This new material pulls clean drinking water straight out of the air

Daniel Taeger/Shutterstock.com

This could solve a lot of problems.

One of the ways of sourcing drinking water in areas afflicted by drought is by harvesting it from the air, and now a new material developed by scientists in the US could make this tricky feat easier than ever.

Researchers at Harvard University have taken inspiration from a variety of water-collecting traits in different natural species to develop what could be an unrivalled composite system for harvesting and transporting atmospheric H20.

"Everybody is excited about bio-inspired materials research," said chemical biologist Joanna Aizenberg from Harvard's Wyss Institute for Biologically Inspired Engineering. "However, so far, we tend to mimic one inspirational natural system at a time."

Instead, the team's system combines elements from three distinct plant and animal species to create a material that they claim outperforms other synthetic surfaces designed to trap condensation.

According to the researchers, the major challenges in harvesting water from the air lie in controlling the size, speed, and direction of water droplets as they form and flow on a surface. At the core of their solution to this problem, the researchers copy the external bumps of Namib desert beetles, which help the insect to collect water droplets on its shell.

Aizenberg Lab/Harvard SEAS

Scientists already knew that the bumps' hydrophilic (water-attracting) tops and hydrophobic (water-repelling) surroundings helped them collect water, but Aizenberg's team realised that the convex shape of the protrusions themselves might also be able to harvest water too.

Using modelling, the team found that this natural water-trapping mechanism could be enhanced by mimicking the geometry and slopes of cactus spines, which help drive collected droplets down the slopes.

By combining this further with a nano-coating designed to emulate the slippery surfaces of pitcher plants, the material facilitates greater droplet formation as the water beads downwards.

"We experimentally found that the geometry of bumps alone could facilitate condensation," said one of the researchers, Kyoo-Chul Park. "By 

• optimising that bump shape through detailed theoretical modelling and 
• combining it with the asymmetry of cactus spines and 
• the nearly friction-free coatings of pitcher plants, 

we were able to design a material that can collect and transport a greater volume of water in a short time compared to other surfaces."

The tandem effect of the system – together with a technology developed by the researchers called Slippery Liquid-Infused Porous Surfaces – helps the material collect water in ways that could otherwise prove impossible.

"Bumps that are rationally designed to integrate these mechanisms are able to grow and transport large droplets even against gravity and overcome the effect of an unfavourable temperature gradient," the authors write in their paper, published in Nature.

Not only could this technique help to harvest water from the air in areas affected by water shortages, but it could also be of use to enhance condensation in industrial machinery.

"Thermal power plants, for example, rely on condensers to quickly convert steam to liquid water," said one of the team, Philseok Kim. "This design could help speed up that process and even allow for operation at a higher temperature, significantly improving the overall energy efficiency."

With about 1.2 billion people around the world living with water scarcity and two-thirds of the global population experiencing water shortages on a monthly basis, the potential of technology like this could make a huge difference to so many lives.

ORIGINAL: Science Alert

PETER DOCKRILL

7 MAR 2016

http://www.seas.harvard.edu/news/2016/02/pulling-water-from-thin-air

Pulling water from thin air

INSPIRED BY A DESERT BEETLE, CACTUS AND PITCHER PLANT, RESEARCHERS DESIGN A NEW MATERIAL TO COLLECT WATER DROPLETS

February 24, 2016

By Leah Burrows

An array of slippery asymmetric bumps shows a significantly greater volume of water collected at the bottom of the surface compared to the flat slippery surfaces. (Courtesy of the Aizenberg Lab/Harvard SEAS)

Organisms such as cacti and desert beetles can survive in arid environments because they’ve evolved mechanisms to collect water from thin air. The Namib desert beetle, for example, collects water droplets on the bumps of its shell while V-shaped cactus spines guide droplets to the plant’s body.  

As the planet grows drier, researchers are looking to nature for more effective ways to pull water from air. Now, a team of researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Wyss Institute for Biologically Inspired Engineering at Harvard University have drawn inspiration from these organisms to develop a better way to promote and transport condensed water droplets.

