuff in the middle of the desert.

Tucson resident here. I see acre after acre of alfalfa being grown, with most of that water then being exported to Saudi Arabia for cattle consumption. There is a geopolitical aspect to this, but I will gladly choose Arizona fabs over exporting cattle feed.

Tucson has been doing a very good job recharging our local aquifers and we also had a good monsoon. I was able to harvest 15,000 gallons of rainwater for irrigation on my land.

I view the construction of the fabs as critical infrastructure . Saudi cattle, not so much.

> Tucson resident here. I see acre after acre of alfalfa being grown, with most of that water then being exported to Saudi Arabia for cattle consumption.

(also Tucsonian) Whats really sad is we still have to search far and wide for decent quality hay to feed to our horses...

The fab investments also create a nexus of interesting jobs related to construction and fab operations. I really enjoy working in the latter sector.