1y ago

Desalination system could produce freshwater that is cheaper than tap water

news.mit.edu Desalination system could produce freshwater that is cheaper than tap water

A new solar desalination system takes in saltwater and heats it with natural sunlight. The system flushes out accumulated salt, so replacement parts aren’t needed often, meaning the system could potentially produce drinking water that is cheaper than tap water.

MIT engineers and collaborators developed a solar-powered device that avoids salt-clogging issues of other designs.

More details in their paper here

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Wonder if this is the most reposted article on all of Lemmy?

If I can get a dollar everytime I see an article like this...
- If I can get 10 dollar every time this article is reposted...

The researchers estimate that if the system is scaled up to the size of a small suitcase, it could produce about 4 to 6 liters of drinking water per hour and last several years before requiring replacement parts. At this scale and performance, the system could produce drinking water at a rate and price that is cheaper than tap water.
But can it be scaled up even more? Like cubic meters per hour?
- I just keep waiting for them to actually produce the small suitcase sized product. It sounds like a excellent option for me, as opposed to the $4-5k desalinators that are the options now.
- but why "if"?
  if they're making this research, why wouldn't they "scale up to the size of a small suitcase" and get rid of the "if"?
  
  That's just how research works most of the time. The experimental setup required to build a working prototype and prove the initial hypothesis is always going to be larger and more complex than a mass market appliance. If that appliance ever gets built depends on a huge number of factors too. If the process scales as expected, how complex the device is to produce and if a company thinks that it can make money on it. The researchers, meanwhile, are probably more worried about their next grant funding.
  
  My guess: They don't have the money to do so.

Does it come with or without micro plastics?
- It will certainly comes with a preposterous amount of salt to deal with. That's a critical limiting factor with desalination.
  
  I thought the salt level in the input rises. So you could cycle the input with fresh salt water and pump the higher salt content stuff back to sea.

I find it hard to trust "science journalism". It's always "could" and "if"...
I'll believe it when I see it working. .
- Extreme salt-resisting performance with concentrated seawater To demonstrate the long-term resistance to salt accumulation enabled by TSMD, we conducted a 180-h continuous desalination test of 20 wt % concentrated seawater under 1,000 W m2 (Figures S25 and S26). The corresponding cumulative heat input was 180 kWh m2 , equal to the total solar irradiance of z45 days. 23 Figure 5A shows the saline temperature change of a single-stage TSMD device during the 180-h continuous desalination. The temperature of confined saline layer remained stable throughout the test, indicating reliable heat transfer performance. Figures 5B and 5C show the mass change of the collected freshwater and the resulting water Figure 5. Extreme salt-resisting performance of TSMD when desalinating 20 wt % concentrated seawater (A) Saline temperature as a function of time. Periodic temperature fluctuations were observed throughout the test, indicating the existence of strong thermohaline convection. (B) Real-time mass change of the collected water during the 180-h continuous test. (C) Water production rate as a function of time. The production rate was averaged with a 10-h time interval. A stable production rate was maintained throughout the 180-h operation. Error bars indicate standard deviations. ll Joule 7, 2274–2290, October 18, 2023 2285 Article production rate during the 180-h continuous desalination. The linear profile of mass change (Figure 5B) during 180-h operation indicates a stable water production rate without degradation in performance (Figure 5C). Note that in conventional reliability tests, a cycling operation was adopted. In each cycle, there was a 3–6 h operation under one-sun illumination, followed by a 21–18 h waiting period without solar illu- mination to emulate the nighttime condition and allow the salt rejection (Table S2). In our reliability test, however, we created a more stringent procedure by performing a 180-h continuous test and removing all waiting periods. Considering the salinity (20 wt %) of concentrated seawater used for our test, the total amount of salt rejected during the 180-h operation is equivalent to the accumulated salt in seawater desa- lination (3.5 wt %) throughout z229 day cycling operations (Note S3; Table S2). With the superior salt-resisting capacity, the estimated device lifetime shows 1 order of magnitude improvement compared with the state-of-the-art designs (Table S2).
  The paper is very cool though!! Maybe we are all looking towards a future with plenty of fresh water!

ib4whatdowedowiththesalt
- Sprinkle it on roads during the winter and have it wash back into the ocean, whence it came?
  
  We already have plenty of salt for that.
  Plus the places that are good for solar power don't tend to need salt in the winter...

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