Access to clean water is one of the world's most
pressing problems, but a team of University at Buffalo researchers has come up
with a new take on an old technology that uses sunlight to purify water. They
have invented a way of making the solar-powered purifiers more efficient than
the conventional ones.
Attaining drinkable and clean water is a global problem,
which needs to be addressed as efficiently as possible. Conventional Solar Stills distill impure
water using solar energy to
evaporate, cool then collect the pure water. These Solar Stills are portable
and economical since they do not need electricity to function. The researchers
decided to improve the efficiency of the evaporation process and minimize the
amount of loss of solar energy.
Led by associate professor of electrical engineering
Qiaoqiang Gan, the team has created a device that uses black, carbon-dipped
paper to produce fresh water with what is claimed to be near-perfect
efficiency. The have developed a ‘solar vapour generator’
that cleans the water through evaporation process. They used insulating
polystyrene foam and an absorbent paper coated in carbon black. The water gets
absorbed by the paper and the sunlight gets absorbed by carbon black which is
turned into heat. In this innovative method, about 88% of solar energy gets
converted into heat and the researcher are aiming to convert 100% solar energy
to improve the efficiency of the entire process.
In a solar still, seawater, dirty water, or even green
leaves are set inside a transparent plastic container, which can be as simple
as a polythene bag, and set out in the sun. The light heats the air inside the
still, encouraging evaporation. The water vapor then rises, meets the cooler
thin plastic, and condenses into liquid. This then trickles down the plastic
and is collected into reservoirs to be poured off or sucked out with a straw.
The problem is, though the process can be a literal life saver, it isn't very
efficient.
The commercial solar stills produce only 1 to 5 litres
of water; however, the new and improved solar stills can produce 3 to 10 litres
of water per day. Associate professor of electrical engineering, Qiaoqiang Gan,
has stated that the money required to produce water can be as cheaper as $1.60
per square meter, which is a lot less than the systems which require optical
concentrators.
Funded by the National Science Foundation (NSF), the Buffalo still is a
surprising advance on previous devices. Before, the theoretical upper limit was
1.68 liters (56.8 oz) per hour per square meter, but the new technology manages
2.2 liters (74.4 oz).
The team is now waiting for investors to come forward
to commercialize the device. It will certainly be a boon to those areas which
do not have effortless access to clean water.
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