It is not something as robust in appearance as a machined block of metal, but researchers at Duke University have achieved something no less remarkable: a machine that captures the ubiquitous energy of microwaves and converts it into direct current voltage capable of recharging batteries. It is thought that with modification their design could also capture energy from other sources, including sound and wireless networking broadcasts. Their full research will be presented in the December 2013 edition of the journal Applied Physics Letters.
Allen Hawkes and Alexander Katko, both Duke University students, and electrical and computer engineering professor Steven Cummer built their device from common materials including fiberglass and copper. In a similar fashion to solar cells, the team's device captures ambient microwave radiation. The initial version is found to be producing 7.3 volts of electrical current. In contrast, USB-based chargers for mobile devices produce around 5 volts. The researchers have thus far achieved a dramatic 37 percent energy efficiency: comparable to that of the best solar power cells currently being produced.
The immediate vision of application is that of cell phones recharging in the complete absence of wires. One of the theorized uses for the design could be recovery of "lost" energy and diverting it back into the source of power, potentially opening up an entirely new generation of "green" technology. The architecture and choice of materials used in crafting the device's components allows for optimum energy harvesting, without otherwise creating interference for the unit in which the harvester is installed. People living in hard-to-reach locations might someday draw their electrical power from nearby cellular towers, "soaking up" the energy that would otherwise be lost and useless. The research team has also suggested that satellites in orbit might someday "beam down" microwave energy for harnessing by such devices en masse. And the design is scalable: Cummer observed that, "The beauty of the design is that the basic building blocks are self-contained and additive. One can simply assemble more blocks to increase the scavenged power."
It is difficult not to imagine a day in the not-too-distant future when automobile engines are humming along the highway, powered by the electromagnetic energy all around us that has until now been neglected.
Surely somewhere, John Galt must be smiling