Believe it or not, air contains as much water as six times the world’s rivers combined.
This is mostly in the form of water vapor, and it actually replenishes naturally every 8 to 10 days — give or take. This offers a valuable potential reservoir of freshwater that could be tapped relatively easily.
All we need is the right kind of technology.
Can you distill water from thin air?
As it turns out, you most certainly can. In fact, various water-from-air technologies have existed for some time now.
Working as if by magic, most of these systems are effective at their main task, but tend to consume a lot of energy to do so. In this sense, such technologies are not necessarily sustainable in nature.
In most cases, existing solutions are based on the principle that underlies air conditioning systems — the second law of thermodynamics, and by extension the Carnot cycle. Also applied to other technologies, like refrigerators, it is possible to artificially produce cold surfaces that can be put to use to extract water from the air.
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).
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.
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 s 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.
At that kind of scale, any water produced by Uravu’s technology will be much more expensive than what factories usually have to pay for water. However, this relies on natural supplies being tapped. But that may change sooner rather than later.
According to data from the World Resources Institute’s Aqueduct tool, 17 countries that are home to one-quarter of the world’s population face “extremely high” levels of baseline water stress, where irrigated agriculture, industries, and municipalities withdraw more than 80% of their available supply on average every year.
That is a potential disaster waiting to happen.
Forty-one other countries (where one-third of the world’s population live) face “high levels” of stress, with 40% of the available supply being withdrawn every year. This narrowing of supply and demand leaves these countries and their populations very susceptible to potential droughts in the future.
It could also result in so-called “Day Zero” events like the one that nearly occurred in Cape Town, South Africa in 2018, when the water level of the major dams supplying the city almost reached levels low enough to force the city to turn off most of its water supply.
Another country at serious risk of water stress is Uravu’s home country of India. According to a 2019 report by the government public policy think tank, NITI Aayog, titled “Composite Water Management Index”, India is undergoing the worst water crisis in its history and that nearly 600 million people are facing extreme to high water stress. NITI Aayog also found that nearly 70% of the country’s water is contaminated in some way. This places India in 120th place on WaterAid’s water quality index, out of 122 countries surveyed.
This is very serious.
How can desiccant-based air-from-water systems become scalable?
This is what spurred Bangalore-based startup Uravu to attempt to solve this very problem. After evaluating current solutions in the industry, they soon realized that scalability was a real Achilles heel of the technology.
To alleviate this, Uravu decided to decouple the heating unit and the desiccant unit and alter the thermodynamic processes accordingly. This, they believed, should enable water production capacities to be jacked up in such a concept the sub-systems should also scale independently ultimately bringing the cost of water production significantly down.
For example, for a nominal capacity of 528 gallons (2000 liters) per day, a minimum of 400 Source Global panels would be needed. These 400 panels with repeating parts are merely duplicated without any synergy. On the other hand, for the same 528 gallons (2000 liters) per day capacity, the Uravu system, they found, should only need one set of solar heat panels and one centralized desiccant unit.
The ability to avoid repeating units should, according to Urava, enable the cost of water production to drop by as much as 70 percent! But, that is only half the story.
Existing desiccant/solar-based systems are only really able to generate water during the day. When the sun goes down, the lack of solar radiation obviously renders the solar panels inoperable to any appreciable degree.
As a result, the capacity utilization factor for solutions like Source Global averages out to around 25% per year.
Because the Uravu systems decouple the heat source from the desiccant core, it enables the system to be more flexible, meaning a thermal storage unit can be added that helps in supplying heat to its renewable water-producing machines even during the night.
As a consequence, the capacity utilization factor for Uravu machines is nearly 100% on a sunny day and about 80% yearly. This offers a significant boost in the capacity utilization factor ensures proper utilization of the desiccant unit, and thus, results in a decreased cost of water production.
Another benefit of Uravu’s innovative system is the added advantage of being able to connect its system to any heat source (above 167°F – 75°C) including waste heat, solar heat, biomass heat, etc.
This offers a clear operating and scaling advantage over other competing systems that are limited by their fixed heating and desiccant modules. Uravu’s system also has far many more applications and industries — especially those that generate some waste heat at some point in their activities.
What is more, waste-heat systems are more compact and don’t need large parcels of land as well. They can also effectively run 24 hours a day, thanks to the fact that they undergo multiple cycles of adsorption and desorption throughout the day and night.
What are some of the main applications for water-to-air technology?
Scalable solutions, like those being developed by Uravu, have various interesting applications that might well prove to be a game-changer for various industries.
