PepsiCo's recent call for proposals due February 22, 2002.
PepsiCo mentioned AWGs in its recent call for proposals to improve water use efficiency. You may click on the image above to reach the Innoget website with the proposal call.
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Status of the water-from-air industry in 2021 from the viewpoint of Global Water Intelligence18/11/2021  To access the article please click on the image above This interesting article by Global Water Intelligence (GWI) gives their view of the state of the water-from-air industry in July 2021. Drupps AB provided a link to the full article via their website.
My answers to questions asked in Oct. 20, 2020 Webinar: Introduction to Atmospheric Water29/10/2020  Participants at this well-attended webinar had lots of questions---too numerous to answer during the Q & A period at the end of the webinar. So the three panelists were asked to reply to a set of questions---the answers were sent recently to the registered attendees. Here are my answers to the set of eight questions assigned to me. They cover a variety of topics. I hope you find the answers interesting and useful.
Water vapor, the gas phase of water, diffuses along pressure gradients to zones of lower water vapor pressure. If a lot of water vapor was condensed into liquid water in a specific region such as a city, water vapor from outside the region would flow in immediately. No net loss of atmospheric water vapor density would be observed in the city. Water consumed for domestic water requirements does not exit from the water cycle. Within a day or so the liquid water that is used or temporarily with-held from the water cycle would be returned to the environment by evaporating into atmospheric water vapor. On a clearly bounded terrestrial surface such as a tropical island, atmospheric water vapor processing systems would increase slightly the annual precipitation. Let us say a large-scale AWG array is installed on an island such as Grand Turk (Turks & Caicos Islands). The island has a surface area of 18 square kilometers (1,800 ha). The AWG array produces water from the air at a rate of 75,335 cubic meters annually. This is equivalent to a rainfall of 7,533 mm over one hectare (10,000 square meters). The average annual precipitation of Grand Turk is 604 mm. This value would be enhanced by [7,533 mm/ha/1,800 ha] = 4 mm (or 0.7% annually, an amount less than the natural variability from year to year. The annual total precipitation in the year 2000, for example, was 704 mm. To reinforce the fact that long-term human direct impact on atmospheric water is negligible, note that dehumidifiers and air-conditioners dripping condensate have been increasingly used since the 1950s. I used NOAA global specific humidity data (measured in grams of water per kilogram of air) and subtracted the earlier 30-year 1951 to 1980 annual field from the more recent 39-year 1981 to 2019 field. The resulting map showed several pools of higher specific humidity (+2 g/kg). These are likely related to climate change. Drying of about -2 g/kg is noticeable over the Sahara and Gobi deserts---more likely to be related to climate change than use of HVAC equipment. Over most of Earth specific humidity has been remarkably stable (+/-1 g/kg) for the past seven decades. By the way, I posted the map in the Atmoswater Research blog. Indirect environmental impacts are more likely. These will be related to the materials used in manufacturing AWGs, product life cycle aspects, and so on. Also, AWGs will enable humans to expand their footprint which could increase population density in a region, lead to increased sewage and waste disposal challenges, and increase energy use. These analyses indicate widespread global atmospheric water use will not noticeably affect the world climate.
