In what has to be one of the nicest publicity stunts and advertising campaigns ever, a college in Lima, Peru, advertised the start of classes by building a billboard that sucks drinkable water straight out the air. That might not sound very exciting until you consider that Lima is the second-largest capital built in a desert and that its population struggles to find clean, drinkable water on a daily basis.
How dry is this area? Lima receives only a couple of inches of rain a year. In comparison, our fair city receives about four times that amount, around eight inches of rain a year. Huffpo points out that much of the water it relies upon comes from glaciers in the Andes, glaciers that have been melting at a prodigious rate over the past four decades.
This might seem like magic, but the principle behind it will be familiar to anyone who has ever had nasty air-conditioner water drip on them. Basically, the billboard contains an air conditioner that cools the air down to the point where the water starts to collect, like the condensation on a glass of cold water on a hot day. This condensation is collected, treated to make sure it's safe and collected for use. The process isn't necessarily efficient, but Lima's otherwise miserable hot and muggy weather patterns are perfect for this type of system. While the city might not get much rain, its proximity to the ocean means it gets plenty of moisture, and it's only a matter of turning that moisture into something drinkable.
The billboards can create about 96 liters of water a day, or 9,450 liters of water over the course of three months. The average person needs between two and three liters of water a day to survive, so you can see how a single billboard could make a big difference for a community.