several better ways, multi stage stills and reverse osmosis are leaders of the pack,
https://www.veoliawatertechnologies.com/en/technologies/mult....
Why is desalination so difficult?
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Re: Why is desalination so difficult?
#12Some years ago I toured a maple syrup operation that has the opposite goal: Concentrate the dissolved stuff in the water. Their first stage was reverse osmosis, but only to a point. Second stage is boil, but with aggressive heat recovery from the steam to preheat the incoming liquid. All this to keep the energy cost under control.
Re: Why is desalination so difficult?
#13several better ways, multi stage stills and reverse osmosis are leaders of the pack, https://www.veoliawatertechnologies.com/en/technologies/mult... . https://en.wikipedia.org/wiki/Reverse_osmosis
The author specifically mentions reverse osmosis.
Re: Why is desalination so difficult?
#14It's not difficult. It's just energetically uphill. Undoing entropy costs energy. Second Law of Thermodynamics.
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Re: Why is desalination so difficult?
#15It's not difficult. It's just energetically uphill. Undoing entropy costs energy. Second Law of Thermodynamics.
Dissolving common table salt in water is endothermic. I.e. it consumes energy, not produces.
Re: Why is desalination so difficult?
#16It's not difficult. It's just energetically uphill. Undoing entropy costs energy. Second Law of Thermodynamics.
Conceptually simple things can be difficult to achieve. Like lifting 500lbs or running a marathon.
Re: Why is desalination so difficult?
#17Solar stills are one of those basic survival tools anyone living in an arid region near a salty body of water should understand how to rig. They’re dirt simple and as easy to build as a prison still with the added bonus of only requiring the sun as an external power source. Similarly everyone should know how to rig a basic water purification system using gravel, sand, and charcoal in series. Even just as applied scie…
Water isn’t the most efficient way of doing that but the principle is sound. There are molten salt solar arrays that work similarly.
Idle observation: do people in Materials Science feel like this is the Golden Age for their field?
So many incredible paths to follow: Battery tech. Solar cells. Desalination. Carbon handling. What a time to be alive.
Re: Why is desalination so difficult?
#18I remember reading that it causes some problems related to fishing because the fish all migrate further out.
That’s less the fault of the desalination, more improper/shortsighted disposal of waste byproducts
Re: Why is desalination so difficult?
#19Probably very dumb idea, but would it be feasible to just pump and sprinkle sea-water on hot, dry desert and let it naturally evaporate, and then collect it as fresh rainwater back? i.e. how much water would you need to evaporate to have a noticeable increase in rainfall?
i'd like to see the xkcd author tackle this as a "What If?"
Re: Why is desalination so difficult?
#20Some years ago I toured a maple syrup operation that has the opposite goal: Concentrate the dissolved stuff in the water. Their first stage was reverse osmosis, but only to a point. Second stage is boil, but with aggressive heat recovery from the steam to preheat the incoming liquid. All this to keep the energy cost under control.
In an operation like that, do they heat the syrup under low pressure to reduce the boiling point of water?