“Everybody is excited about bioinspired materials research,” said Joanna Aizenberg, the Amy Smith Berylson Professor of Materials Science at SEAS and core faculty member of the Wyss Institute. “However, so far, we tend to mimic one inspirational natural system at a time. Our research shows that a complex bio-inspired approach, in which we marry multiple biological species to come up with non-trivial designs for highly efficient materials with unprecedented properties, is a new, promising direction in biomimetics.”

The new system, described in Nature, is inspired by 

• the bumpy shell of desert beetles, 
• the asymmetric structure of cactus spines and 
• slippery surfaces of pitcher plants. 

The material harnesses the power of these natural systems, plus Slippery Liquid-Infused Porous Surfaces technology (SLIPS) developed in Aizenberg’s lab, to collect and direct the flow of condensed water droplets.

This approach is promising not only for harvesting water but also for industrial heat exchangers.

“Thermal power plants, for example, rely on condensers to quickly convert steam to liquid water,” said Philseok Kim, co-author of the paper and co-founder and vice president of technology at SEAS spin-off SLIPS Technologies, Inc. “This design could help speed up that process and even allow for operation at a higher temperature, significantly improving the overall energy efficiency.”   

The major challenges in harvesting atmospheric water are controlling the size of the droplets, speed in which they form and the direction in which they flow.  

For years, researchers focused on the hybrid chemistry of the beetle’s bumps — a hydrophilic top with hydrophobic surroundings — to explain how the beetle attracted water.  However, Aizenberg and her team took inspiration from a different possibility – that convex bumps themselves also might be able to harvest water.

Time lapse of droplets growing faster on the apex of the bumps compared to a flat region with the same height. (Courtesy of the Aizenberg Lab/Harvard SEAS)

“We experimentally found that the geometry of bumps alone could facilitate condensation,” said Kyoo-Chul Park, a postdoctoral researcher and the first author of the paper.  “By optimizing that bump shape through detailed theoretical modeling and combining it with the asymmetry of cactus spines and the nearly friction-free coatings of pitcher plants, we were able to design a material that can collect and transport a greater volume of water in a short time compared to other surfaces.”

 

Inspired by a cactus spine, asymmetric topography guides the droplet off the bump. (Courtesy of the Aizenberg Lab/Harvard SEAS)

“Without one of those parameters, the whole system would not work synergistically to promote both the growth and accelerated directional transport of even small, fast condensing droplets,” said Park.

“This research is an exciting first step towards developing a passive system that can efficiently collect water and guide it to a reservoir,” said Kim.

This research was supported by the Department of Energy.

This Tower Purifies a Million Cubit Feet of Air an Hour

Daan Roosegaard worked with scientist Bob Ursem and European Nano Solutions to create the Smog Free Tower. STUDIO ROOSEGAARDE

The tower, shown here in Rotterdam, sucks pollution from the air into its chambers and purifies it. STUDIO ROOSEGAARDE

The air is sucked in from a ventilation system at the top of the tower.STUDIO ROOSEGAARDE

And then it enters a chamber where the pollution becomes positively charged before latching onto grounded electrodes. The particles then becomes trapped in the chambers while the clean air escapes.Studio Roosegaarde

Smog. STUDIO ROOSEGAARDE

Roosegaard is compressing smog particles into jewelry, because why not? STUDIO ROOSEGAARDE

Daan Roosegaard worked with scientist Bob Ursem and European Nano Solutions to create the Smog Free Tower. STUDIO ROOSEGAARDE

THERE’S A MASSIVE vacuum cleaner in the middle of a Rotterdam park and it’s sucking all the smog out of the air. A decent portion of it, anyway. And it isn’t a vacuum, exactly. It looks nothing like a Dyson or a Hoover. It’s probably more accurate to describe it as the world’s largest air purifier.

The Smog Free Tower, as it’s called, is a collaboration between Dutch designer Daan Roosegaard, Delft Technology University researcher Bob Ursem, and European Nano Solutions, a green tech company in the Netherlands. The metal tower, nearly 23 feet tall, can purify up to 1 million cubic feet of air every hour. To put that in perspective, the Smog Free Tower would need just 10 hours to purify enough air to fill Madison Square Garden. “When this baby is up and running for the day you can clean a small neighborhood,” says Roosegaard.

