To Drink Water From Air

Posted on | november 22, 2011 | No Comments

The picture shows an atmospheric water generator, commercially known as Yeti AC-12, which can sit snugly in the corner of a room and generate as much as 10 gallons of pure drinking water per day just from atmospheric moisture. It runs on electricity and the power consumption is well within affordability of most people. If you are interested look up Everest Water here.

Though our water planners largely neglected the unseen Green Water (or more fashionably White Water, which is that part of the vertical unseen water that large water bodies evaporate away into atmosphere, you are not stealing from plants’ water so do not need to feel bad at all), human ingenuity saw this source right from antiquity and tapped it with innovation, as and when required. It’s just that this common wisdom was not trumpeted big time in the name of TECHNOLOGY, as our modern planners love to do.

Belgian inventor Achille Knapen built an air well on a 600-foot high hill at Trans-en-Provence in France. The construction of his “Puits Aerien” took him 18 months to complete (July 1930-December 1931). It still stands today (see picture), albeit in dilapidated condition. The unique structure was described in Popular Mechanics Magazine, thus:

“The tower… is about 45 feet tall. The walls are from 8 to 10 feet thick to prevent the heat radiation from the ground from influencing the inside temperature. It is estimated that the aerial well will yield 7,500 gallons of water per 900 square feet of condensation surface.”

The atmosphere contains 12,900 km3 (3,000 cubic miles) of fresh water, composed of 98% water pour and 2% condensed water (clouds): a figure comparable to the renewable liquid water resources of inhabited lands (12,500 km3). The quantity of water vapor contained within the air is commonly reported as a relative humidity; and this depends on temperature—warmer air can contain more water vapor than cooler air. When air is cooled to the dew point it becomes saturated and moisture will condense on a suitable surface. For instance, the dew temperature of air at 20 °C (68 °F) and 80% relative humidity is 18 °C (64 °F). The dew temperature falls to 10 °C (50 °F) if the relative humidity is only 25%. Air wells traps the dew and turns into water through condensation.

A fog fence or fog collector is an apparatus for collecting liquid water from fog, using a fine mesh or array of parallel wires. Fog contains about 0.05 grams of water per cubic meter, with droplets from 1 to 40 micrometers in diameter. It settles slowly and is carried by wind. Therefore, an efficient fog fence must be placed facing the prevailing winds, and must be a fine mesh, as wind would flow around a solid wall and take the fog with it. The water droplets in the fog deposit on the mesh. A second mesh rubbing against the first causes the droplets to coalesce and run to the bottom of the meshes, where the water may be collected and led away. An ideal location for fog fences is high arid areas near cold offshore currents, where fog is common.

The idea of collecting dew, fog and atmospheric water was always prevalent in human societies. Apart from Knapen, there are quite a number of inventors who tried to harness water from atmosphere sometimes inspired from ancient archeological finds. The notable ones were Russian engineer Friedrich Zibold, the French bioclimatologist Leon Chaptal and the German-Australian researcher Wolf Klaphake. All of them tried experimentally to design and build passive, mass collecting dew collectors with varying degree of success which inspired modern research and formation of The International Organization for Dew Utilization.

Dew ponds are still common on the downlands of southern England, the North Derbyshire and Staffordshire moorlands and in Nottinghamshire. A Dew pond is an artificial pond usually sited on the top of a hill, intended for watering livestock. Dew ponds are used in areas where a natural supply of surface water may not be readily available. Following are two pictures of dew ponds from Chanctonbury Ring, West Sussex and West Leake Nottinghamshire. To understand how ancient is the idea of dew ponds it will suffice to mention that the two Chanctonbury Hill dew ponds were dated, from flint tools excavated nearby and similarity to other dated earthworks, to the neolithic period.

Following are some innovative and remarkable use of atmospheric water:

The air conditioning system of the Burj Khalifa in Dubai, for example, produces an estimated 15 million gallons of water each year that is used for irrigating the tower’s landscape plantings.
A condenser-on-roof installation in a school in Sayara, Kutch, India (one of the most limited rainfall area in the country) collects about 15 millimetres (0.59 in) of dew water over the season with nearly 100 dew-nights. In a year it provides a total of about 9,000 litres (2,000 imp gal; 2,400 US gal) of potable water for the school which owns and operates the site. For this the school uses its 600 square meter roof.

Condenser on roof Sayara

You might have noticed that I have still not mentioned Rain Water Harvesting. I have issues with it. A year ago I turned down an invitation to talk in a public awareness campaign in my home city because the organizers were hell bent on making the title “Rain Water Harvesting – The new millennium water conservation technique.” Rain Water Harvesting a new millennium technique? I have authentic proof that it is practiced for 400 years in my country – till this day with unbroken history. But I will prefer my readers hear it from the source. Meet Anupam Mishra. You will love his English accent.

AUTHOR: Pabitra Mukhopadhyay
URL: http://pabitraspeaks.com
E-MAIL: mukhopadhyay.pabitra [at] gmail.com