MIT Researchers Build Solar-Powered Low-Cost Desalination
October 19, 2024 3:52 PM Subscribe
Without Battery storage (by way of slashdot):
MIT engineers have built a solar-powered desalination system that "ramps up its desalting process and automatically adjusts to any sudden variation in sunlight"
While traditional reverse osmosis systems typically require steady power levels, "the MIT system requires no extra batteries for energy storage, nor a supplemental power supply, such as from the grid." And their results were pretty impressive:
The engineers tested a community-scale prototype on groundwater wells in New Mexico over six months, working in variable weather conditions and water types. The system harnessed on average over 94 percent of the electrical energy generated from the system's solar panels to produce up to 5,000 liters of water per day despite large swings in weather and available sunlight... "
...The system is geared toward desalinating brackish groundwater — a salty source of water that is found in underground reservoirs and is more prevalent than fresh groundwater resources...
[snip]
The researchers' report details the new system in a paper appearing in Nature Water.
MIT:
https://news.mit.edu/2024/solar-powered-desalination-system-requires-no-extra-batteries-1008
Nature:
https://www.nature.com/articles/s44221-024-00314-6
While traditional reverse osmosis systems typically require steady power levels, "the MIT system requires no extra batteries for energy storage, nor a supplemental power supply, such as from the grid." And their results were pretty impressive:
The engineers tested a community-scale prototype on groundwater wells in New Mexico over six months, working in variable weather conditions and water types. The system harnessed on average over 94 percent of the electrical energy generated from the system's solar panels to produce up to 5,000 liters of water per day despite large swings in weather and available sunlight... "
...The system is geared toward desalinating brackish groundwater — a salty source of water that is found in underground reservoirs and is more prevalent than fresh groundwater resources...
[snip]
The researchers' report details the new system in a paper appearing in Nature Water.
MIT:
https://news.mit.edu/2024/solar-powered-desalination-system-requires-no-extra-batteries-1008
Nature:
https://www.nature.com/articles/s44221-024-00314-6
Neat! I was wondering how feasible this was earlier this year while walking by some off grid cinderblock houses built on the Mexican coastline.
posted by deludingmyself at 4:26 PM on October 19, 2024
posted by deludingmyself at 4:26 PM on October 19, 2024
This is really exciting! I hope it can be commercialized/implemented for public use in a pro-social and affordable way.
posted by cnidaria at 5:20 PM on October 19, 2024 [2 favorites]
posted by cnidaria at 5:20 PM on October 19, 2024 [2 favorites]
@deludingmyself If it's on the coast this might be a better solution:
https://news.climate.columbia.edu/2011/03/07/the-fog-collectors-harvesting-water-from-thin-air/
This article's solution will work on a lot of aquifers that don't have potable water now.
posted by aleph at 5:32 PM on October 19, 2024 [5 favorites]
https://news.climate.columbia.edu/2011/03/07/the-fog-collectors-harvesting-water-from-thin-air/
This article's solution will work on a lot of aquifers that don't have potable water now.
posted by aleph at 5:32 PM on October 19, 2024 [5 favorites]
til that the US Bureau of Reclamation has a Brackish Groundwater National Desalination Research Facility.
posted by migurski at 5:50 PM on October 19, 2024 [4 favorites]
posted by migurski at 5:50 PM on October 19, 2024 [4 favorites]
More details here: https://arstechnica.com/science/2024/10/desalination-system-adjusts-itself-to-work-with-renewable-power/
And here I found out:
“So, around 100 years ago we developed reverse osmosis and electrodialysis, which are two membrane-based desalination technologies."
It uses electrodialysis *not* reverse osmosis.
posted by aleph at 5:58 PM on October 19, 2024 [4 favorites]
And here I found out:
“So, around 100 years ago we developed reverse osmosis and electrodialysis, which are two membrane-based desalination technologies."
It uses electrodialysis *not* reverse osmosis.
posted by aleph at 5:58 PM on October 19, 2024 [4 favorites]
Pretty great but it does not state how much $ is needed.
posted by skepticallypleased at 8:24 PM on October 19, 2024
posted by skepticallypleased at 8:24 PM on October 19, 2024
"... does not state how much $ is needed."
That's in the details of the Nature paper, with supplements, that size the components.
Since so much seems to be jury rigged by what they had on hand it's more the technique than the installation. The secret sauce here seems to be the basic algorithm and how to adjust it for the components. Electrodialysis had been known and they detail the problems with previous attempts and how they've solved them with this technique.
posted by aleph at 9:52 PM on October 19, 2024 [5 favorites]
That's in the details of the Nature paper, with supplements, that size the components.
