Picture: Sony Bio Battery

The 50 mW bio battery by Sony is powerful enough to charge a MP3 player and speakers. The bio battery casing is made of a vegetable-based plastic. It measures 3.9 cm (1.5 inch) along each edge and works by pouring sugar solution into the unit, where enzymes break it down to generate electricity. The company said it aims to produce the batteries for commercial use, without specifying when.