Fog collection refers to the collection of water from fog using large pieces of vertical canvas to make the fog condense into droplets of water and flow down towards a trough below the canvas, known as a fog fence.
Through a process known as condensation, atmospheric water vapour from the air naturally condenses on cold surfaces into droplets of liquid water known as dew. The phenomenon is most observable on thin, flat, exposed objects including plant leaves and blades of grass. As the exposed surface cools by radiating its heat to the sky, atmospheric moisture condenses at a rate greater than that of which it can evaporate, resulting in the formation of water droplets.
Historical Origins - Natural or assisted fog collection
The organised collection of dew or condensation through natural or assisted processes is an ancient practice, from the small-scale drinking of pools of condensation collected in plant stems (still practised today by survivalists), to large-scale natural irrigation without rain falling, such as in the Atacama and Namib desert. Several man-made devices such as antique stone piles in the Ukraine, medieval "dew ponds" in southern England or volcanic stone covers on the fields of Lanzarote have all been thought to be possible dew-catching devices.
Modern Development - Artificial fog collection
In the mid-1980s, the Meteorological Service of Canada (MSC) began constructing and deploying large fog collecting devices on Mount Sutton in Quebec. These simple tools consisted of a large piece of canvas (generally 12 m long and 4 m high) stretched between two 6 m wooden poles held up by guide wires, with a long trough underneath. Water would condense out of the fog onto the canvas, coalesce into droplets, and then slide down to drip off of the bottom of the canvas and into the collecting trough below.
The intent was simply to use these devices to study the constituents of the fog that they collected. However, their success sparked the interest of scientists in Chile's National Forest Corporation (CONAF) and Catholic University of Chile. With funding from the International Development Research Centre (IDRC), the MSC collaborated with the Chileans to begin testing different designs of collection facilities on El Tofo Mountain in northern Chile. Once perfected, approximately 50 of the systems were erected and used to irrigate seedlings on the hillside in an attempt at reforestation. Once vegetation became established, it should have begun collecting fog for itself, like the many cloud forests in South America, in order to flourish as a self-sustaining system.
However, the success of the reforestation project is unclear, but approximately five years after the beginning of the project, the nearby village of Chungungo began to push for a pipeline to be sent down the mountain into the town. Though this was not in the scope of CONAF, which pulled out at this point, it was agreed to expand the collection facility to 94 nylon mesh collectors with a reserve tank and piping in order to supply the 300 inhabitants of Chungungo with water.
The project, completed in 1992, initially achieved a spectacular success, with an average production of 15,000 litres of water per day (peaking at 100,000 liters) that could be stored or piped to the village for use in drinking, bathing and irrigating. The accomplishment achieved high publicity, with frequent quotes from the townspeople, for whom water was dangerously scarce before, calling the collectors a “miracle.”
Unfortunately, the IDRC reports that ten years later in 2002, only nine of the devices remained and the system overall was in very poor shape. On the other hand, the MSC oddly states in its article that the facility was still fully functional in 2003, but provides no details behind this statement. In June 2003 the IDRC reported that plans existed to revive the site on El Tofo.
Cause of Failure
The reason for the failure of this project to achieve sustainability can be attributed to many factors. Because the project started off on a different path, the final route that it took was disorganized and lacked clear objectives once the facilities were built. The villagers of Chungungo formed a committee to see to the maintenance and repair of the collectors, funded by collections from the village households, but, ironically, the new water supply caused the population of the village to triple and the committee was unable to acquire the supplementary funds to expand the array of collectors and the reservoir, which would have solved any new water shortage problems easily and cost effectively. It is also suggested that this and other methods of water supply are shunned by the people of Chungungo and towns in other developing countries, who feel that collecting one’s own water lacks prestige and think that the state should pay for such services. In fact, this is exactly what the people of Chungungo wanted as of 2003 – a pipeline costing around US$1 million to be built from Los Choros river, 20 km away.
However, current evidence suggests the failure has been mended, and operations are successful.
Despite the apparent failure of the fog collection project in Chungungo, the method has already caught on in various localities around the world. Nowadays the International Organization for Dew Utilization organization is working on foil-based effective condensers for regions where rain or fog cannot cover water needs throughout the year. Shortly after the initial success of the project, researchers from the various participating organizations formed the nonprofit organization FogQuest, which has set up operational facilities in Yemen and central Chile, while still others are under evaluation in Guatemala, Haiti, and Nepal, this time with much more emphasis on the continuing involvement of the communities in the hopes that the projects will last well into the future. Villages in a total of 25 countries worldwide now operate fog collection facilities. There is also still potential for the systems to be used to establish dense vegetation on previously arid grounds. Overall, it appears that the inexpensive collectors will continue to flourish.
- International Development Research Centre article on the fog collection project
- Meteorological Service of Canada article on fog collection project
- Fog Harvesting, chapter from Source Book of Alternative Technologies for Freshwater Augmentation in Latin America and the Caribbean, UNEP International Environmental Technology Centre
- Renee Cho (2011-03-07). "The Fog Collectors: Harvesting Water From Thin Air". Water Matters: News From the Columbia Water Center. The Earth Institute, Columbia University.
- FogQuest: Sustainable Water Solutions, Canadian organization, historical information on fog collection projects in developing countries
- Dan Collyns (20 October 2009). "How Peru is netting water supplies". BBC News (Lima).