Many places in the World have limited sources of drinkable water, whether it is because of limited rainfall or because of polluted water resources. Without sufficient potable water, the health of possibly billions of people remains at risk. In Lima, Perú, a simple technology helps people harvest water from the fog.
With a population of almost 10 million souls and growing, Lima is the second-largest city in the Americas. Access to clean water is an ongoing problem for the residents in and around the South American capital, and potable water supplies are of critical concern to those left outside of the municipal water distribution infrastructure. From mismanagement by private water companies to the reduction of the glacial water supply, many reasons are to blame for this rampant water insecurity.
Built on a coastal desert, Lima receives only around 1.5 centimetres (half-an-inch) of annual rainfall. At the same time, it does not lack in humidity, averaging 83% year-round.
Nine months of the year, Lima is covered with a blanket of dense fog as the moisture makes its way inland from the ocean to the rain forests. This can include morning fog almost daily, and week-long stretches of overcast skies, mainly on the hilltops or at high altitude.
This is where fog harvesting comes in to provide potable water from thin air.
Million Years Old Technology
The idea is not new. For millions of years, very specialised plants and insects have been harvesting water directly from the air.
For example, the sharp spines and micro-barbs on cacti are designed for more than just protection. The protrusions are also helpful for gathering water from fog. Spines are actually shaped like elongated cones, gradually increasing in diameter from the tip to the base. Because of this shape, water can condense on the spines and drip down onto the cactus roots.
The Namib Desert beetles of southern Africa harvest moisture from the air to survive. They have tiny bumps all over their backs. The tips of the bumps attract water, but the sides repel it. In the morning, a beetle angles itself so that the dew that condenses on its back slides toward its mouth.
For human beings though, who have evolved no such specialisations, we turn to technology and materials sciences. A recent project in Lima, erected by the University of Engineering and Technology (UTEC) in Lima, utilises air-conditioner coils to drop the air temperature below the dew point, forcing potable water out of the air into a receptacle.
Globally, 1 in 10 lack water access. Nearly one million people in Lima lack access to clean, safe water.
The Peruvian Entrepreneur
After living without running water for years, Abel Cruz – the fog harvesting entrepreneur of the slums of Lima – grew tired of waiting to get connected to the grid, and decided to take action. He searched the Internet and got in touch with fog net experts.
He set up dozens of “fog catchers” – nylon nets designed to collect the tiny droplets of water suspended in the foggy atmosphere of the Peruvian Andes.
The water comes from the sky. But it is not rainwater. It is fog.
The micro droplets get trapped in the fine mesh. When enough droplets have accumulated, the water drains through gutters and run down to pipes at the bottom, before gathering into large storage tanks.
Approximately 200 to 400 litres of water is collected daily from each net.
The 60 fog nets installed in this part of Lima, supply free water to 250 households in the slums. The collected water is used to sustain small scale urban farming. Although it is not drinkable yet, poor families can use it to water their crops, wash clothes and household utensils.
The cost of building a ‘fog catcher’ is about $ 500 and can yield up to a small cylinder of 100 litres of water per day, a saving of almost 60% in water usage.
Abel raised funds for hundreds of nets in Peru with his revolutionary initiative Peruvians without Water (Peruanos Sin Agua). He aims to set up even more fog harvesters, and to treat the water in order to make it drinkable.
The technology is life-changing for the poor households who normally have to rely on water tanks being delivered to them.
Still, the system is somewhat energy intensive, so it would not be of much use in areas with little to no access to reliable electricity.
Life-Changing Nature Hack
Life without water is pretty tough. If you are living off the water grid, this could well be a solution.
Fog is moisture, and in some places in the World, this is the only moisture available.
This is the case in the Atacama Desert, the world’s driest desert, which runs along the west coast of South America through Chile and Perú. In the Atacama desert, it never rains. It has often been compared to Mars, and has even been used as a location for shooting otherworldly scenes for television shows.
Materials to be used Steps
How to Build a Fog Catcher
Materials to be used
Special Climatic Conditions
Fog nets require specific climatic conditions to work:
light winds and
land surface to set up the necessary equipment.
There have been few studies comparing the efficiency of the fog nets to other sustainable water sources, and support for the technology is divided among the experts. However, fog harvesting is at an early stage with around 15 such projects worldwide.
The technique can, and has already been, used successfully in other desert locations from the arid Atacama plateau in Chile, to the barren sands of Eritrea…
The water completely changes the landscape. And it has the potential to transform lives.
Could fog nets be a solution for the global water crisis?