Scientists from the Massachusetts Institute of Technology and the University of California-Berkeley have come up with a solar-powered water harvester that can create water out of air, even in low-sunlight and low-humidity situations. And while the device is in prototype form at the moment, it shows a lot of promise, possibly as a source of water for people in drought-affected parts of the world.
In the words of senior scientist Omar Yaghi, a chemistry professor at UC-Berkeley, the prototype is a “personalized water device” that uses solar power to create water off-grid, while operating from a user’s home and “satisfying the needs of a household.” CNET notes that Yaghi had invented the most important feature of the solar-powered device that allows it to create water – its metal-organic frameworks, or MOFs.
As an active ingredient, so to say, in the recipe of creating water from air, MOFs are what happens when one blends metals with organic molecules, creating highly absorbent compounds that could store liquids or gas. At the present, there are about 20,000 types of MOFs out there, each with their own unique properties and uses, but the particular MOFs in the new water harvester are capable of binding to water.
According to Phys.org, Yaghi came up with the concept of MOFs over two decades ago, and had originally started by combining aluminum, magnesium, or other metals with organic molecules in a “tinker-toy arrangement.” There have even been some MOFs that could hold hydrogen or methane, and one of these frameworks is currently being tested by German chemical firm BASF in its natural gas-powered trucks, as tanks with MOFs can hold thrice the amount of methane that can normally be pumped into an empty tank.
As CNET related, it wasn’t Yaghi who created the harvester, but rather a team led by MIT mechanical engineer Evelyn Wang. Her team of students was able to produce almost three liters of water using 2.2 pounds worth of MOFs in just 12 hours, drawing the water from the air and not having to use any solar panels for their device.
While one may think that bright sunlight is required for the harvester to work like it should, the solar-powered water harvester can work even when there isn’t an especially prominent source of sunlight. It can also work in low-humidity conditions (about 20 to 30 percent during the tests), which is what makes the researchers believe that it could be useful for people living in drought-stricken areas.
“This is a major breakthrough in the long-standing challenge of harvesting water from the air at low humidity,” said UC-Berkeley’s Yaghi in a statement. “There is no other way to do that right now, except by using extra energy. Your electric dehumidifier at home ‘produces’ very expensive water.”
When it comes to the solar-powered device delivering water to places in need of it, Yaghi and Wang are hopeful that succeeding devices’ MOFs would be able to absorb a greater percentage of their weight. For the existing prototype, the MOF can only absorb 20 percent of its weight in water, but this figure may be doubled on future MOFs, according to CNET.
The places where such a water harvester would be welcome don’t just include developing parts of the world that tend to be the ones affected by severe water scarcity at some point in the year. California, for instance, may potentially benefit from it, even as its long-standing drought crisis had recently ended. Even with the California drought already over, the state still experiences erratic rainfall patterns, and climate change may pose a further threat to tenuous freshwater levels. As such, the solar-powered water harvester’s capabilities just might be able to help in a pinch.
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