FOOD SECURITYDroughts Are Getting Worse. Is Fog-Farming a Fix?
Tapping low-hanging clouds could be a cheap way to boost dwindling water supplies, according to new research.
The city of Alto Hospicio, in Chile’s Atacama Desert, is one of the driest places on Earth. And yet its population of 140,000 continues to balloon, putting mounting pressure on nearby aquifers that haven’t been recharged by rain in 10,000 years. But Alto Hospicio, like so many other coastal cities, is rich in an untapped water resource: fog.
New research finds that by deploying fog collectors — fine mesh stretched between two poles — in the mountains around Alto Hospicio, the city could harvest an average of 2.5 liters of water per square meter of netting each day. Large fog collectors cost between $1,000 and $4,500 and measure 40 square meters, so just one placed near Alto Hospicio could grab 36,500 liters of water a year without using any electricity, according to a paper published on Thursday in the journal Frontiers in Environmental Science.
By placing the collectors above town — where the altitude is ideal for exploiting the region’s predictable band of fog — water would flow downhill in pipelines by the power of gravity. So that initial investment for collectors would keep paying liquid dividends year after year. “If you’re pumping water from the underground, you will need a lot of energy,” said Virginia Carter Gamberini, a geographer and assistant professor at Chile’s Universidad Mayor and co-lead author of the paper. “From that perspective, it’s a very cheap technology.”
It’s a simple idea that’s already in use around the world. Fog is just a cloud that touches the ground. Like a puffy cloud higher in the atmosphere, it teems with tiny water droplets that gather in the mesh of a fog collector, dripping into a trough that runs into a tank. Communities across South America, Africa, and Asia have been deploying these collectors, though on very small scales compared to other methods like pumping groundwater.
So why haven’t cities expanded their use? For one, if a region gets rain, that volume of water is much higher than what can be extracted from fog, and communities can store that rainfall in reservoirs. Fog collection also requires constant attention, as the devices can break in fierce winds, requiring repairs.
