All the tech in the world is no good if users don't have a way to power it. A few companies are trying to overcome that obstacle with devices that convert heat to electricity. In June, one early front-runner, Vodafone, revealed its Power Pocket, a charger for sleeping bags and clothes that uses body heat to power your phone, debuting it at music festivals around the U.K.
BioLite, whose company motto is “Energy Everywhere,” develops wood burning stove that uses its own thermal energy to charge electronics. BioLite currently makes the backpack-friendly CampStove, which lets you cook while powering your phone off-grid, and is developing a larger version to bring electricity to developing countries.