Electricity Is Being Harvested From Light Breezes 2015-08-19

All portable electronic communication devices require regular access to an energy source, which can be a problem for soldiers in the field. The U.S. Army is testing a new device that harvests energy from even the slightest breeze.

Solar chargers are effective only when the sunlight is relatively strong, but researchers at the Construction Engineering Research Laboratory in Illinois turned to the wind as another natural source of power often present in open spaces.

Four months of constant measuring in an open field showed that during evening hours 70 percent of average wind speed was less than or equal to three meters per second, too slow for a wind turbine, but enough to make a light strip of fabric flutter.

"What has resulted is an innovative prototype with which to generate electricity at remote locations for very low wind situations," said lead engineer Charles Marsh.

Flutter-Mallard device

The Flutter-Mallard portable sustainable electrical generation device has flexible strips affixed to pick-up coils with magnets that convert the vibrating energy into electrical charge.

A special challenge was the design of an electronic device that can turn the constantly changing wind speed, and therefore varying power, into a steady electric current.

But that was not the only problem researchers had to tackle.

"A concurring effort for the storage side of it, remember it was integrated energy generation and storage, was the development as well of some supercapacitor technology for the purpose of storing the electrical power that resulted in a number of publications and also a second patent disclosure," said Marsh.

Many engineering students from the University of Illinois participated in the project.

The device generates about three watts of power. Researchers are now experimenting with strips made of flexible photovoltaic cells that could serve as additional sources of energy during the day.