Water shortage has become the biggest problem in the world nowadays, as most cities are suffering due to water scarcity. It is a vital source, enriched with minerals that are necessary for the Human body, earth contains 70% of water, but unfortunately, most of its percentage is present in the Ocean which we cannot drink. The world population is growing at a faster rate which worsening water shortage, therefore, scientists are devising some techniques to harvest water.
Nobody thinks that fog becomes a source to harvest drinking water, well necessity is the mother of invention. Many of the world’s population are living on the coasts collecting water by fog because it’s a low-level cloud present on the ground. Fog harvesters are generally mesh nets approximately one-meter square, set up perpendicularly in the path of the wind, whenever the wind carries fog, mesh nets catch the droplets so it moves downwards by the gravitational pull, and collected in the containers below. One meter square of mesh net collects 3 liters of water per day.
It is difficult to harvest water if the mesh holes not accurately made of a right size if the holes are too large then fog droplets passes away and if holes are too small it cannot move downwards because of surface tension
Jonathan Boreyko an engineer at Virginia Polytechnic Institute said, “if you make them too small, the water is going to get clogged within a matter of seconds because of surface tension, and so it won’t slide down and won’t be easily collected, It’s hardly reasonable to have someone wringing the clogged mesh constantly.”
Boreyko and his team at Virginia institute develop a fog harp to efficiently harvest water without any problem. Harp is more efficient than fog mesh technique as it made by linear vertical wires which simply passes down the water without clogging, and collects nine liters of water more than previous one.
However, fog harvesters only work in humid areas while in arid regions this method won’t work. So a team UC Berkeley developed a way to harvest water only by using sunlight and a material called metal-organic framework (MOF) which quickly absorbs water even in dry conditions and release it when exposed to sunlight. This device usually contains box within the box, and inside of the box have few kilograms of MOF material while outside is just a transparent plastic container.
At night the box remained open so that MOF absorb water, and in daytime the box is closed so that sunlight heats up MOF material which forces water to condense and collected at the bottom. Sadly, MOF material is very expensive and collects water by only one-third of the cup, Omar Yaghi developer of this device is creating another way which contains cheap material like aluminum instead of zirconium.