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Comment by Skunkleton | Hacker News Reader

I was somewhat skeptical, but it does look like this comment is correct on the whole. An average household uses around .75 cubic meters of water per day, and it takes around 3.5 kWh to desalinate that much water using reverse osmosis (at scale, probably some best case. I didn't look too hard).

On Silicon Valley Power (suck it PG&E losers), I pay around $0.11/kWh. So a full day's water would cost me around $0.40, or around $12/month if I were to somehow magically do this process at home. That is around 1/10th of my current water bill. That leaves plenty of room to still pay for equipment, distribution, etc.

It sounds like the right time to build desalination plants is now.

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>An average household uses around .75 cubic meters of water per day, and it takes around 3.5 kWh to desalinate that much water using reverse osmosis (at scale, probably some best case. I didn't look too hard).

>On Silicon Valley Power (suck it PG&E losers), I pay around $0.11/kWh. So a full day's water would cost me around $0.40, or around $12/month if I were to somehow magically do this process at home. That is around 1/10th of my current water bill. That leaves plenty of room to still pay for equipment, distribution, etc.

That's only the electricity cost. The total cost, factoring in operating costs as well as capital expenditures range from $0.60/m³ to $1.86/m³, with the lower end being $1.63 if we only include first world countries. That leads to a per month cost that's a few times higher than your initial estimate.

Let’s compare SFPUC rates:

https://sfpuc.org/sites/default/files/accounts-and-services/...

W-1A (what a residential user in SF is likely to pay): $7.60 per CCF ($21.51/m^3) for the first 4 CCF/mo.

W-25 (wholesale buyers like other water districts): $4.10/CCF ($11.60 / m^3)

Even rate W-24 (untreated water from reservoir) is about $2.69/m^3. For all I know, the reservoir in question is Hetch Hetchy, but even this rate is above estimates of the cost of desalination.

The obvious conclusion is that the actual cost of desalination is not even close to being a problem. Of course, this is CA, and it’s easy to throw a few tens of $bn at a project and get absolutely nothing out.

Looking at California's total water usage [1] I would guess we are somewhere around 40 MAF per year (I hope. That can't be per day right??). Based on the probably incorrect numbers above, that translates into around a 20 GW demand for water. The diablo canyon nuclear power plant outputs 16 TWh per year. Terrible napkin math puts that at around 12 power plants needed.

Oof.

[1] https://www.ppic.org/publication/water-use-in-california/

12 nukes sounds like a small price to pay to never have to hear California bitch about water again. The other 49 states should chip in to pay for it.

Three months ago, a new SoCal desalination plant was rejected: https://en.wikipedia.org/wiki/Huntington_Beach_Desalination_...

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