British telecommunications company Vodafone wants people to be able to use their phones, even when they’re away from a power source for days on end at music festivals, for example. So this week, the company unveiled a pair of denim hotpants that can actually charge a cellphone by harnessing thermoelectric and kinetic energy. In addition to the Power Pocket shorts, Vodafone also unveiled a sleeping bag that transforms body heat into energy that can be used to charge a phone. These technologies aren’t commercially available just yet, but Vodafone says it will be testing them out at the Isle of Wright Festival in England this week.