For example, technology which makes use of desiccants and can be plugged into various forms of renewable energy sources like solar, waste-heat, or biomass could have an important part to play in the United Nations (UN) Sustainable Development Goals (SDG), specifically Goal 6: To ensure availability and sustainable management of water and sanitation for all. In fact, Uravu Labs was been one of the top five global finalists in the Water Abundance XPRIZE in 2018.
Companies like Uravu hope to build a new kind of fully-renewable water infrastructure for the modern age. To make this a reality, it is vitally important that the technology be made to be scalable and affordable.
Once achieved, many industries could reap the rewards for using this form of technology including, but not limited to, the beverage industry, large office campuses (like Google, Microsoft, etc.), schools, hospitals, independent houses, and populations worse affected by water stress in rural and remote areas.
The former is of most interest to companies like Uravu as it consumes, by its very nature, large amounts of water every year. According to some estimates, somewhere in the region of 1,500 billion liters. According to the Water Footprint Network, a research group that works on water issues, it takes up to 310 liters of water, to produce a half-liter of soda, 300 liters to make a liter of beer, and 140 liters to process the ingredients that go into one cup of coffee.
According to Pardeep Garg, one of the cofounders of Uravu Labs, the company is initially looking at beverage manufacturers as a target market.
“We want to focus on the beverages market which has [demanded] large amounts of high-quality water. The water that our machine harvest has a TDS (concentration of dissolved particles) of 50 after mineralization and a pH of 7, which is exactly within the requirement of beverage companies,” said Garg in an interview with Inc42.
A lot of this comes from groundwater sources which add additional pressure on other consumers of this water. To this end, Uravu aims to replace the groundwater used in beverages with 100% renewable water produced by using their water-from-air technology.
Major players in the industry, like AB InBev, Diageo, Coca-Cola, Pepsi, Nestle, etc. all have a lot to gain from such a transition from both a sustainability and financial point of view.
The same is also true for other environmentally conscious brands.
But there are other important applications for such a system too. For example, residential premises could benefit greatly from the ability to distill their own water on site. Houses and low-rise apartments could even create a self-sustaining source of high-quality drinking water on their properties.
This is especially true for people or communities who live in some of the most inhospitable places on the planet. Populations in remote, rural, and off-grid areas can get access to safe and reliable drinking water without spending hours collecting it from wells or rivers.
Commercial premises and businesses could also benefit greatly by generating their own water. Offices, schools, hospitals, and hotels can improve the hydration of its inhabitants and enable a zero-plastic experience.
For some resources, like packaged beverages, water is one of the largest components. While relatively cheap, water is heavy, and transporting large quantities of it can be a very costly affair.
Because of this, beverage manufacturers usually have some kind of decentralized supply chain where large quantities of concentrate are shipped to various local bottling plants where they are diluted with local water supplies (and sometimes carbonated). This saves the company significant transportation costs. The bottled drinks are then distributed locally.
“A lot of the time, these bottling plants are set up in areas that are already water-stressed, causing immense difficulties for the local communities that live there. This is why we see many protests over bottling plants, and them having to shut down,” said Swapnil Shrivastav, cofounder of Uravu Labs told Inc42, referring to the shutdown of Coca Cola plants in Kerala and Tamil Nadu.
“That is the place where we want to create an impact with our commercial operations. We don’t want communities to be robbed of their drinking water and water they use for agricultural purposes,” explained Shrivastav.
As interesting, and innovative as air-from-water technologies like Uravu’s are, they all have one critical Achilles heel — they will live or die by the efficiencies of massive scale production required to make them commercially viable. However, they also need to be commercially viable in the first place to justify installing them in the first place.
A very real, and unfortunate dilemma.
While a similar problem exists with many other renewable technologies, it might not be possible for the very powerful forces of the “invisible hand” in the market to do its magic and allow the technology to become mainstream. For this reason, startups like Uravu may need government subsidies and incentives, and public and private sector investments to get off the ground.
Uravu, for example, has indicated that they are open to the idea of being part of corporate social responsibility (CSR) initiatives that bring relief to water-stressed areas. In fact, they recently secured some significant pre-seed funding from a group of investors led by Speciale Invest. The round also saw participation from Peter Yolles, Soren Schroder, Shigeru Sumimoto, and Tomoki Kaneko.
This is a boost to the company who will use most of the money to build and test more prototypes for their water-from-air technology.
While these technologies are still very much in their embryonic stage and are still just too expensive for actual paying customers to justify the price, it should only be a matter of time before the technology comes to a roof or back garden near you very soon.