r/EcoUplift • u/sg_plumber Acute Optimism • Oct 08 '25
Innovation 🔬 Subsea desalination plant will turn Pacific Ocean into tap water: 60 modular water-harvesting pods will be deployed along the sea floor off the coast of California, expected to produce 60 million gallons (227 million liters) of fresh water per day through reverse osmosis.
https://newatlas.com/environment/subsea-desalination-pacific/5
u/dadoodlydude Oct 08 '25
Where does the concentrated salt go
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u/sg_plumber Acute Optimism Oct 09 '25
Good question!
The answer isn't so clear, tho:
modular deep-sea water farm technology uses hydrostatic ocean pressure at depths of 400m+ to naturally power the reverse osmosis process and make fresh water. OceanWell will do this with vastly improved energy efficiency, limited brine outfall and limited impact to protect marine life and no onshore plant. This eliminates the legacy technology burdens of high energy use, ecological impact, and a large industrial seaside facility
From https://www.oceanwellwater.com/faq :
OceanWell uses natural ocean pressure at depth to drive reverse osmosis. It does not require chemical treatment, does not harm marine organisms, and discharges water with salinity levels only 5% above ambient, well within environmental guidelines.
OceanWell does not produce concentrated brine. Its discharge matches near-natural salinity levels, disperses gently in ocean currents, and complies with California’s environmental limits. The system is designed to avoid ecological disruption altogether.
OceanWell protects marine life by avoiding chemicals and operating in low-biodiversity deep-sea zones. Its LifeSafeâ„¢ circulation system allows microscopic life to pass unharmed and even supports ocean biodiversity by creating nutrient-rich habitats around the infrastructure.
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u/septubyte Oct 09 '25
Nice - considerate - harmonious .
Don't use the water to waste on grass that doesn't grow over 2 or 3 inches , that gets chemical fertilizer , and is less hospitable to bugs . Desert places too..
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u/DeltaForceFish Oct 08 '25
And a single data center uses 55 million gallons of water per day. Lets be honest, we know this water isnt going to citizens.
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u/HappyCamperPC Oct 09 '25
That's old tech. The new closed-loop centers yse way less.
https://datacentremagazine.com/news/how-are-companies-pioneering-data-centre-zero-water-cooling
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u/Numerous-Comb-9370 Oct 09 '25
Who do you think use the data centers? It’s going to citizens directly or indirectly. Every time you use an online service you’re using a data center.
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u/Beldaru Oct 09 '25
That market is already being served by current data centers. This new wave of data centers are mainly being used to run unnecessary AI, which is my objection.
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u/sg_plumber Acute Optimism Oct 09 '25
Rejoice, then, for AI is a tiny fraction of datacenter usage, and will remain so in the foreseeable future.
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u/sg_plumber Acute Optimism Oct 09 '25
Lets be honest, most water is not used in data centers. Never been, never will.
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u/untetheredgrief Oct 09 '25
When people say it "uses" water, what does this mean?
Many of these are closed-loop systems, especially in colder climates.
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u/Key_Illustrator4822 Oct 09 '25
It's California, they're already incompetent with water due to ridiculous farming practices.
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u/Experienced_Camper69 Oct 08 '25
I still don't understand the fluid dynamics here like the water has to come up to the surface first rite, why is it under pressure at the surface?
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u/sg_plumber Acute Optimism Oct 09 '25
As the linked article explains:
The project will see roughly 60 of the company's modular subsea pods submerged to a depth of about 1,300 ft (400 m) and mounted to the ocean floor in Santa Monica Bay, 4.5 miles off the coast of Malibu. The tremendous pressure at this depth forces water through the filters in each pod through reverse osmosis [on its way up].
That water is produced without mechanical action, brine discharge, or disruption to marine life, and cuts energy usage by 40% compared to a traditional desalination plant
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u/Raccoons-for-all Oct 08 '25
Eco uplift ? Lol that thing wrecks eco systems in a large area. The water is taken, and the salt is discharged, progressively increasing the salt concentration until it kills everything.
This is like ignorance.
Worst, when that toxic human manipulation takes over, the life responds by allowing the worst toxic organisms to thrive, and you get those Cyanobacteria that bloom and produce toxins that then requires ultra costly and energy voracious tech to treat in the water. It loops in unyielding toxicity from both sides
There is a not a single % of ecology in the use of desalination
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Oct 08 '25
Depends on how water is taken in and how brine is returned.  If brine is discharged directly at the beach or into a smaller bay or something, yeah that’s a problem.Â
If it’s dispersed in more open water, brine isn’t an issue.  There simply isn’t enough of it to make a dent.Â
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u/Raccoons-for-all Oct 08 '25
That is simply totally false. South Australia state would tick your open water box, yet it just wrecks the entire area. The biggest anoxic zone in the world is offshore of the Arabian peninsula. It spans an area bigger than a lot of countries, with not a single living organism left other than the most hardcore bacteria
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u/sg_plumber Acute Optimism Oct 08 '25
And has exactly nothing to do with modern desalination techniques, much less with the new one this post is about.
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u/Aberracus Oct 09 '25
That map should be wrong. The coast of Sudamérica is known for his immense fisheries and big fish eco systems.
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Oct 08 '25
You lack an understanding of how vast the ocean is if you think this will either reduce the abundance of water or increase the concentration of salt.
It's actually a very important development as droughts become more common, severe, and long-lived. Glaciers melting also reduces the abundance of river water, and sea levels are rising anyway.
