Sony engineers have built a simple home biofuel battery that runs on old newspapers, cardboard, and other paper products. Using the cellulose abundant in plant fibers, the little battery uses advanced enzymes to break down the woody material into sugars. When combined with oxygen, the brew cooks up plenty of electrons that can charge batteries or power your vintage Sony Walkman (or iPod).
It’s a bit like the science class standby of plugging two wires into a lemon to power an LED clock, but in graduate school. The lemon works because two terminals (the wires) are stuck into acidic lemon juice, a solution that conducts electricity, and the electrons can flow freely from one to the other.
For Sony’s battery, the electrical current is generated after the enzyme cellulase breaks down celluosic matter into glucose sugars, combining these with oxygen and other enzymes, to produce electrons and hydrogen ions. The electric current is conducted by the solution in the battery. The only by-products are water and the acid gluconolactone, an ingredient in cosmetics. Sony displayed its device at the Eco-Products exhibition in Tokyo last month and invited children to drop some old newspapers into the solution, shake, and watch a fan start turning a few minutes later.
Yet the basic approach of using glucose and oxygen to power a device or charge a battery is not limited to cellulose. Medical researchers at the University of Grenoble created a biofuel cell that runs on glucose and oxygen at concentrations common in the body, according to the BBC. This electricity, in theory, can be used to power sensors or even medical devices such as pacemakers, although tests so far have only been conducted in rodents.
The power output from both batteries is still low, but cheap, harmless biofuel batteries that run on paper waste (or the candy bar you just ate) could have applications outside of just a science class curiosity.