More conventional sources of water have these electrical energy costs: - Surface water, public supply: 0.37 kWh/cubic meter (Young, 2014) - Groundwater, public supply: 0.48 kWh/cubic meter (Young, 2014) - Tap water, 0.46 kWh/cubic meter (Gleick & Cooley, 2009) - Municipal water (S California): 3 kWh/cubic meter (Gleick & Cooley, 2009) - Seawater Desalination (reverse osmosis): 2.5 to 7 kWh/cubic meter (Gleick & Cooley, 2009) - Seawater Desalination (reverse osmosis): 2 kWh/cubic meter (Elimelech & Phillip, 2011, p. S1) - Bottled Water: 519 to 945 kWh/cubic meter [Gleick & Cooley, 2009; thermal energy units were converted to electrical energy units (3:1) to derive these values] It was interesting to discover that AWGs used in tropical climates are competitive with bottled water. Keep in mind the apparently cheaper conventional sources may not even be available in some water scarce regions. The desalination costs do not include the apparently difficult to monetize costs of harming local ecosystems with brine disposal. References: Elimelch, M. & Phillip, W. A. (2011) Supporting Online Material for The Future of Seawater Desalination: Energy, Technology, and the Environment. Science 333, 712-717. Gleick, P. H. & Cooley, H. S. (2009). Energy implications of bottled water. Environ. Res. Lett. 4 (2009) 014009 (6pp). Young, R. (2014). Watts in a Drop of Water: Savings at the Water-Energy Nexus. An American Council for an Energy-Efficient Economy (ACEEE) White Paper. Retrieved from https://www.aceee.org/sites/default/files/watts-in-drops.pdf
- AWG rated for 5 gal/day: $300/gal (residential quality) - AWG rated for 10 gal/day: $420/gal (balance of list is commercial/industrial quality) - AWG rated for 40 gal/day: $178/gal - AWG rated for 140 gal/day: $121/gal - AWG rated for 800 gal/day: $98/gal - AWG rated for 1800 gal/day: $82/gal
The energy cost of water produced by a desiccant AWG was estimated two ways (note that kilowatt is a unit of power---the energy unit is kilowatt x hours, kWh, which is power acting over a period of time): a. Specifications for a line of industrial rotary desiccant dehumidifiers (using electrical energy) manufactured by Hangzhou Peritech Dehumidifying Equipment Co., Ltd. (http://www.desiccantwheeldehumidifier.com/sale-2082217-industrial-rotary-desiccant-dehumidifier-silica-gel-economical-dehumidifier.html). Their 14.4 L/day model produces water using 2.8 kWh/L (10.6 kWh/US gal or 10,600 kWh per 1000 US gal). Their 1,102 L/day model produces water using 1.3 kWh/L (4.9 kWh/US gal or 4,900 kWh per 1000 US gal). b. Using information in the SOURCE Global (formerly Zero Mass Water) Patent Application US 2018/0043295 A1. The document includes an example of operation in Amman, Jordan at 14:00 on a July day. Airflow is 90 cfm. Relative humidity is 30%. A solar thermal panel with surface area 1.5 square meters provides 700 W (at 50% efficiency) to heat the desiccant to release captured water at the rate of 0.3 L/h. This information can be interpreted three different ways because international consensus is lacking on comparing different energy sources (e.g., solar thermal versus electricity; read more at the American Physical Society Site https://www.aps.org/policy/reports/popa-reports/energy/units.cfm). We need to make this comparison because the Peritech dehumidifiers and all chilled-coil AWGs are energized by electricity. i. Thermal energy = electrical energy cost of water = (700 W x 1 h)/0.3 L = 2.33 kWh/L; efficiency of solar thermal assumed to be 100% as per OECD/IEA publication guidelines ii. Equivalent electrical energy cost = 0.76 kWh/L; efficiency of solar thermal assumed to be 33% as per DOE/EIA (USA) publication guidelines iii. Equivalent electrical energy cost = 1.17 kWh/L; efficiency of solar thermal assumed to be 50% as stated in the patent application The range of energy costs for the SOURCE Global patent application example is 2.8 kWh/US gal (2,800 kWh per 1000 US gal) to 8.7 kWh/US gal (8,700 kWh per 1000 US gal). Here are some product design notes applicable to atmospheric water generator products. The notes are based on an interview with Mitch Maiman, Intelligent Product Solutions by William G. Wong of Electronic Design magazine (July 26, 2020).
Essential elements
Common design mistakes to avoid
Best process
Embrace smart products
 Please click on the image to go to the article at the Chemistry World website. This is an interesting article about the drinking-water-from-air industry. It also includes a section on fog harvesting. Atmoswater Research got a nice mention!
