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Comment by Retric | Hacker News Reader

Desalination is expensive, but it’s not just about the desalination simply pumping water up hill is costly.

Nevada averages 5,500 ft above sea level. Moving 1 acre foot of water up that high at 100% efficiency takes ~5.6 MWh and a single mid sized farm can use that much water hourly.

Start talking 25 inches of water per year across millions of acres and you’ll need a lot of solar. Worse, commercial reverse osmosis desalination only removes around 95-99% of salt so that farmland is quickly getting degraded.

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So don’t do water intensive farming in Nevada?

Nevada is just an example South Dakota is only 2,200 feet above sea level, but now you need an extra long pipe causing its own issues.

The point is desalination isn’t some magic fix that makes everything ok. The remaining salt is probably the biggest issue.

"The point is desalination isn’t some magic fix that makes everything ok. The remaining salt is probably the biggest issue."

No, but it is a whole lot easier close to the sea. Like most of UAEs cities are. The remaining salt, you could just pipe out in the ocean, if you go in some km towards a current and spread it out enough. Salt in the ocean is only a local problem, if it does not diffuse quickly enough.

And for deserts with a high altitude or that are more inland, no, desalination is probably not the solution.

Salt in the desalinated water not salt in the ocean.

Then don't farm in Nevada?? Humans don't consume that much water and lot of it can be recycled.

Humans generally use negligible mounts of water, the only meaningful water shortages are based around agriculture.

take a black pvc pipe,stick one end into seawatter,add destillation collection crevices and overflowholes,put the other end up high on a hill

That doesn’t work. There’s a pressure difference across a desalinization system, it doesn’t output high pressure water.

its desalination and pumping via destillation by sunlight. it works.

its basically a heat driven capillary system.

"5,500 ft above sea level"

What your talking about works on small hills near sea level, but runs into real physical limitations. It's also slow and thus vastly more expensive per acre foot than commercial systems.

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