Climate: what if ocean steam became drinking water?

Posted Jan 7, 2023, 2:00 PM

Drinking water made from the evaporation of the oceans. This is an invention that takes the opposite view of warming seas , unfortunately accentuated by climate change. At the origin of this one, a team of American researchers from the University of Illinois (USA), who in the scientific journal “Nature” , explains the principle and the virtues via a study. Their process would take the form of extraction structures located off the ocean coast and capable of capturing and condensing water-saturated air, before routing it through pipes to be stored and distributed.

Advantage of the process compared to that of conventional desalination, according to the researchers: it would be less energy-consuming, and would have a lower environmental impact. Desalination plants release pollutants such as brine and waste water loaded with heavy metals.

Reproduce the natural water cycle

The installation proposed by the American scientists circumvents this obstacle thanks to a natural chemical principle: by evaporating and being transformed into gas, the sea water loses almost all of its salt naturally. Also, dispensing with this salt extraction step considerably lightens the seawater transformation mechanism, compared to desalination. In addition, the extraction stations could very well operate using renewable energy produced by wind turbines.

“This technique reproduces the natural cycle of water, the only difference is that we can guide the destination of the water evaporated from the ocean”, summarizes a co-author of the study, Francina Dominguez, specialist in atmosphere.

According to the calculations of the authors of this study, a vertical capture surface 210 m wide and 100 m high would have the capacity to provide a sufficient volume of humidity to meet the daily drinking water needs of approximately 500,000 people. on average.

They obtained this result through a simulation on 14 water-stressed sites located near major population centers, such as the cities of Los Angeles (USA), Rome (Italy) or Chennai (southeast of the India). According to the models, this type of device could generate between 37.6 billion and 78.3 billion liters of water per year depending on the conditions of each site.

Visual representation of the installation invented by the authors of the study.Praveen Kumar and Scientific Reports

The cost of a large cruise ship

How much would such an installation cost? “If the marginal cost of water does not increase, we assume that the cost of building an atmospheric vapor collection and condensation facility is US$600 million, or about the cost of building a a large cruise ship or an oil rig,” the scientists say.

A cost three times higher than a desalination plant, estimated at around 200 million dollars. Aware of this gap, the researchers argue that there is room for improvement to bring down the price of their installation. They assure in particular that it will last longer than a desalination station and will be more solid.

For the most arid regions

Praveen Kumar, co-author of the scientific paper and professor at the University of Illinois at Urbana-Champaign (UIUC) explains: “As global warming continues, we are going to have to find a way to increase the freshwater supply, because conserving and recycling water from existing sources, while essential, will not be enough to meet human needs. We believe that the method we have just proposed can achieve this on a large scale. »

And Afeefa Rahman, another co-author, underlines: “our method provides an effective and necessary approach for the adaptation to climate change , especially for vulnerable populations living in arid and semi-arid regions of the world. »

According to a recent report from the World Meteorological Organization a UN agency, 3.6 billion people do not have access to water for at least one month a year and this figure is expected to rise to more than five billion by 2050. Among the main causes, increasingly long and frequent chronic droughts, particularly in the countries of the Horn of Africa, such as Somalia and Ethiopia.

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