Pulling clean, unlimited energy from thin air sounds so ridiculous that you’d be excused for thinking it’s some sort of unfunny joke.
We heard about it a couple of weeks ago and we’re still shaking our heads.
But it is real … and it’s spectacular!
The concept relies on harnessing the charge that already exists in water droplets, which are in the air everywhere all the time.
Think of how powerful a bolt of lightning is. That’s a random discharge of a massive amount of electrical energy from a cloud – which is, after all, simply a mass of water droplets in the air.
Now think about managing the process of collecting that electrical energy by doing not much more than gathering those droplets of water to harvest the electrical charge they carry.
It’s a bit more complicated, but not really much more than that.
A man-made cloud
A team of engineers at the University of Massachusetts recently proved the concept. They showed that nearly any material can be turned into a device that continuously harvests electricity from humidity in the air.
They essentially created a human-built, small-scale cloud that produces electricity predictably and continuously so that it can be “harvested”.
The “harvester” can be made of almost any material, as long as it’s engineered in the right way which enables the water droplets to pass through tiny holes.
As the droplets pass through, the upper part of the material retains a stronger charge than the lower part, and that charge imbalance, in effect, creates a sort of battery.
The beauty of it is that this battery will run as long as there is any moisture in the air, which is all day and all night, so it doesn’t rely on the sun or the wind (as the two most common current renewable sources of energy do).
Now to the science
The secret to the success of this process is a feature or property that the material the harvester is built from must have: holes smaller than 100 nanometres (nm) in diameter, or less than a thousandth of the width of a human hair.
The reason for this is a parameter known as the “mean free path”, which is the distance a single molecule of a substance – in this case, water in the air – travels before it bumps into another single molecule of the same substance. When water molecules are suspended in the air, their mean free path is about 100 nm.
The team of engineers developing the concept realised that was the “magic” number, and if they made their harvester from a thin layer of material filled with nanopores (tiny holes) smaller than 100 nm, the electrical charge of water molecules could be harnessed.
As the water molecules pass from the upper to the lower part of the material, they bump into the edges of the nanopores. In the process, the upper part of the layer is bombarded with many more charge-carrying water molecules than the lower part, creating a charge imbalance.
That’s what happens in a real cloud when the upper part increases its charge relative to the lower part, resulting in lightning.
In this case, we’re engineering a man-made cloud that acts as a perpetual battery powered by the ever-present humidity in the air.
What would these look like?
What we’re currently calling “Air-gen” devices (they might get a catchier name at some point) can, in theory, be built in any size and using a wide range of materials.
The material used might depend on the location, for example, certain materials might be more effective and longer lasting in tropical areas with a lot more moisture and heat, while different materials might be more suited to arid regions or colder parts of the world.
Because air humidity diffuses in three-dimensional space and the thickness of the Air-gen device is only a fraction of the width of a human hair, many thousands of them could be stacked on top of each other, efficiently scaling up the amount of energy without increasing the footprint of the device.
An Air-gen device at scale would be capable of delivering kilowatt-level power for general electrical utility usage.
“Imagine a future world in which clean electricity is available anywhere you go,” says Jun Yao, assistant professor of electrical and computer engineering in the College of Engineering at UMass Amherst, the senior author of the paper outlining the breakthrough.
“The generic Air-gen effect means that this future world can become a reality.”
Discoveries like this get us excited because it shows the potential for a better future where humanity can benefit from cleaner, abundant, cheap energy.
Some of the biggest scientific leaps forward were discovered by mistake or in the process of trying to understand more about a scientific phenomenon. If a small amount of energy can be pulled from the air, who’s to say that a large amount of energy can’t?
We’ll keep watching this space and report on progress – all while sending good vibes to the scientists.
University of Massachusetts Report: https://onlinelibrary.wiley.com/doi/full/10.1002/adma.202300748