J-WAFS in Action: Quenching world thirst – Producing water out of thin air

Mircea Dincă, Associate Professor, Department of Chemistry at MIT and Evelyn Wang, Gail E. Kendall Associate Professor in the Department of Mechanical Engineering, are researching a cutting-edge technology to harvest water from the air. Funded by the Abdul Latif Jameel Water and Food Security Lab (J-WAFS) at MIT, the project has potentially huge implications for regions of water scarcity, like the Middle East and North Africa.

Opening Doors spoke to Professors Dincă and Wang about the project and its aims.

What is the main issue you are seeking to address with this research project?

Access to clean water is one of the biggest challenges we face in the world today. While a substantial amount of water is available in the form of vapor in the atmosphere, current techniques such as dewing and fog capture are limited in terms of their efficiency and energy requirements.

We’re proposing to develop a water harvesting technology that will be well-suited for producing water in remote or water-stressed areas like the Middle East. Our approach harvests water from ambient air through special materials called Metal Organic Framework (MOF) materials.

In simple terms, can you briefly describe your proposed solution and how it works?

MOFs are very dense powdery materials that look a bit like sugar, and they have very strong adsorption qualities. We incorporate the MOFs into a device, which looks a bit like a clear-sided box that allows them to be exposed to the air. We don’t just put the MOFs in the box, though. First, we need to incorporate them into some sort of hard matrix, such as carbon salt, because the powder itself does not have very good thermal activity.

The MOFs capture the water vapor from the air and store it, like tiny sponges, through adsorption. To release the adsorbed water, the device is heated via a low-grade heat source, such as sunlight, the water condenses and it can then be collected. People would simply turn on a tap on the side of the device to extract the water, which would be good enough to drink or use for other household jobs.

What advantages do MOF have over techniques such as dewing and fog capture?

Dewing and fog capture techniques are only suitable for conditions of high relative humidity. In environments of low relative humidity, like the Middle East, North Africa and other regions of water scarcity, dewing and fog capture are exceptionally energy intensive and not commercially viable. So there is a significant opportunity for our research to make a huge difference to arid regions where dewing and fog capture are out of the question.

Why have the water adsorption properties of MOF remained relatively unexplored?

MOFs are a class of materials that have been around for about 40 years. People knew they had very strong adsorption qualities, but the focus was on gases. Water can be quite corrosive and reactive when it comes into contact with MOFs, so a big recent challenge has been to develop MOFs that are stable to use with water.

One of our breakthroughs has been to develop materials that are in the same class as these well-known MOFs, but which differentiate themselves from other MOFs by the fact they are very water stable and have exceptional water adsorption qualities.

A single gram of our material can adsorb more water than any other compound in the same class or, in fact, any other material.

 

What are the key challenges you need to address in this project?

We’re always looking at how to improve the water adsorption capacity and the cycling of the material. That is, how many times it can be re-used. Obviously, the more cycles you can have using the same material, the better, be it a thousand or ten thousand. This type of experiment hasn’t been done yet simply because it is time consuming.

We also need to scale-up the device. Right now, we can create prototypes on a small scale, but ultimately, we want to be able to develop larger devices that deliver enough water for, say, a typical family. So that means developing devices that can produce 12-15 liters of water per day.

Are the potential production costs of these ‘super sponges’ low enough to make it a mainstream solution?

Yes, we have looked at the costs quite extensively and made comparisons with similar materials. Our projections put the cost at somewhere between the US $10 – 25 per kilogram, and we estimate each device would require around 5kg to 10kg of material, so the materials cost is low enough to make our solution commercially viable.

What could this mean for areas living under severe water stress? How big a difference could it make?

There is enormous potential for this technology to make a big difference in water scarce regions like the Middle East and North Africa.

Many people are aware of the energy challenges facing our societies, and the need to focus on more sustainable sources of energy. Fewer people are aware of the challenges around water scarcity and water stress that face many regions of the world; challenges that are only going to get more and more serious.

It is projected that in a few years over 30% of the world’s population will not have access to a sustainable source of fresh water. So being able to address this, especially in remote areas that other infrastructure cannot easily reach, could be a game-changer.

 

Your J-WAFS funding is for two years, until August 2019. Will your research be complete by then?

We think this stage will be complete, yes. We should have a viable, proven prototype by then. The next stage would be to keep refining and improving it, and to explore the potential to commercialize it, probably with external industry partners.

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