'Squeeze' the mist takes ... water

In the 1990s in Chile, in the mountains of El Tofo, one of the driest places in the world, Chungungo village no longer provided enough clean water for the people, but had to buy it. Scientists from Chile and Canada have come up with the idea: "Squeeze water" from the mist blown into the village by the sea wind.

On an area of ​​5,000m ² , they spread nearly 100 mesh panels made of polypropylene, size 4x12 m. The result was unexpected, the small droplets in the mist were "trapped" in the net, flowed into the catch system, giving up to . 15,000 liters of water every day.

Dew nets in the mountains of El Tofo, Chile (Photo: Ciencia.cl)

" This allows for a very pure, inexpensive amount of water, at a very simple level of technology ," said Robert Schemenauer, Canada's FogQuest organization leader in dew frost collection.

'Thanks to such nets, people can . make water in desert areas, where rainwater is very scarce. It is important to choose the appropriate location. There is also a need for regular maintenance to make the system work efficiently '.

The ' dewy ' technology of many people in El Tofo continued to study until 2002 with the testing of many different materials and models. Up to now, it has been applied and continues to be perfected in 25 countries around the world such as South Africa, Tanzania, Nepal, Peru . and recently this is in Yemen. Many similar works are under construction in Guatemala, Haiti .

Make the sky catch up

To be most effective, it is recommended to spread the net at convenient locations on the high peaks from 400 m to 1,000 m, perpendicular to the wind direction. On average, polypropylene meshes can ' capture ' up to 30% of the dew water, from 17 liters to 42 liters of water / m2 per day. However, the performance of the system is still erratic due to being dependent on the 'sun and rain rain'. The less polluted air in the grid, the better.

Mist collection system in Gujarat (northwest India).(Photo: Le Figaro)

Scientists do not stop there, another ' hunting ' object is . night dewdrops, which people have known for a long time. The most common way is to recover the dew thanks to a condensing device.

In the Gujarat region (northwestern India), a dry place, people have a simple way to do it. With the help of the French Opur Organization, on an area of ​​850 square meters, they dug the ditches and covered them on an insulating sheet, the surface is a coating of color paint capable of emitting infrared to help cool itself. Of course. Thus, the temperature on the surface of the coating is reduced to 4 to 10 degrees Celsius, making it easy to condense.

Water from the dew is deposited in the ditches that are directed into the tank and processed. On average, this giant ' condenser ' provides villagers with 350 liters of water a day. When completed, Gujarat ' water plant ' will have an area of ​​up to 12,000m ² , allowing every night to withdraw 6,000 liters of water, enough to meet the needs of the village. Bottled clean frost water is sold for only half the price of water produced by traditional water plants. The price of 1m ^{2 of} coating in Europe is 2 euros, while in India only 0.4 euros.