Decentralized Desalination

I’m always intrigued by technologies which deviate from the old style “huge factory, huge output” model - things like solar power or residential farming. Here’s one for desalination, which claims to produce 4-6 liters of potable drinking water per (sunlight) hour from salt water:


Solar sea water purification units were SOP for Navy pilots for decades. They were an inflatable sphere, with a structure inside that evaporated the seawater, then recondensed, and collected. the fresh water at the bottom, for consumption.



The problem with the navy model is that it does not function continuously, the high salt content water has to be removed and fresh sea water added. This seems to have been solved with the new model.

When scaled up to the size of a small suitcase, the system could generate 4 to 6 liters of drinking water per hour and remain operational for several years. At this size, it may be more cost-effective than tap water to provide drinking water.

I have seen several versions of single use devices for campers. The problem to solve is the continuous unattended functioning and sufficient volume to make it practical.

The Captain


The research paper indicates that hypersalinated waste water discharge is a key design consideration to solve for scaled production.

Like solar panels, this works passively in direct sunlight. Unlike solar panels, there is a delay to production wherein the process must be energized to begin water circulation. It would be interesting to see how this works even at the Meter scale (exposed working surface is 1sqm).

They postulate production at scale, but their working prototypes are 10cm2 and use “sunlight power” of 1Kw/m2 of artificial energy.

I’m not shooting holes, but suggesting the promised theoretical maximum production is just that: a theoretical maximum.

I may have missed it, but their economic models rely on extended service intervals to amortize the initial costs. I didn’t see their time scale basis for “order of magnitude drop in cost per unit of freshwater” to support the “cheaper than tap water” claim.

Very interesting technology, here.

For the science geek, they provide rough instructions for how to make the device in the paper.

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