In the past few years, we have covered a whole host of amazing emergency smartphone chargers here. The HydraCell Power Cube is also worth a look. It can generate power for your light or smartphone with saltwater. You will be able to enjoy 100 hours of light and up to 10 phone charges off-grid.
The HydraCell Cube has a a recyclable plastic construction. The waste it produces is biodegradable too. Like what you see? You can back this project on Indiegogo.