Using a special strain of bacteria, a research team at the University of Massachusetts Amherst has created nanowires that can make an electric charge by pulling humidity—even tiny amounts—from air.
At first, the group thought the effect depended on the bacterial wires and the perforated film in which they were wrapped.
Now the researchers have discovered that almost any material that conducts electricity can be used.
Instead, the key lies in the size of the perforations in the coating.
The coating is made up of two layers of film. The top layer has holes small enough to hold water molecules in place without letting them squeeze through.
As the molecules gather and try to push through the holes, they generate an electric charge greater than the charge in the lower layer. The difference creates an electric current that can be carried away on the wires.
The effect is similar to the way that clouds create lightning. Clouds are masses of water droplets, each holding a charge. As temperatures and other conditions in the air change, those charges are released.
“What we’ve done is to create a human-built, small-scale cloud that produces electricity for us predictably and continuously so that we can harvest it,” computer engineer Jun Yao, who led the research, told a press briefing.
Because the effect depends on the size of the pores and not on the material itself, a range of materials could be used to create power. Local materials could be used or, if necessary, special materials could be recruited to suit certain climates or other conditions.
More importantly, the nanofilm is so thin that hundreds of the cells could be stacked to generate power at kilowatt scale.
The design also is sensitive enough to produce usable power from near-desert conditions, the developers say.
TRENDPOST: For the foreseeable future, the world will have an insatiable hunger for electric power. Especially in emerging nations, that hunger will be particularly hard to satisfy without major investment in renewable or fossil-fired generation.
This simple device, engineered from cheap, local materials, could electrify large parts of the world that otherwise would have to wait for more expensive solutions.