There is a fundamental minimum amount of energy needed to desalinate: you can't take less energy to do it,than you could gain back (from osmotic pressure) if you allowed the desalinated water to expand a cylinder containing the residual brine. This is large. This paper is a thermal method, so it doesn't have an electricity input, but to justify their efficiency claim, they should really compare against what you could do by using the same surface area for solar panels, driving a conventional setup. My (limited) understanding is that conventional reverse osmosis is not far from the theoretical optimum, energy-wise, the main difficulties being operational (the membranes need declogging). And of course RO is more expensive than rain.
This paper is interesting, however, in directly producing crystalline salt, which is lower volume than brine and easier to dispose of, maybe even valuable.
Sure, but typically desalination plants are located in a single physical place, so a discharge pipe dumping brine 24x7 is bad for all of the things around it, as the local concentration is extremely high.
I wonder what the linear diffusion gradient would look like for that. Like the perforated garden hoses or whatever for soaking soil. Aquatic organisms grow so quick though very curious on the constraints for something like this.
I liked the idea of loading it up on a ship that sails out releasing as it goes out and back. Make it solar powered or even go old school with literal sails.
I thought they tend to pipe far out and discharge as far below the surface as possible, since there is a lot of surface life and it is less damaging this way.
Ships (with long submerged pipes) would be prone to weather events and generally less reliable than an installed pipe. Perforation would be prone to clogging from build up so a nonstarter I would expect. Adding flex tubing and a relocation robot would be a maintenance headache as well. Not sure there is an easy optimization.
And it doesn't even need to be a rigid pipe. A flexible pipe made out of, say, waterproof fabric, could be cheaply made to extend miles while remaining open due to the pressure of the water pumped into it.
depends of course, how easy does the brine dissolve, how long does it take that it is so diluted that it can't do any harm, without that information it's not easy to tell
Persian Gulf has 20% more salt in water because of the humans which are throwing the oversalinated waste back into the sea. Dehidrated salt may be a big deal for some areas because of no waste into input.
There is a fundamental minimum amount of energy needed to desalinate: you can't take less energy to do it,than you could gain back (from osmotic pressure) if you allowed the desalinated water to expand a cylinder containing the residual brine. This is large. This paper is a thermal method, so it doesn't have an electricity input, but to justify their efficiency claim, they should really compare against what you could do by using the same surface area for solar panels, driving a conventional setup. My (limited) understanding is that conventional reverse osmosis is not far from the theoretical optimum, energy-wise, the main difficulties being operational (the membranes need declogging). And of course RO is more expensive than rain.
This paper is interesting, however, in directly producing crystalline salt, which is lower volume than brine and easier to dispose of, maybe even valuable.
This appears to be the same New Rochester article as 4 days ago with 20 comments.
https://news.ycombinator.com/item?id=48349507
This reads like hyperbole:
> The brine byproduct wreaks havoc on sea life when it’s deposited back into the ocean by raising the salt level and lowering oxygen in the water.
Managing return of concentrated brine should be entirely tractable in the literal ocean.
Sure, but typically desalination plants are located in a single physical place, so a discharge pipe dumping brine 24x7 is bad for all of the things around it, as the local concentration is extremely high.
Seems like you could run a long perforated tube to diminish that effect.
I wonder what the linear diffusion gradient would look like for that. Like the perforated garden hoses or whatever for soaking soil. Aquatic organisms grow so quick though very curious on the constraints for something like this.
I liked the idea of loading it up on a ship that sails out releasing as it goes out and back. Make it solar powered or even go old school with literal sails.
I thought they tend to pipe far out and discharge as far below the surface as possible, since there is a lot of surface life and it is less damaging this way.
Ships (with long submerged pipes) would be prone to weather events and generally less reliable than an installed pipe. Perforation would be prone to clogging from build up so a nonstarter I would expect. Adding flex tubing and a relocation robot would be a maintenance headache as well. Not sure there is an easy optimization.
And it doesn't even need to be a rigid pipe. A flexible pipe made out of, say, waterproof fabric, could be cheaply made to extend miles while remaining open due to the pressure of the water pumped into it.
Things left underwater tend to collect things on it which would make this much less porous over time.
depends of course, how easy does the brine dissolve, how long does it take that it is so diluted that it can't do any harm, without that information it's not easy to tell
These are often built near shallower parts along the coast where changes are more pronounced.
> without waste
...except for the huge piles of salt.
If the salt was not waste, surely people would already be extracting it from the brine and the existing methods would also be "without waste".
Persian Gulf has 20% more salt in water because of the humans which are throwing the oversalinated waste back into the sea. Dehidrated salt may be a big deal for some areas because of no waste into input.
What about removing oil from water, have we conquered that yet?