Testing greenhouse shade nets in collection of fog for water supply

Abstract

Fog is an important source of water for some inhabitants of arid regions where other sources of freshwater are scarce. Fog collection was carried out with polymeric greenhouse shade nets in order to investigate the feasibility of using similar shade cloths in fog water supply schemes in areas where the Raschel mesh that is used in standard fog collectors (SFC) is not available. The fog collectors were made from outdoor and indoor aluminet greenhouse shade nets of varying percent shade coefficient. The indoor weave is similar to that found in the Raschel mesh that is used in SFCs and proved to be more suitable for fog collection than the outdoor one. Fog collection with collectors made from the indoor weave mesh of varying percent shade coefficient indicates that the 40% shade coefficient is more appropriate for fog collection than the 60% and 90% mesh. The aluminet collectors appear to combine both fog and dew collection. The latter would make a 35% shade coefficient aluminet (‘metal’-coated) collector more efficient than the plain polypropylene mesh that is used in fog collectors, particularly in low elevation areas where fog deposition is lower and therefore, the contribution of dew to the total collected volume is a significant one. The results of this study will enable prospective users of fog water to select the right weave and percent shade coefficient of a given mesh that is to be used for fog collection in areas where the Raschel mesh is not available.