|
|
|
|
|
|
|
What the World
Needs Now is an . Drinking Water from Thin Air
|
Previous Issues |
|
A while back, I saw a demonstration of device which could
pull enough water from thin air to keep an insulated tank full of a few gallons of clean
pure cool water. The unit was plugged into an AC wall outlet but did not need any
plumbing. I think this is a wonderful idea. It sure beats man handling bottled
water jugs. |
|
The system I saw used a refrigeration method to capture the
water using a simple condensation technique. Air laden with water vapor is passed
over chilled metal plates, causing dew to form on the plates. The dew is siphoned
off, filtered, sterilized and then dumped into the insulated storage tank. I’m
wondering if such a system might work outside, powered by a solar panel. The solar
panel would be mounted high on the pole, to keep it out of harms way. A small wind
mill on top of the pole might also work. Such systems might be scattered out in a
desert or on hiking trails, well away from any power or water source. A flag and
even a blinking light might be mounted on top of the pole, so people some distance away
would know where to get water. It could be a real life saver. |
|
Instead of the refrigeration method perhaps there are other
ways to extract water from the air. There are some materials which can act as a
water sponge. The sponge would be a solid material with a very high affinity for
water vapor. Once it has captured sufficient water, the material might be heated by
the sun, to drive off the water, where it is condensed and stored. The high temperatures
during the sweating process would also kill any bacteria in the water. The water
would then be held in a storage tank, perhaps containing as much as 10 gallons. The
dry sponge material would get recycled to capture more water. |
|
Another classic technique to extract water from air is
to use the air itself as a refrigerant gas. Air is compressed with a rotary
compressor. This process heats the gas. The hot gas is then routed
through a number of radiator coils exposed to the ambient air. The cooler
compressed gas is then sent to an expander. This rapid decompression cools the air.
The cooler air can’t hold onto much water, so water precipitates out. The
pipes routing the cool air in the expander can also help to condense more water by
fans blowing air over the coils. I like this method since the compressor is
the only moving part. Some energy would be needed to pump the collected water
through the filters and into to the storage tank. UV lights might be added to
sterilize the water. An interesting experiment would be to see if concentrated
sunlight, which has a lot of UV light in it, could be used to help with the
sterilization process. |
 |
 |
|
No Plumbing Water
Maker |
Water Fountain |
| |
|
 |
 |
| Wind
generator and Solar Panel |
Wind
generator and Solar Panel |
 |
Let’s see if this is practical. Hot dry
desert air will have a low relative humidity. After some research and
calculations, this works out to about 4 grams of water per cubic meter of air.
A cubic meter contains about 35 cubic feet. A single fan might be able
to move about two cubic meters of air each minute. If we assume that
only 50% of the water contained in the volume is actually captured, then about
4 grams of water per minute could be collected, even during the driest
conditions with just one fan. Two fans might generate 8 grams per
minute. This may seem like a pretty small amount but it does add up.
If you run the two fans continuously for 24 hours each day, then 11,520 grams,
11.5 liters or 3 gallons of water could be captured each day. This seems
like a reasonable amount. A 10 gallon reservoir would be filled in less
than four days. To maintain that 10 gallon tank, as water is drawn off by
users of the system, it might be nice to size the solar panel so the system
could operate day and night by storing the excess power during the day for
night operation. If a wind generator were included, then both power
systems might be able to keep the water collection system running
continuously. For some popular locations, say on a popular hiking trail,
three gallons of water per day may not be enough. This means the system
would have to be scaled up by collecting more air. |
|
12v 67cfm Muffin Fan |
|
|
|
|
|
|
|