It does this by ionizing airborne smog particles. Particles smaller than 10 micrometers in diameter (about the width of a cotton fiber) are tiny enough to inhale and can be harmful to the heart and lungs. 

Ursem, who has been researching ionization since the early 2000s, says a radial ventilation system at the top of the tower (powered by wind energy) draws in dirty air, which enters a chamber where particles smaller than 15 micrometers are given a positive charge. Like iron shavings drawn to a magnet, the the positively charged particles attach themselves to a grounded counter electrode in the chamber. The clean air is then expelled through vents in the lower part of the tower, surrounding the structure in a bubble of clean air. Ursem notes that this process doesn’t produce ozone, like many other ionic air purifiers, because the particles are charged with positive voltage rather than a negative.

Ursem has used the same technique in hospital purification systems, parking garages, and along roadsides, but the tower is by far the biggest and prettiest application of his technology. Indeed, it’s meant to be a design object as much as a technological innovation. Roosegaard is known for wacky, socially conscious design projects—he’s the same guy who did the glowing Smart Highway in the Netherlands. He says making the tower beautiful brings widespread attention to a problem typically hidden behind bureaucracy. “I’m tired of design being about chairs, tables, lamps, new cars, and new watches,” he says. “It’s boring, we have enough of this stuff. Let’s focus on the real issues in life.”

Roosegaard has been working with Ursem and ENS, the company that fabricated the tower, for two years to bring it into existence, and now that it’s up and running, he says people are intrigued. He just returned from Mumbai where he spoke to city officials about installing a similar tower in a park, and officials in Mexico City, Paris, and Beijing (the smoggy city that inspired the project) also are interested. “We’ve gotten a lot of requests from property developers who want to place it in a few filthy rich neighborhoods of course, and I tend to say no to these right now,” he says. “I think that it should be in a public space.”

Roosegaard has plans to take the tower on a “smog-free tour” in the coming year so he can demonstrate the tower’s abilities in cities around the world. It’s a little bit of showmanship that he hopes will garner even more attention for the machine, which he calls a “shrine-like temple of clean air.” Roosegaard admits that his tower isn’t a final solution for cleaning a city’s air. “The real solution everybody knows,” he says, adding that it’s more systematic than clearing a hole of clean air in the sky. He views the Smog Free tower as an initial step in a bottom-up approach to cleaner air, with citizens acting as the driving force. “How can we create a city where in 10 years these towers aren’t necessary anymore?” he says. “This is the bridge towards the solution.”

ORIGINAL: Wired

09.18.15

A Bamboo Tower That Produces Water From Air

The WarkaWater tower is an unlikely structure to find jutting from the Ethiopian landscape. At 30 feet tall and 13 feet wide, it’s not half as big as its namesake tree (which can loom 75 feet tall), but it’s striking nonetheless. The spindly tower, of latticed bamboo lined with orange polyester mesh, isn’t art—though it does kind of look like it. Rather, the structure is designed to wring water out of the air, providing a sustainable source of H 2O for developing countries.

Created by Arturo Vittori and his team at Architecture and Vision, the towers harvest water from rain, fog and dew. This isn’t a new idea—people have been doing this for as long as they’ve needed water, often with air wells. Often built as high-rising stone structures, air wells gather moisture from the air and funnel it into a basin for collection. The WarkaWater functions in much the same way, using mesh netting to capture moisture and direct it into hygienic holding tank accessed via a spout.

How the system works. Illustration: WarkaWater

We wrote about the towers last year when Vittori unveiled a full-size prototype. The company has a newer version of the WarkaWater and a Kickstarter campaign to fund field testing in Ethiopia later this year. Based on tests performed in its Italian lab, the company claims the latest iteration can harvest 13 to 26.4 gallons of water daily. That’s less than most people flush away each day, but a significant quantity in a country where some 60 million people lack sufficient potable water.

