Passive gray water refrigeration?

[chiefdanfox]

What about Mohammed Bah Abba's pot-in-pot system for veggies, other perishables?
Simple Idea:
Two clay pots of different diameters, small one inside of the larger, the space is filled with sand, which is kept moist (use grey water?). As the moisture evaporates from the larger pot, it cools the temperature of the interior pot (where the food is) by a few degrees. This guy got the Rolex award for this, and it looks like it could be made very inexpensively, and might be a great way to get rid of some of the gray water.
No? Maybe the addition of a holding tank and a dripper to feed water into the sand? I'll make a mock up of this, and I can test it in pretty dry, 100 degree temps. I'll let you know.

I have never been on the playa, but my guess is that the "sand" is too fine to use, and there may be prohibitions to harvesting the playa, although the amount looks small (post hole till?)

There is a nice two-page pdf with pictures:
www.cross-current.com/pdf/lowtechcooling.pdf

[ibdave]

I have never been on the playa, but my guess is that the "sand" is too fine to use, and there may be prohibitions to harvesting the playa, although the amount looks small (post hole till?)

There is a nice two-page pdf with pictures:
www.cross-current.com/pdf/lowtechcooling.pdf

Looks like a great Idea.. But you would have to bring your own sand and take it back with you. The Playa is to fine and lock the moisture in to fast. I would think it wouldn't allow the grey water to seep deep enough..
Thanks for the post.. it's very interesting

[phil]

I have never been on the playa, but my guess is that the "sand" is too fine to use, and there may be prohibitions to harvesting the playa, although the amount looks small (post hole till?)

It's not sand at all, but a very fine powder. Adding water turns the powder to something akin to cement, so you'd get one use, then you'd have a cement that holds the two pots together.

Using real sand, the system does look like a way to use grey water, although the sand would then be 'contaminated' and have to be disposed of off the playa.

Additionally, post holes are discouraged on the playa, although allowed. See
http://www.burningman.com/preparation/e ... nment.html
and search for "digging holes" for more information. You could not use the contaminated dirt to refill the pos tholes. (The page I link to says "potholes," but I think they mean post holes.)

[chiefdanfox]

I figured that the playa was mostly evaporite minerals, so a bag of sand. If this thing works, I'll just bring it as is. I guess adding a little bleach to the grey water, or at least into the sand at some undefined interval would kill the microbes, and I could just spread the sand around the yard when I get home. That is about like I thought. I'll make one, and throw a thermometer inside, and see if is worth hauling out to the playa.

[capjbadger]

After looking at that PDF and from what I know of the process, it seems they left out a couple critical details. The outer pot must be unglazed so it is porous to the water. That will give you a larger surface area for the water to evap from and should provide better cooling. Also the inner pot should be glazed so that the grey water does not leach into the area where your food is. I'd bet the ceramic would filter it pretty well, but why take the chance, eh?

[diane o'thirst]

I'd stick with a cooler because a pot would break easier, spilling the sand and wrecking your evap fridge. The ice meltwater can be used to bathe/cool your feet. My neighbour brought her bougainvillea one year and watered it with her cooler meltwater.

I understand you can keep shell eggs in a pot of oil if you keep it in the shade.

[chiefdanfox]

Good point on the inner pot being glazed, but unsure, since I assumed unglazed on both, thinking that microbes can't make it through an unglazed ceramic filter, which is used on ceramic filter purifiers. Perhaps it boils down to the mineral used in the ceramics. Anyone know the math? 20 microns, 10 microns (40 microns?) to filter harmful microbes? Not worried about viruses, since I am not fixing to strain the portapotty water.
I also dig the comment about breakage, but if this thing gets broken in my camp, then there are also broken bones and large lacerations to deal with; certainly an outside mark, but not one I am necessarily preparing to deal with. I doubt a little grey water is of any concern over splinting legs and pools of blood. I mean really. I have not heard that there is open warfare on the playa...I guess I should bring the trebuchet?

I just thought it might be cool to bring a little green into the mix. I know coolers are easier, as long as the electricity holds. It takes a fair amount of burning coal to make the eiswurfel.

[capjbadger]

Yeah, coolers are easier. I built my own out of my icechest. Poped a hole in the top, stacked a couple peilter junctions, a simple heat sink on the cold side and a heatsink w/fan on the hot side. Slaped that bad boy in the hole and hooked it up to my battery bank and solar panels.
Damn thing starts iceig over in a couple minutes. I hope it will pull heat out of the cooler that seeps in and cuts my ice use. I'll let everyone know how well it worked after the burn.