Producing electricity out of nothing may seem some sort of science fiction stuff, but a new technology relying upon nanowire-sprouting bacteria can do just that, as long as there is moisture in the air.
New research depicts that when composed into a film, these wires, which are protein filaments that carry electrons away from the bacteria, can generate sufficient power to bright up a light-emitting diode.
Generating Energy From Air
The film functions by consuming humidity from the air in the environment. Even though scientists are not clear on how these wires function, the small power plants are able to do that: 17 connected devices are able to produce 10 volts, which is sufficient electricity to power a mobile phone.
The new technique is referred by some as ‘a milestone advance,’ including Guo Wanlin, a materials expert at Nanjing University of Aeronautics and Astronautics who was not part of the team that discovered the technology. Guo studies hydrovoltaics, a molecular method to harvest electricity from water.
The way hydrovoltaic devices function isn’t entirely known. When water drops engage with specific types of graphene or other materials, an electric charge is produced, and electrons travel through the materials. However, researchers have numerous questions regarding the way these devices manage to produce electricity.
“I think a deeper understanding … is needed,” says Dirk de Beer, a microbiologist creating microsensors at the Max Planck Institute for Marine Microbiology.
Scientists are just starting to understand how electron-generating bacteria work. Over 15 years ago, co-author Dered Leveley, a microbiologist at the University of Massachusetts (UMass), Amherst, and his team found out that a bacterium, known as ‘Geobacter,’ carries electrons from organic material to elements composed out of metal, such as iron oxides.
A Device Able to Recharge
Two years ago, UMass graduate student Liu Xiaomeng observed the fact that, at times, the isolated nanowires suddenly produced current. Initially, his adviser, UMass electrical engineer Yao Jun, was doubtful, but ultimately, they found out that when they interposed a thin film of the nanowires between two gold plates and left it there, they could continually get power for a minimum of 20 hours. The device was also able to recharge itself.
After a few failed ideas to make the device generate more electricity, the researchers had one final clue: when they left the nanowires in a less humid room, it generated less current, implying that moisture was the main element.
They then subjected the device to various levels of moisture. It functioned best in air of approximately 45 percent humidity, but also in settings as dry as the Sahara Desert or as moist as New Orleans, the researchers stated in a paper published in the journal Nature.
Relying on Geobacter
Because the ‘air-gen’ device, as Yao calls it, needs no external power, it can be utilized in numerous places, not only for solar panels or wind turbines. If it can be developed, it shows ‘great potential for practical applications,’ according to Guo.
Using water vapor is a novel technique to ‘get renewable, green, and cheap energy directly from atmospheric moisture,’ says Qu Liangti, a materials scientist at Tsinghua University.
When it comes to harvesting nanowires, Loveley has also suggested a way. Growing Geobacter is rather challenging, so Loveley has genetically modified the easy-to-grow bacterium Escherichia coli to create nanowires. The E.coli generated nanowires of the same size, and with an identical conducting power as Geobacter’s, he and his team stated in a November 2019 paper published in bioRxiv.
However, a prepared source of nanowires might not be sufficient, Gemma Reguera, a microbiologist at Michigan State University, said. She has utilized E.coli to make peptides, which are the protein nanowires’ building blocks. Still, for now, the device depends on Geobacter’s nanowires.