

Self-filling water bottle turns humidity into drinking water for cyclists - davidbarker
http://news.distractify.com/pinar/kristof-retezar-fontus/

======
pmontra
Half a liter in a few hours is way less than a cyclist needs. This is
renewable and a bottle isn't but I can pack much more water in the volume of
the device and get other water when I stop. If I can't find water maybe I'm in
bigger troubles than half a liter can save me from (in a desert, really?).
It's not worth it.

However, put a bigger device on a car or on a boat and that can be useful.

~~~
Havoc
>Half a liter in a few hours is way less than a cyclist needs.

I guess you can use it to top up then. e.g. Bring 1 litre instead of the 2 &
rely on this to cover the shortfall.

>It's not worth it.

Not yet. Cutting edge near prototype stuff rarely is "worth it".

------
lern_too_spel
Cyclists drink half a liter per hour in cool conditions. In the hot, humid
conditions necessary for this to produce its maximum of half a liter per hour,
they should drink at a much higher rate.

~~~
mslev
I can see this being pretty useful for long touring rides, where you're riding
for a long time but not necessarily pushing very hard.

~~~
Someone
_" After more than 30 experiments, I finally achieved a constant drop-flow of
one drop of condensed water per minute"_

Guessing the diameter of a drop at 1mm, and assuming it to be cubic, that is
60 cubic mm per hour. Rounding up, we get 1 cc per hour. A U.S. teaspoon is
just under 5 cc. Alternatively, get a small cup of water every 24 hours.

There can be about 30 cc of water in a cubic meter of air, so you would have
to pump 16 cubic meter of air through this thing and extract all the water to
get at 500cc per hour. With a 10 by 10 cm opening, that is a 1600m long
column. A bicycle can easily do ten times that speed, so that sounds doable,
but that is at maximum efficiency and the article doesn't say he has done
that, so I fear that 500cc is wishful thinking.

~~~
lern_too_spel
Straight from the article:

"Under the right climatic conditions, Fontus can easily produce half a liter
of water in an hour's time."

We already know that it can produce half a liter per hour, but those same
climatic conditions are when a cyclist needs significantly more than half a
liter per hour.

~~~
Someone
I read that differently. On the one hand, there is the experimentally
confirmed drop a minute. On the other hand, they do not state that that half
liter has been confirmed experimentally.

I still doubt that number. Looking at
[http://atmosphericwatersolutions.com/wp-
content/uploads/2012...](http://atmosphericwatersolutions.com/wp-
content/uploads/2012/03/AquaBoy-Flyer-PDF-2.pdf), I see a machine that weighs
38 kg, consumes 373W of power, and produces 'up to 17 liters of water a day'.
This thing would be an order of magnitude smaller, and produce almost the same
quantity of water. Possible? Maybe. Likely? No. Because of that, I would like
to see experimental confirmation of that half a liter per hour before
accepting it as a given.

Also, see
[http://en.m.wikipedia.org/wiki/Atmospheric_water_generator](http://en.m.wikipedia.org/wiki/Atmospheric_water_generator)
which claims the U.S. army and FEMA use a system that needs a gallon of fuel
for 'up to' five gallons of water. If something like this were known to be
more efficient, I think it is likely they would use it.

~~~
lern_too_spel
The aquaboy data sheet only goes up to 25°. At 30°, it would produce more than
a liter per hour.

------
NickNameNick
I wonder what the power requirements are,

The cooling system has to be cooling the air that passes through it down to
the dew point, if the ambient temperature and the dew point are too far apart,
it's going to consume too much power to be practical.

~~~
miahi
It also looks solar powered-only, so its efficiency is not better when the dew
point is closer (night/morning).

Linking a small solar cell (I would say ~1W from the shown surface) to a
Peltier element (known power hog, a really small one takes at least 4W) is not
a solution for efficiency.

~~~
NickNameNick
Wolfram alpha says it takes ~1.3kj to change the temperature of 1m^3 of air by
1 degree C. Obviously this will vary enormously with temperature and humidity,
but it gives us a number to work with.

Wikipedia, and a post by 'someone' tells us there is ~30cc of water per cubic
meter of air at 100% humidity and 30c. (This could be a reasonable set of
envoronmental conditions in Washington DC for example).

The mass of water in 100% humidity air is

28c 27.22g
[http://www.wolframalpha.com/input/?i=mass+of+water+in+1+cubi...](http://www.wolframalpha.com/input/?i=mass+of+water+in+1+cubic+meter&f1=28+%C2%B0C&f=MoistAirMoistureContent.Tdb_28+%C2%B0C&f2=1+bar&f=MoistAirMoistureContent.P%5Cu005f1+bar&f3=100+%25&f=MoistAirMoistureContent.RH_100+%25)

30c 30.34g
[http://www.wolframalpha.com/input/?i=mass+of+water+in+1+cubi...](http://www.wolframalpha.com/input/?i=mass+of+water+in+1+cubic+meter&f1=30+%C2%B0C&f=MoistAirMoistureContent.Tdb_30+%C2%B0C&f2=1+bar&f=MoistAirMoistureContent.P%5Cu005f1+bar&f3=100+%25&f=MoistAirMoistureContent.RH%5Cu005f100+%25)

So we can extract ~3g, or 3cc of water from saturated air, with the use of
~2.6kj (assuming 100% efficiency, which is unlikely)

Some of the highest power density batteries I've handled are 5 cell, 5500mAh
li-poly batteries for model aircraft use, with a total energy capacity of
around 180kj,

Or ~ 200g of water.

I think I'd rather carry a water bottle.

------
davidw
Here in Italy, every little town has at least one water fountain; often near
the church or town square. Even in the summer, if you're good about stopping
often, you could probably get by with just a small water bottle.

------
tzakrajs
For some reason I wouldn't want to drink the water after biking through a
swampy area.

------
Icybee
If you cycle through areas with a lot of traffic, could the water end up
contaminated with vehicle exhaust?

~~~
e12e
I'm pretty sure most harmful exhaust would be more harmful when breathed in,
than when drunk?

~~~
notfoss
Sorry to be pedantic, but if you are pretty sure, then how come you end your
sentence with a question mark?

~~~
iterationx
You don't sound sorry.

~~~
neals
I didn't hear any sound at all.

------
anonu
The lack of electrolytes in the water could actually be extremely dangerous
for a biker. I don't see how this issue is addressed.

~~~
nether
Same with lack of food. Solution: carry it with you.

------
tiku
it needs a piss recycle system that humidifies the air it takes in, tada,
faster filled bottle.

~~~
lafar6502
and has all the electrolytes...

------
Havoc
Thats genuinely impressive. I'd be concerned about the lack of electrolytes
though? Presumably cyclists would need to top those up too.

~~~
lafar6502
If you're concerned about electrolytes, I just invented a much better solution
- just wringe your t-shirt after a ride and pour the water into a bottle,
you'll have all the ions back

------
sitkack
I had a similar design but it was fixed use, like a wind mill but produced
water. Same concept.

------
pbhjpbhj
It's a great idea, but it's going to need a lot of dev to become a product.

------
polskibus
Fantastic! One step closer to making Fremen and Dune technologies reality!

------
thinkling
Kickstarter plz.

