It is amazing how technology has given us the tools to create energy from pretty much anything. The gravity light is an amazing invention that uses gravity to power a light. Originally started as a crowdsourcing project on Indiegogo, it now has been tested in many countries effectively delivering a half hour of light from the gravitational force on a bag of dirt.
If that’s not enough, you can 3D print sand in the desert with solar energy. The Solar Sinter, the invention of Markus Kayser, systematically melts sand using a Fresnel Lens. Fresnel lenses, which used to be fairly common, are the front part of a rear-projection TV. Here’s how to salvage one. How hot can a Fresnel lens get? Try melting a rock at 3800F.