Droughts and water shortages are a global problem and affect more than a billion people every year. This is why researchers are exploring different ways to harvest water directly from the air. Some recent experiments include using metal-organic frameworks (MOFs), fog harvesting machines and mesh towers to capture water from air.
Metal-organic frameworks or MOFs are structures that combine organic and inorganic materials together with strong bonds. They are porous and crystalline, so they can collect and store substances such as gases or water. Researchers at MIT found that MOF-801, a type of material with zirconium oxide and fumaric acid, can trap water from air. It is possible to transfer the water from the MOF to a collection chamber with simple heat from sunlight. After 12 hours, MOF-801 pulled 3 quarts (2.8 liters) of water from the air with humidity at 20 percent.
Fog Harvesting Machines
Fog naturally has water vapor, and it is another source of harvesting this precious liquid from the air. Researchers developed a variety of fog harvesting machines, but the simplest remains a nylon or mesh net to collect water droplets, which fall into a collection bin or trough. Unfortunately, most nets are not an ideal way to harvest liquids because the pores are usually too big to capture all the water. Advanced fog harvesting machines have better nets with smaller pores.
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Mesh towers such as Warka Water have a simple yet effective design. The structures can harvest rain, dew or fog. Warka Water looks like a giant vase that is 30 feet tall. Its lightweight materials make it easy for air to flow through the structure, which allows it to capture water droplets. There is a mesh net inside to trap and collect water. During the day, the tower can harvest 25 gallons of water from the air.
One common concern about harvesting water from the air focuses on the impact the technology may have on local water cycles. However, current research shows that there does not appear to be a serious effect. The water cycle is able to continue normally. It is possible that researchers are not seeing an impact because most harvesting technology is on a smaller scale and does not influence global weather patterns.
Another concern is the cost of the technology. Even mesh nets for fog harvesting can cost several hundred dollars. The Warka Water tower has a price tag of $500. Metal-organic frameworks are even more expensive to design and build. Access to the tech is also a problem. Some of the areas that need these products the most are rural, isolated and poor. If people cannot access or afford the products for harvesting water from the air, then they serve no purpose.