Biofuel has many forms, ranging from the ethanol used in cars throughout Brazil to the famous and dreaded anaerobic digesters that convert waste into methane gas or even the used vegetable oils that power Brightons famous lemon bus. The standard definition of biofuel is any fuel derrived directly from living matter and increasingly with the price of non renewable energy rising scientists are constantly seeking more efficient means of harvesting bioenergy. Bioenergy presents an attractive prospect as the raw materials, unlike non renewable sources of energy, are extremely cheap and readily available. However what if we could make it even cheaper? We produce masses of energy each day and much of it goes to waste. What if there was a way to harness the energy produced by our own bodies, an extremely efficient energy extractor. This is exactly what scientists have been attempting to achieve over the last two decades and now it looks as if we are on the brink of a biofuel revolution.
A new kind of fuel cell has been designed, named the enzymatic biofuel cell, it takes advantage of the fact that our bodily fluids are rich in glucose and water. It uses the power of enzymes, proteins that our bodies use in order to speed up reactions, to generate energy from these simple materials. The fuel cells are comprised of two electrodes one electrode for glucose and one for oxygen. They prodocude energy by removing electrons from glucose and donating electrons to molecules of oxygen. This is all assisted by a glucose oxidasing enzyme and a oxygen reducing enzyme that speed up the entire process. It was announced in 2007 that Sony had designed the most powerful enzymatic biofuel cell, nicknamed the biobattery it is capable of producing up to 50mW of energy. This was deemed a great sucess and the biobatteries have even been used in a demonstration to power a small mp3 player however to date no biobattery has been produced commercially due to its small power output.
But now the research has been taken further and the focus has been switched away from producing a battery capable of powering electronics and towards an internal battery that could be implanted and used inside the body. This has been the aim of Serge Cosnier and his team for several years and in 2010 they managed to implant an enzymatic biofuel cell inside a rat for 40days with no adverse affects to behaviour of physiology reported. The cell itself functioned exactly as it would outside of the organism and produced a steady stream of energy throughout the 40 day period. But what advances does the fuel cell in this form offer?Currently one of the greatest limitations to artificial organs, limbs and pacemakers is the amount of energy required to keep them going and conventional batteries cannot cope with the demand. Pacemakers require little energy but the prospect of going under the knife to replace a battery, no matter how infrequent, seems a little absurd. The enzymatic biofuel cell would only need be implanted once as its energy sources are constantly renewed in our own bodies, it also is protected by a special casing that does not allow antibodies access to it meaning that our immune system cannot reject it. Artificial organs and limbs present even more of a challenge in terms of energy however with the advent of the implanted biofuel cell now we have the opportunity to advance these technologies aswell.
However at the moment the technology is limited, the power generated by these fuel cells is extremely minimal at the moment, but it is early days and already Dr Cosnier is working on a system that may produce 50 times the power of his original implanted fuel cell. The potential for such technology is endless and as our increasing energy demands begin to reach crisis levels we continue our search for alternative solutions. Though far from perfect thanks to the enzymatic biofuel cell we may just find ourselves in a situation one day where a bottle of lucazade will have the same function as a packet of batteries.