Solar Powered Water Harvester Can Draw Out Liters of Water from Desert Air

By Kris WalkerApr 14 2017

Researchers form UC Berkeley have demonstrated a water harvester device that is capable of pulling liters of water out of the air in desert like conditions. Whats better is that is powered directly from the sun.

Desert like conditions typically have low humidity levels making it difficult to extract anything that resembles water from the air. However, this device can draw out literally liters of water from the air in conditions that have humidity levels as low as 20%, common is desert environments.

The solar powered harvester was constructed from a a metal organic framework (MOF) and as a prototype operating at 20-30% humidity with around 2.2 pounds of MOF can draw 2.8 liters of water from the air over a 12 hour period.

This is a major breakthrough in the long-standing challenge of harvesting water from the air at low humidity. There is no other way to do that right now, except by using extra energy. Your electric dehumidifier at home ‘produces’ very expensive water.

Omar Yaghi - UC Berkeley

Metal Organic Frameworks

Now over 20 years old, Metal Organic Frameworks, created by Omar Yaghi, consist of combining metals like magnesium or aluminum with organic molecules to create rigid, porous structures ideal for storing gases and liquids and upon their inception two decades ago, over 20,000 have been created with some being able to hold methane and hydrogen.

It was in 2014 that Yaghi and the team at UC Berkley succefully syntheized a metal organic framework that was capable of binding water vapor through the combination of zirconium metal and adipic acid. Bringing this to the attention of Evelyn Wang, a mechanical engineer at MIT allowed them to come together and create a succesul water collecting system from the MOF.

How the Water Harvester Works

The water harvester consists of more than two pounds of metal organic framework (MOF) crystals 'compressed between a solar absorber and a condenser plate, placed inside a chamber open to the air. As ambient air diffuses through the porous MOF, water molecules preferentially attach to the interior surfaces. X-ray diffraction studies have shown that the water vapor molecules often gather in groups of eight to form cubes.'

The metal organic framework heats up via the sun and 'drives the bound water toward the condenser, which is at the temperature of the outside air. The vapor condenses as liquid water and drips into a collector.'

This work offers a new way to harvest water from air that does not require high relative humidity conditions and is much more energy efficient than other existing technologies.

Evelyn Wang - MIT

Still as a prototype time and further researchw will tell whether this could be something that could become a viable option in producing liters of water in developing areas where a lack of water and clean water are still a concern. With our bodies needing 2 liters of water a day - this protoype would be able to produce that under 12 hours in arid areas.

Reference

UC Berkeley