 Go to article by clicking on image above This article is a good overview of the COVID-19 virus in relation to systems processing drinking water and wastewater. Water-from-air machines (atmospheric water generators, AWGs) are, of course, small-scale drinking water systems. Even though the drinking water within the system may be safe, spigot handles and machine surfaces could be contaminated by viruses and bacteria. Machine users should wash their hands before operating the machine. Machine surfaces, spigots, and spigot handles should be sanitized frequently. For the air-side of water-from-air systems, relevant information is provided at ASHRAE Resources Available to Address COVID-19 Concerns. For the water-side of water-from-air systems there are two good sources of information:
 The Water-from-Air Industry is actively growing! This chart is from the data table below tabulating the founding years for Water-from-Air companies [suppliers of Atmospheric Water Generators (AWGs)]. Companies that failed between 1990 and the present are not included. Only those companies with active websites as of today are included. Founding year information is from the company websites or the LinkedIn profiles of the companies or their founders. The two pre-1990 companies were not set up initially as water-from-air equipment suppliers. Companies started in the 2016–2017 peak years were not apparently a direct response to the Water Abundance XPrize competition which ran during 2016–2018. Founding years were not available for 11 of the 73 companies listed below. The last 10 years saw the formation of 37 firms—half of the existing companies. There has been no apparent merger and acquisition activity. Dozens of companies are marketing actively their AWGs. At least two or three dozen units are operating worldwide (see Case Studies page). According to O'Callaghan and others (2018) when "at least 3 companies actively offer versions of the technology; [with] more than 12 full-scale units in operation" this is one signal the industry is in the "Early and Late Majority" stage which can typically last 12 to 16 years. Two other signals stated by O'Callaghan and colleagues are that "Consulting engineers now specify the technology..." and "Efficiencies [are] gained in engineering design and process optimization." Reference: O'Callaghan, P. and others (2018). Development and Application of a Model to Study Water Technology Adoption. Water Environment Research, June 2018, 563–574. Data Table pre-1990 (2)
1992 (1)
1994 1995 1996 1997 (2)
2000 2001 (2)
2006 (2)
 This YouTube video by the Dutch foundation, Happy With Water Foundation, reviews several atmospheric water vapour processing methods and then states that an absorption cooling method using solar energy and vacuum tubes with heat pipes reduces the energy cost of water making it relatively more affordable and practical compared to most other options.
 Water-from-Air Quick Guide In response to a reader's comments, the July 2018 reprinted second edition incorporates enhanced temperature versus relative humidity psychrometric tables in Chapter 4 with wider temperature ranges (0–55 °C; 32–132 °F) for finding water vapour density, humidity ratio, and dew-point. This makes the tables more useful for cities like Abu Dhabi, Doha, and Dubai.
This reprint also has a revised Appendix 6: Economics of Off-grid Solar PV for WFA. There are two detailed examples in the Appendix. The first example is for a 1.05 kW input power atmospheric water generator using 1-phase electric power. The second example is for a 2.1 kW input power atmospheric water generator using 3-phase electric power.The Appendix presents clear diagrams showing the main components of single-phase and three-phase off-grid solar PV systems. The Appendix concludes by revealing, for each example, the ratio comparing the price of an off-grid solar PV system to the price of the atmospheric water generator. The Water-from-Air Quick Guide may be purchased from Amazon. 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. 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". 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. 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)  Thirty-two cities that have been identified as likely to run out of sustainable natural water supplies by the Nature Conservancy and the BBC (see text). Click on map to enlarge. 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.
A Water-from-Air System Hourly Analysis Model for San Francisco, California is available as a free download on the Atmoswater Research website. During the prevailing California Drought, seventeen rural communities were identified by the California Department of Public Health as having "drinking water systems at greatest risk". Two of the affected counties, Sonoma and Santa Cruz are adjacent north and south respectively to San Francisco. Therefore, it is interesting to take a tour through the San Francisco hourly analysis model to see what it can tell us about the feasibility of using water-from-air machines (atmospheric water generators) as alternative or additional water resources in drought affected communities in Sonoma and Santa Cruz. Tour Stop 1  Tour Stop 1: Input values include the water-from-air machine's water production rate at a specific combination of temperature and relative humidity. The chilled surface temperature is also used as a model input value. (Click to enlarge) Tour Stop 2  Tour Stop 2: Daily Water Production graph with an interpretation of the modeled result, (Click to enlarge) Tour Stop 3  Tour Stop 3: Daily Average Water Production by Month with an interpretation of the modeled result. In a water crisis situation, each person needs 5 L/day of drinking water. Total daily water demand per person to take care of their drinking, cooking, sanitation, and bathing needs is typically 50 L/day. (Click to enlarge) Tour Stop 4  Tour Stop 4: Hourly Production Rate Annual Frequency Distribution with an interpretation of the modeled result. (Click to enlarge) Tour Stop 5  Tour Stop 5: With an average daily water production of 703 L/d, one machine could serve 14 people at the 50 L/d level or 140 people at the minimal 5 L/d level of drinking water consumption. Water storage is needed to distribute the annual water production evenly over the year. Several machines can be distributed throughout a region to serve larger populations. Water-from-air is a unique decentralized way of obtaining water. It is not absolutely necessary to think of a central water production hub. The machines can be placed where they are needed. Tour Stop 6  Tour Stop 6: The core of the model with hourly input and output values. (Click to enlarge) Tour Stop 7  Tour Stop 7: This is an excerpt from the daily water production table that is generated from the hourly weather data. The hourly air temperature, relative humidity, and air pressure values enabled calculation of the hourly water vapour density (the water resource). Tour Stop 8
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) I hope you found this tour interesting! The entire model output consists of 120 pages. Becoming familiar with how a water-from-air machine responds with its freshwater production to the hourly weather at a site is a unique experience that really helps make sound decisions about whether or not to use these machines in various drought situations.
