Sometimes it seems there are about as many ways to charge gadgets as there are products waiting to be plugged in, but how about a battery that runs on Coca Cola?

Sony's latest take on the Bio Battery we saw a couple of years ago was on display at the International Hydrogen & Fuel Cell Expo in Tokyo this week.

Glucose breakdown

It works on the principle of getting an enzyme to break down glucose, then manipulating electrons and hydrogen atoms. The waste product is simply ordinary water.

The new Bio Battery can generate 70mW of power from 28cc of cola, which is approximately twice the output density of the previous model.

Walkman roped in

As per usual in its demonstrations, Sony showed its new technology powering a Walkman (what else?) and a pair of speakers. Not bad for something powered by a squirt of fizzy pop.