Thursday, July 5, 2007

Water From Air, Low-Tech Style

Water From Air, Low-Tech Style
Tracy Staedter, Discovery News

June 15, 2007 — Leaves and spiderwebs beaded with dew have inspired a low-tech solution for collecting fresh water.

WatAir, an inverted pyramid made from elastic canvas, recycled polycarbonate, metal or glass, can reap dozens of liters of water a day from the air. The inexpensive solution could help bring clean drinking water to people in remote or polluted areas.

"The design has minimal special demands. It is low-tech and low-cost, and in fact can be even produced with local means," said Joseph Cory, a PhD candidate at the Technion-Israel Institute of Technology and an architect at Haifa, Israel-based Geotectura Studio.

Cory and colleague Eyal Malka of Malka Architects recently won first place for the invention in the "drawing water challenge" sponsored by WaterAid, an international nonprofit dedicated to providing safe domestic water to poor nations, and U.K.-based Arup, a firm specializing in sustainable designs.

Cory and Malka were inspired by the passive way dew gathers on leaves, spider webs, even on sleeping bags and tents. They designed a four-sided structure shaped like an inverted pyramid, with each panel about 10 feet tall.

At night, dew drops bead up on both the tops and undersides of the panels. Because the dew collecting on top may contain dust, dirt or insects, that water could be used for irrigation. But dew from the underside is drinkable.
Gravity draws the drops downward into tanks, wells or bottles at the bottom.

A structure 315 square feet in size can extract a minimum of 48 liters of fresh water daily. But the dimensions can vary, said Cory, from a small personal unit that fills a water glass to several large-scale units that provide water for a community.

The low-tech approach requires only low-cost materials and is quick and easy to deploy, said Cory. WatAir can be built locally, but is durable enough to be dropped by parachute from a plane.
The cost could be offset by printing sponsor logos or advertisements onto the canvas sheets.

"It is simple, practical, adaptable, sustainable, flexible and draws inspiration from nature resulting in a minimal intervention with potentially a big impact," said Frank Lawson, a senior engineer at Arup.

Cory and Malka are also looking into modifications to WatAir that could help produce energy.

They are currently investigating embedding photovoltaic cells into the canvas to convert sunlight into electricity. The energy could be used to power electrical appliances or charge batteries. Or it could be used to cool the surface of the dew panels, which would allow the structure to produce water all day long.

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