The San Francisco model shown here used weather data from 1993 because that was available as a free sample from a weather data vendor. Given the realities of climate change it would be interesting to run the model with 2013 data. I can run models for key drought locations in California. The price per model run report is [ask for quote] (USD). Please allow up to five business days for delivery as a PDF download.  The Water-fom-Air Resource Chart for Praia, Cape Verde (click to enlarge). Why use a Water-from-Air Resource Chart? Well, this colourful output from a computer model is a marvelous tool for understanding how well water-from-air machines (atmospheric water generators; AWGs) would perform at your location. "Knowledge is power"--there is value to being well-prepared before talking to equipment suppliers, consultants, or project colleagues.
Let me guide you through this information-packed chart.
Charts for many different locations are available from Atmoswater Research. You are welcome to ask me to produce charts for places of interest that are not listed yet.  Click on image to read the article. 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.  Spain location map (with latitude and longitude). Click to enlarge. "España sufre sequías cada vez más intensas y prolongadas" ["Spain suffers droughts that are increasingly long and prolonged"; Interempresas.net] Water-from-air Resource (WFAR) Resource Charts are available for five sites in Spain. These sites represent five climate zones. Operating conditions by month for atmospheric water generators range from unreliable to excellent depending on site latitude, elevation, distance inland, and season. Please see the charts for details. The table below ranks the sites from highest to lowest WFAR Annual Index. Water production is poor or unreliable during the winter months. Hourly water production analyses would be useful for better understanding the feasibility of water-from-air system operation at these sites.
 Jamaica location map (click to enlarge) Jamaica has a history of droughts. The most recent was in 2013.
A Water-from-air Resource (WFAR) Resource Chart is available for Kingston, Jamaica. This site (9 m elevation) is in the equatorial | winter dry climate zone which encompasses the entire island country. Operating conditions by month for atmospheric water generators are consistently excellent. Please see the chart for details. The Water-from-Air Resource Annual Index = 1.22.  Egypt location map (with latitude and longitude). Click to enlarge. Important environmental issues in Egypt are water scarcity, pollution of the Nile River, solid waste, and loss of biodiversity (UNEP, 2013, Arab Region Atlas of Our Changing Environment, page xiv). Can water-from-air technology address the water scarcity issue? Water-from-air Resource (WFAR) Resource Charts are available for three sites in Egypt. These sites represent one climate zone. Operating conditions by month for atmospheric water generators range from unreliable to excellent depending on site latitude, elevation, distance inland from the Mediterranean Sea, and season. Please see the charts for details. The table below ranks the sites from highest to lowest WFAR Annual Index. The coastal site of Alexandria is suitable for year-round effective operation of water-from-air systems even though the water-from-air resource grade ranges from poor to excellent. In contrast, Cairo and Aswan will have periods of unreliable operation during the low sun season. Hourly water production analyses would be useful for better understanding the feasibility of water-from-air system operation at these sites.
 Kuwait location map (click to enlarge) Important environmental issues in Kuwait are water scarcity, groundwater salinity, land degradation, desertification, pollution, and impacts of the Gulf War (UNEP, 2013, Arab Region Atlas of Our Changing Environment). Can water-from-air technology address the water scarcity issue?
A Water-from-air Resource (WFAR) Resource Chart is available for Kuwait City. This site (54 m elevation) is in the arid | desert | hot arid climate zone. Operating conditions by month for atmospheric water generators range from unreliable to fair. Please see the chart for details. An hourly water production analysis would be useful for better understanding the feasibility of water-from-air system operation in Kuwait City (Water-from-Air Resource Annual Index = 0.45).  Algeria location map (with latitude and longitude). Click to enlarge. Important environmental issues in Algeria are desertification, water scarcity, and pollution (UNEP, 2013, Arab Region Atlas of Our Changing Environment, page xiv). Can water-from-air technology address the water scarcity issue? Water-from-air Resource (WFAR) Resource Charts are available for four sites in Algeria. These sites represent three climate zones. Operating conditions by month for atmospheric water generators range from unreliable to good depending on site latitude, elevation, distance inland from the Mediterranean Sea, and season. Please see the charts for details. The table below ranks the sites from highest to lowest WFAR Annual Index. The coastal site of Algiers is suitable for year-round effective operation of water-from-air systems even though the water-from-air resource grade ranges from poor to good. In contrast, Batna, Biskra, and I-n-Salah will have periods of unreliable operation during the low sun season. Hourly water production analyses would be useful for better understanding the feasibility of water-from-air system operation at these sites.
