Fog Harvesting Could Be Spain’s Answer To Drought

Is Spain on the brink of becoming a semi-desert? Recent climate change forecasts seem to suggest so.

Spain is grappling with a significant rainfall deficit, intensified by recurring summer heatwaves. As of today, several Spanish towns are still experiencing water cuts. However, a ground-breaking invention could hopefully change this, offering a sustainable solution to Spain’s water crisis, writes El Español, Saturday, September 9.

Harnessing Fog

For centuries, fog collectors have been a reliable source of water, especially in countries like Peru, Chile, and Morocco. Yet, there was a catch. The water harvested wasn’t always safe for consumption due to atmospheric pollutants. This meant an additional step of purification was necessary.

But now, scientists from the EHT Institute in Zurich and the Max Planck Institute for Polymer Research in Mainz have made a breakthrough. ‘By combining fog collection with water treatment, it can be used in regions with air pollution. For example, in densely populated urban centres,’ reveals Ritwick Ghosh, the lead researcher.

The Science

Historically, the Inca Empire in the 13th century used rudimentary fog collectors. They placed buckets under trees to capture condensation in fog-rich areas. Today’s fog collectors, however, are more sophisticated.

They use fog nets or fences, large mesh structures that guide water droplets into a collection channel below. The principle is straightforward. Atmospheric moisture condenses on cold surfaces, forming dew. In the case of fog nets, water condenses on threads and gathers at the base.

Ghosh’s team has introduced a game-changer: a mesh net made of metal wire coated with a blend of polymers and titanium oxide. This unique combination acts as a catalyst, neutralising many organic pollutants in the droplets, rendering the water safe to drink. The polymers ensure that water droplets settle optimally on the mesh and then quickly flow into a collection container.

Sustainability And Efficiency

These innovative fog collectors are not only effective but also sustainable. Located in areas like the Canary Islands or Algeciras, where ‘cloud forests’ thrive, they demand minimal maintenance. Their energy source? Pure sunlight. The titanium dioxide in the mesh needs ultraviolet light exposure to function. A mere 30 minutes of sunlight can keep it active for a full day, thanks to its photocatalytic memory.

In laboratory tests in Zurich, the team transformed eight per cent of artificially generated fog into water and neutralised 94 per cent of the added organic compounds. ‘In cooling towers, the steam escapes into the atmosphere. In the United States, where I live, we use a lot of fresh water to cool power plants,’ Thomas Schutzius, another researcher, points out. ‘It would make sense to capture some of that water before it escapes and ensure it doesn’t pollute if we want to return it to the environment.’

As Spain faces an impending water crisis, this innovative fog harvesting technique might just be the beacon of hope the country needs.