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I think that depends how much build-out you have to do in order to install the kind of capacity required for a $40B semiconductor fab, which would hypothetically need some kind of major energy storage infrastructure or backup source in the event that solar is the main source of electricity.

> Large semiconductor fabs use as much as 100 megawatt-hours of power each hour, which is more than many automotive plants or oil refineries do. [0]

If a fab is running at that consumption rate for twenty hours every day for one year, it will consume approximately all of Arizona's 735,000 MWh of annual utility-scale solar, wind, and geothermal net electricity generation. [1]

Contrast that with the annual hydroelectric generation of Itaipu Dam in South America, at 79,440,000 MWh in 2019. [2]

[0] https://www.mckinsey.com/~/media/mckinsey/dotcom/client_serv... [pdf]

[1] https://www.eia.gov/state/print.php?sid=AZ

[2] https://www.power-technology.com/projects/itaipu-hydroelectr...



> Large semiconductor fabs use as much as 100 megawatt-hours of power each hour

Ooof, this kind of writing where the author doesn't understand units just gets my goat. Just say it uses 100 MW! Geez.


I prefer it as written, because the additional information of timeframe for measurement indicates that the author is not talking about momentary/peak power.


I'd still much rather see "100 MW continuous" over "100 megawatt-hours of power each hour". And the former actually tells you a lot more than the latter, as with the latter it could be bursty (e.g. much more than 100 MW momentary draw), which would be a lot harder to supply. Fortunately for everyone the power draw is actually steady.


Which indicates the author knows nothing about how semiconductor fabs use power. Power usage is stable with a few percent...and 100MW is really on the low side for this fab. If all 6 phases are completed as they are expected to be...it's more like 250MW.


I think we can forgive the author for the low estimate considering that this project didn't exist publicly at the time of writing.

How does power usage remain stable in a fab? Please say more about how that works.


Much of the power is used for keeping air clean with temperature and humidity controlled in a very tight range. More energy is used for water cooling, waste treatment and other facilities. The rest of the power is used for production tools...which when a fab is running are generally consistent users. The power usage will scale with wafer loading, but again advanced fabs like these will run at near 100% capacity for years at a time.


Your EIA source is for generation in the month of august only. Total solar generation in Arizona is much higher than that. Very roughy 1,500x nameplate capacity = total annual generation in Arizona. 5,600 mw capacity in 2021, 8,400,000 mwh annual generation.

https://en.wikipedia.org/wiki/Solar_power_in_Arizona

All fabs have battery backup regardless of power source, although with solar you would need a much larger one indeed. Either way, the scale of solar power generation easily supports these new fabs.

https://www.eia.gov/electricity/generatorcosts/ Cost is ~1,65B per GW of solar. 30% subsidy from government = ~1.1B per GW to generate ~ 1,500,000 mwh. They’re dirt cheap. Unfortunately battery storage, while it exists at this level, is more in the range of 800M to be safe (1600 mwh of storage). https://www.tesla.com/megapack/design

So all power infrastructure would be less than 5% of the cost of the plant, and that’s overbuilding solar needs by 4x (meaning even on the crappiest day power wise you’ll have more than enough) and having 16 hours of backup power which is also overkill.


Here is a solar plant in California, which broke ground over a decade ago, that produces 550 MW of power, for $2.5B. Build even a small version of one of these and its 100 MW power needs are met.

https://en.m.wikipedia.org/wiki/Topaz_Solar_Farm


The 550 MW "nameplate capacity" is peak. The capacity factor of 26.6% means that it actually only produces about 146 MW on average. Nuclear power plants generally have a capacity factor above 90%.


146 MW on average is still more than this facility needs.


Nope...once all phases are built they will be using ~250MW of power.


Not during the night and not when it is cloudy. Averages are vey bad numbers for something which is on 24/7.


Electricity usage is much, much lower at night in Arizona because everyone turns AC off due to temperature drop. Plenty of baseload generators that can be better utilized at night with increased manufacturing.


Kinda. Depends on the season. In the summer, its still 80 degrees at night in Phoenix.


Do the plants typically run at night? Also, doesn't the capacity factor account for these variations already?


No, you would need a large storage facility as well.

A nameplate capacity of 550 MW with a capacity factor of only 26% almost certainly means there are a lot of times when it isn't generating any power at all, or at least none to speak of.


Right, but if those align with the times where the plant is not used at all (night), does it matter? That being said, I have no idea what the normal operational schedules are for these types of facilities.


I'd wager a large sum that if you're investing $40 billion in a plant, you're going want it running 24/7/365.


And definitely not if the clouds suddenly blow in when the process is at a critical stage.


Solar farms are one of the fastest electricity generators to build. AZ will have no problem stepping up production in the face of demand.




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