Fog catchers: a solution for collecting water in times of drought
Collectors can harvest up to 400 liters of water a day, transforming life in arid areas where there is a high presence of fog, like the Atacama desert.
Water is an increasingly scarce resource. According to the Intergovernmental Panel on Climate Change (IPCC), nearly half of the global population face water shortages for at least part of the year. And around 25 countries, home to a quarter of the world population, suffer extreme water stress every year, says the World Resources Institute. Although the situation is already serious, it’s thought that the number of people living under severe water stress will grow to around one billion by 2050.
In a world that’s getting drier and drier, fog catchers are seen as an innovative low-cost, sustainable solution. The technology, which uses meshes to capture fog and turn it into potable water, is transforming life in arid zones with a high fog presence, such as the Atacama desert in Chile, the Peru coast, and in the north of Gran Canaria, one of Spain’s Canary Islands.
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How do fog catchers work?
Fog catchers, or fog harvesters, were invented in the 1970s by the Chilean physicist Carlos Espinosa in answer to a terrible drought affecting Antofagasta in the north of the Chile. The region is home to one of the most arid deserts in the world, the Atacama. Espinosa, known as the “fog catcher”, donated the patent for his technology to Unesco, allowing its free use anywhere in the world.
The process is simple but effective: fine meshes are installed that capture the tiny drops contained in the fog and convert them into water usable by humans. In general, these nets are placed in high-altitude locations, between 300 and 800 meters above sea level, where the fog is the most dense and the wind strongest.
When the mist passes through these structures, the microscopic droplets stick to the fibers of the mesh, forming bigger drops which then slide down into pipes that transport them to storage tanks.
“The fog-catching process is simple: fine meshes are installed that capture the tiny droplets contained in the fog and convert them into potable water”
As such, the method collects water that would otherwise be lost in the air. It doesn’t try to create new water, but recover the humidity contained in the fog. This way, the water can be used to water crops and in some cases for human consumption.
The benefits of capturing water from fog
Other technologies exist that allow water to be extracted from the air, such as hydroponic panels that use solar energy to condense water vapor, and desiccant systems that use hygroscopic materials to absorb humidity in the air.
But it is the fog catchers which stand out for their efficiency and simplicity. Since they were invented, they have improved significantly, incorporating denser nets and using corrosion-resistant materials such as polypropylene and polyethylene, to boost efficiency and durability. They are also now available in a range of sizes and configurations, from small units designed for domestic use to large installations for community and industrial projects.
In optimum conditions, a fog catcher of one square meter can capture between 3 and 5 liters of water, depending on the area’s humidity. In some places, they have been able to capture up to 30 liters of water per day. In coastal zones in Peru, for example, a fog harvesting system is able to collect up to 400 liters a day. On Mount Boutmezguida, Morocco, they have managed to capture up to 6,300 liters daily.
From Chile to the world
Chile is the country with the highest hydric stress in Latin America and could find itself without potable water entirely by 2050, i.e. in 26 years’ time, according to the latest report by the World Resources Institute.
Indeed, most of the fog catchers have been installed in northern Chile, where drought conditions are more extreme. In Coquimbo region, one of the five most affected by water scarcity, Punta Palmeras wind farm, operated by ACCIONA Energía, for example, uses high-density polyethylene fog harvesters to gather thousands of liters of water per year, which it uses for watering replanted areas in the facility.
But this technology is no longer limited to Chile. Fog catchers are also appearing in other Latin American countries such as Peru, Ecuador, Colombia, Mexico, Guatemala and the Dominican Republic. They can also be found in Spain, South Africa, Croatia and Yemen, and even Cape Verde, Africa, demonstrating their versatility and effectiveness in different climates and geographies.
In Lima, the driest megacity in America, fog-catching nets have been installed on coastal hillsides. This is a fragile, unique ecosystem where relative humidity can rise to over 80%, and up to 100% in the coldest months.
In these areas innovators such as Peruvian engineer Abel Cruz have developed more advanced systems, which include software for adjusting the orientation of the nylon meshes according to wind direction. Their three-dimensional design combines water capture with a system that generates vapor and condensation using aluminum and glass. Thanks to these advances, his fog harvesters have managed to capture between 200 and 400 liters of water per day.
Elsewhere, in Spain, the Canary Islands have adopted innovative technologies for tackling severe droughts and associated fires. In 2023, fires devastated almost 20,000 hectares, aggravating even further the water scarcity on the islands.
Although the archipelago is known internationally for its leadership in seawater desalination, it has also turned to fog harvesting to overcome water scarcity and restore ecosystems devastated by fires. Since 2020, the project LIFE Nieblas, co-financed by the European Union, has responded by installing fog catchers that supply water for restoring and reforesting fire-devastated areas. The water obtained can even be drunk and is marketed under the name, Nieblagua (Fogwater).
Fog catchers are a practical and effective solution for tackling water shortages in the driest regions of the world. Their capacity for collecting water from fog and supplying it for human and agricultural use demonstrates that, with innovation and adaptation, it is possible to mitigate some of the most critical impacts of climate change. As regions go about implementing this technology, fog catchers can play a crucial role in sustainable water management in an increasingly dry world.
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