MANILA, Philippines – There’s a fairytale about a giant who questions a tailor about his supposed feats and challenges him to prove his strength by squeezing water from a stone. The tailor pulls out a small round of cheese. Apparently, giants have very poor eyesight as this one couldn’t tell the difference and crushes it in his hand, a skill that earns him the giant’s respect.

Squeezing cheese worked for the tailor because it holds a lot of water. German researchers have now suggested applying a similar technique to humid air, extracting drinking water where one might not think to look to help meet the world’s demand for water.

Specially useful

The scientists at the Fraunhofer Institute for Interfacial Engineering and Biotechnology think that this process of wringing water from air would be especially useful in arid regions such as the desert where bodies of water are scarce.

They envisioned building tall, salt-filled towers that could absorb the water from the air then send the liquid through first a vacuum and then a condenser to produce the salt-free water. They said the water towers could have solar energy collectors apt again for a desert environment or other renewable power sources so that the whole process can be done even if there aren’t any electrical wires or outlets to plug into around.

Fraunhofer researchers said such water towers could be built in a variety of sizes, enough to provide drinking water for a single person or an entire community. They also noted that a prototype of the equipment had been built and was being tested to see if the idea of collecting water from air could work outside of the lab.

It’s worth noting that a single cubic meter of air holds just 11 milliliters of water. To get an idea of how much that is, consider that if the air cube had dimensions equal to the height of basketball player LeBron James, the water content would supply about a tenth of the contents of a can of Coke.

The German extraction process might not yield enough to supply more than a veritable drop in the bucket, but each drop definitely counts. According to the United Nations Educational Scientific and Cultural Organization, every person needs access to 20 to 50 liters of clean water “free from harmful contaminants” on a daily basis in order to meet their basic needs.

Many researchers are also looking into how to extend straining water resources by factoring in available amounts of so-called “blue water,” sourced from rivers and groundwater, “green water” collected in the soil from rains and “gray or recycled water” collected from household uses such as in the kitchen and in a washing machine, though water from toilets is excluded.

Another project

Since a significant portion of the world’s clean water resources go toward meeting agricultural needs, finding, developing and cultivating water-efficient crops for each part of the world is another project being studied. As the world’s population continues to grow, agricultural demand for water is predicted to increase as well to meet the increased demand for food, and to supply feedstocks for biofuel production.

For this reason, the United Nation’s Food and Agriculture Organization has a team looking into ways crop yields can be increased on limited water supplies. And in the June 2 issue of the journal Proceedings of the National Academy of Sciences, Dutch engineers calculated the water efficiency footprints of some of the most widely used and most promising biofuel feedstocks to find out how regional water supplies affect decisions involving where these crops should be grown in.

E-mail the author at massie@massie.com.