Sunlight can double the Etón Rukus Solar speaker’s battery life to more than 10 hours. A 40-square-inch monocrystalline solar panel provides the 7.4-volt battery with power to play songs from a Bluetooth-paired phone or MP3 player. A low-power E Ink display shows battery status.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.