Case study: how to collect water?
Where a Namibian beetle teaches us how to collect water efficiently. A device to extract water from air conditioning systems is being adapted from the tool designed by a Namibian beetle to survive in one of the hottest places on earth.
Stenocara eburnea - Creative Commons
Why this study?
How does it work?
One of the solutions proposed to take up the challenge could be inspired by
the amazing system developed by Stenocara, a beetle living in the Namib Desert,
to collect drinking water from periodic fog-laden winds. This water-collecting
ability is critical to the survival of the beetle as the Namib Desert is one of
the hottest places on earth where rainfall hardly reaches 12 mm a year.
Short-lived early-morning fogs coming from the sea pass over the desert sands
only about six times a month.
Andrew Parker (Oxford University) and Chris
Lawrence (QinetiQ) studied the structure of Stenocara's back and figured out how
the beetle captures water from the wind (*):
Stenocara's elytra, the hardened outer pair of wings, are covered with large bumps. The peak of each bump is smooth and attracts water. Tiny rounded nodules, no wider than a human hair, cover the slopes of each bump and the troughs in between. The nodules are coated in wax, making them hydrophobic. When the fog rolls in, the beetle tilts its body into the wind. The water droplets from the fog are repelled from the nodules but stick to the peaks of the bumps. The droplets grow until they are large enough to roll down from the top of the peaks and are channeled to a spot on the beetle's back that leads straight to its mouth.
Stenocara's bumpy armor offers a good model for designing technologies to collect water for drinking and for agriculture in arid regions. Oxford University and UK defence research firm QinetiQ are collaborating to develop such devices. Prototypes have shown that these are several times more effective than net harvesting methods used to collect water from fog in remote mountain towns of Peru and Chile. On the other hand, a device based on the Namibian beetle is under manufacture in the UK and in USA to extract water from air conditioning systems (**).
Sources:
- (*) Nature, vol.414, 1 November 2001, p33
- (**) Design patent No. PCT/GB02/000671
