• Mesh being tested for use on fog-harvesting devices by Shreerang Chhatre and colleagues at MIT.

    Photo: Patrick Gillooly

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Out of thick air

MIT graduate student is working to make water available for the world’s poor by refining the tools and techniques of fog harvesting.


In the arid Namib Desert on the west coast of Africa, one type of beetle has found a distinctive way of surviving. When the morning fog rolls in, the Stenocara gracilipes species, also known as the Namib Beetle, collects water droplets on its bumpy back, then lets the moisture roll down into its mouth, allowing it to drink in an area devoid of flowing water.

What nature has developed, Shreerang Chhatre wants to refine, to help the world’s poor. Chhatre is an engineer and aspiring entrepreneur at MIT who works on fog harvesting, the deployment of devices that, like the beetle, attract water droplets and corral the runoff. This way, poor villagers could collect clean water near their homes, instead of spending hours carrying water from distant wells or streams. In pursuing the technical and financial sides of his project, Chhatre is simultaneously a doctoral candidate in chemical engineering at MIT; an MBA student at the MIT Sloan School of Management; and a fellow at MIT’s Legatum Center for Development and Entrepreneurship.

Access to water is a pressing global issue: the World Health Organization and UNICEF estimate that nearly 900 million people worldwide live without safe drinking water. The burden of finding and transporting that water falls heavily on women and children. “As a middle-class person, I think it’s terrible that the poor have to spend hours a day walking just to obtain a basic necessity,” Chhatre says.

A fog-harvesting device consists of a fence-like mesh panel, which attracts droplets, connected to receptacles into which water drips. Chhatre has co-authored published papers on the materials used in these devices, and believes he has improved their efficacy. “The technical component of my research is done,” Chhatre says. He is pursuing his work at MIT Sloan and the Legatum Center in order to develop a workable business plan for implementing fog-harvesting devices.

Beyond beetle juice

Interest in fog harvesting dates to the 1990s, and increased when new research on Stenocara gracilipes made a splash in 2001. A few technologists saw potential in the concept for people. One Canadian charitable organization, FogQuest, has tested projects in Chile and Guatemala.

Chhatre’s training as a chemical engineer has focused on the wettability of materials, their tendency to either absorb or repel liquids (think of a duck’s feathers, which repel water). A number of MIT faculty have made advances in this area, including Robert Cohen of the Department of Chemical Engineering; Gareth McKinley of the Department of Mechanical Engineering; and Michael Rubner of the Department of Materials Science and Engineering. Chhatre, who also received his master's degree in chemical engineering from MIT in 2009, is co-author, with Cohen and McKinley among other researchers, of three published papers on the kinds of fabrics and coatings that affect wettability.

One basic principle of a good fog-harvesting device is that it must have a combination of surfaces that attract and repel water. For instance, the shell of Stenocara gracilipes has bumps that attract water and troughs that repel it; this way, drops collects on the bumps, then run off through the troughs without being absorbed, so that the water reaches the beetle’s mouth.

To build fog-harvesting devices that work on a human scale, Chhatre says, “The idea is to use the design principles we developed and extend them to this problem.”

To build larger fog harvesters, researchers generally use mesh, rather than a solid surface like a beetle’s shell, because a completely impermeable object creates wind currents that will drag water droplets away from it. In this sense, the beetle’s physiology is an inspiration for human fog harvesting, not a template. “We tried to replicate what the beetle has, but found this kind of open permeable surface is better,” Chhatre says. “The beetle only needs to drink a few micro-liters of water. We want to capture as large a quantity as possible.”

In some field tests, fog harvesters have captured one liter of water (roughly a quart) per one square meter of mesh, per day. Chhatre and his colleagues are conducting laboratory tests to improve the water collection ability of existing meshes.

