The mad scramble for spare chargers and outlets could soon be over, thanks to Vodafone’s Power Pocket Charger.

Phones can now be charged via body heat, using a technology that can be woven into a sleeping bag or clothes pocket. Developed by the University of Southampton’s Electronics and Computer Science Department, the application uses thermocouples, which are pairs of thermoelectric material that are small and flexible enough to stitch into fabric. Print enough of them, connect them together, attach a plug and you have yourself a charging station in the back of your pants.

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The technology takes advantage of the temperature difference between the inside and outside layer of clothing (or sleeping bag).

“One side of that is cold and the other is hot, and when you get a flow of heat through it you can create a voltage and a current,” Stephen Beeby, professor of electronic systems at the University of Southampton, said in a statement. “Voltage and current together equals electrical power.”

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The material is making its debut this weekend at the Isle of Wight music festival. So right around the time you’ve realized you can’t find your charger, head on over to the Vodafone tent, slip into a sleeping bag and charge your phone up. Heck, you might want to take a nap. After all, the festival lineup is more than a snooze.

Assuming the inside of the sleeping bag is normal body temperature, the fabric provides a good amount of juice. “Eight hours in the sleeping bag, roughly speaking, will provide 24 minutes of talk time and 11 hours of standby time.”