Comment by cwalv | Hacker News Reader

Comment by cwalv | Hacker News Reader

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> This isn't something cities could or should solve by switching to (expensive) desalination

In 2015, the Southern Nevada Water Authority completed a "3rd straw" into Lake Mead to safeguard water availability, at a cost of $817M [1], which is enough to cover the power costs to desalinate Nevada's CO river allotment for ~23 years. It's been a while since I looked into it, but I once ran the numbers and the cost of that 3rd straw was comparable to the cost of building a solar power plant that would generate enough electricity to cover the desalination for NV's allotment as well.

Notes:

Nevada's allotment of water from the Colorado River is 279k acre ft / yr (actual use is 242k acre ft / yr in 2021) [2]. There are desalination systems available that require 3452 kw / acre ft [3]. Southern Nevada wholesale rate of $.37 / MWh [4].

[1] https://www.nps.gov/lake/learn/the-third-straw.htm [2] https://www.lasvegasnevada.gov/News/Blog/Detail/lake-mead-wa... [3] http://www-formal.stanford.edu/jmc/progress/water.html [4] https://thenevadaindependent.com/article/nv-energy-introduce...

Desalination traditionally needs a source of water to desalinate. Then you need somewhere to put the brine.

The ocean is traditionally the answer to both these needs. Nevada is not a good candidate for a desalination plant.

> Nevada is not a good candidate for a desalination plant.

No, but it's a good candidate for a solar power plant, and the water source is shared with major coastal metro areas. You'd of course want to move the power to the coast; an amount of water equivalent to that produced by desalination could be withheld upstream, in Nevada.

That said, I still think they made the right move building the 3rd intake, even at such expense. That intake is below the "dead pool" level, while the other 2 are not .. so even if ppl can't sort things out politically and continue to draw the water down past the point that it won't flow over the dam, NV will still be able to draw their "allotment". And of course, it's very hard to build desalination plants in CA, no matter how much sense it makes.

> Southern Nevada wholesale rate of $.37 / MWh [4].

Typo. That should be $37/MW-hr, not $0.37/MW-hr (article quotes $36.67 / MW-hr)

Desalinated water would have to be pumped uphill along way for the coast. Desalination makes much more sense for coastal communities in that regard, but it won’t be that useful for agriculture.

Or you could use transmission lines to push the electricity to the coast, and just keep the equivalent water from flowing downstream.

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