A thin-film device made from nanometer-scale protein wires harvested from the microbe Geobacter sulfurreducens can generate continuous electric power in the ambient environment, according to a new study published in the journal Nature.
Graphic image of a thin film of protein nanowires generating electricity from atmospheric humidity. Image credit: Yao and Lovley labs, University of Massachusetts Amherst.
“We are literally making electricity out of thin air. The Air-gen generates clean energy 24/7,” said Dr. Jun Yao, an electrical engineer at the University of Massachusetts Amherst.
“It’s the most amazing and exciting application of protein nanowires yet,” added Professor Derek Lovley, a microbiologist at the University of Massachusetts Amherst.
The Air-gen device can generate power even in areas with extremely low humidity such as the Sahara Desert.
“It has significant advantages over other forms of renewable energy including solar and wind, because unlike these other renewable energy sources, the Air-gen does not require sunlight or wind, and it even works indoors,” Professor Lovley said.
The device requires only a thin film of protein nanowires less than 10 microns thick.
The bottom of the film rests on an electrode, while a smaller electrode that covers only part of the nanowire film sits on top. The film adsorbs water vapor from the atmosphere.
A combination of the electrical conductivity and surface chemistry of the protein nanowires, coupled with the fine pores between the nanowires within the film, establishes the conditions that generate an electrical current between the two electrodes.
The current generation of Air-gen devices produces a sustained voltage of around 0.5 V across a 7-μm-thick film, with a current density of around 17 µA/cm2.
“I saw that when the nanowires were contacted with electrodes in a specific way the devices generated a current,” said Xiaomeng Liu, a Ph.D. student at the University of Massachusetts Amherst.
“I found that that exposure to atmospheric humidity was essential and that protein nanowires adsorbed water, producing a voltage gradient across the device.”
Next steps the scientists plan include developing a small Air-gen ‘patch’ that can power electronic wearables such as health and fitness monitors and smart watches, which would eliminate the requirement for traditional batteries.
They also hope to develop Air-gens to apply to cell phones to eliminate periodic charging.
“The ultimate goal is to make large-scale systems,” Dr. Yao said.
“For example, the technology might be incorporated into wall paint that could help power your home. Or, we may develop stand-alone air-powered generators that supply electricity off the grid.”
“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.”
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X. Liu et al. Power generation from ambient humidity using protein nanowires. Nature, published online February 17, 2020; doi: 10.1038/s41586-020-2010-9
