Researchers at the University of the West of England (UWE Bristol) – the same laboratory that recently introduced the prototype urinal that generates electricity via microbial fuel cells – have now created a pee-powered distress radio built into a foldable, portable paper-based microbial fuel cell system .

Using bacteria to produce power from human waste is where microbial fuel cells (MFCs) show great promise in providing electricity to even the most remote, inaccessible places on Earth. However, their uptake and use may be reduced by the expense of their components and the toxicity of their remains once the units have reached the end of their serviceable lives.

The priority for Dr Jonathan Winfield and his team at the UWE Bristol BioEnergy Centre, then, was that MFCs were made much smaller, lighter and cheaper than conventional units, as well as being safely disposable. In this vein, the researchers chose to use recycled, common materials to construct their new prototype device.

Building on aspects of technology already produced at UWE Bristol to power mobile phones, the new prototype device is an origami-inspired, pyramid-style design made from recycled photocopier paper impregnated with three layers of latex external waterproofing. This external layer serves as the cathode, while the internal layer forms the proton exchange membrane and reactor body, and acts as the device's anode.

Coated with dormant biofilms of electricity-generating bacteria that rapidly return to life when doused in urine, the thin film of tiny bio-generators on the surface of the anode are capable of surviving for extended periods of time dried out and in cold storage, making them ideal for use in rarely deployed emergency radio beacons. According to the researchers, these pyramid-shape bioreactors can currently be stored for up to eight weeks before being reactivated with fresh urine.

Working most efficiently with fresh morning urine, but even able to produce power with the likes of cattle pee, the device is claimed capable of creating enough energy to operate a radio transmitter just 35 minutes after activation. With two of these fuel cells connected in series, the device is reported able to transmit radio signals at approximately six-minute intervals for up to 24 hours, which the team believes could potentially make all the difference in a life-threatening situation.