Self filling water bottles

[Roll Tide]

Was watching Henry Ford Innovation Nation on TV. They has a segment on a self filling water bottle. It can extract up to .8 l of water per hour from the atmosphere. You can see it at fontus.at (Austria). Its not available now but you can sign up with your email to be notified when it goes on sale.

[Trailweaver]

Bet it could do better than that in the south, with our humidity level as high as it is!

[Greenlight]

I've seen the commercials for it, and the .8 liter is under optimal conditions. Looks promising, and the technology has been around for a long time. Imagine hiking for a couple of miles expecting the bottle to be full, and there's only half a ounce of water in there.

[Feral Bill]

I have not yet done the calculations, but I seriously doubt that getting the energy to make this happen is practical. I'll report back.

[Feral Bill]

I'm Back! To condense a liter of water you have to remove 540 Kilo-calories of energy. That equals 627.87 wall hours, or 2,142.381 271 Btu. Not gonna happen, folks, at least not as a portable unit.

[Tuckahoe]

Why do folks buy into this stuff?

[Feral Bill]

But the principle worked so well on Tatuine in Star Wars!

[Leo L.]

Best part of it is the landscape in the ads video, showing places I will touch during my 3-weeks hike starting tomorrow.

[Frye]

I remember reading about this product a few years ago while trying to keep up with all things cycle related. Back then I think they were only hyping a cycle version of the product that also seemed impractical, and looking at the non-bike version it seems just as useless.

If the product requires 'ideal conditions' to function usefully it should typically be shelved as an useful piece of gear in the backcountry. If it cannot perform its task in a variety of situations, this sort of gear becomes nothing more than a luxury item at best, and a useless brick if the meteorologist gets it wrong... I'm not bringing a product along that is supposed to provide such a vital necessity if I can't have at least some faith in it operating when I need or want it too.

It's like calling a bug bivy a shelter because it'll keep you dry in ideal conditions.

Am I really going to plan an extended route in the backcountry and ignore water sources because I have this product? No, I won't. The company though seems to be making claims to the contrary though, claims I think some could say passes as dangerous hyperbole.

A HIKER MUST EITHER PLAN HIS ROUT IN A WAY THAT HE ALWAYS FINDS FRESH WATER SOURCES, OR HE MUST PACK HIS BACKPACK VERY HEAVILY IN ORDER TO HAVE WATER FOR THE WHOLE JOURNEY. FOOD IS IN COMPARISON MUCH LIGHTER, IF WELL CHOSEN, BECAUSE YOU CAN COMPRESS IT. BUT WATER WEIGHS WHAT IT WEIGHS; YOU DON’T HAVE MUCH OF A CHOICE.
THESE PROBLEMS ARE A GREAT RESTRICTION FOR HIKERS AND OUR MAIN GOAL BECAME TO FIND A SOLUTION THAT WOULD GIVE ADVENTURERS THE FREEDOM TO GO WHEREVER THEY WANT!

I'm sure most of us would take this with a grain of salt, but these are the sort of claims that can get novices in trouble.

[Nodust]

But the principle worked so well on Tatuine in Star Wars!

The mushrooms that grew on the evaporators were worth the effort, evidently.

[Frye]

Best part of it is the landscape in the ads video, showing places I will touch during my 3-weeks hike starting tomorrow.

Is that the video that doesn't actually show the product being used until the halfway point? Some nice shots of it strapped to the pack though I guess...

[Leo L.]

Is that the video that doesn't actually show the product being used until the halfway point? Some nice shots of it strapped to the pack though I guess...

Whenever in the video you watch a hiker or a biker it's in this area.
Biking is illegal there, of course.

Anyway, a nice try to get money from the innocent...
And remembers me on the ADE 651, different category, but similar danger to the innocent user.

[waywardfool]

FOOD IS IN COMPARISON MUCH LIGHTER, IF WELL CHOSEN, BECAUSE YOU CAN COMPRESS IT.

So, they also threw Einstein under the bus? If you compress something, it gets lighter? I guess you are squeezing the dark matter out of it?

