Despite being an indispensable resource, approximately two-thirds of the world’s population faces the serious issue of water scarcity. In addition, about one third of the world’s ground water basins are being unsustainably depleted. With diminishing groundwater supplies, and a large number of persons having severely limited access to potable water, an intervention of sorts is needed. All is not lost however, especially not with Omar Yaghi of UC Berkeley (University of California, Berkeley) on the case. His work on metal-organic frameworks(MOFs) lead to him teaming up with Evelyn Wang of MIT (Massachusetts Institute of Technology) to create a water-collecting system, capable of operating in dry climates at a humidity level of just 20 per cent.
Metal-Organic Frameworks
MOF crystals have been demonstrated previously in other applications such as the capturing of carbon dioxide from exhaust gases, and other chemical uses. Now, it is their time to shine in the area of water harvesting. The MOF used in Yaghi and Wang’s water harvesting device makes use of a combination of zirconium and adipic acid. This MOF is particularly adept at trapping water molecules in low humidity conditions.
Water Harvesting With The Help of Metal-Organic Frameworks
For a water harvesting device to be viable, it should be able to function effectively with minimal energy requirements. The MOF crystals absorb water and this trapped water is then evaporated. This is done using heat energy collected from the sun by the solar absorber. Finally, the condenser plate, cools down the water vapor, allowing water droplets to be collected. The team’s prototype managed to gather 2.8 liters of water over a 12 hour period. The beauty of this system, is that it would not require major infrastructural changes in order to be implemented. The MOF crystals are naturally adept at trapping water, and all that is needed to release the water is sunlight. This makes this system an excellent candidate for use in remote areas. In addition to being great for remote areas in need of water, this system could also be implemented on an even wider scale. Traditional methods of water collection and delivery involve massive underground plumbing networks. These decentralized systems, if perfected, could be used instead in every household to fulfill our water needs.
Improvements to Be Made
This MOF water harvesting system, although promising, has yet to be perfected. There is at least however, a promising working prototype already. Kaghi and Wang are working steadfastly on improving their system to harvest more water. Kaghi notes that in order to have a continuous supply of water from their system, it could be designed in such a way as to suck up water during the night and release water during the day. Another option is to configure the solar absorber to produce water vapor at a faster rate. To hear Yaghi himself speak on the device, take a look at this video, where he breaks everything down simply and explains the basic working principle of his device.
Final Thoughts
Yaghi and Wang’s water harvesting device is a viable means of sustainably gathering water which has low energy requirements. It is technologies like this that can help alleviate the world’s water woes and it can do so with minimal environmental impact.
