Manhat water distillation - possible solution to purifying salt water

I came across something on my Facebook feed today that I thought y'all might find interesting. This company, Manhat, is pioneering some passive water desalination solutions in the UAE. Here are some relevant videos and links to get people started:









Arab News Article

Khaleej Times Article

The National News Article

Company Home Page

Alright, so as a permaculture community I thought we could collectively analyze this and determine if its viable or Solar Freakin' Roadways pt. 2 (for the uninitiated, Solar Freakin' Roadways got a lot of hype some years ago but hasn't produced much, and upon further reflection didn't make sense).

The claims of this startup are as follows (I think all of these are covered in the videos):
-Their technology can take salt water from salt lakes or the ocean and create distilled water directly on the surface of the lake or ocean
-It requires 0 electricity to operate on a day to day basis
---this is in contrast to current desalination technology which requires quite a bit of energy to distill water
-This technology could also be replicated for water transportation
-This technology does not create brine (water with heavily concentrated amounts of salt, which, as it turns out, can stay distinct from normal saltwater)
---this is also in contrast to current desalination technology which creates brine as a by-product, and then has to deal with that brine somehow

In many ways, this seems like an extremely attractive option--particularly in the driest parts of the world that also have access to large saltwater bodies. But I'm wary of hype because I am often caught in its trap then become disillusioned by uninspiring realities. So I'm going to analyze a bit of this and state some possible problems. The more scientific among us could, perhaps, correct or modify some of my initial thoughts.

1. This technology just uses the sun to create freshwater. The technology just accelerates the water cycle in a localized position and captures the water so that it doesn't return to the ocean/lake. The device is placed in the ocean/salt lake, the water evaporates during the day and then condenses in the apparatus at night. It can then be utilized immediately (though, because it is distilled, it shouldn't be drunk by humans without first adding minerals).
---problem - the sun doesn't always shine. I think this technology would be extremely useful in areas with very little cloud cover (which characterizes its place of origin) but would be less helpful in areas where fog and cloud cover dominate the climate. So, extremely useful where it's likely most needed--so probably not a big issue.

2. I don't know what these devices are made out of.
---problem - I don't know the footprint of building the apparatus nor do I know if manufacturing can be scaled

3. I like how this technology skips the electricity step. I feel like it's similar to annualized thermal inertia in that way. Why convert sunlight to electricity to heat when one can convert sunlight directly to heat? Also, I'm a fan of having as few moving parts as possible. Makes repairs more straightforward, in my very limited experience.

4. No brine? This technology purportedly does not create brine--which is a huge problem with current desalination practices. This was one claim I was a little wary about. It seems like evaporation inside the container will leave the remaining water saltier than before. I guess that the difference between this and the creation of brine is that the remaining saltwater in the apparatus can be quickly mixed within the larger body of water, spreading out the extra salt so that the overall concentration isn't a concern. This would contrast with super-concentrating the saltwater into brine and then dumping the brine back into the ocean. That's my best guess--but I'd need someone better at hydrology than me to assess what is happening.

5. How much fresh water does the apparatus produce, exactly? In the video featured in The National News article, the inventor states that the apparatus can produce enough water to irrigate one tree per day. Perhaps further iterations will produce more water, but that doesn't seem like much. If the cost is high or the material production is environmentally costly, it may be difficult to justify the technology on a large scale without producing much more water.

So does anyone have thoughts on a technology like this? Should I avoid the hype? Or could this be a game-changer?

The tech has been around for a long time. Basically a "water still" . If you want to try it out find a body of water. Set up a sheet of glass or plastic at an angle with a southern exposure. You will heat up the water, it will evaporate. As it rises it will condense on the glass or plastic. All you have to do is collect it. They just put together a design , which they will patent, and sell.

I watched the first two videos and I admit I'm still skeptical.  #2 Son is an engineer with a big interest in water scarcity, and says that if done on any sort of production scale, it will increase the local salt concentration unless the water is moving rapidly through/around the "greenhouse structure". So they may not be dumping a concentrated brine in one spot, but they're still increasing the salinity of the ocean and our oceans are already struggling. There have been plenty of solar evaporation desalination projects before on various scales - the concept works. If you want large quantities of fresh water, #2 Son thinks vacuum distillation would offer more potential.

Miles' analysis is correct. This technology has been used since forever, but some of the claims as stated are more marketing than physics. Of course it leaves a more concentrated solution of salts behind. It has to.