Since so much seems to be jury rigged by what they had on hand it's more the technique than the installation. The secret sauce here seems to be the basic algorithm and how to adjust it for the components. Electrodialysis had been known and they detail the problems with previous attempts and how they've solved them with this technique.
posted by aleph at 9:52 PM on October 19, 2024 [5 favorites]
What happens to all the salt?
posted by CheeseDigestsAll at 7:22 AM on October 20, 2024
posted by CheeseDigestsAll at 7:22 AM on October 20, 2024
What happens to all the salt?
There are 2 loops of water going through the electrodialysis stack. The anode side loop gets more dilute while the cathode side loop gets more concentrated. Eventually you end up with a very concentrated brine you're going to have to deal with. Maybe it even has commercial value.
posted by mikelieman at 8:11 AM on October 20, 2024 [1 favorite]
There are 2 loops of water going through the electrodialysis stack. The anode side loop gets more dilute while the cathode side loop gets more concentrated. Eventually you end up with a very concentrated brine you're going to have to deal with. Maybe it even has commercial value.
posted by mikelieman at 8:11 AM on October 20, 2024 [1 favorite]
What happens to all the salt?
This question has always puzzled me.
Yeah, the salt brine from desalination plants being dumped right back into the ocean or local aquifers is a problem because desalination plants typically don't want to deal with it, but it seems like you could send it out to evaporation ponds and just sell the salt or form a partnership with a salt producer to handle that.
We already harvest megatons of salt from the ocean. Sure, salt is pretty much cheaper than good dirt now, but t's an essential product. Put your desalination plants in places where you can process the salt and it's a win-win.
Sea salt manufacturers are basically the opposite of desalination plants and are more or less functioning as solar stills where their waste product is pure water as evaporated water vapor.
While it's probably not economically feasible to build million acre solar still greenhouses over salt evaporation ponds using plastics - it sure seems like these two industries could compliment each other and work side-by-side.
And, yeah, you usually want your desalination plants as close to population centers as possible to reduce pumping costs of clean water, and solar salt evaporation ponds need vast amount of land and are usually located farther away from population centers - but it seems that there would be a nice mid-way point and balance somewhere, and pumping clean, pure water and/or using aqueducts to move water long distances has been more or less a solved problem for thousands and thousands of years.
And if you could get large scale solar stills working you basically have free solar desalination and salt production in one shot, it's passive, and the only moving parts or power would be water pumps and mechanized salt handling machinery, and you wouldn't need plastic RO filters to do it.
posted by loquacious at 9:25 AM on October 20, 2024 [1 favorite]
This question has always puzzled me.
Yeah, the salt brine from desalination plants being dumped right back into the ocean or local aquifers is a problem because desalination plants typically don't want to deal with it, but it seems like you could send it out to evaporation ponds and just sell the salt or form a partnership with a salt producer to handle that.
We already harvest megatons of salt from the ocean. Sure, salt is pretty much cheaper than good dirt now, but t's an essential product. Put your desalination plants in places where you can process the salt and it's a win-win.
Sea salt manufacturers are basically the opposite of desalination plants and are more or less functioning as solar stills where their waste product is pure water as evaporated water vapor.
While it's probably not economically feasible to build million acre solar still greenhouses over salt evaporation ponds using plastics - it sure seems like these two industries could compliment each other and work side-by-side.
And, yeah, you usually want your desalination plants as close to population centers as possible to reduce pumping costs of clean water, and solar salt evaporation ponds need vast amount of land and are usually located farther away from population centers - but it seems that there would be a nice mid-way point and balance somewhere, and pumping clean, pure water and/or using aqueducts to move water long distances has been more or less a solved problem for thousands and thousands of years.
And if you could get large scale solar stills working you basically have free solar desalination and salt production in one shot, it's passive, and the only moving parts or power would be water pumps and mechanized salt handling machinery, and you wouldn't need plastic RO filters to do it.
posted by loquacious at 9:25 AM on October 20, 2024 [1 favorite]
If you use it for sodium battery production, you can measure brackish water in watt-hours per liter.
posted by Callisto Prime at 10:24 AM on October 20, 2024 [3 favorites]
posted by Callisto Prime at 10:24 AM on October 20, 2024 [3 favorites]
As I understand it, that may work/help for the desalination next to the oceans, local aquifers frequently have contaminants like Arsenic that makes it hard to deal with easily. Though it can always be used as a source for further processing.
posted by aleph at 10:29 AM on October 20, 2024 [1 favorite]
posted by aleph at 10:29 AM on October 20, 2024 [1 favorite]
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