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This Solar-Powered Device Converts Air
Into Water Even at Low Humidity
“This is a major breakthrough in the long-standing challenge
of harvesting water from the air at low humidity.”
into a collector.
Upon placing the prototype, with a kilogram
of the MOF material, on the roof of an MIT
building for 12 hours, it collected 2.8 liters of
water under conditions of 20 to 30% humidity.
One of the paper’s senior authors from
Berkeley and discoverer of MOFs more than
two decades ago Omar Yaghi said that this
is a major breakthrough in the long-standing
challenge of harvesting water from the air at
low humidity.
There have been several attempts towards
converting air into water. One of them is Water-
Gen, which uses a system that optimizes
condensation through a set of plastic “leaves”
to funnel air in various directions.
Now, researchers from MIT and Berkeley have
developed their own version in case we do not
have water to consume anymore. It is solar-
powered and works in low humidity.
The harvester they invented uses a material
known as a metal organic framework (MOF)
which extracts the water from the air. What
it does is combine metals with organic
molecules to form porous structures which are
excellent in storing gases and liquids.
“There is no other way to do that right now,
except by using extra energy. Your electric
dehumidifier at home ‘produces’ very
expensive water,” he said.
For now they used that MOF material,
but Yaghi believes that other MOFs could
potentially double the present absorption
capacity of the current MOF which is 20% of
its weight in water. The device could have a
higher efficiency as well when there is a better
harvesting technology.
“There is a lot of potential for scaling up the
amount of water that is being harvested,” said
Yaghi. “It is just a matter of further engineering
now.”
It can have different compositions which in
turn store various substances like hydrogen,
carbon dioxide, or natural gas.
In the case of this research, they used an MOF
derived from zirconium metal and adipic acid,
enabling the device to harvest water vapor
from the atmosphere.
The MOF is heated by the sunlight which
allows the water to get into a condenser of
the same temperature as the outside air. The
vapour condenses into liquid form and drips
Water Leaders • May 2017
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