The Chilean city of Alto Hospicio, situated 600 meters above sea level in the Atacama Desert, is one of the driest areas in the world. It receives less than 1 millimeter of rainfall per year. The city gets most of its water from porous underground rocks, but another source is emerging: the fog that forms overnight and in the early morning, which can be harvested using a mesh hung between two poles. When the fog cloud passes through the mesh panel, droplets form on the surface, which then drip down into pipes and storage tanks. Designed by researchers from the Pontifical Catholic University of Chile and Mayor University, Chile, the mesh panels were tested for a year and a half at higher altitudes outside the city limits. They captured between 0.2 and 5 liters per square meter (L/m2) per day, which would be enough water to supply the city for drinking, irrigation, and agricultural production. Based on an average annual capture rate of 2.5 L/m2 per day, it was estimated that 17,000 m2 of panels could produce 300,000 liters per week, enough to meet the water demand of the local residents. The results, however, depend on the density of the fog, which varies throughout the year, as well as the wind and the relief (Frontiers in Environmental Science, February 20).
