News that doesn't receive the necessary attention.

Saturday, May 16, 2015

Water for Chile desert trapped by fog catchers-BBC

May 16, 2015, "Trapping humidity out of fog in Chile" BBC, by Fellipe Abreu and Luiz Felipe Silva


The dry, red earth could almost be mistaken for a Martian landscape.

It is in fact the Atacama desert in Chile, one of the driest places on Earth.

Average rainfall here is less than 0.1mm (0.004 in) per year and there are many regions which have not seen any precipitation for decades.

But while there is little rain, the clouds here do carry humidity.

Coastal fog forms on Chile's shore and then moves inland in the form of cloud banks. The locals call it "camanchaca".

The fog is made up of minuscule drops of water which are so light they do not fall as rain. During a particularly severe drought in 1956, scientist Carlos Espinosa Arancibia had an idea.

The retired maths and physics professor from the University of Chile carried out a series of experiments in the highest hills near the city of Antofagasta.

There, he came up with the idea of the fog catcher: netting with tiny openings of approximately 1mm across to capture the tiny water droplets in the fog.

The droplets accumulate in the netting and form a bigger drop which eventually runs off the netting into a canal underneath.

From there, it is channelled through a pipe to containers at the base of the hills, ready for use. And the research continues today.

The town of Pena Blanca boasts one of the biggest study centres for the fog catchers. There are six big nets in the hills overlooking the town. 

Technical adviser Nicolas Schneider says that thanks to the fog catcher they have managed to combat the desertification of the region.

He says that 100 hectares now are again covered in the flora once typical for the region.

"We're planning to provide local families with water from the fog catcher in the near future," Mr Schneider says.

At the heart of the community is a small building which also uses water from the fog catcher: the town's small artisanal brewery.

Fog Catcher Brewery is small. It only produces has three vats and one cold store producing about 24,000 litres per year, but it is the pride and joy of its owner, Miguel Carcuro.

"The water from the camanchaca is of excellent quality and gives our beer a special quality," he says. 

The project's backers say the fog catchers are cheap and sustainable.

An average-sized fog catcher of 40sq m costs between $1,000 (£635) and $1,500 depending on the material used. 

They say its impact on the environment is minimal as the metal posts can be discreetly hidden among vegetation.

As the water is transported down the hill by gravity, there is no extra cost involved for transport, they say.
 
It is an idea which has been exported to other arid regions in Peru and Mexico. 

The largest expanse of fog catchers is located in Tojquia in Guatemala, where 60 fog catchers trap 4,000 litres of water a day. 

Prof Pilar Cereceda of the University of Chile says she hopes that within a decade Chile will have enough fog catchers to supply the whole Atacama region. 

"I dream of the day in which the fog catchers can compete with desalination plants, which is not environmentally friendly.""

Image caption: "Fog catchers are nets which can catch minuscule droplets of water," F. Abreu



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