Engineers Found A Way to Generate Electricity From Thin Air
Green energy, as far as we’ve implemented it, is at best a shade of greenish-brown — army, perhaps, or olive. Solar farms harness the sun’s renewable energy but require large swaths of land and rare Earth metals. Wind power has a minimal carbon footprint, but, like solar, gets stored in batteries made from lead and lithium. Nuclear power is appealingly low carbon, but the risk of another Chernobyl is hard to stomach. All of these options are a huge improvement over coal power, but there’s real pressure to find an energy source that’s truly scalable, cheap, and 100% green.
Last week, scientists from the University of Massachusetts Amherst rose to the challenge, presenting a low-cost device they call the Air-gen, which generates electricity from thin air — enough to theoretically power devices like cellphones and electric cars. And since it doesn’t require harsh chemicals to produce, “the whole process,” corresponding author and assistant electrical engineer professor Jun Yao tells OneZero via email, is “green.”
Improbable as it sounds, the device’s technology is based on a natural phenomena: electricity-generating threads of proteins, called nanowires, that emanate out of a tiny bacteria called Geobacter sulfurreducens (a plush toy version of the bacteria looks like a Cheeto with tentacles). In the paper they published in the journal Nature last week, Yao and his co-authors describe their key discovery: Moisture suspended naturally in the air is the “driving force” behind the electricity-generating ability of the nanowires.
Think back to high school physics. Electricity is basically the flow of electrons, the negatively charged particles that circle atoms, from an area of high charge to an area of low charge. Water can be a good source of these charged electrons if it can be broken up into its building blocks, hydrogen, and oxygen.
The team theorizes that when a tangle of the nanowires is pressed into a mesh-like film, water from the air collects only at the top of it and breaks up into two Hs and an O, freeing up the water’s electrons. This gives the top of the film a greater charge than the bottom, setting up the perfect conditions for electrons to flow. When the researchers sandwiched one of these films between two gold electrodes to create a circuit, the tiny device produced a voltage of 0.5 volts across a film just seven micrometers thick. (A charged car battery, for comparison, measures at about 12.6 volts.)
“The whole process is green.”
Essentially, the Air-gen can generate a flow of electrons without much input, thanks to the impressive biology of Geobacter’s nanowires. Co-author and distinguished microbiology professor Derek Lovely, who has dedicated more than 30 years of study to the electric microbe, compares the wires to individual human hairs — a thread made up of different proteins, only 20,000 times thinner than what you’d pluck out of your scalp.
Before we can slap patches of these nanowire films onto an iPhone or Fitbit, their production will need to be scaled up so that multiple patches can work in tandem to generate enough electricity to power modern devices. Figuring out how to mass-produce the nanowires, plus devising a “clever engineering strategy” to put them together in a compact way, says Yao, will be key.
They’ve already started tackling the former problem by attempting to cut Geobacter bacteria itself out of the picture. “It is not easy to make large quantities of wires with Geobacter,” explains Lovley. Some bacteria are easier to grow en masse than others. Because it grows so quickly, E. coli has become scientists’ go-to for genetic engineering. Lovley’s team engineered a strain of E. coli that produces Geobacter’s nanowires, so now they have a ready supply.
“Now that we have solved the microbiological bottleneck, the engineers can begin designing larger Air-gen devices,” he says.
There’s still the question of whether the technology is as miraculously green as it seems to be. Yao maintains that production of the nanowires is completely harmless to the environment — and cheap to boot — because “we simply feed renewable feedstocks into the bacteria without harsh/toxic chemical involved.” The cost, according to an estimate from Lovley, would be 100-fold lower than that needed to make semiconductor-grade silicon, which is used for solar cells.
From the nanowires to the way they’re produced to the energy generated, says Yao, “All are green.” When the green label is placed on technology, he points out, it often “only means that the energy production part is green, and can still generate e-waste.”
Lovley says that there isn’t any existing technology that resembles Air-gen, as far as he’s aware. There doesn’t appear to be a patent on the Air-gen at the time of this article’s publication, but the research was funded by a seed fund through UMass-Amherst’s Office of Technology Commercialization and Ventures. The team appears set to scale up quickly.
The way Yao sees it, powering a large device with the Air-gen is only a matter of adding up many tiny generators. It’s analogous to using “thousands of battery cells” to “drive a Tesla car,” even though each individual battery cell only has limited energy. They can potentially power small-scale wearables, medium-scale electric tools, or even a remote station, as long as they can scale quickly. And they seem confident that they can.
In a cheeky tweet last week, he sent a “final response” to reviewers of their Nature paper: a gif of Gene Wilder in Young Frankenstein, mouthing his iconic line “It could work!”
“Now that we can make more wires, addressing this question should be relatively straight forward,” Lovley says.
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Lead Image: UMass Amherst/Yao and Lovley Labs
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