We might finally harness the limitless fresh water vapor hidden above the oceans

Using 14 water-stressed locations worldwide, they also wanted to demonstrate that this structure would remain feasible in the face of ongoing climate change.

The researchers conducted atmospheric and economic assessments to determine the best location for hypothetical offshore constructions that were 210 meters wide and 100 meters tall.

Their calculations led them to conclude that many water-stressed places worldwide could benefit from trapping moisture over ocean surfaces. In particular, large subtropical population centers could receive fresh water from the predicted water yield of the proposed structures.

Dry western U.S. regions are key targets

"Water scarcity is a global problem and hits close to home here in the U.S. regarding the sinking water levels in the Colorado River basin, which affects the whole Western U.S.," Kumar said in a press release. 

"However, in subtropical regions, like the Western U.S., nearby oceans are continuously evaporating water because there is enough solar radiation due to the very little cloud coverage throughout the year," he added. 

Wet areas will become wetter and dry areas will become dryer, according to well-known climate change forecasts. The researchers claim that their new ocean vapor-harvesting technique benefits from this forecast of increasingly drier circumstances.

"Oceanic vapor flux will only increase over time"

"The climate projections show that the oceanic vapor flux will only increase over time, providing even more fresh water supply," said graduate student and co-author of the study Afeefa Rahman Rahman.

"So, the idea we are proposing will be feasible under climate change. This provides a much-needed and effective approach for adaptation to climate change, particularly to vulnerable populations living in arid and semi-arid regions of the world."

The researchers noted that previous methods of desalination, cloud seeding, and wastewater recycling had patchy success. Desalination facilities are used in various regions of the world. Still, they have sustainability problems because of the brine and wastewater they create that is rich in heavy metals. In fact, California recently rejected plans to install more desalination plants.

Tapping into the natural water cycle

"Eventually, we will need to find a way to increase the supply of freshwater as conservation and recycled water from existing sources, albeit essential, will not be sufficient to meet human needs. We think our newly proposed method can do that at large scales," Kumar stated.

The fact that this suggested solution mimics the natural water cycle is one of its more elegant aspects, according to the researchers.

"The difference is that we can guide where the evaporated water from the ocean goes," co-author professor Francina Dominguez said. 

"When Praveen approached me with this idea, we both wondered why nobody had thought about it before because it seemed like such an obvious solution. But it hasn't been done before, and I think it is because researchers are so focused on land-based solutions – but our study shows other options do, in fact, exist," she added.  

Significantly, the study opens the door for creative infrastructure investments that can successfully solve the growing global freshwater shortage.

The study was published in the journal Nature Scientific Reports on December 6.

Abstract:

While significant parts of the globe are already facing significant freshwater scarcity, the need for more freshwater is projected to increase in order to sustain the increasing global population and economic growth, and adapt to climate change. Current approaches for addressing this challenge, which has the potential to result in catastrophic outcomes for consumptive needs and economic growth, rely on increasing the efficient use of existing resources. However, the availability of freshwater resources is rapidly declining due to over-exploitation and climate change and, therefore, is unlikely to sustainably address future needs, which requires a rethink of our solutions and associated investments. Here we present a bold departure from existing approaches by establishing the viability of significantly increasing freshwater through the capture of humid air over oceans. We show that the atmosphere above the oceans proximal to the land can yield substantial freshwater, sufficient to support large population centers across the globe, using appropriately engineered structures. Due to the practically limitless supply of water vapor from the oceans, this approach is sustainable under climate change and can transform our ability to address present and future water security concerns. This approach is envisioned to be transformative in establishing a mechanism for sustainably providing freshwater security to the present and future generations that is economically viable.