Passing Through
Image: Anne Lummerich
American chemical engineers have created a new generation of fog nets inspired by the toktokkie beetle. Chilean architects have redesigned flat fog collectors as spiralling fog-catching towers. Can these two creations collect enough water to feed growing communities?
Technology in pictures
Engineers' story
Distinctive hydrophilic bumps and hydrophobic grooves enable the beetle to catch fog.
Image: Jennie Hills - Science Museum, London
An inspiring insect
The Namibian desert beetle survives by drinking fog water that collects on its shell. Chemical engineers at Massachusetts Institute of Technology (MIT) are working with researchers at the University of Oxford and the Natural History Museum, who discovered the shell’s structure, to mimic its amazing qualities.
‘Fog accumulates on rough bumps on the beetle’s back and trickles to its mouth through smooth waxy grooves,’ explains Shreerang Chhatre from MIT. ‘We are working to recreate this artificially in the lab, by coating a mesh with a smooth water repellent and tiny synthetic particles to create a rough water-collecting surface.’
Lab tests using fog machines have produced promising results.
Image: Shreerang Chhatre
Holey does it
Making a good fog catcher is not as simple as creating a larger version of the Namibian desert beetle’s shell…
‘If we built a large beetle shell, the solid surface would force the wind and fog around, so it wouldn’t work,’ says Shreerang. ‘We have to maximise the surface for the water to attach to, but still allow the wind to pass through and bring the fog with it. So we’re experimenting to get the net mesh right. We’ve made a special coating to spray onto nets that mimics the water-loving molecular structure of the beetle’s back.’
The spiral hexagonal shape of the coastal fog tower is designed to provide multiple fog-catching surfaces. Image: Alberto Fernandez Gonzalez/ Susana Ortega Gomez
Reach for the skies
Architect Alberto Fernandez and industrial designer Susana Ortega have created a coastal fog tower in Chile. Their aim is to improve stability and durability, compared to the simple rectangular fog nets.
‘The added height should increase the amount of water caught, as the tower can reach into denser, faster fog higher off the ground,’ explains Alberto. ‘We used computer models to test our theories. The real tower was built in 2010 and survived an earthquake. But it won’t be collecting fog until summer 2012, so we’ll have to wait for the results.’
This concept design shows the envisioned 200 metre fog tower.
Image: Alberto Fernandez Gonzalez/Susana Ortega Gomez
Cloud-scrapers
The chemical engineers and fog tower designers believe it’s important to create fog collectors which are affordable and can be set up in rural areas. But could fog also be harvested on a bigger scale?
‘We imagined what it would be like to build a fog skyscraper,’ says Alberto. ‘Unlike our prototype, this wouldn’t be made of wood and has a more complicated shape. The water would be collected into a filtering system before being channelled out. Built along a coastline, these towers could form the backbone of a new farming region.’
What the experts think
Fog mainly blows in with the prevailing wind from the coast when it descends over the city of Lima, Peru. Image: Anne Lummerich
What potential?
‘Fog collectors are used in ten developing countries. They’ve got great potential, they’re cheap to buy, need minimal maintenance and don’t require power.’
But he’s not sure if current research into beetles and towers is the right approach.
‘Changing the surface of the mesh may affect the rate at which the water drains, but I don’t think it’ll change the amount of water collected. Also, fog usually approaches from one direction. This means several sides of an expensive tower collector may be unproductive.’
With fog nets people can catch their own water rather than travelling long distances to fetch it.
Image: Flickr/Rudy A Giron
Water to spare...
For those who live without access to mains water, having a personal supply from fog collectorscan transform daily life.
‘In past years we always had to travel for a kilometre or more to fetch water in containers by donkey,’ says Leonso Funes Ramos, a grandfather and community leader living in Guatemala.
‘This summer we haven’t had water shortages due to the collectors. We’ve had enough water – to drink, to wash, to give the animals. We’ve even had water to spare.’
A community comes together to build a reservoir for collected fog water in Peru.
Image: Anne Lummerich
Coming together
Fog collection was proved to work many years ago, but the bigger challenge has been to get communities to embrace and sustain it.
New projects now focus on community participation, which has wide-reaching benefits, as Melissa Rosato from FogQuest explains:
‘We wanted to break the unhealthy cycle of dependency on aid seen in development work. The people now feel empowered by their new knowledge that enables them to use fog nets and provide water for their families.’
Water from expensive private water trucks can be the only option for families without a mains water supply.
Image: Anne Lummerich
Source of income
Anne Lummerich and Kai Tiedemann, from the organisation Alimon, have set up fog collectors with communities who live on the outskirts of Lima, Peru, the second largest desert city in the world.
‘Fog collectors can be a source of income,’ says Anne. ‘People sell the water or use it to irrigate cash crops. They also save money by not buying water from the trucks. Since the work can be done close to home it’s a great benefit, especially for parents who have to provide for their kids and look after them.’