6 ms·

Fog-harvesting system could provide potable water for the world’s driest regions

18 points by interconnector 13y ago

dalke 13y ago
This title is a bit of an over-exaggeration. As the article says, "Systems to make use of this airborne potable water already exist in at least 17 nations." The title implies that it's relatively new technology. For some historical background, an early fog harvesting project started in Chile in 1987, and the success from that kicked off projects in other countries. (Based on a cursory search I just did.) The linked-to article then clarifies the importance of this new work: "But the new research shows that their efficiency in a mild fog condition can be improved by at least fivefold, making them far more feasible and practical than existing versions."
- schiffern 13y ago
  Fog harvesting's a lot older than that. The Bimbache people used a communal fog-harvesting tree to provide water on an otherwise uninhabitable island in what's now the Canary Islands. They led the drip lines to gravity-fed channels, which directed water straight to their dwellings. Clever systems like this demonstrate what we already knew — that indigenous people were (and are) no dummies. http://en.wikipedia.org/wiki/Garo%C3%A9 http://en.wikipedia.org/wiki/Garo%C3%A9 http://archive.org/stream/mobot31753002257217#page/152/mode/2up/search/Canary http://archive.org/stream/mobot31753002257217#page/152/mode/...
  - aaron695 13y ago
    As wiki says it's just a legend.
    - schiffern 13y ago
      Sorry about that; I didn't check if wiki was actually accurate. That'll teach me to trust an uncited article. :\ Check out the other link.
  - dalke 13y ago
    Interesting! Though in reviewing the second link I find very little that was definite. It recounts things second- and third-hand. Some claim a single tree could provide water for 8,000 people and their animals, another said for 80 families. Some say it was a single tree, others from multiple trees. You say "otherwise uninhabitable land", but Brown's 1910 guide book points out that people lived there, grew grains, and pastured animals. As there are "practically no springs", people needed to build cisterns to catch rainwater. The translated Spanish document (from the last 1500s?) says there are three streams on the island, and that the tree (which was not seen by the Spaniard) is a third type of water source. Since the 1910 inhabitants didn't use this tree as a water source, I presume that cisterns and those small springs were enough for them, and so would have been enough for the Bimbache. For that matter, how did the first Bimbache live there if it was otherwise uninhabitable. Did they need to find the tree(s) before they could settle? You write "which directed water straight to their dwellings" but Duret (1605) writes that the tanks of water were at the foot of the tree, and that the remnants from the 1612 storm were still there in 1753. But I don't see anything in those accounts about channels or pipes leading the water to people's homes. (The Wikipedia page says "The Bimbaches later filled water chaffs and water was transported to towns to all parts of the island", but as part of a legend, and without a citation.) This is not me rejecting the idea that fog collection was done before the 1980s. Indeed, the Wikipedia page for 'Fog collection' lists several "natural or assisted" collection methods. Nor am I rejecting the idea that the Bimbache used trees as a fog collector. What I'm commenting on is that the information I've read is suggestive, but not definitive, and that what I've read doesn't fully match with what you wrote here. What I would like to see might include measurements of water run-off from one of those trees, growing in the same area and archeological evidence of an irrigation system, rather than carrying water from cisterns. BTW, I really like one of the accounts in that second link about that sense of astonishment by the British scientists at Cape Town who, 110 years ago or so, found out that the fog around Table mountain provides a huge amount of water.