FogQuest workers say there is more to fog harvesting than technology, however. “You have to get the local community to participate from the beginning,” says Melissa Rosato, who served as project manager for a FogQuest program that has installed 36 mesh nets in the mountaintop village of Tojquia, Guatemala, and supplies water for 150 people. “They’re the ones who are going to be managing and maintaining the equipment.” Because women usually collect water for households, Rosato adds, “If women are not involved, chances of a long-term sustainable project are slim.”

Finding financing for fog harvesting

Whatever Chhatre’s success in the laboratory, he agrees it will not be easy to turn fog-harvesting technology into a viable enterprise. “My consumer has little monetary power,” he notes. As part of his Legatum fellowship and Sloan studies, Chhatre is analyzing which groups might use his potential product. Chhatre believes the technology could also work on the rural west coast of India, north of Mumbai, where he grew up.

Another possibility is that environmentally aware communities, schools or businesses in developed countries might try fog harvesting to reduce the amount of energy needed to obtain water. “As the number of people and businesses in the world increases and rainfall stays the same, more people will be looking for alternatives,” says Robert Schemenauer, the executive director of FogQuest.

Indeed, the importance of water-supply issues globally is one reason Chhatre was selected for his Legatum fellowship.  

“We welcomed Shreerang as a Legatum fellow because it is an important problem to solve,” notes Iqbal Z. Quadir, director of the Legatum Center. “About one-third of the planet’s water that is not saline happens to be in the air. Collecting water from thin air solves several problems, including transportation. If people do not spend time fetching water, they can be productively employed in other things which gives rise to an ability to pay. Thus, if this technology is sufficiently advanced and a meaningful amount of water can be captured, it could be commercially viable some day.”

Quadir also feels that if Chhatre manages to sell a sufficient number of collection devices in the developed world, it could contribute to a reduction in price, making it more viable in poor countries. “The aviation industry in its infancy struggled with balloons, but eventually became a viable global industry,” Quadir adds. “Shreerang’s project addresses multiple problems at the same time and, after all, the water that fills our rivers and lakes comes from air.”

That said, fog harvesting remains in its infancy, technologically and commercially, as Chhatre readily recognizes. “This is still a very open problem,” he says. “It’s a work in progress.”


Topics: Alumni/ae, Chemistry and chemical engineering, Graduate, postdoctoral, International development, Legatum Center, Materials science, Mechanical engineering, Students, Water

