Water From Air (WFA): Yes, It’s Mass & Commercial Production is possible

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Without water, humans cannot live, it’s an universal truth. Since time began, we have lived by the water and vast tracts of waterless land have been abandoned as too difficult to inhabit. Also in regions with a dry (arid) or mainly dry (semi-arid) climate the production of drinking water is a grave problem.

Water is life!
Water is life!

Historically, Water has been collected from the air for at least 2,000 years using air wells in Middle Eastern deserts, and later in Europe. The Incas were able to sustain their culture above the rain line by collecting dew and channeling it to cisterns for later distribution. Historical records indicate the use of water-collecting fog fences. These traditional methods have usually been completely passive, requiring no external energy source other than naturally occurring temperature variations.

In movie Star Wars, Luke Skywalker’s family on Tatooine used Atmospheric water generation on their moisture farm.

On average, more water evaporates here than is compensated as a result of precipitation. The ground is therefore dried out and the generally salty groundwater is often only found at great depths. Additionally, in many cases the groundwater level is steadily dropping or so-called fossil, non-renewable aquifers are used. A sustainable production of drinking water from groundwater that can also be used for future generations is thus not possible. The use of surface waters is also difficult in these regions, especially at a great distance from the sea.So this water resource can be developed as a source of drinking water.  The entire process consists of mainly 2 stages:

  1. Absorption of air humidity
  2. Desorption (distillation and condensation)

Absorption of air humidity: The humidity or moisture from the air is absorbed by a concentrated saline solution (brine). To absorb the air humidity in the saline solution, a large interface with the air and a long contact time are necessary. This is done by allowing the saline solution to flow slowly down sorption strings in tower-shaped, naturally ventilated plant modules and to absorb the water from the air. By means of a special design of the sorption strings an efficient mass transfer is achieved and the saline solution is diluted by the substantial absorption of water.

Desorption (distillation and condensation): The diluted saline solution is distilled and the water separated from the saline solution is condensed as drinking water.

Producing water from the air
Image Courtesy: Fraunhofer-Gesellschaft

The water has to be separated from the circulating saline solution (desorbed), and so a distillation process follows. The distillation is effected by means of gravity-assisted, multiple-stage vacuum evaporation. To do this, the saline solution, diluted with water, is subjected to a vacuum, which considerably reduces the evaporation temperatures. The advantage of this is that these temperatures can be achieved with simple solar thermal collectors or also with waste heat. Since the plant works with a negative pressure, it is also possible to use the thermal energy employed several times in various evaporation stages with different pressures. The water vapor produced in the distillation is condensed and can be used as high-quality drinking water.

Advantages of Water from air generation:

  • Produces water directly from the air
  • Needs no water source
  • Totally free from bacteria
  • Water contains no harmful chemicals
  • Recycles and cleans the air
  • Is an effective dehumidifier
  • Easy set up
  • Low maintenance
  • Cost efficient
  • Water produced is at half the cost of bottled water.
  • Purity of water compliant to WHO, BIS norms

The extraction of atmospheric water may not be completely free of cost, because significant input of energy is required to drive some AWG processes, sometimes called “trading oil for water”. Certain traditional AWG methods are completely passive, relying on natural temperature changes, and requiring no external energy source. Research has also developed AWG technologies to produce useful yields of water at a reduced (but non-zero) energy cost.

With Inputs from Wikipedia & Fraunhofer-Gesellschaft