Scientists at the University of Massachusetts Amherst have developed a
device that uses a natural protein to create electricity from moisture in the
air, a new technology they say could have significant implications for the
future of renewable energy, climate change and in the future of medicine.
As reported today in Nature, the
laboratories of electrical engineer Jun Yao and microbiologist Derek Lovley at
UMass Amherst have created a device they call an “Air-gen.” or air-powered
generator, with electrically conductive protein nanowires produced by the
microbe Geobacter. The Air-gen connects electrodes to the
protein nanowires in such a way that electrical current is generated from the
water vapor naturally present in the atmosphere.
“We are
literally making electricity out of thin air,” says Yao. “The Air-gen generates
clean energy 24/7.” Lovely, who has advanced sustainable biology-based
electronic materials over three decades, adds, “It’s the most amazing and
exciting application of protein nanowires yet.”
The new
technology developed in Yao’s lab is non-polluting, renewable and low-cost. It
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, Lovley says, because unlike these other renewable
energy sources, the Air-gen does not require sunlight or wind, and “it even
works indoors.”
The Air-gen
device requires only a thin film of protein nanowires less than 10 microns
thick, the researchers explain. 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 researchers
say that the current generation of Air-gen devices are able to power small
electronics, and they expect to bring the invention to commercial scale soon.
Next steps they 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.
Yao says, “The
ultimate goal is to make large-scale systems. 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.”
Continuing to advance the practical biological capabilities of Geobacter,
Lovley’s lab recently developed a new microbial strain to more rapidly and
inexpensively mass produce protein nanowires. “We turned E.
coli into a protein nanowire factory,” he says. “With this new
scalable process, protein nanowire supply will no longer be a bottleneck to
developing these applications.”
The Air-gen discovery reflects an unusual interdisciplinary
collaboration, they say. Lovley discovered the Geobacter microbe in the mud
of the Potomac River more than 30 years ago. His lab later discovered its
ability to produce electrically conductive protein nanowires. Before coming to
UMass Amherst, Yao had worked for years at Harvard University, where he
engineered electronic devices with silicon nanowires. They joined forces to see
if useful electronic devices could be made with the protein nanowires harvested
from Geobacter.
Xiaomeng Liu, a
Ph.D. student in Yao’s lab, was developing sensor devices when he noticed
something unexpected. He recalls, “I saw that when the nanowires were contacted
with electrodes in a specific way the devices generated a current. I found that
that exposure to atmospheric humidity was essential and that protein nanowires
adsorbed water, producing a voltage gradient across the device.”
In addition to
the Air-gen, Yao’s laboratory has developed several other applications with the
protein nanowires. “This is just the beginning of new era of protein-based
electronic devices” said Yao.
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