Fog harvesting provides an alternative source of freshwater through a technique used to capture water from wind - driven fog. Fog harvesting systems are typ ically installed in areas where the presence of fog is naturally high, typically coastal and mountainous regions. The systems are usually constructed in the form of a mesh net, stabilized between two posts that are spread out at an angle perpendicular to t he prevailing wind carrying the fog. As the wind passes through the mesh, drops of freshwater form and drip into an underlying gutter, from which pipes lead the water into a storage tank.
- Does not require energy to operate
- Decreases pressure on local freshwater reservoirs in low water availability periods
- Provides an additional source of freshwater in dry coastal and mountainous regions, thus increasing quality of life in communities
- Provides generally clean water that can be used immediately after harvesting
- Minimizes costs and the need to transport freshwater into the area, which is difficult to reach
Fog harvesting systems are best installed in open locations with a fairly high elevation that are exposed to wind flow. Meteorological and climatic information such as predominant wind-flow direction might have to be gathered to identify optimal placement. After technical setup, training may also be necessary to introduce the system and its maintenance requirements to the local community. Thick fog, high wind speeds, and tighter mesh material can all improve the efficiency of the harvesting system. The water harvesting rate ranges between 5.3 litres per m2/day and 13.4 litres per m2/day depending on the season, location and type (material used) of the harvesting system (Organization of American States , n.d.). Water collected from fog harvesters can be used for a wide range of purposes, including potable water, irrigation, and other domestic applications. The mesh, typically nylon, polyethylene or polypropylene netting, is tightly spread between two firmly planted posts.
- Harvested volume can be difficult to predict, particularly in long term, as it depends on the presence of fog, wind speed, etc.
- In some coastal regions the quality harvested fog water for drinking is inferior due to high concentrations of chlorine, nitrate and minerals
- Large fog harvesting constructions may damage or impede flora and fauna
- Harsh weather conditions such as very strong winds and snowfall can damage harvesting systems