Fresh Water Out of Thin Air
As the things heat up, glaciers are melting without being as replenished in winter, rivers are being sucked dry by the combined water needs of agricultural and urban areas, and drier conditions are affecting more areas of the planet, reductions in the availability of potable water relative to the demand also result in more conflict between regions and countries. Large numbers of people are suffering from inadequate supplies of drinkable liquid. This is particularly so for an unprecedented number of refugees displaced from homelands where reliable water provisions were more often the norm. Even in the U.S., there are distressing water access competitions between the needs of city dwellers and of farmers or ranchers. For lack of fresh water, 2.4 billion people have inadequate toilets and 0.7 billion (one in 10 of us) do not have enough safe, clean liquid for drinking or bathing. Whether we ascribe them to man-made or natural causes, over the planet as a whole climate changes are leading to less rainfall on large swaths of the globe.
Just as the "green revolution" assured more abundant food stocks and so prevented the starving of billions predicted in such books as Paul Ehrlich's Population Bomb, modern technology, against most expectations, is coming to the rescue again in several interesting ways to help us deal with a decrease in natural water sources.
WaterSeer, a device developed by an alliance between VICI-Labs, the Peace Corps, and the University of California at Berkeley, requires no external power source, provides up to 11 gallons of water a day, and is cheap, just $134 as of when made public in 2016. It depends on a small above ground wind turbine that easily rotates in local breezes and on circulation to an underground chamber six feet into the soil, where lower temperatures condense water out of the air. A simple hand pump delivery system connected to the water collection chamber allows people to easily access the needed moisture that is completely potable, ready for cooking, cleaning, drinking, and other needs.
But what if one lives in a place where at times, likely as not, there are not even light breezes? A prototype water harvester, the device again developed with the help of UC Berkeley, uses ambient sunlight and a metal-organic framework (MOF) created my MIT to absorb water directly from the air. It can work even in low humidity (down to only 20-30%) and condenses the water vapor for drinking. As fashioned to date, a single harvester is not sufficient for the water needs of a family or community. However, its successful demonstration proves that similar arrangements could at least provide for the thirst requirements of a person traveling in a dry region. This early version pulls 3 quarts of water out of low humidity air over a 12-hour period, sufficient that, since the device is portable, a hiker stranded in an arid place could be assured of survival without access to local water so long as he had brought along his own MOF device. Future models are anticipated that would scale up the potential of such harvesters. In future, we may anticipate times when off-grid solar powered MOF sources of potable water might be available to households, cities, and refugee camps.
Other humidity harvesters are coming along too. Fuel cell cars can provide about a quart of drinkable water for each several miles driven in even arid regions, enough for the needs of passengers.
Owners and operators of greenhouses know that the differences in temperature and humidity between outer and inside conditions readily provide extra condensation and run-off. With a few modifications, this can be utilized to both augment the watering needs inside greenhouses and provide drinking water for their workers. There are already such projects in desert areas of the Middle East.
Passive dew gathering systems date back to ancient times but have been enhanced via technology that takes advantage of differences in temperature between the sunnier sides and shadier portions of modern collection surfaces.
It is common to see drinking dispensers associated with cooling devices such as refrigerators. Similarly, a variety of industrial cooling functions can have systems attached for the collection of and access to drinkable water.
There have also been brine desiccation systems developed that remove extra humidity from the air and provide it, now separated from the briny solutions, at dispensers for potable water uses.
An Arizona University spin-off company, Zero Mass Water, has created solar panels that condense water vapor out of the air, pass the resultant liquid through filters, and dispense it.
Unfortunately, thus far none of these and related remedies are enough for the combined industrial, agricultural, and personal needs of a highly populated and thirsty planet. They are, though, encouraging signs of things to come. Just as the possibilities for solar power were hard to grasp a few decades ago, but now solar energy has become at once efficient and relatively cheap, so it may be hard to foresee the potential of various means of removing water vapor from the air and readily condensing it into fresh liquid for a variety of our uses. With a bit of imagination, however, we may find it plausible that in the next generation or two a wide range of low-cost and off-the-grid water providing devices will be ubiquitous not merely among developed country populations but in Third World regions as well. The water vapor already in our atmosphere is staggeringly vast, well beyond our conceivable needs for some time to come. As with virtually limitless renewable energy from wind or sun, so with renewable water from the air. Once humans can inexpensively and on a large scale tap into this moisture where and when they want, problems based on water scarcity will be replaced by great opportunities in a newly potable water rich world.
Device Pulls Water From Dry Air, Powered Only by the Sun. Robert Sanders in news.berkeley.eu; April 13, 2017;
Wind-Powered Device Can Produce 11 Gallons Per Day of Clean Water from the Air. Derek Markham in treehugger.com; October 10, 2016.