From charging your phone to powering your car, urine is tipped to be a fuel for the future.
Now researchers have created a pair of ‘socks’ which generate energy when urine is pumped over fuel cells by the wearer’s footsteps.
The socks, which contain microbial fuel cells (MFCs) are able to power a wireless transmitter to send a signal to a computer, but the technology could one day power phones and smartwatches, for example.
Scientists at the Bristol BioEnergy Centre at the University of the West of England (UWE) fitted the socks with miniaturised MFCs.
MFCs use bacteria to generate electricity from waste fluids – tapping into the biochemical energy used for microbial growth and converting it directly into electricity.
The 24 individual soft MFCs inside the socks were supplied with fresh urine in soft tubes placed under the heels of the socks
The waste fluid was circulated around by the human operator walking, which creates a ‘push-pull’ pumping action.
Normally, such systems would rely on a mains powered pump to circulate the urine.
The manual pump was inspired by a simple fish circulatory system and the action of walking caused the urine to pass over the MFCs and generate energy.
In the experiment, published in the journal Bioinspiration and Biomimetics, the system successfully ran a wireless transmission board, which was able to send the message ‘First Wearable MFC’ every two minutes to a computer-controlled receiver.
WHAT ARE MICROBIAL FUEL CELLS (MFCs)?
Microbial fuel cells are energy converters that turn organic matter directly into electricity by utilising the metabolism of live micro-organisms.
The electricity is a by-product of the microbes’ natural life cycle.
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.
It is worth noting that the ‘socks’ are much lumpier and chunkier than the ones we usually wear and include an insole as well as lots of tubing, valves and the fuel cells.
The 24 individual soft MFCs can hold up to 648 milliliters of urine.
However, Professor Ioannis Ieropoulos, who led the research, said it ‘opens up possibilities’ for using urine to power wearable devices.
‘Having already powered a mobile phone with MFCs using urine as fuel, we wanted to see if we could replicate this success in wearable technology,’ he said.
‘We also wanted the system to be entirely self-sufficient, running only on human power – using urine as fuel and the action of the foot as the pump.
… Scientists say any organic waste could be used in place of urine, turning it into a ‘valuable’ green technology and an alternative to fossil fuels.