Appendix - Fog Harvesting

Summary

Fog Harvesting

[The following is an abridged version of the chapter on ‘Fog Harvesting’ taken from the Source Book of Alternative Technologies for Freshwater Augmentation in Latin America and the Caribbean (Part B section 1.3); a publication of Unit of Sustainable Development and Environment, General Secretariat, Organization of American States, Washington, D.C., 1997. It is being reproduced here by permission]

This innovative technology is based on the fact that water can be collected from fogs under favorable climatic conditions. Fogs are defined as a mass of water vapor condensed into small water droplets at, or just above, the Earth's surface. The small water droplets present in the fog precipitate when they come in contact with objects. The frequent fogs that occur in the arid coastal areas of Peru and Chile are traditionally known as camanchacas. These fogs have the potential to provide an alternative source of freshwater in this otherwise dry region if harvested through the use of simple and low-cost collection systems known as fog collectors. Present research suggests that fog collectors work best in coastal areas where the water can be harvested as the fog moves inland driven by the wind. However, the technology could also potentially supply water for multiple uses in mountainous areas should the water present in stratocumulus clouds, at altitudes of approximately 400 m to 1 200 m, be harvested.