In a study published in November of 1987 titled “Anaerobic production of magnetite by a dissimilatory iron-reducing microorganism” baffled scientists, with its ability to produce magnetite without the need for oxygen.
Thirty-three years later researchers may have finally realized the true potential of this unusual microbe, to create electricity out of thin air!
A team from the University of Massachusetts Amherst has created a device called “Air-gen”. Electrical Engineer Jun Yao explains:
We are literally making electricity out of thin air. The Air-gen generates clean energy 24/7.
The microbes used for the Air-gen are part of the Geobacter genus, which are electrically conductive protein nanowires. The Air-gen is covered with a thin layer film of these nanowires that is just 7 micrometers thick, between two electrodes.
The key is the layer is also exposed to the air, which allows for it to absorb water vapors from the atmosphere. This allows for the Air-gen to generate a continuous electrical current. The scientists say they think the charge is created by a moisture gradient and a diffusion of protons in the nanowire.
The team goes on to explain:
This charge diffusion is expected to induce a counterbalancing electrical field or potential analogous to the resting membrane potential in biological systems. A maintained moisture gradient, which is fundamentally different from anything seen in previous systems, explains the continuous voltage output from our nanowire device.
Afterward, Yao said this discovery essentially happened by accident. He noticed during their experiments that the devices seemed to be conducting electricity all by themselves.
“I saw that when the nanowires were contacted with electrodes in a specific way the devices generated a current. I found that exposure to atmospheric humidity was essential and that protein nanowires adsorbed water, producing a voltage gradient across the device,” said Yao.
The Air-gen can produce a sustained voltage of around 0.5 volts and has a density of 17 microamperes per square centimeter. While this is not much, it’s only the beginning. The team is confident that by connecting multiple devices, it would be enough to charge small electronic devices.
Yao excitedly talks about the potential of this discovery:
The ultimate goal is to make large-scale systems. Once we get to an industrial scale for wire production, I fully expect that we can make large systems that will make a major contribution to sustainable energy production.
This includes the possibility of using nanowires incorporated into wall paint that could help to power a home. What scientists knew 33 years ago was this strange bacteria found on shores of the Potomac River was special, they just didn’t know how special.
