Fog harvesting systems — giant nets that collect and funnel billions of tiny drops of water into a reservoir — are already in use in parts of the world where rainfall is rare. But researchers at MIT, working with experts from the Pontifical Catholic University in Santiago, Chile, have found a way to vastly improve those nets, increasing the amount of water they collect by as much as five fold.
Their research found that the three main factors affecting how efficiently a net was able to collect water were the size of the material used, the spaces between the filaments, and the addition of a chemical coating.
So with that information at their disposal, they found that the most efficient design for a fog-collecting net was one made of stainless steel filaments, three or four times as thick as a human hair, and spaced about twice as far apart. Think of a design similar to a window screen. And to help as much as the trapped moisture be collected, a special coating was applied that made it easier for the drops to succumb to the pull of gravity.
The new design promises to capture as much 10 per cent of the moisture in fog as it passes through the mesh, and given previous designs could barely muster two per cent, it’s a vast improvement that promises to relieve water demands in many parts of the world. At the least, the system could easily be marketed to the perpetually foggy city of San Francisco and surrounding areas, replacing startups with fresh water as their most valuable export. [MIT news]