Vodafone is to trial prototype phone-charging technology at the Isle of Wight festival this weekend. Developed by the University of Southampton's Electronics and Computer Science Department, the Power Pocket exploits the Seebeck effect, exploiting the difference in temperature between the human body and its surroundings to generate an electrical current which can be used to recharge a smartphone. Vodafone has woven the pocket into a sleeping bag (called Recharge) and a pair of shorts (called Power shorts) to test the technology.
"Basically, we're printing down pairs of what are called 'thermocouples,'" says the University of Southmapton's Professor of Electronic Systems, Steve Beeby. "You print lots of those down and connect them up to make a thermoelectric module." The product is the culmination of decades of research into printed, smart and thermoelectric materials, Beeby explains in a press release.
Beeby says that an eight-hour sleep will provide 24 minutes of talk time or 11 hours of standby time (though this will depend on the phone, clearly). "That's assuming the inside of the sleeping bag is 37 degrees," he says in the press release. But what's the corresponding ambient temperature required for this performance? "The calculations assumed an ambient temperature of 10º C but that 17º C might be lost across other materials i.e. the thermoelectric module sees 10º C," Beeby tells Gizmag. The actual current and voltage were not calculated, but could be based on Seebeck coefficients, he explained.
The material is still in development, and there is more work to do so far as durability goes. However, Beeby estimates that, what with similar research going on elsewhere (see Power Felt, for example), thermoelectric materials will be woven into clothing as a matter of course over the next decade.
As Beeby notes, this isn't a unique idea. In fact Vodafone's competitor Orange pulled a similar stunt with thermoelectric Wellies for Glastonbury Festival a few years ago.