On October 22, the Skysource / Skywater alliance won the "Water Abundance Xprize" and a $ 1.5 million reward for its device that could extract water from atmospheric humidity. While some News References claimed that the device could solve the global water crisis, hydrologists and water defenders warn that this is not a ball ankle solution.
Congratulations on @skysourcewater, The Grand Prize winner of $ 1.75M Water Abundance XPRIZE powered by @TataCompanies and @dfat_iXc! Their technology successfully withdrew over 2,000 liters of water from the air using 100% renewable energy. pic.twitter.com/Miz0yJcV49
– XPRIZE (@xprize) October 21, 2018
The atmospheric water generator that won the first place is called Wood in energy-developed water – or WEDEW, and is a system that converts humidity into air into drinking water using wood and other organic sources of energy. It collects at least 2,000 liters of water per day at an operating cost of less than 2 cents per liter.
While the creation of thin air water seems too good to be true, the mechanism is quite simple.
How to Make Rain in a Box
Air-to-water converters are basic cool collectors and operate in a manner similar to how droplets are condensed in cold drink bottles. They use energy to maintain a temperature called a dew point where such condensation can occur. However, technology needs some improvement to make it sustainable for commercial sales in many developing parts of the world.
All finalists in the event made similar devices that turned water vapor into drinking water, differing in the amount of water collected and the renewable energy source they used. These devices work thanks to the huge reservoir of untreated water vapor in the atmosphere. Like Swapnil Shrivastav, Managing Director of Uravu – one of the five finalists of the event – explained on the concept of technology:
The Earth's atmosphere contains about ten times the amount of water present in all the rivers of the Earth that have been collected, 12 quadrills if a number is added. In addition to this abundant quantity, it is refilled every 7 to 8 days from the natural cycle of evaporation and condensation.
Obstacles have to be overcome
While some reports claim that atmospheric water generators could potentially solve the global water crisis, appliances are effective solutions to water scarcity only in certain areas under certain circumstances.
An important parameter for the operation of these devices is the relative humidity (RH) that is the fraction of the humidity present in the atmosphere relative to the total moisture content it can maintain. The importance of RH is even recognized by Skywater, which notes on his Frequently Asked Questions website:
Ideal relative humidity ranges between 40% and 100% and the temperature between 65F and 105F. The volume of water is based on 80F and 80% RH. Anything else will bring extra water production and anything less will also reduce water less than the benchmark.
Even Shrivastav noted while talking to TNW that operating costs still have to be reduced so that these devices are commercially viable in many rural and dry areas of the world. He added that while air-water conversion technology today produced water at an operating cost of 1.4 to 2.1 cents per liter (1-1.5 Rs per liter), desalination – the process of removing excess salt and minerals from the oceans – could produce the same amount with much lower operating costs (5-15 per liter) without taking into account the cost of infrastructure and other external factors.
While in areas with terrestrial spaces the portable and modular nature of atmospheric water generators seems to be more useful than desalination water, there could be cheaper alternatives even at these points if water was available and only cleaning needed.
Air / water converters require 150-170 KWh of energy to produce 1000 liters of water (7-10 KWh for the whole day), while reverse osmosis (RO) filtration can do the same 3-10 KWh.
It's not a ball ankle solution
The idea of using atmospheric water generators to resolve the global water crisis was also challenged by Kimberly Duong, a drought management researcher at UC Irvine. Duong added that there is no one-size-fits-all approach to resolving water scarcity. Speaking to TNW he said:
I think that this technology could work in specific areas and environments, such as rural areas with relatively wet weather, low population density, plenty of sunshine, institutional support and a few other alternatives to water supply or water conservation. I do not believe that this technology works for densely populated and urban areas with high demand for water, high electricity demand, complicated bureaucracy and minimal available land.
I think that for the latter case (densely populated urban areas), water retention and improved water efficiency are low-end fruit that is already available, can be implemented in a way that fits the community's environment and is sustainable.
While new technology to combat water scarcity is certainly welcome, air-to-water converters are not a magic bead, but a solution to a different list, bringing us closer to a comprehensive solution.
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