Scientists are harvesting water by building fog harps and zapping the air

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Scientists are harvesting water by building fog harps and zapping the air

Unread post by allynh » Thu Jan 02, 2020 6:02 pm

I saw an episode of the PBS Newshour about harvesting water from fog. It starts simple with a mess, then MIT found that if they add electricity to the water vapor that the mesh attracts the water for collection.

This is something to follow over time.

How scientists are harvesting fog to secure the world's water supply

Fog collection

Scientists are harvesting water by building fog harps and zapping the air ... ent-crisis
Water, water everywhere and not a drop to drink

Angela ChenJun 8, 2018, 2:04pm EDT
big sur fog
The Earth is 70 percent water, but almost all of that liquid is seawater us humans can’t drink. Already, California is besieged by drought, while citizens in South Africa’s Cape Town try to push back Day Zero, the day the city runs out of water. As our population grows and temperatures rise, the global water crisis worsens, spurring scientists to develop better ways of harvesting water.

Around the world, people living on coasts collect water by harvesting the fog. “Fog is a cloud very low on the ground,” explains Jonathan Boreyko, an engineer at Virginia Polytechnic Institute and State University who studies nature-inspired fluids. Fog harvesters are mesh nets, usually one meter squared, erected perpendicular to the path of the wind. As the wind blows fog through the device, the mesh catches the droplets, and gravity pulls the water down into containers underneath. Most of the time, fog harvesters collect about three liters a day per square meter of mesh.

mit fog collectors
The beauty of fog harvesters, explains Boreyko, is that they take very little effort. The harvesters can be used in remote areas and don’t need constant supervision; just set it up, and collect water at the end of the day.

But they’re not very efficient, in part because the mesh holes have to be just the right size. If they’re too large, the droplets will escape through it. “But if you make them too small, the water is going to get clogged within a matter of seconds because of surface tension, and so it won’t slide down and won’t be easily collected,” Boreyko says. It’s hardly reasonable to have someone wringing the clogged mesh constantly.

So Boreyko worked with Virginia Tech industrial designer Brook Kennedy to create a more efficient harvester that they call a “fog harp.” (Their research was recently published in ACS Applied Materials and Interfaces.) Kennedy had spent time in northern California, where the giant redwoods get almost a third of their water from the rolling fog that comes in from the Pacific. “Their needles aren’t shaped like volleyball nets or screen door mesh,” says Kennedy. “They’re linear, and that was the little bit of insight that connected with what Jonathan had been working on.” Inspired by the trees, Kennedy and Boreyko’s “fog harp” only has vertical wires.

Fog harp
Photo: Courtesy of Jonathan Boreyko
The fix — taking away the horizontal wires — seems deceptively simple. Yet tests using a humidifier showed that there was no way for the harp to clog because droplets simply slid down the wires. Instead of collecting three liters of water for every square meter of material, they increased it to nine liters.

Next, the team hopes to do field tests outdoors and collaborate with manufacturers to cheaply produce fog harps on a mass scale. Already, says Boreyko, the two have heard from people in Bangaldesh, vineyard owners in Mexico, and investment firms in South Africa trying to solve the Day Zero crisis. For them, water is a humanitarian issue. According to the World Health Organization, half of the world will be living in areas where water isn’t easily available by 2025, while other reports show that global water shortages pose a threat to the national security.

The fog harp is a low-tech improvement on the traditional fog harvester, which only collects about 1 to 3 percent of the fog passing by. In a paper published today in Science Advances, a team from the Massachusetts Institute of Technology created a higher-effort, and higher-tech, fix. When air approaches an obstacle (like mesh wires), it tries to go around it. Now, when that air includes droplets of water, the water also tries to go around, meaning that a lot of the water is lost. MIT engineer Maher Damak discovered that manipulating the electrical forces around the fog could solve this problem, making the harvester much more efficient.

Here’s how it would work: You have the mesh fog harvester. Just a few inches away is a vertical structure of roughly the same area, with electrodes on it. (The electrodes would need to be attached to a power source, though Damak says it takes very little energy.) The electrodes zap the air, electrically charging the droplets of water and making them move toward, instead of around or away from, the wires. Essentially, the electrodes make the fog droplets attracted to the mesh, according to Damak, leading to almost 100 percent efficiency.

This method inspired Damak to start a water-harvesting startup called Infinite Cooling with fellow MIT engineer Karim Khalil. They want to take this same idea and apply it to power plants, which Khalil says are one of the biggest users of water in the country. Most of the water is used to cool the plant down; in cooling towers, water is boiled into giant clouds of fog called cooling plumes. Khalil and Damak want to place fog harvesters near cooling plumes to collect and reuse water that would otherwise be lost.

