A technology that makes water out of air

In the small town of Lucena in southern Spain, they can make water out of air. The amount of water in the atmosphere depends on a number of things, but it’s about 1% on average. While this may not seem like much, water vapor is the third most abundant gas in the atmospheric layer that surrounds us, especially in the mile or so closest to the Earth’s surface. According to the United Nations, 2.3 billion people live in water-stressed countries, so a business group from Córdoba in southern Spain decided to do something about it. Five years ago they started GENAQ, a company that builds atmospheric water generators now used in more than 60 countries around the world. This year, GENAQ won an award for the industry with the greatest growth potential. The company also leads STRATUS, a European research project developing technology to generate drinking water by condensing ambient humidity, which some researchers see as a solution for drought-stricken areas.

The idea is not new, and many so-called water-makers have enjoyed their 15 minutes of fame on television programs and news reports. Carlos Garcia, GENAQ’s CEO, is wary of such charlatans, so he strives to describe the company’s work in factual and simple terms. “It’s easy to understand if you look at the water produced by air conditioners.” The challenge is to make this process efficient enough to offset the energy consumed by producing a sufficient amount of drinking water. GENAQ has succeeded in developing an efficient water generation process that can even be powered by photovoltaic panels, reducing energy demand to a minimum.

The basic principle is the dew point, the temperature at which water vapor in the air condenses. Calibrated to local conditions, GENAQ’s systems take in air and use refrigeration technologies to produce condensation. They then filter and purify the water with ultraviolet light to avoid using sanitizing chemicals. If necessary, they add minerals to produce “water that’s close to the quality of distilled water,” said García. This process enables GENAQ to achieve three objectives: efficiency – lower energy consumption per liter manufactured (0.22 kilowatt-hours per liter on average); a variable flow of drinking water that exceeds health requirements; and reliability – a system with a long lifespan (up to 20 years of useful life) that can be used in remote locations.

The price per liter of water produced by GENAQ’s machines depends on atmospheric conditions and the energy source used. The company uses an environmental test chamber that can replicate the atmospheric conditions of the location where the machinery will be installed. On average, it costs between two and four cents to produce one liter. “Much cheaper than bottled water, but more expensive than tap water,” said García.

GENAQ builds several sizes of water generators. Models for the average home, office or public building like a school or hospital, can produce 20-50 liters per day. For larger demands (emergency situations, military operations, oil rigs and larger communities), they have water generators that can produce 500-5,000 liters of water per day. The machines require no special installation other than connection to the available energy supply (grid, generator or photovoltaic) and cost $2,000-$100,000.

GENAQ systems are most efficient in areas with temperatures between 50-120°F (10-50°C) and 10-90% humidity. “They are most useful between Holland and South Africa. Our machines are very efficient in the Sahara, but not in Reykjavík [Iceland’s capital], where they don’t need them anyway,” joked Garcia.

The company’s initial market is any urban or rural population that lacks access to quality drinking water, or that has been deprived of its water supply due to an armed conflict or natural catastrophe. Because this target market is so large, the company predicts that over the next three years, it will exceed net sales of $100 million and double its workforce to 800 employees. Carlos García has another ambitious goal in mind: “To eliminate all plastic water bottles.” In early December, the company delivered the first module for a factory in France that will eventually produce 100,000 liters per day of mineral water in glass bottles.

But for now, the initial vision of providing quality drinking water to the world is an enormous challenge in itself. According to the World Water Council (WWC), 3.5 million people die every year because of low-quality drinking water. Eliminating plastics bottles will also become invaluable, as the United Nations estimates that in 13 years the volume of microplastics in the oceans will exceed the volume of fish.

The growing scarcity of global water resources creates expectations that water generation systems can become an alternative drinking water supply, but García thinks that this prospect is still far in the future. “They are not intended to alleviate droughts,” he said, although he mentions the company’s research with hydroponic greenhouses, a cultivation system that uses minimum amounts of water. GENAQ continues to research methods of achieving maximum efficiency with the lowest energy consumption and cost per liter, the key to extending the practical applications of atmospheric water generators.

Praveen Kumar of the Prairie Research Institute and Francina Dominguez of the University of Illinois’ (USA) Department of Atmospheric Sciences, have authored a study published in Scientific Reports on the feasibility of capturing water vapor from the atmosphere just above the ocean surface and transporting the moisture-laden air to land where its condensation can provide fresh water.

“[Water] scarcity is a global problem. We need to find a way to increase the supply, because while water conservation and recycling is essential, it’s not enough to meet human needs. But when there is sufficient radiation, the oceans continuously evaporate water. We believe our method can do that on a large scale,” said Kumar.

The generators envisioned by Kumar and Dominguez would be floating offshore structures measuring 210 meters wide and 100 meters high. The estimated water yield of these facilities could provide sufficient fresh water for large population centers in the subtropical areas with the most optimal atmospheric conditions.

Afeefa Rahman, an environmental engineer at the University of Illinois Urbana-Champaign (USA), says that this type of system will become even more effective in the future. “Climate change projections show that ocean vapor will increase over time, thereby increasing the fresh water supply,” she said.

Desalination or wastewater reuse techniques are constrained by high investment and operating costs, and also produce brine and heavy-metal waste. To address these limitations, a Belgian company named HydroVolta is participating in the SonixED project, which aims to exploit the largest water reserve on the planet – oceans. Why oceans? Because just 3% of the world’s water is fresh and only a third is accessible, the rest being trapped underground and in snowpack and glaciers.

“Saltwater needs to be treated so that people can drink it and industries can use it,” George Brik, HydroVolta’s CEO, told Horizon magazine. Current desalination technology relies on electrodialysis, where ions pass through membranes to separate salt from water. But these membranes clog easily, and large amounts of energy, chemicals and high pressure are needed to clean and restore them to service. HydroVolta uses ultrasound to clean these critical membranes.

“Existing technologies waste about 60% of the seawater that they take in. Our new technology reverses that proportion. We can produce 65 liters of drinking water from 100 liters of seawater,” said Brik. HydroVolta is currently testing its systems in the North Sea.

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