New low cost, highly effective way to produce fresh water

[George_SD]

No more need for expensive watermakers. This can be DIY-ed.

https://news.utexas.edu/2022/05/23/l...om-desert-air/

The team developed a low-cost gel film made of abundant materials that can pull water from the air in even the driest climates. The materials that facilitate this reaction cost a mere $2 per kilogram, and a single kilogram can produce more than 6 liters of water per day in areas with less than 15% relative humidity and 13 liters in areas with up to 30% relative humidity.....


The researchers used renewable cellulose and a common kitchen ingredient, konjac gum, as a main hydrophilic (attracted to water) skeleton. The open-pore structure of gum speeds the moisture-capturing process. Another designed component, thermo-responsive cellulose with hydrophobic (resistant to water) interaction when heated, helps release the collected water immediately so that overall energy input to produce water is minimized.


“It’s straightforward enough that anyone can make it at home if they have the materials.”

Making the film requires only the gel precursor, which includes all the relevant ingredients poured into a mold.

“The gel takes 2 minutes to set simply. Then, it just needs to be freeze-dried, and it can be peeled off the mold and used immediately after that,”

[Zanshin]

Umm, the "freeze-drying" process is both time-consuming and energy intensive and also requires expensive equipment. The common household freeze-drier is a Harvest Right and cost around $5K and is far too bulky to be used aboard a sailboat. But it could be used as an emergency one-off backup watermaker that doesn't take up much weight.

[George_SD]

I think it is only needed in order to let the gel set correctly. Maybe even a regular freezer could do it, if given more time.

Once created, material appears to be stable.

[GordMay]

SHPF presented a stable performance for 14 cycles per day at 15% RH (70 min capturing and 30 min releasing) and 24 cycles per day at 30% RH (30 min capturing and 30 min releasing), respectively.

“Scalable super hygroscopic polymer films [SHPF] for sustainable moisture harvesting in arid environments” ~ by Youhong Guo et al

”... With rapid sorption-desorption kinetics, SHPFs operate 14–24 cycles per day in arid environments, equivalent to a water yield of 5.8–13.3 L kg−1 ...
... The key steps of atmospheric water harvesting (AWH) involve moisture capture and water release, followed by a simple filtration or purification process ...
... Thermoresponsive HPC permits controllable interactions between polymer chains and water molecules, realizing the release of water within 10 min to achieve 14 sorption-desorption cycles at 15% RH and 24 cycles at 30% RH per day ...
... The captured water in the SHPF can be released by >70% within 10 min through mild heating at 60 °C ...”

Open Access Paper ➥ https://www.nature.com/articles/s41467-022-30505-2

[flightlead404]

idk about this, but I did just read of another technology out of MIT which was a suitcase sized desalinator based on electrolysis.

http://https://news.mit.edu/2022/por...ast%20Company.

Their prototype generates drinking water at a rate of 0.3 liters per hour, and requires only 20 watt-hours per liter.

Pretty slow production, I have no idea of the energy efficiency compared to traditional watermakers.

[leecea]

If I read all the material correctly:

- they were using a film thickness measured in micro-meters, then quoting the amount of water produced per kg of film. I can't imagine how many square meters of 100 micro-meter film would weigh 1 kg but I assume it is a lot.
- their system diagram showed the collected water going through a treatment step before it could be used. They did not mention what was required in that step.
- they appeared to estimate that 4 kWh of electricity was required per liter of water. Not completely sure about that number.

[Tellie]

Originally Posted by leecea

If I read all the material correctly:

- they were using a film thickness measured in micro-meters, then quoting the amount of water produced per kg of film. I can't imagine how many square meters of 100 micro-meter film would weigh 1 kg but I assume it is a lot.
- their system diagram showed the collected water going through a treatment step before it could be used. They did not mention what was required in that step.
- they appeared to estimate that 4 kWh of electricity was required per liter of water. Not completely sure about that number.

4,000 Wh for a liter of water?

[Rumrace]

Thanks GEOrge. Great info and thread

[hzcruiser]

If it's that easy why aren't there lots of products out there ready to go and produce water by condensation? Every A/C is doing it, but they need a fair bit of power for that...

[waterman46]

Originally Posted by hzcruiser

If it's that easy why aren't there lots of products out there ready to go and produce water by condensation? Every A/C is doing it, but they need a fair bit of power for that...

I have wondered if normal AC unit condensation could be collected in useful quantities. Most cruising is done in tropical areas with very high humidity. But with any of these alternate technologies, a purification step is needed - lots of nasty bugs can collect and reproduce in the condensate. The purification will require either UV or heat, so more power needed if you want to drink it.

[contrail]

Originally Posted by flightlead404

idk about this, but I did just read of another technology out of MIT which was a suitcase sized desalinator based on electrolysis.

http://https://news.mit.edu/2022/por...ast%20Company.

Their prototype generates drinking water at a rate of 0.3 liters per hour, and requires only 20 watt-hours per liter.

Pretty slow production, I have no idea of the energy efficiency compared to traditional watermakers.

Quite poor. A good Spectra watermaker will get you a gallon and a half for those same 20 watts. Cruise RO is more like 2 quarts. Perhaps the folks at MIT don't know about all the watermakers available.

[ChrisJHC]

Originally Posted by contrail

Quite poor. A good Spectra watermaker will get you a gallon and a half for those same 20 watts. Cruise RO is more like 2 quarts. Perhaps the folks at MIT don't know about all the watermakers available.

I’m sure the prototype of the Spectra wasn’t as efficient as they are now.
Sounds like an interesting technology that could be useful once it’s mature.

[contrail]

Originally Posted by ChrisJHC

I’m sure the prototype of the Spectra wasn’t as efficient as they are now.
Sounds like an interesting technology that could be useful once it’s mature.

Actually, the first Spectras made eight gallons per hour with a draw of 8 amps per hour, which is every bit as efficient as the one's today. And the original Recovery Engineering Power Survivors (now Katadyn) made 1.4 gallons for 4 amps. So, this new technology has a way to go. I hope they do make it, but they are overstating their advantages, for the moment.

[odonnellryan]

Originally Posted by contrail

Quite poor. A good Spectra watermaker will get you a gallon and a half for those same 20 watts. Cruise RO is more like 2 quarts. Perhaps the folks at MIT don't know about all the watermakers available.

Poor but does not require filters or the maintenance and space the average watermarker requires. Also seems like it will be much cheaper and hopefully reliable.

[Caleb_Grey]

Originally Posted by ChrisJHC

I’m sure the prototype of the Spectra wasn’t as efficient as they are now.
Sounds like an interesting technology that could be useful once it’s mature.

They've been working on it for 10 years and millions of dollars and all they have to show for it is 2 gallons a day and a $100,000 prize they gave themselves, oh and 10x the energy use of a typical desalination device.