Now, Khalil and Damak are building a pilot version of their fog collector that will be installed near MIT’s Central Utility Plant by the end of the year. There’s plenty of longer-term potential too, says Damak. Because the water that the towers used is purified and distilled, it’s possible that one day this method can be used with sea water to strip out the salt, and then used in nearby communities.

Arid regions need water, but fog harvesters work best in humid areas. So, a team at UC Berkeley has developed a method of collecting water from the desert using only sunlight. A few years ago, scientists reported on the unique properties of a material called a metal-organic framework (MOF). MOFs absorb liquids very easily, even in dry conditions, but then release these liquids when there’s sunlight. In 2014, this was just an idea, but in a paper published today in Science Advances, scientists tested their water-gathering device in Scottsdale, Arizona, where the humidity can be as low as 8 percent.

The device is essentially a box inside a box, says study co-author Omar Yaghi, the UC Berkeley chemist who developed MOFs. The inside has a few kilograms of MOFs, while the outside box is transparent plastic.

Harvester filled with a material that absorbs water
Photo: Courtesy of UC Berkeley
During the night, the plastic box is open so that the MOF grains can absorb the water from the air. During the day, the plastic box is closed so that the sunlight goes through the plastic, heats everything up, and forces the water out of the MOF. The water, turned into condensation, drips down to the bottom, where the scientists collected it. (It’s safe, too, notes Yaghi, who said one of the team members drank the water.)

The device is small, and collected about one-third of a cup of water per pound of MOF. MOFs, unfortunately, are very expensive, but Yaghi and his team are creating a cheaper version with aluminum instead of zirconium. He’s also considering making a more active version; if you include a fan that pushes air through, it’s possible that you could collect a lot more water. And next, they plan to test the device in one of the hottest, driest places in the US: California’s Death Valley.
This is the paper mentioned

Electrostatically driven fog collection using space charge injection

This is the video for the company and their website.

Infinite Cooling - MIT delta v Demo Day 2017

Infinite Cooling

This is the other paper mentioned using non-electrical attraction.

Practical water production from desert air ... 98/tab-pdf

I think that they need to talk to the MIT guys to jazz up their system. HA!

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Re: Scientists are harvesting water by building fog harps and zapping the air

Unread post by crawler » Wed Jan 08, 2020 9:15 pm

Nice. But i don't understand much of the paper. But i see that they don't mention Gerald Pollack, nor EZ water, hencely i suspect that their theory is deficient.
STR is krapp -- & GTR is mostly krapp.
The present Einsteinian Dark Age of science will soon end – for the times they are a-changin'.
The aether will return – it never left.

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Re: Scientists are harvesting water by building fog harps and zapping the air

Unread post by The Great Dog » Mon Jan 13, 2020 6:46 pm

There's also the projection of ionized particles into the atmosphere to "wring-out" the clouds: ... nmaker.htm

And... ... f=4&t=1850

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Re: Scientists are harvesting water by building fog harps and zapping the air

Unread post by allynh » Sun Oct 24, 2021 9:12 pm

Vapor-collection technology saves water while clearing the air
David L. Chandler
MIT News Office
August 3, 2021
MIT's nuclear plant
About two-fifths of all the water that gets withdrawn from lakes, rivers, and wells in the U.S. is used not for agriculture, drinking, or sanitation, but to cool the power plants that provide electricity from fossil fuels or nuclear power. Over 65 percent of these plants use evaporative cooling, leading to huge white plumes that billow from their cooling towers, which can be a nuisance and, in some cases, even contribute to dangerous driving conditions.

Now, a small company based on technology recently developed at MIT by the Varanasi Research Group is hoping to reduce both the water needs at these plants and the resultant plumes — and to potentially help alleviate water shortages in areas where power plants put pressure on local water systems.

The technology is surprisingly simple in principle, but developing it to the point where it can now be tested at full scale on industrial plants was a more complex proposition. That required the real-world experience that the company’s founders gained from installing prototype systems, first on MIT’s natural-gas-powered cogeneration plant and then on MIT’s nuclear research reactor.

In these demanding tests, which involved exposure to not only the heat and vibrations of a working industrial plant but also the rigors of New England winters, the system proved its effectiveness at both eliminating the vapor plume and recapturing water. And, it purified the water in the process, so that it was 100 times cleaner than the incoming cooling water. The system is now being prepared for full-scale tests in a commercial power plant and in a chemical processing plant.

“Campus as a living laboratory”

The technology was originally envisioned by professor of mechanical engineering Kripa Varanasi to develop efficient water-recovery systems by capturing water droplets from both natural fog and plumes from power plant cooling towers. The project began as part of doctoral thesis research of Maher Damak PhD ’18, with funding from the MIT Tata Center for Technology and Design, to improve the efficiency of fog-harvesting systems like the ones used in some arid coastal regions as a source of potable water. Those systems, which generally consist of plastic or metal mesh hung vertically in the path of fogbanks, are extremely inefficient, capturing only about 1 to 3 percent of the water droplets that pass through them.

