Water is the one resource that all life on Earth needs to survive – That’s a fact. From contamination with chemicals like lead and arsenic to human and animal excrement, and from severe droughts to overpopulation and political disagreements over water resources, our supply of clean drinking water is becoming scarce.
According to the BBC, by 2025, two-thirds of the world’s rapidly growing population is projected to be living in conditions of severe water stress. There are already 2.1 billion people living without clean water. Most all of them are also the world’s poorest. Most have no other option but to drink water they know is contaminated and causing half a million deaths every year.
And in richer countries, water is being drained from aquifers and river basins to provide for intensive agriculture and industry, depleting the precious resource faster than it can be replenished. And even in richer countries, we are now finding our water sources are contaminated with everything from radioactive materials, to arsenic and lead.
Enormous lakes in the sky
There is one thing that is for sure – All air, from the aridest of deserts to humid cities contains water vapor. Worldwide, an estimated 3,100 cubic miles (12,900 cubic kilometers) of water is suspended as humidity in the air around us. This amount of water is more than all the water in Lake Superior, the largest lake in North America.
Let’s make a distinction here. We are not talking about clouds. We are talking about the moisture or humidity in the air we breathe. It’s the beads of water we see on the outside of a can of soda on a hot day or the droplets of water that appear as dew on the grass in the morning.
So, with this vast lake of water surrounding us, it is only good sense to make this freshwater source available. Pulling water from the air is not a new concept. Think of dehumidifiers used in some homes. The machines pull the moisture out of the air, but the water is not clean and does not contain the minerals we need.
And for practical purposes, a home dehumidifier is not a good choice for meeting a home’s water requirements. So that leaves the issue open to other technologies, including some rather traditional ones that seem to work very well.
Water From Air companies
Durban, South Africa-based Water From Air makes a WFA water cooler for homes that is capable of producing 32 liters of water a day. The company has several sizes of their WFA water cooler available for purchase, but they do require electricity.
The company’s smallest system produces 32 liters of water a day and is essentially a purification plant that is a plug and play. The machine draws water vapor straight from the source (the air) and converts this into water. This water then passes through carbon filters, TCR filter and reverse osmosis. It is also sterilized thoroughly through 3 UV lights, removing pathogens, algae, and bacteria.
And while the company’s website does not give any estimates on how much electricity it takes to produce one liter of water, Roland Wahlgren, a Canadian water consultant, estimates that the typical energy consumption is around 0.4-kilowatt hours per liter (which costs 5.2 US cents, at current US electricity prices).
However nice the machines may be, they do require the right amount of relative humidity – the amount of water present in air, as a percentage of the amount needed to reach saturation. For most of the devices, that figure is above 60 percent for optimal functioning, which is fine if you live in Costa Rica.
There are ways to get around the WFA technologies, which to some people may seem nothing more than a really big dehumidifier. Instead of refrigeration coils, a ‘desiccant’ material absorbs water from the air like a chemical sponge, and there are a number of companies using this approach because, with most of them, the humidity can be as low as 10 to 15 percent.
A Scottsdale, Arizona start-up company, Zero Mass Water was founded in 2014 by Cody Friesen, associate professor of materials science at Arizona State University. He developed a system called Source that uses solar panels to produce drinking water from the sun and air.
Source works by passively absorbing moisture from the air using a special humectant material. In turn, the solar panel converts solar energy into electricity that is used to power the process that drives the water back out of the collection material. The water is then evaporated to remove pollutants.
With the Source setup, one solar panel can provide potable water for a family of four, and multiple panels can provide water for large facilities, such as a hospital. The company raised $7.02 million to back a series of pilot projects to prove how simple cost-effective access to clean water can be.
“Our desiccant was developed inside my research group at Arizona State University”, explains Friesen, whose childhood in the Arizona desert gave him a natural affinity for water preservation. “You need something that absorbs water at ultra-low humidity, even 5% humidity. For example, when you leave the lid off the sugar bowl, it gets kinda clumpy. Sugar is a natural desiccant, but it does that really slowly. Now imagine an engineered material that does that very fast.”
Warka Water is a unique development
There is one more “water from air” system that deserves mention because it does not require electricity, solar or anything exotic in the way of innovative materials.
It was designed for the poorest regions of the world. It is called Warka Water harvesting. The Italian architect behind it, Arturo Vittori, got the idea when designing a moon base for NASA.
“When you design for such an extreme environment as outer space you have to bring water from Earth and then recycle and reuse the water in a closed system”, explains Vittori. “The same thing happens on planet Earth – the water cycle does this naturally for us.”
Vittori and his team got inspiration from several sources, including bio-mimicry, local traditions, and the Warka tree which is a giant wild fig tree native to Ethiopia. It constitutes a very important part of the local culture and ecosystem by providing its fruit and a gathering place for the community.
Warka Water relies only on natural phenomena such as gravity, condensation, and evaporation and doesn’t require electrical power. It is a vertical structure designed to harvest water from the atmosphere. Warka Water mainly uses local natural and biodegradable materials. It is not meant to be a permanent structure, although it can be maintained as such.
In addition to drinking water, the water generated by the Warka tower can be used for irrigation, reforestation, and ecosystem regeneration. The first Warka Tower was erected in Ethiopia in 2015. When the seasonal fogs come, the tower produces water constantly.
“But even when there is no rain and no fog, nightly condensation still happens”, says Vittori. “The capacity of [our] water tank ranges from 1,600 liters up to 100,000 liters.”
