The 411 on Atmospheric Water Collectors!
Atmospheric water harvesting (AWH) is emerging as a promising means to overcome the water scarcity of arid regions, drought stricken farmlands and urban areas where the water sources are contaminated (see Flint Michigan) and most especially for inland areas. Atmospheric water collectors can solve a lot of water use issues in fact one unit costs between 3k and 5k per household and larger models can assist whole towns or villages. By adding a unit to each new house built, homeowners' water concerns are a thing of the past as well as the need to pay an ever rising water bill! Researchers from the American Chemicals Society had the following to say about the subject.
“Currently approximately four billion people are suffering from water scarcity and this trend is severely increasing globally. Conventional fresh water access relies on rainfall, rivers, and lakes, with uneven distribution, depending on the geographic location. Climate change, population growth, and water pollution issues have further exacerbated the imbalance of water resource distribution and difficulties of clean water access for the masses. Research efforts, although limited, has been devoted in the last two decades to address this issue of water stress with various technologies, such as wastewater purification and seawater desalination.”
However, the utilization of these technologies are restricted by cost and water transportation capacity, especially for the undeveloped and landlocked regions. Most of the other freshwater resources are contained within ice caps, glaciers, and deep groundwater, which are difficult to acquire. The global water reservoirs and their corresponding restrictions are seemingly insurmountable pertaining to securing a way to economically distribute this resource globally. In this context, water vapor in the atmosphere, which has been ignored until fairly recently, can be seen as a feasible supplementary fresh water resource, because not only does the atmosphere contains a large quantity of water vapor around 1.29 × 1013 m3, (5,16) but also this water vapor is ubiquitous (everywhere) and it can be acquired without any restrictions of geographical and hydrologic conditions, being beneficial to household access to safe water without additional purification steps. Hence, to develop a globally accessible water resource, the reliable approach of atmospheric water harvesting (AWH) is crucially desirable
In areas where water is scarce or polluted, atmospheric water generators are reliable sources of clean, safe water. For domestic applications, they can reduce or eliminate the need for bottled drinking water. Atmospheric water generators don't work the same everywhere! Scientists and a growing number of companies that make air-from-water devices are working on harvesting water from the atmosphere in ways that are practical, efficient, and inexpensive. But mining moisture from air isn’t easy, scientists agree there won’t be a single technology that’s best for every locale. In foggy areas, the answer may be putting up systems that can coax water droplets suspended in the air to coalesce. In humid climates, where the air is thick with water vapor but the vapor hasn’t nucleated into droplets, devices that can condense and collect it might be best. And in arid regions like deserts, specialized machines that can absorb what little moisture that’s around had to be developed. The creator of the most recent groundbreaking technology for this type of collector is Moses West he created a prototype and now mainstay atmospheric collector that is used at sites of hurricanes and natural disasters all over the world.
Water is all around us it remains trapped in the atmosphere until the right conditions release it as rain or snow. Another innovator in the field is Omar Yaghi, a chemistry professor at the University of California, Berkeley, who has helped find a way to grab that water anytime we need it. Using a device called a metal-organic framework (MOF). This is basically a sponge-like compound that looks like sand to the naked eye, and which is extremely dense. Depending on the materials involved, the MOF can be constructed to harvest different chemicals, from industrial emissions to natural gas.
Yaghi and his team at U.C. Berkeley found that a metal-organic framework that includes the element zirconium will capture water out of the air at night, store it, then release it during the daytime upon exposure to the heat of sunlight – no electricity needed. They collaborated with researchers from the Massachusetts Institute of Technology to build the water-collecting device and are working to develop a version with the capacity to serve a single-family home at a competitive price. Water presents a challenge since it competes with carbon dioxide for the adsorptive sites in the pores of MOFs. Developers of the tech noticed that some MOFs exhibit a unique uptake of water. A highly cooperative phenomenon seems to dominate the uptake and result in a sharp water permeation of the MOF at very low relative humidity. In essence, inside these MOFs, one has solid water in hot weather and lots of it!
To get the water out, one simply needs to heat the materials to a mere 45C (113F). This is the temperature required inside the enclosed device, which most likely will be higher than the outdoor temperature. This provides enough energy to break those weak bonds and release the water from the pores. This was very surprising, but also exciting. It meant that certain MOFs can be used to trap water from the atmosphere especially in arid climates, and then be released easily for collection.