Today, I learned about Aalto University's Water Scarcity Atlas from The Water Network. The atlas is a useful and credible resource for learning about various aspects of the water supply challenges facing humanity. For those of us in the water-from-air community it is definitely worth visiting and bookmarking. The atlas is a useful guide to the regions on which to focus water-from-air research and development efforts.The data & code section of the atlas website had a link to the City Water Map Initiative whose data source was

McDonald and others (2014). Water on an urban planet: Urbanization and the reach of urban water infrastructure. Global Environmental Change 27, 96–105.

This paper gives the results of the first global survey of the water sources for the world's largest cities. Table 2 in the paper lists the largest cities enduring water stress. The cities (in order of population) are Tokyo, Delhi, Mexico City, Shanghai, Beijing, Kolkata, Karachi, Los Angeles, Rio de Janeiro, Moscow, Istanbul, Shenzhen, Chongqing, Lima, London (UK), Wuhan, Tianjin, Chennai, Bengaluru, and Hyderabad.

Enjoy watching our 4 minute 40 second video presentation about using mechanical dehumidification technology for obtaining drinking water from the water vapour in the air. To access the video, just click on the image above.

Chemical & Engineering News published an interesting article about drinking-water-from-air technologies which may be accessed at ​by clicking on the page excerpt image above.

The September 28, 2018 earthquake and tsunami disaster in Palu has caused shortages of clean water (see for example, "Palu earthquake, tsunami victims get clean water support", The Jakarta Post). The Water-from-Air Resource Chart for Palu is a free download.  

Moscow and London among the cities that could run out of drinking water? Yes, according to a BBC report in February 2018.

Moscow's drinking water comes mostly from surface water. Industrial pollution affects surface water in Russia.

London has relatively low average annual rainfall feeding the Thames and Lea rivers which supply much of London's drinking water. Capacity limits are being approached and are likely to be exceeded in the next couple of decades.

Although Moscow and London are not ideal sites for a year-round water-from-air resource, there is enough moisture in the air during the summer months to allow machines to operate.

The new Water-from-Air Resource charts for Moscow and London, now available for purchase and download at the Atmoswater Shop, will be of interest to city planners and others concerned about ensuring water security for the people living in these two cities.
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• Nature Conservancy reference 

​Thermoelectric cooling technology has had wide appeal as an alternative to mechanical refrigeration cooling technology for at least twenty years. Thermoelectric systems avoid the use of hazardous, harmful refrigerants and noisy compressors​. Low coefficient of performance (COP, in the range of 0.9–1.2) is the main problem preventing widespread use of thermoelectric cooling especially for systems requiring large cooling capacities (Riffat & Ma, 2004). A COP of 1.2151, achieved using a multistage thermoelectric module, was considered "remarkable" by Patel and others (2016)  Only smaller capacity niche applications have been commercialized.

There have been several peer-reviewed papers published and patents issued for atmospheric water generators or dehumidifiers using thermoelectric cooling devices which use the Peltier effect. Some information and products have been featured on websites. Each reference below represents a clickable link to more information.

Examples of papers

Atta, R. M. (2011). Solar Water Condensation Using Thermoelectric Coolers. International Journal of Water Resources and Arid Environments, 1(2), 142–145.

Milani, D., Abbas, A., Vassallo, A., Chiesa, M., & Bakri, D. A. (2011). Evaluation of using thermoelectric coolers in a dehumidification system to generate freshwater from ambient air. Chemical Engineering Science 66(12), 2491-2501.

Muñoz-Garcia, M. A., Moreda, G. P., Raga-Arroyo, M. P., and Marin-González, O. (2013). Water harvesting for young trees using Peltier modules powered by photovoltaic solar energy. Computers and Electronics in Agriculture 93, 60–67.

Nandy, A., Saha, S., Ganguly, S. & Chattopadhyay, S. (2014). A Project on Atmospheric Water Generator with the Concept of Peltier Effect. International Journal of Advanced Computer Research, 4, 481–486.

Suryaningsih, S. & Nurhilal, O. (2016). Optimal design of an atmospheric water generator (AWG) based on thermo-electric cooler (TEC) for drought in rural area. AIP Conference Proceedings 1712, 030009 (2016); doi: 10.1063/1.4941874

Davidson, K. B., Asiabanpour, B., & Almusaied, Z. (2017). Applying Biomimetic Principles to Thermoelectric Cooling Devices for Water Collection. Environment and Natural Resources Research 7(3), 27–35.