    - schiffern 13y ago
      Yes, it seems I overstated their dependence somewhat. Obviously water is important, so you want redundant systems so you have water in both rainy and dry times. Multiple systems on different scales (family, village, and island) is a possible explanation for the disparate accounts. Even today most human systems come in different scales. >Since the 1910 inhabitants didn't use this tree as a water source, I presume that cisterns and those small springs were enough for them, and so would have been enough for the Bimbache. That depends on how many inhabitants and what they're doing. I can't find historical population numbers, unfortunately. Today's population of ~10,000 uses industrial desalination. >But I don't see anything in those accounts about channels or pipes leading the water to people's homes. Check out pp 156: "It falls into a pond made of brick, floored with stones very tight, by pipes of lead conveyed from the tree to it, and thence divided into several ponds through all the island. They which dwell up-hill fetch it in barrels." All in all, a fascinating technology. It's amusing how the western accounts attribute everything to luck/God, but that's colonialism for ya. ;) (If you can't tell, I'm a fan of Clarke's [revised] Third Law, "Any sufficiently advanced technology is indistinguishable from nature." It's even been proposed as a solution to the Fermi paradox: http://www.nextnature.net/2012/02/any-sufficiently-advanced-civilization-is-indistinguishable-from-nature/ http://www.nextnature.net/2012/02/any-sufficiently-advanced-...)
ForFreedom 13y ago
That would not be applicable in desert regions.
- NotHereNotThere 13y ago
  How so? From reading around a bit, I found several sources that indicate fog is present in the desert.
  - lutusp 13y ago
    There's no basis for the idea that there is never fog in the desert, as long as there's sufficient water vapor. But a very dry desert climate cannot fog up for lack of water vapor. Remember that fog forms when temperature and dew point collide. But without water vapor, there's no meaningful dew point. http://en.wikipedia.org/wiki/Dew_point http://en.wikipedia.org/wiki/Dew_point Quote: "The dew point is the temperature below which the water vapor in a volume of humid air at a given constant barometric pressure will condense into liquid water at the same rate at which it evaporates."
Core-TX 13y ago
Hmmm, that reminds of Arakis. Are they called windtraps ? ;)
- bjterry 13y ago
  Or moisture vaporators in Star Wars, which Luke's uncle and aunt owned.
tocomment 13y ago
If h2o is heavier than other components of air like o2 and nitrogen why can't we just run air through a giant centrifuge to get the water out?
- schiffern 13y ago
  Because that's more expensive than a sheet?
- aaron695 13y ago
  Generally with these schemes the fog is from the ocean so you have unlimited saltwater to desalinate, the idea is to get water with little energy cost.
sologoub 13y ago
If used on a large scale, I wonder how this would affect the environment around the collection sites. As is now, the fog goes somewhere and I'm sure some organisms rely on it getting to where it's going. If the water is collected with enough efficiency, there could be significant unforeseen consequences.
cz20xx 13y ago
Tatooine

