Sony is still working on powerful, environmentally friendly bio batteries
Users can recharge the battery by using a bottle of coke, for example, when their cell phone died. The energy that can be generated by the glucose found in a single bowl of rice is the same of that in 96 AA batteries.
This sounds pretty cool but the bio batteries still look pretty big at 39x39x39mm. And depending on what you power with them, you need to carry around several of them.
Sony is currently exhibiting the bio battery at the 6th Hydrogen and Fuel Cell Expo in Tokyo.