The Air Well
An interesting invention that has never been implemented on a large scale was designed in 1931 by M. Achille Knapen. He succeeded in condensing and extracting water from warm air to irrigate fields and vineyards in southern France with what he called, an "air well" (See U.S. patent no. 1,816,592). Looking like a 40-foot concrete beehive, it was possible to produce as much as 6,000 gallons of water daily for every 1,000 square feet of condensing surface. An airwell can be built on practically any scale, and the wall materials can be concrete blocks, bricks or concentric hollow shells filled with sand or earth. A small airwell 12 feet high and 12 feet across with walls 2 feet thick can supply a generous output of daily water. It can be fitted with top and bottom air pipes, and a multitude of condensing plates on the inside. Warm air circulates and gives up moisture on the cool inside condensing plates angled downward toward a catch basin at the bottom were it is collected. Using scrap and local materials, makeshift air wells could help solve many water problems in drought ridden areas of the world, especially in Third World countries.