dalke 13y ago

This title is a bit of an over-exaggeration. As the article says, "Systems to make use of this airborne potable water already exist in at least 17 nations." The title implies that it's relatively new technology. For some historical background, an early fog harvesting project started in Chile in 1987, and the success from that kicked off projects in other countries. (Based on a cursory search I just did.) The linked-to article then clarifies the importance of this new work: "But the new research shows that their efficiency in a mild fog condition can be improved by at least fivefold, making them far more feasible and practical than existing versions."

schiffern 13y ago
Fog harvesting's a lot older than that. The Bimbache people used a communal fog-harvesting tree to provide water on an otherwise uninhabitable island in what's now the Canary Islands. They led the drip lines to gravity-fed channels, which directed water straight to their dwellings. Clever systems like this demonstrate what we already knew — that indigenous people were (and are) no dummies. http://en.wikipedia.org/wiki/Garo%C3%A9 http://en.wikipedia.org/wiki/Garo%C3%A9 http://archive.org/stream/mobot31753002257217#page/152/mode/2up/search/Canary http://archive.org/stream/mobot31753002257217#page/152/mode/...
- aaron695 13y ago
  As wiki says it's just a legend.
  - schiffern 13y ago
    Sorry about that; I didn't check if wiki was actually accurate. That'll teach me to trust an uncited article. :\ Check out the other link.
- dalke 13y ago
  Interesting! Though in reviewing the second link I find very little that was definite. It recounts things second- and third-hand. Some claim a single tree could provide water for 8,000 people and their animals, another said for 80 families. Some say it was a single tree, others from multiple trees. You say "otherwise uninhabitable land", but Brown's 1910 guide book points out that people lived there, grew grains, and pastured animals. As there are "practically no springs", people needed to build cisterns to catch rainwater. The translated Spanish document (from the last 1500s?) says there are three streams on the island, and that the tree (which was not seen by the Spaniard) is a third type of water source. Since the 1910 inhabitants didn't use this tree as a water source, I presume that cisterns and those small springs were enough for them, and so would have been enough for the Bimbache. For that matter, how did the first Bimbache live there if it was otherwise uninhabitable. Did they need to find the tree(s) before they could settle? You write "which directed water straight to their dwellings" but Duret (1605) writes that the tanks of water were at the foot of the tree, and that the remnants from the 1612 storm were still there in 1753. But I don't see anything in those accounts about channels or pipes leading the water to people's homes. (The Wikipedia page says "The Bimbaches later filled water chaffs and water was transported to towns to all parts of the island", but as part of a legend, and without a citation.) This is not me rejecting the idea that fog collection was done before the 1980s. Indeed, the Wikipedia page for 'Fog collection' lists several "natural or assisted" collection methods. Nor am I rejecting the idea that the Bimbache used trees as a fog collector. What I'm commenting on is that the information I've read is suggestive, but not definitive, and that what I've read doesn't fully match with what you wrote here. What I would like to see might include measurements of water run-off from one of those trees, growing in the same area and archeological evidence of an irrigation system, rather than carrying water from cisterns. BTW, I really like one of the accounts in that second link about that sense of astonishment by the British scientists at Cape Town who, 110 years ago or so, found out that the fog around Table mountain provides a huge amount of water.
  - schiffern 13y ago
    Yes, it seems I overstated their dependence somewhat. Obviously water is important, so you want redundant systems so you have water in both rainy and dry times. Multiple systems on different scales (family, village, and island) is a possible explanation for the disparate accounts. Even today most human systems come in different scales. >Since the 1910 inhabitants didn't use this tree as a water source, I presume that cisterns and those small springs were enough for them, and so would have been enough for the Bimbache. That depends on how many inhabitants and what they're doing. I can't find historical population numbers, unfortunately. Today's population of ~10,000 uses industrial desalination. >But I don't see anything in those accounts about channels or pipes leading the water to people's homes. Check out pp 156: "It falls into a pond made of brick, floored with stones very tight, by pipes of lead conveyed from the tree to it, and thence divided into several ponds through all the island. They which dwell up-hill fetch it in barrels." All in all, a fascinating technology. It's amusing how the western accounts attribute everything to luck/God, but that's colonialism for ya. ;) (If you can't tell, I'm a fan of Clarke's [revised] Third Law, "Any sufficiently advanced technology is indistinguishable from nature." It's even been proposed as a solution to the Fermi paradox: http://www.nextnature.net/2012/02/any-sufficiently-advanced-civilization-is-indistinguishable-from-nature/ http://www.nextnature.net/2012/02/any-sufficiently-advanced-...)

ForFreedom 13y ago

That would not be applicable in desert regions.

NotHereNotThere 13y ago
How so? From reading around a bit, I found several sources that indicate fog is present in the desert.
- lutusp 13y ago
  There's no basis for the idea that there is never fog in the desert, as long as there's sufficient water vapor. But a very dry desert climate cannot fog up for lack of water vapor. Remember that fog forms when temperature and dew point collide. But without water vapor, there's no meaningful dew point. http://en.wikipedia.org/wiki/Dew_point http://en.wikipedia.org/wiki/Dew_point Quote: "The dew point is the temperature below which the water vapor in a volume of humid air at a given constant barometric pressure will condense into liquid water at the same rate at which it evaporates."

Core-TX 13y ago

Hmmm, that reminds of Arakis. Are they called windtraps ? ;)

bjterry 13y ago
Or moisture vaporators in Star Wars, which Luke's uncle and aunt owned.

tocomment 13y ago

If h2o is heavier than other components of air like o2 and nitrogen why can't we just run air through a giant centrifuge to get the water out?

schiffern 13y ago
Because that's more expensive than a sheet?
aaron695 13y ago
Generally with these schemes the fog is from the ocean so you have unlimited saltwater to desalinate, the idea is to get water with little energy cost.

sologoub 13y ago

If used on a large scale, I wonder how this would affect the environment around the collection sites. As is now, the fog goes somewhere and I'm sure some organisms rely on it getting to where it's going. If the water is collected with enough efficiency, there could be significant unforeseen consequences.

cz20xx 13y ago

Tatooine