By Rehan Iqbal
Normally, we get our water from wells, underground aquifers, lakes and rivers. However, there’s also water in the air. On a hot, humid summer day, 3,000 square feet of air can hold a gallon of water. Atmospheric water generators capture that moisture, turning it into something you can drink. That means you can have a source of clean drinking water almost anywhere, with minimal setup. How do these machines work, and where can they be used?
How Do Atmospheric Water Generators Work?
Have you ever noticed a pool of water under your car after you’ve driven it in the summer? Have you had to deal with water leaking out of a refrigerator or a window air conditioner? That water is a byproduct of the refrigeration process. The warmer the air is, the more moisture it can hold. If you chill that air below its dew point, it has to release some of that moisture. This is what leaves dew on the ground in the morning and puddles around refrigeration equipment.
Both dehumidifiers and atmospheric water generators use refrigeration to extract water from the air. However, an AWG is built to maximize water extraction, and it has the treatment systems needed to make that water safe for drinking.
All refrigeration units, whether they’re used for air conditioners, refrigerators, freezers or water generators, work by the same principles. Gas heats up as pressure increases, and cools down as pressure decreases. A compressor pressurizes the gas, which then goes to a condenser. This radiator removes the heat from the gas. This cooled, compressed gas goes through an expansion valve. As the gas expands, it drops in temperature. This cold gas passes through a second radiator, called an evaporator. Blowing air through the evaporator cools it down, forcing it to release moisture.
If an AWG is a Refrigeration Unit, Can it Be Used as an Air Conditioner?
Portable AWGs put the entire system, including the condenser and evaporator, into a single unit. That means the heat from the condenser and cold from the evaporator is in the same area. If anything, the area will be slightly warmer around an AWG, due to heat from the electric motor.
Do Atmospheric Water Generator Work Anywhere?
No. While you don’t need a traditional water source, like a well or a pond, there are limits on the climate conditions where these machines will work. Since temperature affects how much moisture the air can hold, it has a drastic effect on performance. Most AWGs struggle with temperatures below 60 degrees, and won’t work at all below 50 degrees.
AWGs need humid air, so there’s water to extract. In places with a desert climate, the humidity is too low for the machine to effectively capture water. While you can set up one of these machines indoors, access to moist air will be limited, especially if you’re using an air conditioner. That’s because the air conditioner’s evaporator removes most of the water before it reaches the AWG’s evaporator.
The AWG must be covered, if it’s used outside. Otherwise, rain can freeze to the cooling side of the AWG. Industrial water generators have their own enclosures, while household and portable units need to be under a roof or awning.
What’s the Difference Between a Solar Water Generator and a Solar Ready Water Generator?
Solar water generators use different technology than AWGs to collect water. Instead of refrigeration, they use chambers that allow water to evaporate and collect in a cistern. Some of these systems have integrated solar panels, which power on-board fans. These generators work under extreme conditions, but they require immense amounts of space and a climate that is consistently sunny. These systems are mostly used in deserts. The design allows these generators to extract water from low humidity air, and since land is cheap, the area they require isn’t an issue.
Solar ready AWGs are designed with solar power in mind. These machines have water storage that doesn’t require constant power, and sensors that can get the generator back on track when there’s a power interruption. That said, these are still refrigeration units, so they require a lot of electricity. Power requirements can vary widely depending on local weather conditions and water requirements. They’re also powered by alternating current, so you need to convert the DC power from a solar panel to household AC power. Most portable setups use a dedicated solar power station and a set of solar panels.
How Do AWGs Make Water Safe to Drink?
AWGs have an initial storage tank to hold contaminated water from the evaporator, and a drinking water tank that holds water that has been cleaned and decontaminated. Many systems use two enclosures. One enclosure holds the generator and initial storage tank, while the second holds most of the water filtration equipment and the clean water tank. This makes the AWG easier to move around. Some small scale systems pack everything into a unit that’s about the size of a water cooler.
Filtration starts with an electrically-charged dust filter. It attract dusts from air entering the AWG, while minimizing air flow restriction. These filters are washable, so they never need to be replaced.
Water from the evaporator is sent to a small holding tank. Some systems have a UV light or an ozone generator in this tank to kill pathogens, while others use one of these treatments elsewhere in the system. UV light has a short wavelength that penetrates cells and breaks bonds in DNA and RNA. Once these chemical instructions are broken, the cell dies. UV lights are sometimes used in the clean water storage tank to prevent pathogen growth during water storage. Ozone is a powerful oxidation agent. It reacts with the molecules that make up the cells, breaking them down. Ozone is generated by sending an arc of electricity through the air. Systems that use ozone generate it for the initial storage tank, since most of the electric demand is inside the generator.
From there, water is pumped into a filtration system. Most AWGs use a series of carbon filters. These filters remove VOCs, heavy metals and other toxins. Activated carbon has a massive surface area. H2O has no trouble passing through this type of filter, but other chemicals cling to the carbon’s surface. Catalytic carbon has a treated surface that is electrically charged. This attracts heavy metal ions, removing contaminates like lead. Finally, this treated water goes to a clean water storage tank.
Is Water from the Generator Hard or Alkaline?
No. Mineral content is low, and there is little left in treated water to change its pH. Typically, the pH of water from an atmospheric water generator is between 7 and 8.5, so it’s neutral or slightly basic. This makes it safe to drink, and it won’t negatively affect plumbing or storage containers.
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