To do this, ambient air is passed over these cold surfaces, and a fraction of the humidity in the air is condensed out as freshwater. While using air as a source of water makes sense, given the abundance of water vapor in the atmosphere, using electricity-intensive air-conditioners to produce water from air adds a significant carbon footprint to such water and is not sustainable in the long term.
Existing solutions from companies like the Israeli-based Watergen, and the Indian company Maithri Aquatech use these air conditioning-based solutions to produce water from air. While they work well, it takes a lot of power to do so — somewhere in the order of 300-600 Wh/L. This is costly financially, but if the electricity is generated using fossil fuel sources, such as conventional combustion-engined generators or coal-burning power plants, it can also be costly for the environment.
Options do exist to combine them with solar PV panels but the enormous electrical load and the increased need for battery storage still increase the cost of such water significantly.
So, what is the solution?
One option is to move away from the heat pump approach and use desiccants, which can alleviate the high energy demands of more active systems.
This is a relatively unexplored technology, and the desiccant materials in question are usually specially designed to have a high affinity for water vapor in particular. It also requires some heating demand to work.
This solution is not entirely new, and companies like Source Global, also known as Zero Mass Water, were among the first players to use a desiccant-based technology in the water-from-air space. The company has attracted much attention and was rewarded with multi-million dollar funding from investors like Jeff Bezos and Bill Gates.
Their setup consists of two key subunits: the desiccant unit and the thermal unit, which are both physically attached to each other. Solar energy powers fans draw in ambient air and push it through a hygroscopic — or water-absorbing — material that traps water vapor from the air. The water vapor is extracted and passively condenses into liquid that is then collected for use. The panels each have an output of around 1.32 gallons (5 liters) per day per unit. However, each unit weighs around 220 lb (100 kg) and occupies an area of about 32.3 sq ft (3 sq m).
water from air is magic
Extracting water from the air might seem like magic, but nature beat us to it. Source: Solvin Zanko/Minden Pictures
Scaling the product size beyond 1.32 gallons (5 liters) per day would require adding significant weight and panel area. The system also relies on direct sunlight to operate, limiting its use to areas that are already relatively sunny and dry.
Moonshot factory, a research arm of Alphabet, has also developed a water-from-air product based on a similar approach that also couples the two units physically.
However, it also suffers from limited water generating capacity. When a higher volume of water is needed, additional modules are simply added, without any system optimization and cost reduction, such as the case when Source Global creates large water farms by connecting hundreds of Hydropanels.
This means existing solutions like these have fairly limited scalability - a serious problem for making them commercially viable and attractive for potential customers.
How does Uravu's system work?
One of the most interesting innovations on the road to viable water-from-air systems is that being developed by Uravu. Their working prototype channels air into a chamber containing desiccating material, like silica.
Here water is absorbed from the air.
Once fully saturated with water, the water-logger desiccant material is then heated to extract the water in liquid form through a process known as "desorption".
From there, the water can be filtered, treated, etc, ready for use. Simple, yet effective!
This approach is relatively less capital intensive, requires less energy to run, and also requires much less maintenance than other similar solutions. The desiccant used in the machine has a shelf life of around ten years, and the rest of the components are mostly conventional electronic components like fans and pipes. The entire process can be powered using solar energy, biomass, or industrial waste heat.
As we previously mentioned, Uravu's system is much more scalable than its competitors.
If you were to install, say, 100 source units of Zero Mass Water's system they would only work together with the same operating efficiency as a single unit operating by itself. Uravu’s machine, however, can take advantage of the better economies of scale that can be achieved with a custom-built solution.
"The heating unit used for the desorption process is one of the most energy-intensive parts of Uravu’s machine’s process. The team behind Uravu envisions massive large-scale plants with centralized solar heating systems akin to the district heating plants used to heat entire gated communities and sections of cities. These large-scale centralized solutions will also simplify maintenance," explain Inc42.
“The cost of water in the first pilot will be expensive. Going forward, our first milestone will be to achieve a cost of INR 5 per liter for a single rooftop unit that can produce 20 liters of water a day,” explained Garg. “But as the scale goes up, we are expecting the cost to go down significantly to about INR 2.5 per liter," he added.