Faeces could soon be used to power a future generation of mobile phones, scientists claim. Researchers have discovered a natural process that occurs within the bacteria found in poo, that could help improve ‘bio batteries’. It is hoped the discovery could produce energy for portable technology, such as smartphones, mobiles, tablets and laptops. The study from the University of East Anglia (UEA) in Norwich focused on how electrons cross bacterial proteins. Both human and animal waste contains bacteria, which ‘breathe’ minerals of iron - much like we breathe oxygen. An electrical charge is released as a side effect during this ‘breathing’ process. The charge is released from the cell, similar to the neutral wire in a household plug, and can then be harnessed. The scientists looked at proteins called ‘multi-haem cytochromes’ that are contained in a species of bacteria called Shewanella, found in faeces. Lead researcher Professor Julea Butt, from the university’s schools of chemistry and biological sciences, said: ‘These bacteria can generate electricity in the right environment.
‘This is an exciting advance in our understanding of how some bacterial species move electrons from the inside to the outside of a cell and helps us understand their behaviour as robust electron transfer modules. ‘We hope that understanding how this natural process works will inspire the design of bespoke proteins which will underpin microbial fuel cells for sustainable energy production.’ Researchers from University College London and the Pacific Northwest National Laboratory in Richland, Washington, were also involved in the study. In July last year, scientists at the Bristol Robotics Laboratory claimed to have developed the world’s first urine-powered smartphone.
They created a way of using urine as a power source to generate electricity. While many people might turn their noses up at the energy source, the researchers said that it is the ‘ultimate waste product’ and does not rely on the erratic nature of the wind or the sun. Dr Ioannis Ieropoulos, an expert at harnessing power from unusual sources using microbial fuel cells at the University of West England, Bristol, which was also involved in the research, said: ‘No-one has harnessed power from urine so it’s an exciting discovery. ‘Using the ultimate waste product as a source of power to produce electricity is about as eco as it gets. ‘One product that we can be sure of an unending supply is our own urine. ‘By harnessing this power as urine passes through a cascade of MFCs, we have managed to charge a Samsung mobile phone. Microbial fuel cells, or MFCs, are energy converters that turn organic matter directly into electricity by utilising the metabolism of live micro-organisms. He explained that at the time, the microbial fuel power stack they developed generated enough power to enable text messaging, web browsing and a short phone call.
Dr Ieropoulos said: ‘The concept has been tested and it works - it’s now for us to develop and refine the process so that we can develop MFCs to fully charge a battery. ‘Essentially, the electricity is a by-product of the microbes’ natural life cycle, so the more they eat things like urine, the more energy they generate and for longer periods of time.’ The electricity output of MFCs is relatively small and the researchers are currently only been able to store and accumulate low levels of energy into capacitors for short charge and discharge cycles. However they claim that this is the first time that scientists have been able to directly charge the battery of a device such as a mobile phone and it should be seen as a significant breakthrough.
HOW DO BACTERIA BREATHE?
Many micro-organisms can, unlike humans, survive without oxygen. Some bacteria survive by ‘breathing rocks’ instead - especially minerals of iron. They derive their energy from the combustion of fuel molecules that have been taken into the cell’s interior. A side product of this reaction is a flow of electricity that can be directed across the bacterial outer membrane and delivered to rocks in the natural environment - or to graphite electrodes in fuel cells. This means that the bacteria can release electrical charge from inside the cell into the mineral, much like the neutral wire in a household plug. Professor Julia Butt explained: ‘Proteins conduct electricity by positioning metal centres – known as haems - to act in a similar way to stepping stones by allowing electrons to hop through an otherwise electrically insulating structure. ‘This research shows that these centres should be considered as discs that the electrons hop across.’