Drinking water from desert air

A method has been developed to extract water from the desert air in extremely dry conditions.

The technology embodies the idea that no matter how dry on Earth it is, there is a mixture of moisture in the air. When this method is put into practical use, it is expected that everything will play a key role in survival in dry desert. In addition, climate change can be used in desertification areas and extraterrestrial exploration.

Researchers at the Massachusetts Institute of Technology (MIT) in the US have experimentally demonstrated the effectiveness of a new water extraction system and reported it in a recent issue of the journal Nature Communications.

The research team first proposed the concept for the device last year, and confirmed the feasibility of the device in field trials in Tempe, Arizona, this year. In order for this device to become practical, it is necessary to expand the scale of the device.


Water can be extracted at 10% relative humidity

Senior author Evelyn Wang, a professor of mechanical engineering, added some important improvements to the article after publishing the initial concept in a paper published last year in the journal Science. Sameer Rao, a postdoctoral researcher, and Kim Hyun-ho (Ph.D., Ph.D., Ph.D., Ph.D., Ph.D., Ph.D., 2014) are co-authors of the paper, MIT and four researchers from the University of California, Berkeley.

Wang said, “There was a lot of expansion and some criticism,” said Wang. “I have clearly demonstrated and validated all the questions raised last time in this paper.”

Based on relatively new high-surface-area materials called metal-organic frameworks (MOFs), this system can extract drinking water even in the driest desert with a relative humidity as low as 10% The researchers said. The way to extract water from the air that is currently in use must be much higher. The method of obtaining water from the mist is 100% of the humidity, the method of obtaining water from the dew based on cooling requires a humidity of 50% or more, and both methods require a considerable amount of cooling energy. In light of this, the new system can produce water even in the driest regions of the world with very low humidity.

Currently producing 0.25 liters per kg of surface structure per day

Wang said on the rooftop of the US Arizona giant’s test facility that it was running a field test at a representative of the dry area and said, “You could actually get water below the dew point.” The dew point refers to the temperature at which saturation is reached and the condensation of water vapor begins when the unsaturated air is cooled.

According to the researchers, the device operated only with sunlight and was small in size for proof of concept, but when the device is enlarged, it can get more than 0.25 liters of water per kilogram of surface structure (MOF). By introducing the best materials for this device, Kim said that the extraction volume is three times higher than the current device. “Unlike conventional methods of extracting water from very low humidity air, this method has the advantage of being able to extract water under extreme conditions,” Wang said.


The team is running a water extraction experiment. Ⓒ MIT News / Research team

Dr. Lao said that not only does the system operate at lower humidity than the way the water is obtained at dew point, but the existing system consists of parts that can be broken down like pumps and compressors, And emphasized that it can operate in a passive manner.

High-quality water without impurities

In a previous paper, he described the system operation as passive, but now he has proven that the system is actually capable. The system now operates according to the daylight cycle of sunshine, but he added, “With the low heat of the low grade, such as biomass or waste heat, you can continue to operate.”

Wang will continue to work on expanding the system and improving efficiency at the next stage, saying, “We will make a system that can produce water of several liters.” The current test system is for proof of concept and is small in size, producing several milliliters of water. It is a plan to expand it to the extent that it can be supplied to each household in the future.

The team tested the water produced by the test system and found no signs of impurities. “The mass spectrometer measurements showed that no material leached from the MOF into water,” Wang stressed. “This shows that the materials that make up the system are very stable and can get high quality water.”