The increase in demand for electricity and also the growing issues of climate change have prompted scientists to make innovations in creating electricity. Known renewable energy technologies such as solar cells, thermoelectric devices, and mechanical devices have specific environmental requirements and limitations.
With advancements in research, using the atmospheric moisture seems to offer an alternative. However, available technologies can only produce an intermittent and brief burst of power in the ambient environment.
A new study published in the journal Nature described a thin-film device made from nanometer-scale wires gathered from Geobacter sulfurreducens, a type of microbe that can generate non-stop electric power. This device called "Air-gen" or air-powered generator created by the electrical engineer Jun Yao and microbiologist Derek Lovley at UMass Amherst generates clean energy out of thin air, 24 hours a day.
Air-gen is developed in Yao and Lovley's laboratory and is said to be non-polluting, low-cost, renewable and can generate power even in areas with low humidity. They say that this discovery reflects an unusual interdisciplinary collaboration.
More than 30 years ago, Lovley discovered the Geobacter microbe in the mud of the Potomac River and later discovered its ability to produce electrically conductive protein nanowires. Yao used to work at Harvard University where he engineered electronic devices with silicon nanowires before coming to UMass Amherst. The two scientists joined forces to know if useful electronic devices could be made with the protein nanowires they harvested from Geobacter.
How does Air-gen work?
The researchers explained that Air-gen requires a thin film of protein nanowires less than 10 microns thick. The bottom part of the film rests on an electrode, while another electrode, smaller in size covers only part of the nanowire film on its top. It then absorbs water vapor from the atmosphere.
To establish the conditions needed to generate an electrical current between the two electrodes, it needs a combination of the electrical conductivity and surface chemistry of the protein nanowires together with the fine pores between the nanowires within the film.
Xiaomeng Liu, a Ph.D. student at the University of Massachusetts Amherst said, "I saw that when the nanowires were contacted with electrodes in a specific way the devices get current."
He added that exposure to atmospheric humidity was essential as the protein nanowires absorbed water, enabling the production of a voltage gradient across the device.
The future of Air-gen
The scientists also plan to make small Air-gen 'patch' versions in replacement of traditional batteries used in power electronic wearables such as health and fitness monitors and smartwatches.
In addition to that, they also aim to make Air-gen cell phone batteries to lessen the periodic charging when normal phone battery runs out of energy.
Dr. Yao said that the ultimate goal of Air-gen is to make large-scale systems. The technology may be incorporated into wall paint that could help power homes, and maybe someday develop a stand-alone air-powered generator that helps supply electricity off the grid.
"This is just the beginning of a new era of protein-based electronic devices," said by Dr. Jun Yao.
The scientists expect that once this technology gets to an industrial scale for wire production, making large systems of it will make a major contribution to sustainable energy production.