Varanasi and Damak found that vapor collection could be made much more efficient by first zapping the tiny droplets of water with a beam of electrically charged particles, or ions, to give each droplet a slight electric charge. Then, the stream of droplets passes through a wire mesh, like a window screen, that has an opposite electrical charge. This causes the droplets to be strongly attracted to the mesh, where they fall away due to gravity and can be collected in trays placed below the mesh.

Lab tests showed the concept worked, and the researchers, joined by Karim Khalil PhD ’18, won the MIT $100K Entrepreneurship Competition in 2018 for the basic concept. The nascent company, which they called Infinite Cooling, with Damak as CEO, Khalil as CTO, and Varanasi as chairperson, immediately went to work setting up a test installation on one of the cooling towers of MIT’s natural-gas-powered Central Utility Plant, with funding from the MIT Office of Sustainability. After experimenting with various configurations, they were able to show that the system could indeed eliminate the plume and produce water of high purity.

Professor Jacopo Buongiorno in the Department of Nuclear Science and Engineering immediately spotted a good opportunity for collaboration, offering the use of MIT’s Nuclear Reactor Laboratory research facility for further testing of the system with the help of NRL engineer Ed Block. With its 24/7 operation and its higher-temperature vapor emissions, the plant would provide a more stringent real-world test of the system, as well as proving its effectiveness in an actual operating reactor licensed by the Nuclear Regulatory Commission, an important step in “de-risking” the technology so that electric utilities could feel confident in adopting the system.

After the system was installed above one of the plant’s four cooling towers, testing showed that the water being collected was more than 100 times cleaner than the feedwater coming into the cooling system. It also proved that the installation — which, unlike the earlier version, had its mesh screens mounted vertically, parallel to the vapor stream — had no effect at all on the operation of the plant. Video of the tests dramatically illustrates how as soon as the power is switched on to the collecting mesh, the white plume of vapor immediately disappears completely.

The high temperature and volume of the vapor plume from the reactor’s cooling towers represented “kind of a worst-case scenario in terms of plumes,” Damak says, “so if we can capture that, we can basically capture anything.”

Working with MIT’s Nuclear Reactor Laboratory, Varanasi says, “has been quite an important step because it helped us to test it at scale. … It really both validated the water quality and the performance of the system.” The process, he says, “shows the importance of using the campus as a living laboratory. It allows us to do these kinds of experiments at scale, and also showed the ability to sustainably reduce the water footprint of the campus.”

Far-reaching benefits

Power plant plumes are often considered an eyesore and can lead to local opposition to new power plants because of the potential for obscured views, and even potential traffic hazards when the obscuring plumes blow across roadways. “The ability to eliminate the plumes could be an important benefit, allowing plants to be sited in locations that might otherwise be restricted,” Buongiorno says. At the same time, the system could eliminate a significant amount of water used by the plants and then lost to the sky, potentially alleviating pressure on local water systems, which could be especially helpful in arid regions.

The system is essentially a distillation process, and the pure water it produces could go into power plant boilers — which are separate from the cooling system — that require high-purity water. That might reduce the need for both fresh water and purification systems for the boilers.

What’s more, in many arid coastal areas power plants are cooled directly with seawater. This system would essentially add a water desalination capability to the plant, at a fraction of the cost of building a new standalone desalination plant, and at an even smaller fraction of its operating costs since the heat would essentially be provided for free.

Contamination of water is typically measured by testing its electrical conductivity, which increases with the amount of salts and other contaminants it contains. Water used in power plant cooling systems typically measures 3,000 microsiemens per centimeter, Khalil explains, while the water supply in the City of Cambridge is typically around 500 or 600 microsiemens per centimeter. The water captured by this system, he says, typically measures below 50 microsiemens per centimeter.

Thanks to the validation provided by the testing on MIT’s plants, the company has now been able to secure arrangements for its first two installations on operating commercial plants, which should begin later this year. One is a 900-megawatt power plant where the system’s clean water production will be a major advantage, and the other is at a chemical manufacturing plant in the Midwest.

In many locations power plants have to pay for the water they use for cooling, Varanasi says, and the new system is expected to reduce the need for water by up to 20 percent. For a typical power plant, that alone could account for about a million dollars saved in water costs per year, he says.

“Innovation has been a hallmark of the U.S. commercial industry for more than six decades,” says Maria G. Korsnick, president and CEO of the Nuclear Energy Institute, who was not involved in the research. “As the changing climate impacts every aspect of life, including global water supplies, companies across the supply chain are innovating for solutions. The testing of this innovative technology at MIT provides a valuable basis for its consideration in commercial applications.”

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