Examples of Patents

Peeters, J. P. and Berkbigler, L. W. 1997. Electronic household plant watering device. United States Patent 5,634,342. [expired, now in public domain]

Wold, K. F. 1997. Plant watering device and method for promoting plant growth. United States Patent 5,601,236. [expired, now in public domain]

Reidy, J. J. 2008. Thermoelectric, High Efficiency, Water Generating Device. United States Patent 7,337,615.

​Waite, R. K. & Neumann, A. (2017). Water production, filtration, and dispensing system. United States Patent 9,731,218 B2.

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Examples of Websites

The "instructables" website published the article "How to Make a Dehumidifier (Thermoelectric Cooling) in 2016.

Amazon.com sells several models of "thermoelectric portable compact dehumidifiers".
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​References

Patel, J., Patel, M., Patel, J., & Modi, H. (2016) Improvement in the COP of Thermoelectric Cooler. International Journal of Scientific & Technology Research 5(5), 73–76.
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Riffat, S. B. & Ma, X. (2004) Improving the coefficient of performance of thermoelectric cooling systems: a review. Int. J. Energy Res. 28: 753-768 (DOI:10.1002/er.991)

The target market for atmospheric water generators, in the broadest sense, are people in locations with perennial water shortages due to population growth, climate change, and lack of enough sustainable surface or groundwater within a radius of 100 km. The reference for these defining conditions is: Lalasz, R. (2011). New Study: Billions of City Dwellers in Water Shortage by 2050; retrieved from https://blog.nature.org/conservancy/2011/03/28/pnas-billions-city-urban-water-shortage-2050-nature-conservancy/. A study led by the Nature Conservancy defined these conditions. At least 23 cities fit these conditions. From north to south they are: Shenyang, Beijing, Tehran, Haifa, Tel Aviv, Jerusalem, Lahore, Delhi, Dubai, Riyadh, Abu Dhabi, Kolkata, Mexico City, Mumbai, Hyderabad, Manila, Chennai, Bengaluru, Caracas, Lagos, Cotonou, Abidjan, and Johannesburg. Some small tropical islands such as Grand Turk, Turks and Caicos Islands and Sal Island, Cabo Verde also fit these defining conditions. Recent reports such as “The 11 cities most likely to run out of drinking water - like Cape Town” by the BBC (http://www.bbc.com/news/world-42982959; 11 February 2018) suggest that we could add other cities to the Nature Conservancy’s list. From the BBC report here are nine more cities to add to the list of those likely to run out of sustainable natural water supplies: Cape Town, São Paulo, Cairo, Jakarta, Moscow, Istanbul, London, Tokyo, and Miami.Water-from-Air Resource Charts are available for all the highlighted locations mentioned in this post—just click on the location name to go to the relevant page in the Atmoswater Shop. By the way, if you like bargains, the charts for the 23 water-scarce cities listed by the Nature Conservancy are all included in the book, Water-from-Air Quick Guide.

Several new water-from-air resource charts for cities in India are now available for purchase and download at ​https://www.atmoswater.com/store/c130/India.html. The cities include Bikaner, Dhubri, Dibrugarh, Kota, Srinagar, and Trivandrum. 

I have the privilege of being accepted as one of the presenters during the Technical Sessions at the 23rd Annual Caribbean Water and Wastewater Association (CWWA) Conference and Exhibition scheduled for October 6-10, 2014 at Atlantis Resorts on Paradise Island, Bahamas. Here is the Abstract of my paper:

Regional droughts in the Caribbean are common. Water managers seeking solutions to water scarcity are often unfamiliar with the option of using water-from-air technology. Maps of the specific humidity composite mean for Junes and Decembers during the ten-year period 2004–2013 quantify the water-from-air resource demonstrating it is suitable for operation of water-from-air systems in Caribbean countries. Quantitative investigations by the author found droughts and long-term climate change do not appear to affect the magnitude of the Caribbean region’s water-from-air resource. Case studies include one for a proposed water-from-air commercial greenhouse on Grand Turk. Another case is about the experience of commissioning a 2500 L/d water-from-air machine in Belize City. Lessons learned from the case studies are outlined.

