Harvesting water from air has been around for a while, but the cost of doing so is often prohibitive. Communities in parched areas of the planet often have very few options to get clean water but the high cost of getting any water to them makes the task next to impossible. As an example, one extraction method currently used consumes between 40 and 90 percent of the total system’s energy requirements by condensing the vapor after using electrical refrigeration to cool the air.
Scientists from the Technion (Israel) recently reported findings in a new study that shows a saving of between 5% and 65% of the traditional electrical energy requirements needed to extract water from air. These numbers are based on modeling results and scientists report that the system will produce high-quality water.
According to an International Organization for Dew Utilization study published in 2000, amounts water vapor comparable to all the underground and surface liquid freshwater on the planet is present in the atmosphere around us.
The new design, pioneered by scientists from the Technion (Israel), uses a liquid desiccant to separate the vapor from air first and then cool only the vapor rather than cooling the air first.
Three interconnected cycles (air, water and desiccant) were studied over a range of ambient conditions using modeling techniques. Different operation conditions resulted in various optimal configurations being identified. The savings reported are ascribed to the vapor separation process.
When integrated into atmospheric moisture harvesting systems, the liquid desiccant separation stage can work under a wide range of environmental conditions. Solar or low-grade heating is used as a supplementary energy source. The researchers believe that the performance of the combined system is far superior to anything being currently used.