A researcher is trying to improve
fog harvesting by improving the mesh used. This is a good idea.
Taking it a bit farther, I suspect
that one liter production per meter is quite attainable. That then suggests that a simple sail rig
carrying a ten by ten meter mesh will be able to produce 100 liters of
water. A little experimentation could
give us something more compact and even easier to manage. In the meantime I am quite happy to rig a
simple sail operating edge on to any wind and draining into the root mass of an
adjacent tree.
In that way we can walk a forest
up a coastal zone quite easily since an established forest will produce its own
humidity and capture much of its own water taking much of the burden away from
the sails.
On top of that it is bound to be
very cheap and need little maintenance.
We can now envisage going to a
ruined coast where we establish a break of mangroves at the water’s edge and
plant trees inland as far as the fog takes you with these fog sails. In time the newly established forest will stabilize
and permit further expansion inland producing wealth for the growers.
Namib Beetle inspires new 'fog harvesting' research
By Ben
Coxworth
21:55 April 26, 2011
Mesh being tested for use on fog-harvesting devices by Shreerang
Chhatre and colleagues at MIT (Photo: Patrick Gillooly)
For years, people living in high-altitude or coastal arid countries
have been collecting drinking water by harvesting fog. More specifically,
they've mounted pieces of fine netting over top of containers, left the setup
overnight, then collected the fog droplets that got caught in the net and
rolled down its fibers into the container. While it might sound like a rather
insubstantial way of acquiring water, under the right conditions it can yield a
surprisingly large amount of liquid. Now, a chemical engineering graduate
student from the Massachusetts Institute of Technology (MIT) is looking to
improve on the technique.
Shreerang Chhatre was inspired by the Namib Beetle, an insect that
collects water droplets on bumps on its back, then drinks them when they roll
down to its mouth. His "fog harvesters," like those created by
other scientists, use a mesh panel in place of a net. Even solid materials such
as plastic sheeting will work, although they can create wind currents that
carry some of the moisture away.
In tests of existing fog harvesters, some have been able to collect
one liter (about a quart) of water per meter of mesh, per day.
Chhatre is trying to boost that output by refining the materials that
the mesh is made from, attempting to strike a balance between hydrophilic
materials that attract water droplets, and hydrophobic materials that then send
them on their way down into the collection container. The Namib Beetle employs
a similar strategy, with hydrophilic bumps that droplets stick to, and
hydrophobic channels that allow those droplets to slide down to its mouth
without being absorbed along the way.
Much as improving the amount of water obtainable from fog harvesters is
a technical problem, it's also a social one – most of the potential users
likely couldn't afford such a device. To that end, Shreerang is hoping that
people in developed nations might also start using them, simply to offset their
consumption of fresh water from traditional sources.
The more units that are sold to such First World consumers, the lower
the prices could be for Third World recipients,
and the more accessible the technology would become.
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