Water harvesting from air is something that we usually see in sci-fi films. If you’ve seen one, then it was probably for humid regions, because the air has a lot of moisture. It would be impossible to harvest water in dry areas like desert. But not anymore. This water harvesting device will let you do exactly that.
Omar Yaghi, James and Neeltje Tretter chair in chemistry at UC Berkeley and a faculty scientist at Lawrence Berkeley National Laboratory and a faculty scientist at Lawrence Berkeley National Laboratory, and his team has invented the technology and made a successful field test of their water collecting device. They’ve made a prototype last year and they made the report in the June 8th issue of Science Advances journal.
In the journal, those Berkeley researchers demonstrated how they could get drinkable water from desert air or in areas of low humidity without any external energy, and it doesn’t cost too much. The next-generation harvester device is a perfect solution for people who live in parts of the world that have little to no water. It could cheaply supply clean water to those regions.
Yaghi said, “For the first time, we are demonstrating that you can harvest drinkable amount of pure water from the dry desert air every day, using essentially just a simple cheap box, with no additional energy and electricity required other than the natural sunlight. All of these are possible because of a revolutionary porous novel material inside the box called metal-organic framework.”
So, this harvester can still collect water even at sub-zero dew points. “The key development here is that it operates at low humidity, because that is what it is in arid regions of the world,” said Yaghi.
He continued, “There is nothing like this. It operates at ambient temperature with ambient sunlight, and with no additional energy input you can collect water in the desert. This laboratory-to-desert journey allowed us to really turn water harvesting from an interesting phenomenon into a science.”
The inventor also works with King Abdul Aziz City for Science and Technology in Riyadh, Saudi Arabia. This water harvesting technology is a part of their joint research in Center of Excellence for Nanomaterials and Clean Energy.
Essentially, this harvester device is a box inside a box. The inner box has a bed of MOF that functions to absorb moisture from air. The outer box is around 61 centimeter plastic cube with transparent top and sides.
They open the top at night to let air flow in so that the MOF can do its job. During the day, they replace it so the box can drive water back out of the MOF. the water will end up on the inside of the outer box and fall to the bottom.
Field test takes place in Scottsdale, Arizona. It’s a place where the relative humidity drops from 40% at night to 8% during the day. Therefore, researchers could easily scale it by adding more water absorber (MOF).
MOF has internal cavities and channels, giving it vast surface area. A sugar cube sized MOF has an internal surface area that’s as big as a full football field. Yaghi stated, “This high surface area ensures high capacity for the captured water.”
The current MOF, made from expensive zirconium, could harvest around 3 ounces of water per pound (88 ml). However, Yaghi stated that he has created aluminium-based MOF called MOF-303. It’s 150 times cheaper than zirconium and it captures more water, about twice as much. Therefore, new harvesters could produce about about 170 ml per day. It’s still not much, but it’s enough to show that there are possible solutions.
“There has been tremendous interest in commercializing this, and there are several startups already engaged in developing a commercial water-harvesting device. The aluminum MOF is making this practical for water production, because it is cheap,” said Yaghi.
This successful journey, of course, comes with challenges. One of the biggest that the engineers face when they’re designing water harvesters is figuring out how to keep the device cool. The harvester has to be cooler than the air around it in order to ensure the forming of water vapor.
Engineers might going to use a cooling fan, which is quite practical in areas with easy access to electricity. But what about undeveloped regions where the water is still incredibly scarce? This challenge is yet to be solved.
Yaghi stated that this device is really important for regions without any access or limited access to clean water. “My vision is to achieve ‘personalized water,’ where people in water-stressed regions have a device at home running on ambient solar, delivering the water that satisfy the basic needs of the individuals,” he said.
He’s looking forward to the next field test. It’s going to test the aluminium-based MOF in Death Valley. He’s waiting the right time when the temperature reaches 43 degrees celcius in the daytime and around 21 degrees at night, with the humidity as low as 25%.
There are still a long road ahead before this device becomes commercial and it could come to market. Engineers and researchers still need to make the device bigger to capture more air and get more water, as well as experiment with newer and cheaper MOFs. Yaghi realizes that, but he is equally optimistic that this invention can help the world to be a better place and provide clean water to people in need.
Do you think this water harvesting device will be realized shortly? And do you think this is a feasible solution for all people in poor countries or regions with so limited access to clean water? Or maybe you know another technology/invention that provide better solution? Tell us what you think in the comments down below. Make sure to read this article to know how to not waste clean water.