If you’ve never heard of fog harvesting, you’re not alone. The very idea of being able to capture something like fog sounds ludicrous. However, around the world people living on coasts collect water by harvesting the fog. A fog harvester (pictured below) is a mesh net that is erected perpendicular to the path of the wind. As the wind blows fog through the device, the mesh catches the droplets, and gravity pulls the water down into containers underneath. Most of the time, fog harvesters collect about a gallon a day for every 10 feet of mesh. The beauty of fog harvesters is that they require very little effort. They can be used in remote areas and don’t need constant supervision. Just set it up, go on about your day, and collect the water at the end of the day. Unfortunately, they’re not very efficient, in part because the mesh holes have to be just the right size. If they’re too large, the droplets will escape through them; if they’re too small, the droplets get clogged and won’t be collected. That’s why scientists at Virginia Tech have created a more efficient harvester they call a “fog harp.” Inspired by how water droplets filter through the needles of California’s giant redwoods, researchers developed a set of vertical wires that the droplets slide down. The linear situation of the wires prevents clogging, allowing the fog harp to collect three times what traditional fog harvesters collect, leading to almost 100% efficiency. A pilot version of the fog harp is being installed near MIT’s Central Utility Plant where further testing can be done. Next, they plan to test the device in one of the hottest, driest places in the U.S.: California’s Death Valley.
