As there becomes more of a focus to reduce reliance on fossil fuels and search for viable renewable energy sources, one alternative could be within us all. Joe Young reports.

It may not be the most glamorous idea but researchers are hoping urine-powered microbial fuel cells (MFCs) will be a useful energy source in the future.

Back in 2002, University of the West of England PhD student, Dr Ioannis Ieropoulos was part of a project to build an energetically autonomous robot. Various technologies were being considered and Ioannis started experimenting with feeding MFCs different chemical substances to see how much electricity could be generated.

“Back then it was more out of scientific curiosity than something that could be practically implemented,” he says.

Ioannis soon discovered the chemical properties of wastewater, dead flies, prawn shells and rotten fruit had potential to be a viable electricity generator. Over the subsequent 14 years, he and his team have been researching the mechanisms involved to develop an understanding of how to more efficiently use the chemicals to generate electricity.

As a result of this work, the team also discovered that urine is an excellent fuel for microbial electricity generation, due to its constituent chemicals sodium, phosphorous, potassium and nitrate (among many others).

“We started by figuring out how urine could be chemically broken down. Once we established it could be done by the microbes for electricity production we then asked what we could use it for.”

The team has developed MFC-integrated wearable socks that use a flow of urine to generate electricity through an oxidation reduction process.

Every MFC system in the past had used a main power source to generate electricity but this wearable has a tubing system that uses footsteps as a pump to create the flow of urine, to pass over the MFCs.

The team successfully powered a wireless transmitter to send a signal to a PC proving they had made the first ever self sufficient MFC electricity generator.

“The wearable is at an early stage of development but we are hoping to push out the technology as a commercial product in the future,” Ioannis says.

Through support and funding from the Bill and Melinda Gates Foundation and the Engineering & Physical Sciences Research Council there is another direction the research may lead that is closer to commercialisation. That is developing MFCs as a technology that could provide electricity for communities or individuals in developing or remote areas that lack the infrastructure for electricity supplied from a grid.

MFCs may have potential as a technology that could be integrated with toilet facilities to generate electricity and at the same time clean the waste so it doesn’t spread disease.

“MFCs consist of two half-cells, a negative and positive, separated by a semi-permeable membrane. The membrane allows certain substances to pass through but not others. Depending on how the membrane is constructed and positioned we can drag out all the dirty waste water and recover the useful chemicals, while generating electricity,” Ioannis says.

“These chemical compounds are normally found in natural environments and we tend to use them in many different ways in everyday life. We can extract and synthesise a good portion of these chemicals via various industrial processes.”

The technology produces low levels of power which can be used for low powered lighting or recharging electronic devices but if appropriately scaled it could potentially be used for whole households or communities. The research team is exploring these capabilities for MFCs.

With human waste as an energy source, through MFC technology wherever there are people there can be sustainable energy.

“I would like to think there is a big role for MFCs in future energy production. It simply depends on how well we do the engineering and how efficiently we implement the technology because it has numerous applications and can be incorporated into many different aspects of everyday life.”