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Simple, solar-powered water desalination

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Re: Simple, solar-powered water desalination

#151
post #146

Earlier quoted context omitted.

Regarding remote locations- they usually lack water altogether. A long time ago, as a kid i read about a experiment in a GEO-magazine harvesting water directly from air. The used idea was a hygroscopic chemical (Silicagel) collects the moisture from the air. Sunlight heats the silica gel- which releases the moisture as steam- which then condenses in a destil. It was very little water for a lot of effort, but the comp…

You can make a solar still without desiccants. Dig a hole somewhere that will get sunlight most of the time, drop a cup in the bottom to catch water, and create a funnel with a plastic sheet. (If you don't have a plastic sheet, branches can work.) There are various ways to optimize it, but a single water trap isn't going to keep a person alive.

But if they're cheap and easy, and a person could make a dozen, that changes things a bit. But still, I think we're still talking about short term survival only. If that's your environment, the local flora & fauna are unlikely to be prolific enough to fill other needs without extensive effort. Unless, you know, you've got a Still suit and can call giant worms and stuff.

Re: Simple, solar-powered water desalination

#152
post #31

Earlier quoted context omitted.

One fascinating (well, to me) component of modern RO desalination systems is the rotary pressure exchanger. Such a simple device, but so important. It looks like something from the 19th century, but the base patent was issued in 1988. https://en.wikipedia.org/wiki/Pressure_exchanger

I found this video which seems to animate the concept nicely: https://www.youtube.com/watch?v=udffed4Pq3g

Awesome. The video made it crystal clear.

Re: Simple, solar-powered water desalination

#153
post #77

Efficiency in desalination is measured by comparing the energy expenditure to the enthalpy of vaporization of water (basically the energy required to distill water by boiling it). The current state of the art reverse osmosis desalination plants use about 3.2 KWh of electricity per cubic meter of fresh water ( https://pdfs.semanticscholar.org/d4d7/821d585699719289dddd10... ). This technology uses about 173 KWh of sola…

> For large-scale desalination, however, it is almost certainly more cost-effective to use solar panels, batteries, and large scale reverse osmosis systems. For large scale desalination, you need to attach tiny magnetic particles (think nano-scale) to the salt, and then extract it with magnets. And as a byproduct, you'll get Lithium.

Is thata dangerous byproduct? Or is the lithium isolated and of usable quality as feed stock for the battery industry?

Re: Simple, solar-powered water desalination

#154
post #9

"than 1.5 gallons of fresh drinking water per hour for every square meter of solar collecting area." Units, people. Units. Be imperial. Be metric. Hey! Be both!

I prefer all measurements of mass converted to stones, and volume converted to the volume of a 1-stone stone from the nearest drystane wall, provided the stone is one-hand wide and high.

Re: Simple, solar-powered water desalination

#156
post #9

"than 1.5 gallons of fresh drinking water per hour for every square meter of solar collecting area." Units, people. Units. Be imperial. Be metric. Hey! Be both!

It comes out to about 0.4 liters per square foot, for those of you who are confused.

It also makes the Kessel run in 1.21 JiggaParsecs.

Re: Simple, solar-powered water desalination

#157
post #9

"than 1.5 gallons of fresh drinking water per hour for every square meter of solar collecting area." Units, people. Units. Be imperial. Be metric. Hey! Be both!

It comes out to about 0.4 liters per square foot, for those of you who are confused.

Or, let's see... 5.7 millimeters!

Re: Simple, solar-powered water desalination

#160

When I was in Boy Scouts loooong ago, there were instructions and diagrams for making solar stills out of a sheet of plastic, a cup, rocks and dirt.

Same. I wonder how well they worked; I've never seen one made.

It surely would require fairly specific conditions to work well; a wet ground and low humidity.

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