Atmospheric water generator An atmospheric water generator (AWG), is a device desiccants such as lithium chloride or lithium bromide that extracts water from humid ambient air. Water vapor to pull water from the air via hygroscopic processes.[2] in the air is condensed by cooling the air below its dew A proposed similar technique combines the use of solid point, exposing the air to desiccants, or pressurizing the desiccants, such as silica gel and zeolite, with pressure air. Unlike a dehumidifier, an AWG is designed to render condensation. the water potable. AWGs are useful where pure drinking water is difficult or impossible to obtain, because there is almost always a small amount of water in the air that 2.1 Cooling condensation can be extracted. The two primary techniques in use are cooling and desiccants. Condensor Evaporator Electrostatic Air Filter The extraction of atmospheric water may not be com- Warm Air Out pletely free of cost, because significant input of energy Fan Moist Air In Warm Air is required to drive some AWG processes. Certain tradi- Out tional AWG methods are completely passive, relying on Capillary Tube natural temperature differences, and requiring no exter- Water Line Water nal energy source. Research has also developed AWG Filters technologies to produce useful yields of water at a re- Compressor Pump Ozone Generator duced (but non-zero) energy cost. Refrigerant Flow 1 History Example of cooling-condensation process. In a cooling condensation type atmospheric water gener- The Incas were able to sustain their culture above the rain ator, a compressor circulates refrigerant through a con- line by collecting dew and channeling it to cisterns for denser and then an evaporator coil which cools the air later distribution. Historical records indicate the use of surrounding it. This lowers the air temperature to its dew water-collecting fog fences. These traditional methods point, causing water to condense. A controlled-speed fan have usually been completely passive, requiring no exter- pushes filtered air over the coil. The resulting water is nal energy source other than naturally occurring temper- then passed into a holding tank with purification and fil- ature variations. tration system to help keep the water pure and reduce the risk posed by viruses and bacteria which may be collected from the ambient air on the evaporator coil by the con- 2 Modern technologies densing water.[3] The rate at which water can be produced depends on Many atmospheric water generators operate in a manner relative humidity and ambient air temperature and size of very similar to that of a dehumidifier: air is passed over a the compressor. Atmospheric water generators become cooled coil, causing water to condense. The rate of water more effective as relative humidity and air temperature production depends on the ambient temperature, humid- increase. As a rule of thumb, cooling condensation at- ity, the volume of air passing over the coil, and the ma- mospheric water generators do not work efficiently when chine’s capacity to cool the coil. These systems reduce the temperature falls below 18.3°C (65°F) or the relative air temperature, which in turn reduces the air’s capacity humidity drops below 30%. This means they are rela- to carry water vapor. This is the most common technol- tively inefficient when located inside air-conditioned of- ogy in use, but when powered by coal-based electricity fices. The cost-effectiveness of an AWG depends on the it has one of the worst carbon footprints of any water capacity of the machine, local humidity and temperature source (exceeding reverse osmosis seawater desalination conditions and the cost to power the unit. by three orders of magnitude) and it demands more than The Airdrop system consists of a mast-like tube with a four times as much water up the supply chain as it delivers [1] wind-powered turbine that sucks air down into a coiled to the user. metal pipe buried in the earth. There, the air is cooled un- An alternative available technology uses liquid, or “wet” til it hits 100% humidity and the water starts to condense 1 2 7 REFERENCES out. This technology is basically a cooling condensation by erecting wind traps that funneled dew-laden air into system that takes advantage of the significant tempera- cool underground caverns. ture difference between underground and the air above In Star Wars, Luke Skywalker’s family on Tatooine used it. The inventor, Ed Linacre, was James Dyson Award atmospheric water generation on their moisture farm. Winner in 2011.[4] Video of Edward Linnacre’s AirDrop Irrigation In the Star Trek: The Next Generation episode "The Inner Light", Captain Picard suggests building “atmospheric condensers” for a planet experiencing prolonged drought. 