AWGs, Water From Air Sounds Like Magic. The Energy Bill Is the Catch
There are roughly 13,000 cubic kilometres of water floating through Earth’s atmosphere at any given time. We can’t see most of it, but we feel it every humid summer morning. For decades, engineers have been trying to turn that invisible reservoir into drinking water. And for more than 2 decades we’ve been writing about the promise. When you first hear about Atmospheric Water Generators (AWGs) and the ability to pull water from thin air, the idea sounds like magic.
We’ve covered companies in this space before, like Watergen, but unless the company is also providing a sustainable source of power, the tech isn’t worth its weight in salt. Unless of course you are putting them in emergency or military situations where there is no other choice for accessible drinking water.
For years AWG companies have been seducing us: forget digging deeper wells, building desalination plants or trucking bottled water into remote villages. Just put a machine outside the village or hotel and pull moisture from the atmosphere and drink it.
Companies in this space include Watergen, GENAQ, SOURCE Global and a long list of smaller atmospheric water generator companies who have pursued versions of this idea. Most essentially use refrigeration technology to cool air below its dew point, and collect the residue, much like air conditioners do in your home. Here are 5 ways to reuse your air con water.
Others AWGs use desiccants or advanced materials that capture water molecules and release them later. SOURCE Global for instance takes another approach with solar-powered hydropanels that use hygroscopic material to capture atmospheric moisture.
The science works but the harder question is whether the energy equation works.
We aren’t actually making water from nothing
Anyone who has watched water drip from an air conditioner has already seen atmospheric water generation. Warm air contains water vapor. When you cool that air sufficiently and the vapor condenses into liquid water. But cooling huge quantities of air takes energy.
One experimental study of an atmospheric water generator found energy consumption ranging from about 0.84 kWh per liter under favorable conditions to roughly 2.1 kWh per liter under less favorable conditions. Another study found a range between 0.75 and 4.71 kWh per liter, with warm, humid conditions performing best. You can read more about atmospheric water generator performance in this ScienceDirect study.
That is why putting an atmospheric water generator in Miami and putting one in the Sahara are fundamentally different propositions. The places desperately short of water are often exactly the places where extracting it from dry air becomes thermodynamically difficult and where energy is hard to obtain regularily.
A recent review in Nature Reviews Clean Technology identifies energy consumption as one of atmospheric water harvesting’s central obstacles, particularly in arid regions. But we need to solve the power issue. Fusion could help but that’s a long way off probably.
Water from air needs clean energy
Imagine solving water scarcity by installing millions of atmospheric water generators powered by coal- or gas-heavy electricity grids. We would be using energy that contributes to climate change to manufacture drinking water for communities increasingly suffering from drought and climate change.
Solar energy changes the equation because atmospheric water systems are particularly interesting when they can run directly from sunlight, renewable electricity or waste heat. A recent review of atmospheric water harvesting research from Basra, Iraq found that pairing these systems with solar power could substantially improve their economics and environmental performance. The irony is not lost on us. Basra is home to oil extraction facilities for the world’s biggest oil companies. Yet the people of Basra are exposed to pollution and unstable access to power.
Yet, researchers increasingly see combinations of solar, wind, sorbent materials and intelligent controls as promising routes toward lower-energy water production.
SOURCE Global is already commercializing one interpretation of this model. Its hydropanels use sunlight and air rather than a conventional water connection to produce drinking water, although output still depends on local climate conditions, including sunshine and humidity.
Other companies working in atmospheric water generation include Watergen and GENAQ, both of which have developed systems designed to extract drinking water directly from ambient air and that may ultimately be where water from air makes the most sense.
Not necessarily replacing municipal water systems or producing millions of liters for agriculture, but creating decentralized drinking water where conventional infrastructure is expensive, contaminated, unreliable or simply nonexistent. This could very well work in places like Basra where the locals cannot drink the water because it is too polluted and contributing to explosive rates of cancer, according to one woman I met from Basra recently.
Think AWGs in desert schools, remote communities, disaster zones, islands, military installations and homes beyond municipal water networks. But powered by abundant clean energy, and combined with better materials that can capture moisture without brute-force refrigeration, it could become an important piece of the water puzzle. And these systems should be up and running in Gaza already. With the proximity to Europe and the intense global outpouring of support Gaza should be a new frontier of humanitarian help, not a disaster zone.
The atmosphere contains an extraordinary amount of water. It’s time we use it.
