Hacker News Reader

Comment by lukan | Hacker News Reader

You can call it overpopulation, I call it underdesalination. There is lot's of sun there and lot's of seawater.

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.

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.

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.

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.

According to ChatGPT it takes at least 3 kWh to desalinate 1000l of salt-water.

Following that math and its estimates on solar panels that would come down to 0.003 m^2 of solar panels per liters.

UAE is about 83.6 billion m^2, lets assume half of that can be covered in solar panels, so that would be enough to desalinate 13 trillion liters of water.

That sounds like it could be enough for a country like UAE by a factor of 10, if ChatGPT's math is right (probably not) and water can be desalinated instantly (probably not).

If your thought experiment leads you to consider that half the country, or even 5% of the country, should be covered in solar panels, then there a problem somewhere.

So your reference is “According to ChatGPT”. Did you feel anything when typing this?

So, your argument is "you used ChatGPT for this". They didn't even write the comment with GPT, they just used it as a starting point for some napkin math. The other commenter not only dismissed the idea, but also emphasized how unrealistic and poorly planned it is by responding to the contents of the content, including how absurd it would be to implement that much solar coverage. I'm sure it's fun to make fun of the large language model, but at least it provided some drive to the conversation, even if its value was in being corrected. Did you feel like your addition was significant?

No, I didn‘t intend to make an argument, I was asking a genuine question because I‘m trying to understand the perspective on the world of people who consider LLM a kind of „source“. To me OP reads like “according to my Ouija board” and I’m frightened by the idea that people on HN are using the output of LLM as “quotable facts” (and not as a tool to start further research outside of it, which would be fine IMO.) I’d like to know if the poster had any doubts using ChatGPT as a source of fact to base their calculations on, when they obviously had access to the internet with all necessary sources to properlt calculate an answer for this basic question.

You can't fix shortage of agricultural or industrial water with desalination because you end up with a bag of potatoes for $50

Desalination only solves water shortages for human consumption. Water shortages mean famine

A single hectare of potatoes need about 7,000 tonns / m3 of water. Desalination costs $1/m3, The cost of growing russet type potatoes for the fresh market was $2032 per acre. So potatoes will be 3 times more expensive

For wheat, the difference is even worse

True, but if you want to grow in the desert, there are more efficient methods and crops to grow, like in closed greenhouses, that keep most of the water.

Why not ship the potatoes in?

Reply on news.ycombinator.com