Comments

This idea was in a sci-fi series, they were distilling watter out of air... Since then I am fond of the idea... Fog comes from the sea water most of the time... Only it is carried free to distant locations, actually to every where... Maybe if we can also distill salty water with resources like fog nets, jeothermal resources, and etc. But need to carry it to long distances... But numbers looks promising in this research... Still stackable, can be used on sides of fields, houses as in joint beneficiant ways... Just if we could use it for agriculture, or car washing...
In areas where water is scarce, fog provides a vital source of water for plants and other life forms. It is a crucial part of the ecosystem. Harvesting it because people are living in an area that doesn't have enough clean drinking water to support human life is short-sighted, as it will change the area's climate in ways that make it even drier. We cannot afford to be human-centric in our decisions anymore, we must look to the big picture. Nevertheless, kudos to the inventor for thinking creatively. There are no doubt applications where this will be useful; I just hope it is not put into wide-scale use in rural areas in a way that accelerates desertification. As the article points out "the water that fills our rivers and oceans comes from our air." Where will it come from if we take it out of the air?
One billion people worldwide do not have access to clean and safe drinking water. Yet a sand filter and bleach (one gallon of household bleach will treat 3,800 gallons of water.)is all one needs. It takes only water, salt, electrodes, and electricity to make bleach. The carbon rods in household batteries are all you need. An apparatus that an eight-grade student could build for a science fair. If one were to collect all the alternators from junk cars and attach them to bicycles that would provide the electricity needed. Yet despite its simplicity it remains out of reach for 1 billion people worldwide. The problem isn't technology its the capitalist system itself. Venture capitalist can make money on the newest electronic gadjet or bombing drone. They don't see a way to make money by providing water to those who can't afford it. Socialist Cuba doesn't have that problem but that's because they made a revolution. Which is exactly what we need to do here.
Congratulations, i expect that reason to do this kind of things can help people to live. In my country is the same problem. if you want to continue in my country with investigations you can call me: att jose villa
I saw this done in Chile over 20 years ago, Along the coast aprox 200 miles north of Santiago.
I recommend an excellent yet humorous and easy to digest book for your pleasure & education: "Eat the Rich: A Treatise on Economics" by P.J. O'Rourke. The book recounts his travels to a number of different countries around the world, trying to figure out first hand why some nations are wealthy and others are poor. Cuba, that socialist paradise, was included in his itinerary. Mr. O'Rourke writes for "Rolling Stone" magazine, hardly a bastion of political conservatism. In case you choose not to invest the time to read his excellent and enjoyable book, here's the conclusion: Societies that engage in vigorous capitalism tend on the whole to be wealthier than those that practice socialism. While there will always be a wide spectrum between the very rich and the very poor in any country, what actually happens is this: In socialist nations, the (very few elitist) rich get richer and the poor get poorer. In capitalist nations, the (quite a few industrious) rich get richer and the poor get . . . richer. True, they don't have as much as the rich, but they do have more than they had before, and they have way more than their poor counterparts do who live in socialist lands. Capitalism is not perfect; as Churchill said, its "inherent vice is that it spreads prosperity unequally." But socialism - the real thing, not the lies they tell you about it in books advocating its adoption as policy - is plainly evil. Again from Churchill, socialism's "inherent vice is that it spreads misery equally." We should encourage ideas like this fog collection device, to improve the human condition, because it is the right thing to do, even if unprofitable. But attempting to lay blame - for the recipients' extreme poverty and genuine need for good drinking water - onto a capitalist system that generally doesn't even exist in the nations in question, is just wrong-headed ignorance of historical facts.
I have been involved in fogwater work since 1995 and my company, Kimre, recently donated media for the latest tests presently being started in Chile. I would be happy to provide information to Mr. Chhatre. gcp@kimre.com. There is a lot of research being done. Unfortunately, the media shown cannot really be successful in the field due to excess pressure drop and low Re-entrainment velocity The business plan is exactly what is needed as the economic and environmental issues are difficult and previous work has mostly been academic; without a business basis. As is pointed out in another comment, negative environmental consequences are possible. I am surprised that Dr. Schemenauer is not mentioned he has been the motivation behind work for years. Curiously, I also worked on water repellent fabrics early in my career.
Associate researchers in our team (Acquaniebla) have been working for over 20 years harvesting water from persistent advection fog. We are also part of the ONG FogQuest, and usually train and supply the volunteers that FogQuest send to different arid parts of the world to install fog water collectors. Currently we are working in new collector design and studying some promising sites in the north of Chile. We plan to work in the future on collecting mesh design and on materials for the collecting media. We will like to get in touch with MIT researchers working in this area and will be happy to collaborate with them.
Hi Sheerang, I really like this idea... One that I recently saw in South Africa and was very impressed. To prevent the privacy, I cannot take the name out, but one of my suppliers' also supplies the specially knitted yarn to a "local" researcher who devised the technique to harvest the fog water... the numbers were quite impressive as well... if i remember correctly about a liter of water per square meter of yarn a day in high dense fog regions...
For our MIT SB thesis in chemical engineering in 1961 we demonstrated dropwise condensation of polar compounds on Teflon. Water was best but several polar organic compounds condensed dropwise as well. Using Teflon-coated threads alone or with other screen materials will probably facilitate fog capture and cause the water to easily run down the screen.
Try google search: water OR "H2O" +harvesting +mesh Aside from some commercial offerings, I see mention of algae growth and dust collecting in "1.3 Fog harvesting": www.oas.org/dsd/publications/unit/oea59e/ch12.htm
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