Here is another smartphone charger that lets you power up your device during natural disasters and emergencies. The JikoPower Spark is a thermoelectric generator that uses heat from fire to recharge for your smartphone. It is capable of charging a wide variety of USB devices. The Spark can charge your USB device in 1 to 4 hours.
To get started, fill the water reservoir with water to keep the top side cool. The temperature difference between the top and bottom side changes the electrical output. The Spark is expected to ship in May 2017.[Source]