Putting fog to work

There aren't many deserts where the air feels soft and moist, as it does along the western fringes of Peru and Chile. Cold water that upwells along the coast keeps the air ultra-stable most of the time. Towns like Chungungo, Peru, may get less than 5cm/2in of rain a year, even as the chill ocean helps produce fog and light drizzle day after day. Despite local subsidies, families may spend as much as 10 percent of their income on their water supply. As part of a demonstration project, Chungungo took advantage of the perennial fog by harvesting it A set of 75 collectors – each about the size of a billboard – were installed by a Canadian research centre on a ridge above the town. Intercepting the moist sea breeze, the collectors gleaned roughly 15,000 litres/3900 gallons of water, which were piped downhill to Chungungo. Although the system was abandoned in 2003 for a variety of reasons, some of them political, similar techniques are being used in other fog-shrouded coastal deserts from Namibia to Oman.