A Star Trek-style device that harvests clean energy out of thin air has been created and could revolutionize green energy.
The recycling machine, named Air-gen, makes electricity from humidity thanks to tiny pores – less than a thousandth of the width of a human hair.
It resembles the replicator in the cult TV show that changes air into any kind of matter – including food or water.
Now scientists are turning science fiction into fact – opening the door to cheap green power for cars, trains and airplanes.
Senior author Dr. Jun Yao, of Massachusetts University, said: “The air contains an enormous amount of electricity. Think of a cloud, which is nothing more than a mass of water droplets.
“Each of those droplets contains a charge, and when conditions are right, the cloud can produce a lightning bolt – but we don’t know how to reliably capture electricity from lightning.
“What we’ve done is to create a human-built, small-scale cloud that produces electricity for us predictably and continuously so that we can harvest it.”
The technique can be scaled up for mass use across the world – in environments ranging from the Amazon rainforest to the Sahara.
Dr Yao said: “Imagine a future world in which clean electricity is available anywhere you go.
“The generic Air-gen effect means that this future world can become a reality.”
The heart of the man-made cloud depends on a phenomenon dubbed the ‘generic Air-gen effect.’
Three years ago the same team showed electricity could be continuously harvested from the air using a specialized material made of protein nanowires grown from the bacterium Geobacter sulfurreducens.
Graduate student Xiaomeng Liu, lead author of the latest study, said: “This is very exciting. We are opening up a wide door for harvesting clean electricity from thin air.”
The breakthrough could help save the planet – bringing the widespread commercialization of electric vehicles a step closer.
Dr. Yao said: “What we realized after making the Geobacter discovery is the ability to generate electricity from the air – what we then called the ‘Air-gen effect’ – turns out to be generic.
“Literally any kind of material can harvest electricity from air – as long as it has a certain property.
“It just needs to have holes smaller than 100 nm (nanometers) – or less than a thousandth of the width of a human hair.”
This is because of a parameter known as the ‘mean free path’ – the distance a single molecule of water travels in air before it bumps into another.
The researchers realized they could design an electricity harvester based around this number made from a thin layer of material filled with nanopores smaller than 100nm.
They would let water molecules pass from the upper to the lower part of the material.
Each pore is so small it would easily bump into the edge as they pass through – meaning the upper part would be bombarded with many more charge-carrying water molecules than the lower.
It creates a charge imbalance, like that in a cloud, as the upper part increased its charge relative to the lower part. This would effectually create a battery – one that runs as long as there is any humidity in the air.
Dr. Yao said: “The idea is simple but it’s never been discovered before – and it opens all kinds of possibilities.”
The harvester could be designed from literally all kinds of material, offering broad choices for cost-effective and environment-adaptable fabrications.
Dr. Yao said: “You could image harvesters made of one kind of material for rainforest environments and another for more arid regions.”
Since humidity is ever-present the harvester would run 24/7, rain or shine, at night and whether or not the wind blows.
It solves one of the major problems of technologies like wind or solar – which only work under certain conditions.
Humidity diffuses in three-dimensional space. The thickness of the Air-gen device is only a fraction of the width of human hair.
So many thousands can be stacked on top of each other – efficiently scaling up the amount of energy without increasing the footprint of the device.
Such an Air-gen device would be capable of delivering kilowatt-level power for general electrical utility usage.
It is described in the journal Advanced Materials.
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