Africa Water, Sanitation & Hygiene December 2018 Vol.13 No.6 | Page 14

Water Supply
Water is in the air
W
ith global demand for water expected to
increase by nearly one third by 2050, and
around two billion people already lacking access
to safe drinking water, it is easy to see why there is such
a buzz around innovative technologies to produce water
from the air.
It is estimated that the atmosphere contains around six
times as much water as all the world’s rivers. However,
until recently, atmospheric water generation was
often deemed too costly, too energy-intensive and too
inefficient.
Hertz says systems like WeDew could offer innovative
ways to help those who lack access to both power and
clean water. “I can envision locally-owned micro-utilities
that offer local economic opportunities for the emergent
class in developing countries,” he said.
Other innovators have developed similar systems. US
company Zero Mass Water’s SOURCE technology
involves roof-mounted solar panels that can pull on
average 4 – 10 litres a day from the air. A fan draws in the
Now innovators are combining renewable energy
technologies with cutting-edge water capturing methods
to respond to needs in some of the world’s driest places
without adding to the carbon emissions fuelling global
warming and contributing to water scarcity.
Take WeDew, the winner of this year’s Water Abundance
XPRIZE, which challenged inventors to extract a
minimum of 2,000 litres of water per day from the
atmosphere using 100 per cent renewable energy at a cost
of no more than two cents per litre.
Created by The Skysource/Skywater Alliance, WeDew
converts biomass into water and energy, while capturing
greenhouse gases.
“In simple terms, we are making a rainforest in a box, and
clouds in containers where cold and heat collide in the
form of a personal or small community-scaled energy and
water appliance,” said David Hertz, a California-based
architect who led the team that created WeDew, or Wood-
to-Energy Deployable Emergency Water.
“We have created an augmented environment that makes
the Skysource WeDew agnostic as to its climate and
matches the energy output to create over 2,000 litres of
drinking water per day regardless of climate... The device’s
main attribute is its ability to deploy rapidly and to not
only provide fresh potable water from air and dense
energy generation but also heating, cooling or refrigeration
as a by-product in a relatively compact form,” he said.
A biomass gasifier generator is used to run the system.
WeDew says it operates at less than one tenth the cost of
solar power while occupying the area of a single panel.
The gasifier is fuelled by organic by-products such as
wood chips, coconut shells or whatever biomass is locally
available. Biomass gasification superheats the material
and converts it into electricity, hot humid air and biochar,
which can be added to soil to store carbon.
In this way, WeDew not only sequesters atmospheric
carbon dioxide but turns it into a value-added product,
which helps plants grow.
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Africa Water, Sanitation & Hygiene • December 2018
water vapour and it is absorbed using a unique hygroscopic
concept that also cleans the water.
Zero Mass Water is active in Kenya, South Africa and
Australia, where it has partnered with the Australian
Renewable Energy Agency to set up a demonstration
project involving 150 hydropanels in schools, farms, homes
and water-stressed communities.
These successful innovators demonstrate the kind of
out-of-the-box thinking that UN Environment hopes will
abound at the fourth UN Environment Assembly. The
motto for the meeting is: think beyond prevailing patterns
and live within sustainable limits.
In Kenya, Majik Water uses non-toxic desiccants, like silica
gel, to capture water from the air. Air is pulled into the
device by a solar-powered fan and the desiccant absorbs
the water. Solar energy is then used to heat the desiccant
and release water vapour, which is then condensed and
filtered with activated carbon.
The proof-of-concept prototype generates 10 litres of
water per day and was shortlisted for the Royal Academy
of Engineering’s Africa Prize for Engineering Innovation
in November 2018.
One of Majik Water’s founders, Clare Sewell, says that in
the short term, water-from-air technologies are, and should
be, a niche solution to be used when clean drinking water
from natural sources is not readily available.