Researchers in Chile have identified a promising solution for providing drinking water to some of the world’s driest cities through a method known as fog harvesting. This innovative approach has been studied in Alto Hospicio, a desert city in northern Chile, where average annual rainfall is a mere 0.19 inches (5 mm). The study highlights the potential of capturing water from fog, a resource that remains largely untapped in the region.
Lead researcher Dr. Virginia Carter Gamberini from Universidad Mayor emphasized the pressing social issues facing Alto Hospicio, including poverty and drug-related problems, which are exacerbated by a lack of reliable water supply. Residents in the city’s slums currently depend on water delivered by truck, making access to clean water a significant challenge.
The researchers noted that dense clouds of fog frequently gather over Alto Hospicio, presenting an opportunity for water collection. Fog harvesting involves hanging fine mesh nets between poles, allowing moisture-laden clouds to pass through. As the fog condenses on the mesh, droplets form and are channeled into storage tanks. This method has been successfully employed on a smaller scale in various regions, particularly in rural areas of South and Central America.
Dr. Carter believes that scaling up fog harvesting could provide a sustainable water source for urban areas where it is critically needed. The team conducted assessments to determine how much water could be harvested and combined this data with satellite imagery and weather forecasts. Their findings indicate that the fog from the Pacific Ocean could supply the slums of Alto Hospicio with a reliable source of drinking water.
The researchers calculated that an area of 17,000 square meters of mesh could meet the weekly water demand of 300,000 liters currently supplied by trucks. Additionally, just 110 square meters of mesh could fulfill the annual irrigation needs for the city’s green spaces. The harvested fog water could also support hydroponic agriculture, yielding up to 44 pounds (20 kg) of vegetables per month.
Alto Hospicio is situated on the edge of the Atacama Desert, one of the driest places on Earth, where underground aquifers are the main water source. However, these aquifers have not been replenished for thousands of years, leading to an urgent need for alternative sustainable water sources due to growing urban populations and increasing demands from mining and industry.
Dr. Gamberini highlighted Chile’s unique geographic advantages for fog harvesting, with its long coastline and mountainous terrain creating ideal conditions for fog formation. The research team is currently working on a comprehensive "fog harvesting map" of the country to identify additional areas where this method could be implemented.
The potential of fog harvesting to enhance resilience against climate change while improving access to clean water makes it an appealing solution for arid cities facing water scarcity. As urban populations continue to grow, innovative strategies like this may become essential in addressing the global water crisis.