2.2 Wet desiccation One form of wet desiccant water generation involves the 6 See also use of salt in a concentrated brine solution to absorb the ambient humidity. These systems then extract the water • Air well (condenser) from the solution and purify it for consumption. A ver- sion of this technology was developed as portable devices • Dew pond which run on generators. Large versions, mounted on trailers, are said to produce up to 1,200 US gallons (4,500 • Fog collection l) of water per day, at a ratio of up to 5 gallons of water • Rainwater harvesting per gallon of fuel.[5] This technology was contracted for use by the US Army and the US Navy from Terralab and • Solar chimney the Federal Emergency Management Agency (FEMA).[6] • Watermaker A variation of this technology has been developed to be more environmentally friendly, primarily through the use • Solar still of passive solar energy and gravity. Brine is streamed down the outside of towers, where it absorbs water from • Water-Gen the air. The brine then enters a chamber and subjected to a partial vacuum and heated. The water vapor is col- lected and condensed, while the renewed brine is recir- 7 References culated through the system. As the condensed water is removed from the system using gravity, it creates the vac- [1] Environmental Assessment of Air to Water Machines. In- uum which lowers the boiling point of the brine.[7] ternational Journal of Life Cycle Assessment, 18:1149- 1157. [2] Patents; Draw water from air, measure how much water 3 In greenhouses you drink and be kind to the fish you catch. New York Times. July 2, 2001 A special case is the water-generation in greenhouses be- [3] Latest Willie Nelson venture: Water from Air. Atlanta cause the air inside a greenhouse is much hotter and more Journal Constitution. humid than the outside. Particularly in climatic zones with water scarcity, a greenhouse can strongly enhance [4] Airdrop Pulls Water From Air to Irrigate Plants. Wired the conditions necessary for atmospheric water genera- (November 8, 2011) tion. Examples are the seawater greenhouse in Oman, [5] Water Extracted from the Air for Disaster Relief. Na- and the proposed Integrated Biotectural System or IBTS- tional Public Radio; by Nell Greenfieldboyce; October 19, Greenhouse. 2006 [6] Innovation Awards: Ahead of the Pack. Wall Street Jour- 4 Commercial Uses nal. October 30, 2007. [7] Drinking Water From Air Humidity. ScienceDaily (June “AWGs at this time can now be used as a sole source 8, 2009) of water for commercial and industrial applications, [8] Historical Moment in the Monterey Peninsula. PRWeb as well as residential secondary buildings, within the (August 23, 2014) MPWMD.”[8] 5 In fiction In the Dune series, Fremen on the desert world Arrakis collected water from the atmosphere on a massive scale 3 8 Text and image sources, contributors, and licenses 8.1 Text • Atmospheric water generator Source: https://en.wikipedia.org/wiki/Atmospheric_water_generator?oldid=666312070 Contributors: Ray Van De Walker, Jeffq, Carnildo, Enochlau, Giftlite, Khalid hassani, Geni, Karol Langner, Nzseries1, Imroy, Discospinster, Rich Farm- brough, Kbh3rd, Huntster, Cohesion, Pearle, Hooperbloob, Vanished user lkjsdkf34ij48fjhk4, Woohookitty, RHaworth, Al E., GregorB, CharlesC, NeonMerlin, GeorgeBills, Ground Zero, Straker, GreyWyvern, Wavelength, Xaa, Spudbeach, GPS Pilot, Gaius Cornelius, Bovi- neone, Neil McDermott, Retired username, Brandon, Jkelly, Wsiegmund, Chriswaterguy, Nae'blis, TuukkaH, Anthony717, SmackBot, C.Fred, AndyZ, PeterSymonds, Betacommand, Deli nk, Nbarth, OrphanBot, Albertalbs, Quixada, Ashvidia, Jaganath, Biwhite2, Skapur, Kingoomieiii, Thewinchester, Joeatxdobs, NigelR, Sorenriise, KrakatoaKatie, RobotG, Jbaranao, Smartse, IndianGeneralist, Pconrad0, Li- bLord, East718, Vaneetkaushal, Freedomlinux, Puroprana, Rettetast, KTo288, Cogorno, Jeff G., Dbryar, Someguy1221, Flyer22, Aly89, Vice regent, Nnemo, Aitias, DerBorg, Johnuniq, XLinkBot, Hjepsen, Osarius, H2o99, Tide rolls, Frmatt, Slgcat, AnomieBOT, Short Brigade Harvester Boris, Mintrick, T34CH, Grantmidnight, Aquaprada, A8UDI, Konia001, Mateyahoy, Luttinger, Dilipray, Beth Konia US, Koshy73, MartyHyman, Etanbar, Fibroman, Reify-tech, BG19bot, MusikAnimal, Bluelightning87, Moony22, Jblawg, ImpartialGeek, Trackteur, Joel Media and Anonymous: 135 8.2 Images • File:Atmospheric_Water_Generator_diagram.svg Source: https://upload.wikimedia.org/wikipedia/commons/9/9b/Atmospheric_ Water_Generator_diagram.svg License: GFDL Contributors: <a href='//commons.wikimedia.org/wiki/File:Atmospheric_Water_ Generator_diagram.jpg' class='image'><img alt='Atmospheric Water Generator diagram.jpg' src='https://upload.wikimedia.org/ wikipedia/commons/thumb/9/9b/Atmospheric_Water_Generator_diagram.jpg/100px-Atmospheric_Water_Generator_diagram.jpg'