Water is one of the most precious resources on the planet. More than 1 billion people do not have access to a source of clean drinking water, and around 3 billion experience water scarcity at least one month per year. The increasing pressure on freshwater resources motivates the need for exploring new water harvesting methods, critical for global sustainable development. Atmospheric water generator (AWG), or air to water, is a potential under-explored component of the water solutions portfolio. Rapid depletion of fresh potable water reserves, contamination of existing sources, and generation of large amounts of wastewater due to anthropogenic activities have forced scientists worldwide to find alternate sources of potable water. Many countries including the UAE have limited natural water resources and most of the population does not have easy access to clean drinking water. Water scarcity has become a crucial environmental issue worldwide. It has increased substantially in the last decades in many parts of the world, and it is expected to further exacerbate in the future driven by socio-economic and climatic changes. Several solution options could be implemented to address this growing water scarcity, including supply and demand-side management options that span the water, energy, and agricultural sectors. However, these options involve tradeoffs among various societal objectives, especially when the interactions between these objectives are not carefully considered.
This episode provides an overview of one of the most useful solutions to water scarcity issues – Atmospheric Water Generators. It is the first part of a two-part series titled “Atmospheric Water Generation” by Sani Water. Sani Water has been at the forefront of providing their customers with the latest products and advanced water treatment technologies available in the drinking water industry. With “Atmospheric Water Generation Series”, Sani Water aims to educate and inform their customers about the fundamentals of atmospheric water generation and some of the most popular brands of atmospheric water generators available in the market today.
ATMOSPHERIC WATER GENERATOR TECHNOLOGY
Atmospheric water generation (AWG) uses technology to produce potable water from surrounding air. This provides the potential to expand water availability during shortages, contamination events, and other issues that can interrupt drinking water services. Natural disasters, such as hurricanes, and public water infrastructure failures, such as pipe corrosion resulting in contamination issues, have increased the interest in AWG technology as both emergency and long-term supply solutions. AWG generators range from home-based units that can produce 1 to 20 liters of water per day to commercial-scale units capable of 1,000 to over 10,000 liters per day. Water production rates are highly dependent upon the air temperature and the amount of water vapor (i.e., humidity) in the air.
The most used AWG systems employ condenser and cooling coil technology to pull moisture from the air in the same way a household dehumidifier does. Although significant quantities of energy can be required to operate these condenser and fan systems, recent technological advancements have substantially improved the energy-water ratio, Increasing the feasibility of using these systems to help augment the Nation’s drinking water resources.
Diagram Courtesy – GENAQ
The AWG converts water vapor into liquid water, mostly by condensation. It cools the moist air to temperatures below its dew point, causing a phase change from vapor to liquid water over the cooling surfaces, which is then collected. Condensation-based AWGs operate on a vapor-compression refrigeration cycle. The most promising advantage of the AWG is its ability to produce water from relatively dry air and low temperatures. Although relative humidity is a significant factor in the AWG’s efficiency, it is less affected by variable abiotic conditions such as sky emissivity, wind speed, and topographic location than passive condensers. Therefore, it can potentially be operated under a wider range of weather conditions. Moreover, the AWG can produce higher water yields than the passive method through additional energy inputs. AWGs can reach up to 5000 L/day of potable water. Thus, the AWG is a promising option as an alternative or supplemental source of water in dry, inland, and poor water-scarce regions. Several AWG devices are commercially available. These systems are especially suited to areas with high temperatures and humidity levels that increase the water yield due to the increased water content of the air. The water-generation efficiency varies significantly between brands and depends on the meteorological conditions. The estimated in-situ production ranges from 0.3 kWh/to 0.65 kWh/L. AWGs may include air- and water-filtration systems and water-treatment technologies to reduce various types of chemical and biological contamination.
The AWG is considered a promising option as an alternative or supplemental source of safe drinking water, the quality of which, as already noted, is dependent on air and meteorological parameters. Major research areas include economic viability of the AWG process. Based on limited studies and assuming a perfect substitution between AWG machines and bottled water, the financial performance of the AWG machines demonstrates an attractive substitute product in most locations. However, the results also indicate that the current state of AWG does not provide economically viable alternatives for potable tap water or non drinking water sources.
- Kahil, T., Albiac, J., Fischer, G., Strokal, M., Tramberend, S., Greve, P., … & Wada, Y. (2019). A nexus modeling framework for assessing water scarcity solutions. Current Opinion in Environmental Sustainability, 40, 72-80.
- Inbar, O., Gozlan, I., Ratner, S., Aviv, Y., Sirota, R., & Avisar, D. (2020). Producing Safe Drinking Water Using an Atmospheric Water Generator (AWG) in an Urban Environment. Water, 12(10), 2940.