one method of harvesting water from thin air

saw a great video today on a pretty approachable way to pull water from the air.

https://www.youtube.com/watch?v=xsNNp9N2v9Y

Fog nets work great in places that get fog, which would mostly be along the coasts. I loved the perpetually foggy skies in the video.

They don't work inland because fog is so rare.

John,

Thank you for posting this, it is a great idea and really needs serious implementation even here in the USA.
Places like California that get a bunch of water from states further inland. In this study quoted below, it is an
area equivalent to 1.5 times the size of California, 8 states.

The watersheds that supply drinking water to 80% of California’s resident cover almost 157
million acres and span 8 states (Figure 1). These watersheds drain lands that include highly
protected areas (e.g., wilderness areas) and those that have been developed (e.g., downtown
Sacramento). From the map, it is clear that the Sierra Nevada mountains are an important
source of water for the state of California, providing snowmelt for the many lakes and rivers
that drain into the Sacramento and San Joaquin rivers. These rivers, in turn, supply water to the
Sacramento-San Joaquin Delta, a water source that serves roughly 25 million Californians via
the State Water Project. In addition, most southern California cities obtain some of their
drinking water from the Colorado River, which originates in the mountains of Wyoming and
Colorado, and then passes through and drains portions of Utah, New Mexico, Arizona, and
Nevada until it reaches Lake Havasu, on the border between Arizona and California. There, it is
diverted into the Metropolitan Water District’s Colorado River Aqueduct which carries the
water 242 miles to southern California.

Source: http://www.nature.org/media/california/california_drinking-water-sources-2012.pdf

I am including a few different websites and quotes below if people want to learn more.

A single 13ft long by 33ft high net alone can collect 66 gallons of water a day, sufficient for a
family's needs. The water, which is pure and does not need to be filtered, runs down into troughs
and then via pipes into a holding tank.

Source: http://www.fogharvesting.com/fogharvesting.pdf

Large mesh structures, of hundreds of square meters each, could be set up relatively inexpensively; once in place, they cost virtually nothing to operate. They consume no energy, needing only an occasional brushing to remove particles of grit and bugs. “The operating cost is essentially zero,” McKinley says, because “nature has already done the hard work of evaporating the water, desalinating it and condensing the droplets. We just have to collect it.”
Chilean investigators have estimated that if just 4 percent of the water contained in the fog could be captured, that would be sufficient to meet all of the water needs of that nation’s four northernmost regions, encompassing the entire Atacama Desert area. And with the MIT-designed system, Park points out, 10 percent of the fog moisture in the air passing through the new fog collector system can potentially be captured.

Source: http://news.mit.edu/2013/how-to-get-fresh-water-out-of-thin-air-0830

http://www.fogquest.org/

This video is of The Brew Dogs harvesting water with nets to make San Fransisco beer.
https://www.youtube.com/watch?v=Hsuj_TMf5cg

kind of cool to think about how just a small trickle of water in an area that is otherwise dry could start the beginnings of a lush oasis or even a rainforest with a good plan.

I have tried harvesting fog, and not all fog is the same, even in one location. I've seen these kinds of videos and read articles that I feel are quite misleading, as if this is a given, that everyone can do it, and it will provide all the water anyone needs for crops and a household. It's just not true. It's all about location, location, location, and even then it's sporadic.

Some fog is just fog that doesn't even make a windshield wet. Some fog is drizzly and that can provide some water, but the type of surface you get it to condense on is crucial. I've never gotten anything from netting. I have gotten runoff from a tarp over a car canopy structure, but it isn't that much. I can get maybe 3 gallons of water off of a 20x14 foot canopy, with the help of a lot of gutters and 4 garbage cans, that don't do well in the wind, which happens more than the wet fog, so I really don't bother with it anymore. That drizzly fog only happens once in a while, even when it's fog season, so it's not a reliable source, unless you are in some of these places that they have really committed lots of surfaces to get the fog to condense on. A neighbor of mine 2 miles away can get more than I can, so even though we may both be covered in fog, we don't get the same results.

Their website.

http://creatingwater.nl/en/projecten/

Fog doesn't condense onto a surface cos it is already condensed as fog. So while fog nets work it's not the same as the condensation on your windows or metal car roof in the mornings. That is water vapour that has condensed on contact with the surface due to the surface being at or below the dew point. It's an important distinction because when fog collects on a fog net it doesn't alter the combined temperature of the fog and the net. But when vapour condenses heat is released as part of the process of condensation. So you could start with a surface below the dew point but after some condensing has been achieved, the surface will warm and reduce/cease condensation.