Air masses with relatively high water vapor densities (exceeding 12 grams of moisture per cubic meter of moist air) surround San Francisco / San Jose and Los Angeles / San Diego. 'Good' performance is expected from water-from-air systems (atmospheric water generators) operated in these regions. Over the balance of the state, the water-from-air resource is graded as 'fair'.

This map is from the new Atmoswater Research 45-page publication, Atlas of the Water-from-Air Resource for California.

Tour Stop 8: In San Francisco, the diurnal regime of the water-from-air resource is somewhat variable with the seasons. (Click on images to enlarge them)

Abstract from my article published February 11, 2014 on Water Online:

Quantifying the water-from-air resource enables targeting selected cities where installing strategically located stand-alone processors of atmospheric water vapor will have the quickest, most beneficial impact for people facing water scarcities.

While helping a client commercialize water-from-air systems, I got frequent questions about how well atmospheric water generators would perform at various locations around the world. A common misconception was that relative humidity values told the whole story. Higher humidity means more water in the air and better water production. Right? Not really!

The water vapour content of the air, sometimes referred to as "absolute humidity", has the proper scientific name "water vapour density" with units of [grams of water vapour per cubic metre of air]. The water vapour density depends on three measures all at the same time: the air's dry bulb temperature, relative humidity, and atmospheric pressure.

Monthly average climate data for air temperature (dry bulb) and relative humidity is fairly easy to obtain for many places. Average air pressure at a location can be estimated knowing the site's altitude above sea level. Using well-known formulas used in the heating, ventilation, air-conditioning field (HVAC) the average monthly water vapour density can be calculated.

Once water vapour density was known, I could use information about the airflow (in units of cfm or cubic feet per minute) through my client's machines to estimate water production of various designs. The focus on water production was fine for a manufacturer and its customers.

Later, as an independent consultant, potentially dealing with end-users of atmospheric water generators having all sorts of different specifications for airflow I decided it was better to focus on the actual water vapour resource to make charts of wider usefulness.To make it easier to compare how good a site is for atmospheric water generators I had the idea of indexing the water vapour density by dividing the density values by the water vapour density 15.3 g/cubic metre which is the density at the standard measurement conditions of 26.7°C air temperature; 60 % relative humidity. When the water-from-air resource monthly index = 1.00, the expected drinking water production rate from an atmospheric water generator (AWG) at the site should be the same as the machine's specified water-from-air production rate. I gave the Water-from-Air Resource (WFAR) annual index grades (Excellent: Index is greater than or equal to 1.00; Good: Index range 0.76 to 0.99; Fair: Index range 0.51 to 0.75; and Poor: Index range is less than or equal to 0.5) and assigned colours to make it easier to interpret the charts.

A lot of information about a site, all relevant to using water-from-air systems is packaged onto the 8.5 inch x 11 inch landscape format of the charts!

• Geographic coordinates and elevation;
• Monthly average temperature, humidity, pressure, and dew-point;
• Monthly average water vapour density;
• Monthly average maximum mechanical dehumidification efficiency;
• Graph to visualize how temperature, humidity, dew-point, and efficiency vary together by month;
• Graph to visualize and compare monthly average water vapour density with water vapour density at standard conditions;
• Summary of the analysis, identifying the climate zone and expected atmospheric water generator performance for various periods during a year; and
  
• Annual index to compare the water-from-air resource between locations

After a bit of experience using the charts my clients discover some of their business stress evaporates! Here's why:

• They don't have to spend their own time and resources responding to ongoing questions about how good or bad a place is for operating water-from-air systems. This gives just a bit extra time for concentrating on growing their business and profits;
• Risk reduction by understanding the characteristics of the water-from-air resource at a site. Why alienate their customer by selling them a machine that might only work properly a couple of months of the year at a site? Better to forgo that sale and focus on sites where the machine return on investment is more favourable;
• The charts make their business more valuable—they become more of an expert at what they do;
• They find it easier to achieve sales targets because quantitative information, rather than a guesstimate is available; and
  
• Surprises are removed with having solid quantitative knowledge about the water-from-air resource at sites.