Fog-Catchers

While morning dew may settle and dry within a couple of hours, the persistence of fog especially in coastal areas creates a valuable resource for irrigation. Students at the University of Washington have been producing mist and testing various materials to create a long-lasting and efficient fog catching system over the past year.

Fog catching is in no way a brainchild of the 21st century. Inhabitants of the Canary Islands 2,000 years ago used trees to capture water droplets. These days however, with much of the forests having been cut down in countries such as Peru, man-made fog catchers are being used to irrigate land and provide water to villagers.

How fog catchers work is actually quite simple. A mesh plastic net is held up by poles and while the layers of fog move through the nets, water droplets settle and eventually drip down into a bucket. More complex systems such as one in the highlands of Guatemala use piping and divert the water that’s collected, about 2,000 gallons a day, to supply a village of 200 people with a reliable flow of water.

Under the supervision of Susan Bolton, an ecologist and civil engineer at UW, graduate students use their $15,000 in prize grant money from the EPA’s People, Prosperity, and the Planet program to find what materials will catch more droplets while lowering the cost and maintenance of the nets. Robert Schemenauer, an atmospheric physicist from British Columbia who founded the nonprofit FogQuest and has been a part of the creation of most of the fog catching systems around the world, has also been active in the research program. He maintains a strict reminder to the students and professors that they need to think of their audience on the smallest scale. Fog collectors cannot provide enough water for large towns or cities so should not be looked as replacements for municipal water facilities. The material must be cheap enough but durable to last in conditions where they will be used.

Currently, the UW team is experimenting with a fibrous plastic mat, much like the ones that are used to cover turf. They are also changing up the shapes of the nets themselves; instead of using rectangles, making it more of a triangular shape to allow the water droplets to trickle down better.

The students make it clear that the natural fog will not be diverted from an original source. It’s fog that usually goes unharnessed but can help turn around the agriculture in the community they hope to work with in Lomas de Zapallal near Lima, Peru.

Next month, the UW team will present their results along with the other winners of the EPA’s $15,000 grant at the National Sustainable Design Expo in Washington, D.C. They then have a chance to win a $90,000 grant to help continue initiate sustainable programs that will help solve environmental problems, big or small. The grant money will also help them actually execute their program in Lomas de Zapallal.

– Deena Dulgerian

Source:Seattle Times