Invention turns energy in the air into electricity [video]

A Japanese tech firm has created the "rectenna," a device that harvests radio waves and converts them into useable electricity.

Although scientists have long known that tantalizing whiffs of energy radiate from WiFi and other radio frequency waves, it's only recently that the alternative energy industry has started to explore ways to harness this somewhat overlooked resource.

Last year, RCA showcased a prototype device that it claimed can turn WiFi signals into a ready supply of power . And just last month, researchers at the Georgia Institute of Technology announced a breakthrough that may enable consumers to produce an energy collecting antenna using an inkjet printer . Now researchers at Nihon Dengyo Kosaku Co., Ltd, a Japanese tech firm, have created the “rectenna,” a soon-to-be-commercialized device that harvests radio waves and converts them into useable electricity .

The current model two models are designed to collect energy from either WiFi or standard broadcast signals. The WiFi version, which can tap into signals located 10cm away from the source, generates an electrical output at the microwatt level while the terrestrial version, geared toward broadcast signals, produces about 1.2mV and 0.06µW of power. Both devices are also very portable, with the dimensions of the WiFi model measured at 12 mm thick and the terrestrial model at 30 mm.

Admittedly, the amount of electricity provided by the technology isn't much when compared to other forms of renewable energy conversion technology like solar or wind . But the researchers believe that even such a modest boost should be sufficient enough to have practical applications in low-powered electronics, such as sensors. For instance, in a demonstration video, they point out that placing the rectenna as close as 3 to 4 kilometers away from a broadcast tower in Tokyo enabled it to generate even more electricity , somewhere in the ballpark of 6mW of power.

(via DigInfo TV)

Related on SmartPlanet:

This post was originally published on

Show Comments