As imminent of a threat as water scarcity poses, there are parts of the world that have long been arid year-round. New technology that has come out of MIT is promising to change that, potentially providing drinking water in the world’s most arid places by being able to extract water from the air.
MIT first announced the technology last year, which received a great deal of attention as well as some criticism. The updated paper was published late last month and features a number of improvements in response to the criticism.
The paper, titled “Adsorption-based Atmospheric Water Harvesting Device for Arid Climates,” claims the technology can extract water from humidity in the air, even in the driest of climates. After a test run in Tempe, Arizona, the new system successfully extracted water from the dry Arizona air.
The technology uses novel high-surface-area materials, which are called metal-organic frameworks (MOFs); this project specifically uses a zirconium-based MOF, alternatively known as MOF-801. Current methods of potable water extraction require high amounts of moisture in the air for the process to successfully yield potable water. For fog-harvesting methods, 100 percent humidity is required and 50 percent for dew-harvesting methods. MIT’s new technology, however, can extract water at levels as low as 10 percent humidity.
Evelyn Wang, one of the paper’s senior authors, said to MIT News that the team “was field-testing in a place that’s representative of these arid areas, and showed that we can actually harvest the water, even in subzero dewpoints.” The success of the new system suggests that it could respond to the demand for water in arid and semi-arid parts of the world.
The new system is powered solely through solar energy, which may prove to be a challenge if the project is to operate on a larger scale. The system, however, does not have any pumps or compressors that can wear out over time and just requires an excess of sunlight and, thus, operates ‘passively.’
Hyunho Kim, a recent doctorate graduate and also an author of the new paper, said to MIT News that, with the necessary upgrades, the system could produce up to three times the amount of water it currently produces.
The current version can only operate over a single night-and-day cycle with sunlight, they added, but “continuous operation is also possible by utilizing abundant low-grade heat sources such as biomass and waste heat.” The system, after all, was only expected to produce a few milliliters of water. The research team, however, is hoping to be able to produce several liters of water as they upgrade the system.
Wang emphasized that nothing from the MOF material leaked into the water, meaning the water is actually very high quality. The idea behind developing the new system is to one day being able to produce enough units to adequately provide water to individual households in parts of the world where water is scarce.
But MIT is hardly the first to produce water out of thin air. In September 2016, scientists from the Haifa-based Technion Institute of Technology in Israel developed a system that produces clean drinking water free of airborne bacteria from atmospheric vapor.