The WarkaWater tower produces water by harvesting rain, fog and dew from the air. WarkaWater

Caption: A Warka tree. WarkaWater

The tower uses three system to capture each of the weather phenomena. A polyester mesh net fathers moisture from fog, rain collects directly into a holding tank and dew is directly down a funnel into the tank. WarkaWater

Caption: A Warka tree. WarkaWater

A prototype of the fog-harvesting netting. WarkaWater

The new prototype has some key upgrades:

• The exterior is of bamboo rather than juncus, 
• the top of the tower has reflective pieces to deter birds, and 
• the structure is larger (13 feet wide, up from 7). This doubled the surface area of its water-resistant polyester mesh netting—the orange material you see—so more water is collected as fog permeates the fine mesh. 

MIT has been researching a similar fog harvesting technique that draws inspiration from the Namib beetle. The process of collecting rain is straightforward, but capturing dew is slightly more complicated. Dew forms when the surface area temperature drops relative to the surrounding air. This happens most often in the time between nightfall and sunrise. Vittori is researching materials for the funnel section of the WarkaWater (between mesh netting and the tank) that will lose heat as quickly as possible in order to optimize the small window of dew-production.
The WarkaWater will cost around $1,000 to produce and requires no electricity. Vittori says it takes less than an hour to assemble the five modules into a finished tower, making it easily packed and moved as necessary. The practical goal is for the WarkaWater to become an efficient round-the-clock water production machine. But populating the landscape with alien towers is about more than just functionality, it’s about architecture. You can tell Vittori wanted to design something iconic, but beyond that is the tower’s potential to the social nexus of a village. With fabric canopies that stretch out like a peplum skirt, the towers could be a place where people gather to socialize and seek shelter from the sun, just as they would beneath a leafy Warka tree.

ORIGINAL: Wired

In China, documentary film on air pollution quickly goes viral

A Greenpeace photo dated Oct. 14 shows steel plants in northern China's Hebei province. (Lu Guang / Greenpeace)

'Under the Dome,' new film on China's air pollution woes, 

is quickly viewed by over 150 million online

Documentary about air pollution in China goes viral days before two key legislative sessions

The hottest movie in China this weekend wasn’t “Fifty Shades of Grey” or Jackie Chan’s latest, “Dragon Blade.” Instead, a pointed and emotional environmental online documentary has swept the country by storm, putting its air pollution crisis front and center days before the country's annual legislative sessions.

“Under the Dome,” made by a popular former reporter from China Central Television, was released online Saturday. By Monday, it had been viewed more than 150 million times on video portals, dominating social media such as WeChat and Weibo in the way the blue-black dress phenomenon recently swamped the Internet in the U.S.

The Chinese public is really eager for knowledge, actions and solutions. ... People really want a platform and a vehicle to join in the debate and dig deeper into the problem.- Li Yan, head of climate and energy, Greenpeace East Asia

The fact that the film was not censored and was posted on the website of the People’s Daily, the Communist Party mouthpiece, indicated a substantial degree of official support.

A cross between Al Gore’s “An Inconvenient Truth,” a TED talk and a Lifetime tear-jerker, Chai Jing’s film personalizes the smog problem while holding officials’ feet to the fire in ways rarely seen in Chinese media. It suggests how ordinary citizens can take action to demand stricter government controls.

The state-run energy sector comes in for particular criticism, while the impotence of environmental officials is also revealed. More than 20 government officials are interviewed in the film. Chai even traveled to London and Los Angeles to look for answers about how those cities solved their air pollution problems.

The documentary landed just days before this week’s opening of both the National People’s Congress and the Chinese People’s Political Consultative Conference. Though the two bodies are largely seen as rubber-stamp gatherings, they are closely watched for signals about shifts in the government’s priorities and agenda, and the environment is expected to be a key topic this year.

“Under the Dome” also debuted just a day after China named a new environment minister, Chen Jining, who was plucked from his post as president of the prestigious Tsinghua University. The move was a rare example of China appointing a minister who didn’t come up through the bureaucracy, and Chen reportedly sent Chai a text message congratulating her on the film.