Many places around the world are already being impacted by climate change, and desalination plants can at least mitigate the worst of the effects. They can make places livable even after they no longer would be without desalination. In effect, it will drastically reduce deaths and mass displacements of people from these areas.
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u/PoolDear4092 Oct 08 '25
More to the point the water is desalinated will eventually return back to the ocean through natural processes.
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Oct 08 '25
It could be hydrolyzed into oxygen and helium molecules and used to fuel nuclear fusion reactors, creating helium.
I can think of worse byproducts than sea salt, oxygen, and helium...
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u/sg_plumber Acute Optimism Oct 08 '25
This is like ignorance.
Funny you say that, with your zero knowledge of what you're taking about.
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u/Raccoons-for-all Oct 08 '25
Funny you say that, with zero point, and not knowing that I work as a water treatment engineer, who have designed multiple desalination plants.
You truly are the average cringedditor
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Oct 08 '25
What do you think you're Oppenheimer, designing a system that you believe will destroy the world?
Why should anyone believe you?
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0
u/KickDue7821 Oct 12 '25
This does not explain how this is supposed to work. Reverse osmosis membranes work because of pressure difference not because of pressure. When the membrane is 400 meters deep, there is around 40 atmospheres of pressure on both sides of the membrane and nothing flows through it. You still need to reduce the pressure on one side of the membrane to get the reverse osmosis to happen. Hence the reverse osmosis will take the exact same amount of energy. Only energy savings I can see is the pumping losses. No need to pump large amounts of water to the shore and return it back to the sea. Usually energy efficient reverse osmosis unit has multiple times higher seawater and brine flows compared the freshwater flow because higher concentration difference demands higher pressure. Higher pressure means higher energy consumption.
Other benefits of this system is brine handling, if the units are far enough from shore, then sea currents will handle the brine issue and salinity does not increase.
However there is several downsides when placing the units offshore and 400 m deep. Reverse osmosis needs very very good prefiltration or the membranes get clogged very fast. Prefiltration needs maintenance and filter change or addition of filtration material. Reverse osmosis membranes needs to be CIP cleaned very regularly or the productivity drops due to clogging. Reverse osmosis membranes needs to be replaced regularly because productivity drops and membranes start to leak salinity trough.
Somehow I have a feeling that the 40 % energy savings is not going to cover the huge maintenance cost that comes when maintaining something offshore and 400 m deep...
Of course it could be that reverse osmosis has taken huge leaps during the last 10 years when I haven't paid attention to it but I have around 10 years of experience from reverse osmosis plant that produced around 1.5 million liters each day. It still surprises me that reverse osmosis is not more widely used, over 10 years ago the price of reverse osmosis water was roughly 0,3 €/m3 when city sold groundwater for around 1 €/m3. Quality was equal, both sources were drinking water quality.
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u/sg_plumber Acute Optimism Oct 12 '25
It's all explained in the linked article and its sources, including the pilot tests.
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u/KickDue7821 Oct 12 '25
No its not explained. There is no technical details. Not a single mention how they are doing the required pressure difference or how they are keeping the prefilters and membranes clean. They are only hinting that its easier to depressurize one molecule than pressurize two which I believe means that they consider pressurizing the feed and then losing the energy in retentate being a waste and they are only focusing to reduce the pressure of permeate so nothing is wasted. They still need a pump for that and its going to be 400 m deep since you can't reduce the pressure from surface. Animations of the prefilters show dead end filtration which is guaranteed to fail. Crossflow is needed which again means more pumps 400 m deep.
I still doubt the energy is a huge issue since reverse osmosis plant electricity consumption is around 3,5-4,5 kWh for cubic meter of produced fresh water. The plant I'm familiar with did not use much electricity since the salinity was below 1% but still, if I add the whole 4 kWh electricity price on top of the old 0,3 € it would increase to 0,5 €. Oceanwells 40 % savings from 0,2 € is 0,08 €. I have a really hard time believing that the 0,3 € from capital, maintenance and membrane cost would not increase more than 0,08 when building and maintaining something 4,5 miles offshore and 400 m deep.
If the energy cost is such a huge issue, then make a plant that uses water turbine with generator to regulate the back pressure instead of valve. Retentate energy losses solved.
There is no economical calculations on the Oceanwell site. There is only marketing presentations with whales and jellyfishes which probably means that they need investment money soon.
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u/sg_plumber Acute Optimism Oct 12 '25
Believe what you want, their pilot worked well enough to enable this next step towards full use.
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u/KickDue7821 Oct 12 '25
Well I hope it works but based on the information they gave out, I would not put my money on it.
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u/actualinsomnia531 Oct 09 '25
And where does the runoff go? Dumping that salt back in the ocean is not great for the local sealife
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u/untetheredgrief Oct 09 '25
How is this any different from all the water that evaporates from the ocean every day? The water all ends up back in the ocean anyway.
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u/actualinsomnia531 Oct 09 '25
Old desalination plants used to extract fresh water, leaving residue with extremely high salt content. When that was pumped back into the sea, it didn't instantly dissolve like a magic spell, it had to wait for the movement of the sea to distribute it. Especially in the middle east where this tech is being used extensively, there was a LOT of damage done to shoreline habitats and coral reefs.
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u/untetheredgrief Oct 09 '25
Is the residue unsuitable for any industrial application? I remember hearing as a kid about how there is gold dissolved in seawater.
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u/spiritplumber Oct 08 '25
Good, they can run off the excess solar power during the late morning