 Libya location map (with latitude and longitude). Click to enlarge. Important environmental issues in Libya are water scarcity, arable land availability, desertification, and oil development and pollution (UNEP, 2013, Arab Region Atlas of Our Changing Environment). Can water-from-air technology address the water scarcity issue? Water-from-air Resource (WFAR) Resource Charts are available for three sites in Libya. These sites represent two climate zones. Operating conditions by month for atmospheric water generators range from unreliable to excellent depending on site latitude, elevation, distance inland from the Mediterranean Sea, and season. Please see the charts for details. The table below ranks the sites from highest to lowest WFAR Annual Index. The coastal site of Darnah is suitable for year-round effective operation of water-from-air systems even though the water-from-air resource grade ranges from fair to excellent. In contrast, coastal Tripoli and inland Sabha will have periods of unreliable operation during the low sun season. Hourly water production analyses would be useful for better understanding the feasibility of water-from-air system operation at these sites.
 Morocco location map (with latitude and longitude). Click to enlarge. Water-from-Air Resource (WFAR) Charts are available for four sites in Morocco. These sites represent three different climate zones.Operation conditions by month for atmospheric water generators range from unreliable to excellent depending on site latitude, elevation, distance from the Atlantic Ocean, and season. Please see the charts for details. The table below ranks the sites from highest to lowest WFAR Annual Index. The coastal sites of Rabat and Casablanca have a good water-from-air resource allowing year-round effective operation of water-from-air systems. At the higher elevation inland sites of Marrakech and Aguerdi, the water vapour resource in the low sun season decreases to the point where water-from-air systems will have unreliable water production during some periods. Hourly water production analyses are useful for better understanding the feasibility of water-from-air system operation at the inland cities.
 Tunisia location map (with lat. and long.). Water-from-Air Resource (WFAR) Charts are available for four sites in Tunisia. Operating conditions by month for atmospheric water generators range from "unreliable" to excellent depending on site latitude, elevation, and season. Please see the charts for details. The table below ranks the sites from highest to lowest WFAR Annual Index. Although Gabès and Gafsa are in the same climate zone (arid | desert | hot arid), water-from-air systems will perform better in the moister air of coastal Gabès. The warm temperate climate of Tunis to the north has a more consistent water-from-air resource through the year than does the arid climate of Sfax to the south. Tunisia's water-from-air resource exhibits considerable seasonal differences. On balance, the country is a reasonable choice for deployment of water-from-air systems.
 China location map (with latitude and longitude) showing locations which have available water-from-air resource charts (click on image to enlarge). Water-from-Air Resource (WFAR) Charts are available for seventeen sites in China. Operating conditions by month for atmospheric water generators range from poor to excellent depending on site latitude, elevation, and season. Please see the charts for details. The table below ranks the sites from highest to lowest WFAR Annual Index. Generally, water-from-air system performance is better at more southerly sites. Performance is better along the coast than further inland. During the summer months of July and August, when drinking water scarcity is likely to affect people most, water-from-air systems will offer excellent performance except for Hohhot (fair), Taiyuan (good), and Kunming (good). China appears to be a worthwhile market for drinking-water-from-air technologies. At least three equipment suppliers are based in the country.
 Measuring water production from an AWG in Belize 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!
 Water-from-Air Resource Chart for Praia, Cape Verde (click to enlarge). Today, I have a guest post from Walter Wallie Ivison, Director and CEO of World Environmental Solutions, Australia. As usual, Atmoswater Research is not responsible for the contents of external links. While most of us accept water in a similar way to the air we breathe, water still remains one of the concerns for most of the world's population illustrated by the number of hits on Google these days on ways to get water; 300,000 a month on water from the atmosphere is a good example. As we continue to pollute our waters, less fresh water is becoming available for us to drink. More rivers, lakes, and underground aquifers are drying up as the years pass. As bodies of water around the world continue to dry up, we’re seeing more drought conditions spread. There are dust storms in places which have never experienced them until now. As time flows, the amount of agricultural land shrinks, and deserts are growing. |
Roland Wahlgren
I have been researching and developing drinking-water-from-air technologies since 1984. As a physical geographer, I strive to contribute an accurate, scientific point-of-view to the field. Archives
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