Water sourced from desert air – and it's no mirage

Scientists are working to extract moisture from the humid climate of the Sahara

July 10, 2017 Researchers from Massachusetts Institute of Technology have created a device to harvest water from air, best suited for desert conditions. Hyunho Kim and Evelyn Wang / MIT
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The Sahara could become one enormous oasis as scientists work on a new device to gather water – from desert air.

Throughout history, wars have been fought over land, money and beliefs. Yet as the the world’s population outstrips the supply of drinkable water, a new threat may be on the horizon.

Water conflicts across the globe are already taking shape. Residents in north-western Tunisia threatened to cut off the supply of water to the capital, Tunis, last year to protest against economic hardships and continuous water cuts they suffered.

Clashes over the access to water earlier this year between farmers and herders in South Sudan’s Darfur resulted in 70 deaths, according to the UN.

And that is aside from the loss of water due to wars such as the ongoing conflict in Yemen. The Yemeni interior ministry said in 2015 that up to 4,000 people die annually from water-related violence that includes raids on wells and other battles over access involving armed groups. The UN’s Food and Agriculture Organization estimates that about 20 million Yemenis do not have access to drinking water because of the ongoing civil war.

Worldwide, one in 10 people lack access to clean water and researchers are studying ways to increase clean supply as access dwindles amid population expansion. Global water demand is projected to increase by 55 per cent with more than 40 per cent of the world population expected to live in areas of severe water stress by 2050, according to Unesco.

More people will result in a greater need for food, meaning more water will be necessary for increased agriculture. This has led scientists at Massachusetts Institute of Technology (MIT), supported by Saudi Arabia’s Abdul Latif Jameel, to create a device that can extract water from the air.

And the best part: the drier the climate, the better.

MIT’s associate professors Mircea Dinca (chemistry) and Evelyn Wang (mechanical engineering) have developed a solar device that can be used to harvest water in the most arid areas of the globe, including the Mena region.

“The opportunity is to utilise the materials at low humidity ranges, below 30 per cent, which correlate best with places that are pretty arid such as North Africa and parts of China,” says Ms Wang. “This kind of technology could be exciting because of the opportunities it could provide.”

The device involves just three components: a special material; absorbing surface; and a condenser.

Moisture from air, no matter what the humidity levels, attaches to the sponge-like material, which is made from metallic iron found in minerals and other organic matter. The sponge is placed between a black painted surface to collect heat while the bottom remains the same temperature as outside air. Water is released in the form of vapour, which is turned into liquid by the variance in temperature from the top and bottom layers.

Currently the team has only created a device that produces water in grams, but they are looking to scale up quantities to create a prototype.

The cost for the materials is as low as US$20 per kilogram. “And if you count the fan, condenser and other items - that doesn’t end up being a huge cost of the overall device,” Mr Dinca says.

“The key is having enough sunlight and a reasonable humidity range.”

The device works better in areas with humidity levels below 30 per cent, and the amount of material is important. Ms Wang says that 4 litres of water could be produced per kilogram of material a day. There could be up to 10 cycles a day.

“The lower the humidity in which you operate, the more attractive this becomes - and the efficiency of this technology actually increases with lower humidity,” Mr Dinca says.

The contraption may not be best suited for the higher humidity in the UAE, but there are other systems in existence such as fog collectors – or extracting potable water from clouds at ground level.

But for arid places like the Mena region, the scale up of this device could be beneficial. The researchers are looking to grow their experiment up to the kilogram size over the next couple of years.

The Abdul Latif Jameel World Water and Food Security Lab initiative has been promoting water-related research since 2014 to help communities battle dwindling water and more demand.

“With our partnership, MIT is providing an opportunity to tackle some of the most pressing issues related to food and water safety and security in the Middle East and around the world,” says Fady Mohammed Jameel, the president of Community Jameel International.

In Mena – the world’s driest region – more than half of the population lives under conditions of water stress, where demand is more than the supply.

And if the new initiative can be replicated on a mass scale, the Sahara could meet the water needs for many thousands of people.