In “Under the Dome,” Chai admits that for years she was not worried about pollution and never wore a face mask. But she became concerned about China’s dirty skies after discovering during her pregnancy that her unborn child had a benign tumor. She reportedly financed the $160,000 project herself.

Just how much is Asia's ozone to blame for bad air in the U.S.?

Though she refrains from making a direct causal link between smog and the tumor in the film, she says, “When you carry a life inside you, what she breathes, eats and drinks are your responsibility, and you feel fear.”

Though most of the facts presented in “Under the Dome” have been widely presented in foreign and Chinese media, Chai’s celebrity and her approachable style (she uses a cartoon to illustrate what PM 2.5 means, for example) resonate.

“The Chinese public is really eager for knowledge, actions and solutions, and she did a good job of putting all the information together in an easy-to-understand way,” said Li Yan, head of climate and energy at Greenpeace East Asia. “People really want a platform and a vehicle to join in the debate and dig deeper into the problem.”

cComments

In Chinese premier Li Keqiang's annual Government Work Report to China's lawmakers at the opening of their 2015 plenary session, he called pollution a "blight on people's quality of life and a trouble that weighs on their hearts". He has also promised to build a more...

Li predicted that the film’s “unusual” popularity would help empower the Environment Ministry. “The timing of this is really unique, coming ahead of the ‘two meetings’ and with a new environment minister coming on the job,” she added.

But interest in Chai’s film chafed a bit for some longtime players in environmental circles.

“Lots of the statistics she presented had already been released many years ago and many of these issues had already been exposed,” said Wu Di, an environmental photographer. “Now we have to pay attention just because Chai Jing is doing a documentary?”

Still, he said, it was a “great thing” that the film was raising awareness – though he questioned how long the “fever” might last.

Among those interviewed in “Under the Dome” are Xie Zhenhua, deputy director of the powerful National Development and Reform Commission; Han Jun, deputy director of the Communist Party’s central finance affairs office; and Xiong Yuehui, director of the science standards office at the Ministry of Environmental Protection.

Beijing seeks to contain its population, and with it, problems

“About over 60% of the steel factories opened without any approval process. But can you really shut them down or replace them?” Xiong says in the film. “A 10-million-ton steel factory can support 100,000 workers. The steel industry in Hebei [province] has become uncontrollable.”

Ding Yan, director of the vehicle pollution department at the Ministry of Environmental Protection, says in the film that he is “embarrassed” about his work because his agency is so toothless.

In the film, Chai flies over L.A. in a helicopter and points out that the city has managed to decrease pollution even while adding cars to the roads. She hangs out with inspectors doing spot checks of pollution emitted by big rigs, and films a trucker who is being fined $1,000 because his vehicle was caught spewing smoke. (The L.A. segment begins about 1 hour and 17 minutes into the film.)

But in China, Ding tells her his agency doesn’t have the authority to replace or confiscate trucks that fail emission standards.

“So when you go out enforcing the law, you don't even dare to show your teeth?” Chai asks Ding. He replies: “I can't even open my mouth. How can I worry about others seeing my teeth?”

Viewers commenting on the film on the Sina web portal expressed both approval of Chai’s efforts and frustration at the government.

“After watching this documentary, I'm very angry. I finally understand what those ‘public servants’ are doing every day. They're all jerks and only know how to get money from the ordinary people,” wrote one. “Our party, please wake up. Otherwise, no one will trust you anymore.”

At the end of the film, Chai encourages the public to report polluters to a government hotline. Between 8 p.m. Saturday and 6 p.m. Sunday, the Beijing hotline saw the number of calls increase 240% over normal and the city’s environmental protection bureau had to add more operators to the hotline, the Beijing Youth Daily reported.

But in a poll conducted by Phoenix TV after the film’s release, 33.5% of the 27,240 respondents said they have no faith in the government and do not expect the smog to be cleaned in the near future.

Tommy Yang and Nicole Liu in The Times’ Beijing bureau contributed to this report.

Follow @JulieMakLAT on Twitter for news out of Asia

ORIGINAL: LA Times

By JULIE MAKINEN