Atmospheric water generation (AWG) is generally very easy to understand: it is a process of gaining water from the air and supplying it to the places where it is needed most. The technical side is not very complicated. However, when it comes to applying this technology in different climates and circumstances, the process becomes way more complicated.
The future of atmospheric water generation will not be measured by the quantity of water generated under lab conditions; it will depend on how successfully this technology can operate in practice.
Why is this important? Because atmospheric water generation works on the verge of thermodynamics, refrigeration, and water cleaning and delivery systems. The machine that works perfectly at certain temperature and humidity indicators can also serve well in practice conditions.
The climate features in the machinery.
There are two major technology methods of extracting moisture from air.
One of the methods is condensation which requires the utilization of vapor-compression refrigeration to chill the incoming air lower than its dew point which makes moisture to condense. Desiccant system employs rather different method where hygroscopic materials are used to capture water vapour and then regenerate this material with the help of heating.
None of these methods is the best option in all situations. Condensation methods work wonders in relatively warm and humid climate.
This makes the climate data important for the design.
AWGs are usually specified under certain conditions of atmosphere pressure, temperature and the moisture content of the air. The real production can be significantly lower when the temperature or humidity differs from the specified one. Thus, it is wrong to assume that a piece of equipment rated for some figure of litres of water a day will be able to provide with that volume of water all year round.
When creating the systems for commercial or institutional use, the designer has to take into consideration the weather in the area, seasonal humidity and expected operation conditions of the technology.
The real metric is litres per unit of energy
While the term “water from air” may imply that the resource is provided free of charge, one must remember that although the air can be natural and free, extracting humidity from it is an energy-consuming process.
This is why energy efficiency is the key measure in the technology’s performance.
The technological efficiency is influenced by a large number of parameters, such as compressor efficiency, evaporator/condenser construction and design, geometry of the coils, amount of airflow, etc. Minor variations in any of these indicators may lead to a change in the amount of water produced per unit of energy.
That is why litres per kilowatt-hour indicator makes more sense than litres per day.
Moreover, the energy ratio depends on the weather conditions. In conditions of low relative air humidity, less moisture can be extracted from a cubic meter of air, which raises the energy consumption per litre of water produced.
Power infrastructure cannot be an afterthought
The Power infrastructure cannot be assumed to be an unimportant aspect of the implementation process. It must also be considered that the entire system changes as machinery has to operate under different power supply conditions.
The performance and requirements of refrigeration-based AWGs can depend on the frequency, electric generating capacity, the quality of power supplied to the system, and the load of the compressor associated with starting.
The compressors developed for one type of frequency might have different results when used in another.
The starting of the compressors is especially important because it creates a considerable burden for the electrical networks, particularly when the network relies partially on generators, inverters, and renewable sources.
This is the reason why the electrical infrastructure needs to be considered when thinking about the design of water production equipment.
In the case of off-grid applications, the calculations become even more complicated because the designer has to consider renewable generation sources, batteries capacity, generator capacity, maximum power consumption and daily water consumption.
The machine itself is only a part of the entire system.
Producing water is not the same as producing drinking water
Another misconception is that the nature of atmospheric water as a vapor somehow makes it potable.
While it is true that condensed atmospheric water contains very little minerals in dissolved form, the water is still subjected to air and wall surfaces before being collected. This means that air quality, filtration, storage, and microbiological treatment must all be considered.
The treatment process may include many treatments that will depend on the specific application and water quality requirements including filtration through air, sediment filtration, use of activated carbon, membrane filtration, UV disinfection, and mineralization.
The aim is not to produce water, but rather water that will meet the requirements of the applicable drinking water standard.
At the same time, it is worth mentioning that there is an important distinction from traditional water treatment technologies. Atmospheric water comes from moisture, not a source rich in dissolved solids and therefore treatment processes differ. Reverse osmosis is not necessarily important for condensation because there are no dissolved salts in the water that need to be removed.
Ultimately, testing confirms water quality.
The fleet becomes a data system
As active deployments advance from the machines to a fleet, a new technology comes into being: operational data. In modern systems, thermal analysis, humidity, role of compressors, operations of pumps, status of the filters, and amount of produced water can be determined. This variety of operational information assists operators in understanding whether the machines function properly, when maintenance is due, and how they are working in different climates.
The use of this operational data does not need to be confined to monitoring.
In time, it can be utilized for altering control mechanisms and devising maintenance operations. Patterns of operation can be detected with seasonality taken into account, as well as being able to identify anomalies before they cause serious failures.
Thus, this information may create a feedback loop owing to which the design of the systems can be modified.
In the industry that evolves from arrangements, such feedback becomes more essential. A fleet should be more than tens of machines independently utilizing operational data.
From Demonstration to Infrastructure
The key issue in scaling atmospheric water production technology is not how to build ever larger machines, but rather how to make the technique reliable across different climates, power availability and operational environments.
The next stage of AWG shall be characterized by energy efficiency, climate-oriented design, water quality assurance, intelligent monitoring and reliable service infrastructure. Once all these features are in place, the technology of water from air will be able to turn from an exciting possibility to a real decentralized water supply alternative.
About the author
By: Navkaran Singh Bagga is the Founder & CEO of Akvo Atmospheric Water Systems Pvt. Ltd. (akvosphere.com), an Indian manufacturer of atmospheric water generators deployed across 15+ countries.