While there is winter fog in the Atacama (central and southern), often blindingly thick, there is also a heavy mist (all the Atacama and a little further North along the Ecuadorian central coast). You can get soaked through in a few minutes. All you need is surface area. The primary limitation is that the mist layer is not always at ground level, so you need to get your surface area elevated. If you are on a high hill or in the foothills of the Andes then you are in a better position to harvest water. There used to be extensive cloud forests at the cloud band, but they have disappeared in Peru and have been significantly reduced in Ecuador. Where trees have been cleared, surface area is significantly reduced, water stays in the air, surface and ground water dries up. When trees are restored, the streams and springs return.

There are not many areas in the world where this type of water harvesting is workable, the Namib being the only one that comes to mind, though there are probably others.

Mike,

I apologize for spouting off before reading through all the posts in detail. I am glad to see the netting work successfully in the coastal hills near San Francisco. It is certainly a resource that could be utilized. So as to save suffering through the entire Brew Dogs episode, the water harvesting begins at about minute 17.

Though my experience in San Francisco is limited, I don't remember the fog being particularly "misty". I assume the locals will know where and when to find harvestable fog.

Condensation was the wrong word, my bad choice of words. Even San Francisco does not have fog all year 'round. Between October and April there isn't much fog at all. So it is not a reliable source of water. And, yes, there is some wet fog that will be harvestable. I've done it, as I've said, on many kinds of surfaces. it's very random about how much is collected from day to day.

But if someone is led to believe that all fog gets you gallons and gallons of water, it's not true. It isn't a constant source. And if someone buys property with their hard earned money they should not ever, ever rely on a random source of something that others want to believe will get them enough water to "green their desert" or change their growing situation.

And please let's remember that website organizations that ask for money online are only going to paint a rosy picture. People who give money online should expect full factual results of what they are contributing to, and be able to leave objective comments on the website as to whether projects are actually producing what they are claiming, not just read the paragraphs written by the people who want money.

At my place we had dew about 3 times during this growing season. That was really weird, and threw me out-of-kilter. My garden is only typically wet if I am actively irrigating. Within an hour of stopping irrigation, the leaves are usually dry, and within a day the surface of the ground is dry.

I wont say I am above making a post about a subject that I only have miniscule information of.

I try not to assume I know more than the average bear(or permie), I don't. I am not posting out
of a feeling of being slighted. Just sort of a 'general' "this is where I am coming from statement."

I have lived in Iowa, the northwestern area, I have lived in the Des Moines area, center of the state,
I have lived in the Phoenix metropolitan area extensively. And now I have a home in West Virginia, western
side of the state. The weather in each area is different, even in Iowa from one side of the state to the other.
On the northwestern side the ambient air temperature year round is 39 degrees, yes there is a ton of cold
weather that makes the Spring/Summer weather seem fleeting when you have a ton of below zero weather.
In Arizona the ambient average air temperature for Flagstaff area is 65 degrees, in Phoenix it is 85 degrees.
Huntington, West Virginia is 60 degrees. All these temperatures are in Fahrenheit. None of these areas have
reliable fog patterns, they all get foggy though but I would hate to rely on any measurable year round water
accumulation.

This is where I got the West Virginia weather data: World Climate
The Arizona and Iowa statistics were from years ago and may have changed some, but when the numbers
are so drastically different they tend to stick in my brain. It is a pretty cool resource, it even tells monthly
average(I had to add all the months and divide by 12), it tells of rainfall for areas measured, etc.

The areas in the video, if someone would care to watch, do have measurable fog days. I can't remember which
area it was but they said there was 8 months of fog weather. Knowing that they could plan for dry periods.

When I offer thoughts they are always specific to myself, I can't speak for anyone else. I do know people
will put positive or negative spins on information when it is beneficial for them to do so. I was amazed how
carbon footprints were so extensively used by certain political candidates, especially one's that had a company
that profited from this. Yes, I am sure universities that rely on grants may need to color their results. We all
sometimes are guilty of certain leanings. I would hope/pray that if the world lacks clean water whatever could
be done to fix that would be done.

Mike

Mike and all,

Restricting these projects to areas with predictable heavy mist, like the Atacama and Namib deserts, I am confident that they would be beneficial. It would be no less reliable than waiting for rain or snow in any other arid or semi-arid region.

I think that the success of this technology highlights the devastating impact deforestation has had on that region. Imagine what Lima would have looked like 500 or 1000 years ago, with its hillsides dotted with millions of trees (scrubby, but effective) that grabbed water from the air, depositing it into the soil. Any fog(mist) harvesting project ought to coincide with reforestation efforts. I believe there is at least one that integrates the two.


Joseph,

I have often thought that it would be advantageous to harvest the ice fog that curses our valleys during long dry Winter inversions. Any ideas?