[Malto]

Completely unneeded innovation. IT still will weigh more then a quart of dehydrated water. Speaking of which..... I can't seem to find a link to the Mountain House Dehydrated water. I usually buy the water chicken and ground beef in the large #10 cans. Much better value.

[MuddyWaters]

Its certainly theoretically possible.

solar panels , fans, and thermoelectric cooling are all existing technology

The only issues are size, weight, and performance

You are limited of course to about 35F practicle temperature to avoid freezing

So that establishes the minimum % relative humidity you need for it produce any condensate. You essentially have a micro air conditioner, and you drink the condensate drain pan.

At 35 F air will hold 4.4 g water/kg air
At 68F it will hold 15 g water/kg air , this is 100% absolute humidity 4.4/15=.293 = minimum relative humidity
Any less than this, its impossible to condense from the air without temp below freezing.

So, its impossible to work at all at less than 30% relative humidity at 68F.
Low humidity places like western US,NM, Co, Ca, deserts, etc, cool dry weather, winter time, etc. Nada in moderate weather.

At this moment, denver is 96F and 10% relative humidity.At 95F, air will hold 35 g water/kg. 0.1*35=3.5g water , When cooled to 35F, its still not saturated. 3.5 < 4.4 , Will not work, no condensate will occur. Impossible to work.

Where I was in the middle east earlier this year, the relative humidity was 7-9% on hot days. At 104F, air holds 50 g water /kg air.
.08*50=4g water/kg so nope, impossible for it to have worked in the desert in middle east.

All you need to know is how much air it moves and can cool, the relative humidity, the temperature, and you know what water it can produce, and how much power would be needed for a thermoelectric cooler to work, and how big of solar panel would be required. But.. the water and air temperature will likely come now where near to 35F in this little unit, so the require humidity would probably be much much higher.

Water is ~1000 btu/lb roughly.

Some people make a career out of spending other peoples money on things that will never succeed.

[Sarcasm the elf]

I'm Back! To condense a liter of water you have to remove 540 Kilo-calories of energy.

I choose to 1) ignore the bulk of you explanation and 2) Assume that your first sentence means I can simply jam two king size snickers bars into the device and then have it metabolize them into a liter of water.

[FreeGoldRush]

I have not yet done the calculations, but I seriously doubt that getting the energy to make this happen is practical. I'll report back.

"Practical" depends largely on your need. As a homesteader it may be great. As a backpacker it is likely useless.

[colorado_rob]

This one is right up there with using "harmonized water" (or something like that) to prevent sunburn. The mind boggles.

[MuddyWaters]

Investigating this a bit further just for fun:

Lets assume the thermoelectric cooler operates at 40F, and air is 86F with 75% relative humidity.
At 40F the air holds 5 g water /kg air
At 86 it holds 27.7 g/kg. So at 75% RH, it holds 20.7. So its possible to condense 15.7 g water out of a kg of air. Or 7.8 g/lb air since I like lbs better.

so to make 1 Liter water = 1000 g takes 1000/7.8 = cooling of 128 lbs air @ 75% RH from 86 f to 40 F, with associated condensation of water

The heat removed from the air is about 128*0.25 btu/lb-F*45F=1440 btu
the latent heat removed from the water is 2200 btu roughly
The sensible heat of the water is on average, only about 50 btu

total heat load would be 3690 btu

thermoelectric would only be about 50% efficient so electrical duty would be 7380 btu to do this in one hr this would be 2163 watts of power required.

Heres the kicker...solar panels produce about 10 watts per sq ft. So lets say this thingy has 2 ft2 solar panel. It makes 20 watts

Your looking at 100 hrs to make a liter of water under optimal conditions

and of course, we didnt include the power required for the fan.

Thats 100 hrs of sunlight for solar power. 8 days ish.

Much of the time, as I described above , it would do nothing at all in many areas of low humidity.

[Feral Bill]

I choose to 1) ignore the bulk of you explanation and 2) Assume that your first sentence means I can simply jam two king size snickers bars into the device and then have it metabolize them into a liter of water.

Jam the snickers into yourself and metabolize them into water