‘Cloud-milking’: a zero-energy method to keep young trees alive

They call it cloud milking, an energy-efficient method of extracting water from fog that is revolutionizing the regeneration of forests damaged by fire and drought.

The idea started as a pilot project in the Canary Islands. The plan was to exploit the humid “sea of ​​clouds” that hangs over the area to aid in reforestation, and has since been expanded to several other countries to produce drinking water, and water the crops.

“In recent years the Canaries have had a big problem with desertification and we have lost a lot of forest to agriculture. And in 2007 and 2009, because of climate change, there were big fires in forested areas that normally have water,” said Gustavo Viera, technical director of the publicly funded project. in the Canary Islands.

Viera said that after the devastating fires they looked for ways to bring water to remote, mountainous areas without building infrastructure, or using fossil fuels to pump ground water from deep wells.

The project, named Life Nieblas (fog is the Spanish word for mist) has started, supported by the EU, which aims to imitate the way the leaves of the local species of laurel trees capture water droplets from the mist, by using plastic web sheets suspended in the air. As the wind blows the mist through the net, water droplets collect and fall into the buckets below, which are used to water the new shoots until they have enough leaves to take up water on their own. .

However, wind, although important to the original building, proved to be a problem as it destroyed all but the smallest buildings.

“We needed to solve the problem of network fragility while reducing environmental impact,” Viera said. “We created a system that mimics pine needles, which are great for capturing water while allowing air to pass through, and it’s highly scalable and easy to transport to where it’s needed. there.”

In the new models, the water cools down on the beautiful steel leaves of the buildings, echoing the way conifers collect water from the atmosphere.

The water is extracted automatically with no energy supply or CO₂ emissions and no machinery is used to transport it from one place to another. No electricity is used for irrigation and the water area is reduced as no water or rivers are exploited. The only energy required is to build the collectors and put them in place.

A slightly different approach is also being used to reforest an abandoned quarry in Garraf, a rugged area south of Barcelona.

“Here we use water collectors of the type used to prevent herbivores from eating small plants,” said Vicenç Carabassa, the project’s lead scientist, who works for the Center for Ecological Research and Forestry Applications (CREAF), social research institute. Autonomous University of Barcelona.

They collect the rain and dew that falls on summer mornings and provide shade.

Carabassa pointed out that not every type of mist is suitable because some do not have enough moisture. The ideal fog is orographic or mountain fog, which is present in many areas of the Mediterranean and also in northern Portugal.

“The Canaries are the perfect laboratory to develop these techniques,” said Carabassa. But there are some places where the conditions are right and where there is a tradition of catching water from fog, like Chile and Morocco.

This method is already being used to provide drinking water and irrigation water in the Chilean coastal town of Chungungo in the province of Coquimbo, while the collectors in the Cape Verde Islands Life Nieblas, combined with locally made wooden structures, provide with 1,000 liters of water at a time. solar, which is used to irrigate crops and irrigate livestock.

All the information needed to create the fog collectors is available for free to the public on the project’s website, and Viera said they’ve had a lot of questions.

The benefits are obvious. In the Barranco del Andén valley in Gran Canaria, 35.8 hectares (96 hectares) have been replanted and 15,000 different laurel trees have been planted, with a survival rate of 86%, double the number of plantings traditional forests.

“We found the potential of the forest to capture atmospheric carbon and we estimate that we captured about 175 tons of CO₂ per year,” said Viera.

The Life Nieblas project not only saves on the use of fossil energy and CO₂, but is also cheaper and uses less water than conventional reforestation methods.

“We live with drought throughout the Mediterranean and the Canaries and now every drop of water is important,” said Carabassa, adding that we must learn to live with very little water.

“This system will not be an alternative to a desalination plant but in remote areas where water supply is difficult and expensive, this could be a real alternative.”