According to the UN, there is water for everyone on Earth and yet the shortage affects 2 billion people who physically lack it or the infrastructure necessary to take advantage of it. The solutions are technological: use sea and groundwater, reuse waste water, improve efficiency in distribution and consumption and condense it in the atmosphere. The latest research published by Nature This August they show that they have managed to generate water in Death Valley, the enclave of the Californian Mojave Desert considered one of the hottest places in the world, or capture it from the fog and purify it at the same time or emulate spiders and beetles to collect it. But these advances face a curse posed by William Stanley Jevons two centuries ago: as the efficiency in the use of a resource improves, its consumption increases instead of being reduced.
The global demand for water does not stop growing. Throughout the last century, according to the United Nations, consumption grew at a rate twice as fast as the population growth rate and the number of regions with chronic levels of deprivation is increasing. Jesús M. Paniagua, author of Water. History, technology and future (Guadalmazán, 2023), agrees with the UN that “there is enough water on the planet to supply the almost 8,000 million people who inhabit it. But it is distributed irregularly, it is wasted, it is contaminated and it is managed in an unsustainable way,” he warns.
Cristina Monge Lasierra, a political scientist at the University of Zaragoza, recalls in a book on urban supply, published by the Cádiz City Council and the public operators of Aeopas, the warning of former UN Secretary Ban Ki-moon: “The battle for sustainability It will be fought in the cities.” It will be in them where 75% of the population and between 80% and 85% of the wealth will be concentrated. “What happens in the cities and how they relate to the rest of the territory will be key,” highlights Monge.
Although the greatest consumption of water occurs in agriculture and livestock (80%, according to the OECD), its use responds to the demand for food in cities, where the majority of the population resides. The rest of the large consumption is industrial and urban. “Extreme episodes like those experienced by Spain express the urgency of integrating water as an essential element to rethink cities,” warns Luis Babiano, manager of Aeopas.
Technology has made it possible to gain efficiency in water distribution, but there is still a long way to go. According to Francisco Lombardo, president of the Water Economy Forum, “in Spain, more than a quarter of the water distributed through the network is currently lost as a result of lack of investment.” Lombardo is committed to “renewing water infrastructure and digitalization to have much more exhaustive control of water leaks and losses.”
Paniagua agrees on the existence of “very deficient systems that are losing water” and gives the Uruguayan capital as an example: “Montevideo has suffered a supply problem after three years of drought. Its network has losses of 50% and that means that, of every 100 liters that enter from the tanks, 50 are lost.”
To obtain resources, it relies on underground reserves, more conscious consumption, the reuse of wastewater and desalination, systems that it hopes will become cheaper and decarbonized with the rise of renewable energies.
Desalination of seawater requires high energy consumption and generates waste such as brine. Harnessing atmospheric water, particularly in regions with humidity below 70%, also requires a substantial amount of energy making this solution ineffective.
From the desert to spiders
A work published in Nature Water and signed by researchers from the universities of Postech and Berkeley has optimized the process to generate water from the atmosphere in the Death Valley desert, in the United States, with temperatures of up to 57 degrees and relative humidity less than 7%.
“We have corroborated the potential of technology to address the growing challenges of water scarcity, further exacerbated by environmental problems. This technology provides a safe water resource independent of geographical or climatic conditions,” highlights Woochul Song, researcher at Postech.
Another drawback of using atmospheric water, such as that from fog, is the contamination impregnated in it. Researchers at the Federal Institute of Technology in Zurich (ETH) have developed a method that collects water from fog and simultaneously purifies it using a metal mesh coated with a mixture of polymers and titanium dioxide, which acts as a catalyst. chemical.
“Our system can be used in areas with air pollution, such as densely populated urban centers,” explains Ritwick Ghosh, a scientist at the Max Planck Institute who collaborated on the work published in Nature Sustainability.
University of Waterloo professor Michael Tam has developed sponges that continually capture moisture from their environment by mimicking spiders and the strategies of other insects. “A spider web is an engineering marvel and efficiently captures water. The spider does not need to go to the river to drink, as it traps moisture in the air.” His work has been published in Nature Water.
Paniagua trusts in technological solutions. “If you look at history, technology has been getting us out of problems,” he says. In this sense, his work recalls how the digitalization of crop fields, on-plot weather stations, humidity sensors, flow and pressure monitoring systems in irrigation networks or surveillance and tracking drones has become widespread. that optimize the use of resources.
But the author remembers that one of the problems of the technological solution was already anticipated by the British economist William Stanley Jevons two centuries ago. Jevons observed that more efficient steam engines did not imply a decrease in coal consumption, but quite the opposite: efficiency multiplied the number of machines. It is a paradox that explains the increase in traffic when the road network is expanded. “It can happen,” admits Paniagua. “I’m not saying that it will happen in a general way, but it is true that, when you have more irrigation capacity, this surface area increases. I have a friend who claims that if we achieved nuclear fusion to generate a lot of very cheap energy, we would be capable of anything atrocious. In any case, that should not stop us from improving efficiency.”
The other major drawback of the technological solution to the water problem is the disproportionate growth in demand. In this sense, Paniagua focuses on Africa, where there is less access to resources, sanitation and energy, despite the forecast of a demographic explosion. “We must focus on investments and improvements to guarantee supply, purification and sanitation. Megatransfers are not viable for thousands of reasons, from technical to political. “It is a serious problem.”
In March 2023, UNICEF published a report on the plight of approximately 190 million children in Africa who suffer from a lack of safe drinking water, resulting in the tragic deaths of 1,000 children under five years of age every day.
The example of a source
A simple urban drinking water source can be an example of how its management is more complex than it may seem at first glance. In this sense, Luis Babiano highlights how the incorporation of new infrastructure to bring this public service to every 1,000 inhabitants of Cádiz led to detecting an error in the traditional approach of these facilities. “The criteria for its location are formal, accessibility or cost. But they have not been thought of as tools for the construction of a friendly city,” he comments.
The design of the Cádiz network, reflected in the book Public drinking water sources, tried to start from scratch, analyzing the main routes of the neighbors, both during their work days and during their leisure time. Also in their mobility, whether they moved on foot, by bike, by public transport or in their own vehicles. The presence of pets was even taken into account.
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